articles+ search results

COOPERATIVE binding (Biochemistry), PYRROLES, CHOLINE chloride, DENSITY functional theory, and ULTRAVIOLET-visible spectroscopy

• Synthesis and anion binding studies of meso- one walled cyanophenyl extended C4P have been described. • BindFit and DFT studies have revealed 1:1 anion binding stoichiometry. • Maximum anion binding affinity was observed in case of fluoride ion. • Conformational change from 1,3-alternate to cone in the presence of anion has been confirmed by 1H-NMR. • NH-hydrogen bonding and anion-π interactions cooperatively govern anion binding. A novel one-walled meso -cyanophenyl functionalized calix[4]pyrrole (4) was synthesized from cyanophenyl appended dipyrromethane (3) through conventional strategy and also by utilizing deep eutectic solvent of N,N' -dimethyl urea (DMU) & L -(+)-tartaric acid (TA) in a ratio of 7:3. The structural confirmation of 4 was done through 1H-NMR, 13C-NMR, FT-IR, and HRMS spectral data. Anion binding studies of the receptor 4 with several anions (halides, trigonal oxoanions, tetragonal oxoanions, etc.) used as tetrabutylammonium (TBA) salts, were successfully investigated by virtue of UV–Vis spectroscopy and time dependent density functional theory (TD-DFT). Notably, the UV–Vis absorbance titrations performed in CH 3 CN solvent, revealed significantly higher anion binding of receptor 4 with F¯, Cl¯, Br¯, and SCN¯ in comparison to the simple C4P. This can be ascribed to the fact that the cyanophenyl moiety is π-acidic in nature which participates in anion complexation through weak anion-π interactions (observed through 1H-NMR spectroscopy) and hence modulates anion binding through cooperative effect of preliminary NH-hydrogen bonding due to C4P scaffold and anion-π contacts due to cyanophenyl moiety. [Display omitted] [ABSTRACT FROM AUTHOR]

PHOSPHINE oxides, ARYL iodides, ARYLATION, ALKOXY group, ASYMMETRIC synthesis, ACID derivatives, METHOXY group, CLINICAL chemistry, and SONOGASHIRA reaction

Keywords: phosphinates; P-stereogenic centers; nickel catalysis; cross-coupling; asymmetric catalysis EN phosphinates P-stereogenic centers nickel catalysis cross-coupling asymmetric catalysis 1819 1823 5 08/29/23 20230915 NES 230915 Graph P-Stereogenic organic phosphorus compounds, especially chiral phosphinic acid derivatives, are useful in medicinal chemistry, pesticide chemistry, organic materials science, and biochemistry. Moreover, when we employed aryl iodides with a free amino ( B 26 b ) or hydroxy group ( B 27 b ) at the I para i -position of the aryl ring, P-chiral phosphinates were obtained in moderate yields (71 and 68%) and high ee values (88 and 81% ee). [41] However, we found aryl iodides with different electronic properties all gave the corresponding P-chiral phosphinates with moderate to high ee values (62-82% ee); in other words, the enantioselectivity was only slightly affected by the electronic properties of the aryl iodides. During the preparation of our manuscript, Duan and our group separately reported Ni(0)-catalyzed intermolecular reactions of nonactivated aryl halides [39] and Ni(II)-catalyzed intermolecular reactions of heterocyclic halides, [40] respectively. [Extracted from the article]

MACHINE learning, ARTIFICIAL intelligence, DRUG discovery, CHEMOMETRICS, EXPERT systems, and DRUG synthesis

Chemometrics and machine learning are artificial intelligence-based methods stirring a transformative change in chemistry. Organic synthesis, drug discovery and analytical techniques are incorporating machine learning techniques at an accelerated pace. However, machine-assisted chemistry faces challenges while solving critical problems in chemistry due to complex relationships in data sets. Even with increasing publishing volumes on machine learning, its application in areas of chemistry is not a straightforward endeavour. A particular concern in applying machine learning in chemistry is data availability and reproducibility. The present review article discusses the various chemometric methods, expert systems, and machine learning techniques developed for solving problems of organic synthesis and drug discovery with selected examples. Further, a concise discussion on chemometrics and ML deployed in analytical techniques such as, spectroscopy, microscopy and chromatography are presented. Finally, the review reflects the challenges, opportunities and future perspectives on machine learning and automation in chemistry. The review concludes by pondering on some tough questions on applying machine learning and their possibility of navigation in the different terrains of chemistry. [ABSTRACT FROM AUTHOR]

HYDROXYLATION, TITANIUM, HYDROGEN peroxide, EPOXIDATION, and KETONES

The titanium complex of the cis‐1,2‐diaminocyclohexane (cis‐DACH) derived Berkessel‐salalen ligand is a highly efficient and enantioselective catalyst for the asymmetric epoxidation of terminal olefins with hydrogen peroxide ("Berkessel‐Katsuki catalyst"). We herein report that this epoxidation catalyst also effects the highly enantioselective hydroxylation of benzylic C−H bonds with hydrogen peroxide. Mechanism‐based ligand optimization identified a novel nitro‐salalen Ti‐catalyst of the highest efficiency ever reported for asymmetric catalytic benzylic hydroxylation, with enantioselectivities of up to 98 % ee, while overoxidation to ketone is marginal. The novel nitro‐salalen Ti‐catalyst also shows enhanced epoxidation efficiency, as evidenced by e.g. the conversion of 1‐decene to its epoxide in 90 % yield with 94 % ee, at a catalyst loading of 0.1 mol‐% only. [ABSTRACT FROM AUTHOR]

LIGNIN structure, LIGNINS, COVALENT bonds, MOLECULAR weights, SUSTAINABLE development, PETROLEUM, and DEPOLYMERIZATION

Lignin holds tremendous and versatile possibilities to produce value-added chemicals and high performing polymeric materials. Over the years, different cutting-edge lignin depolymerization methodologies have been developed, mainly focusing on achieving excellent yields of mono-phenolic products, some even approaching the theoretical maximum. However, due to lignin's inherent heterogeneity and recalcitrance, its depolymerization leads to relatively complex product streams, also containing dimers, and higher molecular weight fragments in substantial quantities. The subsequent chemo-catalytic valorization of these higher molecular weight streams, containing difficult-to-break, mainly C–C covalent bonds, is tremendously challenging, and has consequently received much less attention. In this minireview, we present an overview of recent advances on the development of sustainable biorefinery strategies aimed at the production of well-defined chemicals and polymeric materials, the prime focus being on depolymerized lignin oils, containing high molecular weight fractions. The key central unit operation to achieve this is (bio)catalytic funneling, which holds great potential to overcome separation and purification challenges. [ABSTRACT FROM AUTHOR]

MOLECULAR structure, CHEMICAL properties, COORDINATE covalent bond, COORDINATION polymers, HYDROGENATION, POLYMERS, ORGANIC synthesis, and ELECTRONIC structure

• Molecular properties, i.e. physical and chemical properties, are affected by the functional groups attached to them. • Phosphinidines have been demonstrated to be highly effective in a variety of cases such as polymer chemistry, organic synthesis for the preparation of polyphosphanes, coordination chemistry, and more recently in catalysis as ligands in cross-coupling reactions. • Various types of metal ions and the ancillary ligands existing in the reaction determine the nature of the created products. ligands have crucial impact on the region-, chemo-, and, of course, stereoselectivity in metal- catalytic processes. [ABSTRACT FROM AUTHOR]

RING-opening polymerization, ACETAL resins, COPOLYMERS, BLOCK copolymers, POLYMERIZATION, MONOMERS, and POLYMERS

Radical Ring‐opening polymerization (RROP) of cyclic ketene acetals (CKAs) emerges to be a valuable polymerization technique. In attracting more attention, RROP has seen a new spike in publications, which the authors will put into perspective. This review will hence address the progress made on the number of available CKAs and the synthetic strategies to get them. In grouping, the available monomers into distinct categories, the enormous variety of available CKAs will be highlighted. Polymerizations of CKAs without vinylenes have the potential to yield fully biodegradable polymers, which is why this kind of polymerization is the focus of this review. Detailing the current understanding of the mechanism, the various side reactions will be noted and also their effect on the overall properties of the final polymers. Current attempts to control the ring‐retaining and branching reactions will be discussed as well. In addition to the polymerization itself, the available materials will be discussed as well as homopolymers, copolymers of CKAs, and block‐copolymers with pure CKA‐blocks have significantly widened the range of possible applications of materials from RROP. Altogether this review highlights the progress in the entire field of RROP just of CKAs to give a holistic overview of the field. [ABSTRACT FROM AUTHOR]

MOLECULAR size, MICROFLUIDICS, POLYDIMETHYLSILOXANE, OVERHAUSER effect (Nuclear physics), SUPRAMOLECULAR chemistry, NUCLEAR magnetic resonance spectroscopy, HYDROGELS, and POLYACRYLAMIDE

The integration of microscopic hydrogels with high specific surface area and physically reactive groups into microfluidic systems for selective molecular interactions is attracting increasing attention. Herein, the reversible capture and release of molecules through host–guest interactions of hydrogel dots in a microfluidic device is reported, which translates the supramolecular chemistry to the microscale conditions under continuous flow. Polyacrylamide (PAAm) hydrogel arrays with grafted β‐cyclodextrin (β‐CD) modified poly(2‐methyl‐2‐oxazoline) (CD‐PMOXA) chains are fabricated by photopolymerization and integrated into a polydimethylsiloxane (PDMS)‐on‐glass chip. The β‐CD/adamantane (β‐CD/Ada) host–guest complex is confirmed by two dimensional Nuclear Overhauser Effect Spectroscopy NMR (2D NOESY NMR) prior to transfer to microfluidics. Ada‐modified molecules are successfully captured by host–guest interaction formed between the CD‐PMOXA grafted chains in the hydrogel network and the guest molecule in the solution. Furthermore, the captured molecules are released by perfusing free β‐CD with higher binding affinity than those grafted in the hydrogel array. A small guest molecule adamantane‐fluorescein‐isothiocyanate (Ada‐FITC) and a macromolecular guest molecule (Ada‐PMOXA‐Cyanine 5 (Cy5)) are separately captured and released for three times with a release ratio up to 46% and 92%, respectively. The reproducible capture and release of functional molecules with different sizes demonstrates the stability of this hydrogel system in microfluidics and will provide an opportunity for future applications. [ABSTRACT FROM AUTHOR]

GENTIAN violet, SCHIFF bases, BASIC dyes, AQUEOUS solutions, COMPUTATIONAL chemistry, EXOTHERMIC reactions, ADSORPTION kinetics, PORE size distribution, and COLOR removal in water purification

• New bis(pyrano[3,2- c ]quinolinone) based on Schiff base was prepared. • The synthesized adsorbent was characterized using several techniques. • The batch adsorption technique toward cationic dye was applied. • The adsorption kinetics, isotherms, recyclability and Thermodynamic parameters were calculated. • The primary adsorption mechanism was confirmed by computational chemistry. Organic compound water pollution is one of the difficult environmental issues facing the advancement of human civilization. So, New bis(pyrano[3,2- c ]quinolinone) based on Schiff base adsorbent was prepared to participate in solving this problem. The synthesized adsorbent was characterized using FT-IR, 1H NMR, XRD, SEM, elemental analysis, N 2 - adsorption-desorption isotherm, S BET , and Pore size distribution studies. The obtained results revealed a significant improvement in the new schiff base surface texture and crystallinity. Further, pH zpc of the new adsorbent has been examined to be 3.7. Its decolorization efficiency toward methylene blue (MB) dye from an aqueous solution was examined. Also, the factors of pH, contact time, reaction temperature, and initial dye concentration were optimized. Overall, this study emphasized that the newly synthesized Schiff base act as an effective adsorbent (99%) at a very short time (5 min., 10 ppm dye concentration, pH = 9 and temperature = 25 °C) and can be regenerated for five cycles for the removal of MB dye from aqueous solutions. Freundlich isotherm model and pseudo-second order kinetic model were fit effectively for the MB dye adsorption experimental data. Also, the calculated thermodynamic parameters revealed a spontaneous and exothermic adsorption reaction. FT- IR study and computational chemistry study proved that the decolorization interaction mechanism between the positive (- N +) sites of MB dye and the negative (- OH) active sites of the new Schiff base adsorbent at the optimum conditions occurred as a physisorption process. [Display omitted] [ABSTRACT FROM AUTHOR]

CELL imaging, PROTISTA, DRUG target, LUMINOPHORES, QUANTUM wells, and PLASMODIOPHORA brassicae

A library of eight different cationic emitters with emission properties in solution and in solid‐state (solution and solid‐state emitters – SSSE) is presented. These compounds, bearing either ammonium or pyridinium groups, have been investigated regarding their photophysical properties as well as their potential application in biological imaging. Besides high quantum yields as well as a high degree of stability during the imaging process, it was additionally revealed that a broad range of biological targets can be addressed, such as different bacterial strains, human cells as well as protists. The reported SSSE approach employing the mentioned robust emitters for biological imaging, will contribute to a rapid and facile way to design and apply affordable emitters with outstanding properties. Additionally, these emitters will overcome the drawbacks of classical luminophores and agents featuring well‐known aggregation‐induced emission (AIE) or aggregation‐caused quenching (ACQ) properties. [ABSTRACT FROM AUTHOR]

HETEROGENEOUS catalysts, FERRIC oxide, CATALYST synthesis, HEMATITE, FOURIER transform infrared spectroscopy, FIELD emission electron microscopy, AROMATIC aldehydes, and CATALYSTS recycling

• First time report on the synthesis of Fe 2 O 3 nanorods (NRs) by a green process via a mixture of Eucalyptus citriodora and Murraya koenigii leaf extracts. • XRD, FESEM, EDX, FTIR, UV-DRS, BET, and VSM analysis confirmed the biosynthesis of Fe 2 O 3 NRs. • Fe 2 O 3 NRs exhibited excellent catalytic performance for the Biginelli reaction. • The synthesized catalyst exhibited high stability, reusability, an excellent yield of Biginelli products, and easy workup. For the first time, mixed-phase (Hematite and Maghemite) magnetic Fe 2 O 3 nanorods were successfully biosynthesis by sol-gel auto-combustion method using the 1:1 mixture of Eucalyptus citriodora and Murraya koenigii leaf extract as a capping agent, and its catalytic effect on synthesis of 6-(chloromethyl)-1,2,3,4-tetrahydro-2-pyrimidinone (THPMs) derivatives were investigated. Further, the phase formation, surface topography, and crystallinity of biosynthesized Fe 2 O 3 nanorods (NRs) were explored using powder XRD (X-Ray Diffraction), UVDRS (UV–Visible Reflectance Spectroscopy), FTIR (Fourier Transform Infrared Spectroscopy), FESEM (Field Emission Scanning Electron Microscopy), EDX (Energy Dispersive X-Ray), and VSM (Vibrating Sample Magnetometry). Furthermore, the catalytic activity of biosynthesized Fe 2 O 3 NRs (C1, C2, and C3) was examined for one-pot synthesis of ethyl 6-(chloromethyl)-1,2,3,4-tetrahydro-2-oxo-4-arylpyrimidine-5-carboxylate via Biginelli reaction. To achieve high yields (93–99 %) of 6-(chloromethyl)-1,2,3,4-tetrahydro-2-pyrimidinone derivatives, this heterogeneous catalytic method is used with a wide range of aromatic aldehydes within a minimum reaction time, simple reaction work-up, and easily recoverable catalyst by an external magnet. The recovered catalyst is then employed for five successive cycles without non-noticeable loss of catalytic activity. We believe that this protocol presents a broad scope for Biginelli reaction through greenly produced and magnetically separable heterogeneous catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

INDOLE compounds, INDOLE derivatives, INDOLE, AMINATION, LSD (Drug), PHENYLENEDIAMINES, TRANSITION metal catalysts, ORGANIC chemistry, and ORGANIC acids

B. Acid-catalyzed indole synthesis An efficient one-pot synthesis of I N i SB 1 sb -substituted indole derivatives ( B 15 b ) was reported by Kutznetsov and colleagues[45]. I. Important methods for indole synthesis Numerous methods for the synthesis of indoles are cited in the literature (Figure 2).[7],[8],[25]Table 2 highlights a few important classical methods for the synthesis of indoles. Recently, there has been increased interest in metal-free indole synthesis as compared to classical metal-assisted indole syntheses. Transition metal-free indole synthesis The synthesis of indoles can be accomplished through special reaction types and routes. [Extracted from the article]

TERPENES, ALKENES, METHYLATION, DITERPENES, PROTON transfer reactions, METHYLTRANSFERASES, and CARBOCATIONS

Terpenoids are built from isoprene building blocks and have numerous biological functions. Selective late‐stage modification of their carbon scaffold has the potential to optimize or transform their biological activities. However, the synthesis of terpenoids with a non‐natural carbon scaffold is often a challenging endeavor because of the complexity of these molecules. Herein we report the identification and engineering of (S)‐adenosyl‐l‐methionine‐dependent sterol methyltransferases for selective C‐methylation of linear terpenoids. The engineered enzyme catalyzes selective methylation of unactivated alkenes in mono‐, sesqui‐ and diterpenoids to produce C11, C16 and C21 derivatives. Preparative conversion and product isolation reveals that this biocatalyst performs C−C bond formation with high chemo‐ and regioselectivity. The alkene methylation most likely proceeds via a carbocation intermediate and regioselective deprotonation. This method opens new avenues for modifying the carbon scaffold of alkenes in general and terpenoids in particular. [ABSTRACT FROM AUTHOR]

ALKENES, METHYLATION, and AMINO acid sequence

A variant with three changes in the amino acid sequence was able to produce methylated derivatives of linear terpenoids with high selectivity by C-methylation of an unactivated alkene. Cover Picture: Methylation of Unactivated Alkenes with Engineered Methyltransferases To Generate Non-natural Terpenoids (Angew. Keywords: Alkene Methylation; Biocatalysis; Late-Stage Modification; Methyltransferase; Terpenoids EN Alkene Methylation Biocatalysis Late-Stage Modification Methyltransferase Terpenoids 1 1 1 06/20/23 20230626 NES 230626 B A methyltransferase b from the green alga I Chlamydomonas reinhardtii i was identified and engineered for late-stage modifications of the carbon skeleton of terpenes. [Extracted from the article]

SOLID phase extraction, PULMONARY surfactant, ANALYTICAL chemistry, SURFACE active agents, PREMATURE infants, and DENSITY functional theory

• A mixed mode DSPE approach was developed using organic polymers. • The method was used to lung surfactants determination in EBC samples. • Density functional theory calculations were used to show the nature of the chemical interactions. • Simplex centroid experimental design was used for optimization of the sorbent composition. A mixed mode dispersive solid phase extraction method was introduced for the extraction of three lung surfactants from exhaled breath condensate samples. Considering the trends to green analytical chemistry, organic polymers including polystyrene (PS), polymethylmethacrylate (PMMA-15 K), and polymethylmethacrylate (PMMA-45 K) were utilized as the sorbent for extraction of the analytes. The extraction capability for each polymer toward the studied analytes was evaluated using simplex centroid design. Based on the results, a mixture of sorbents consisting of PS, PMMA-15 K, and PMMA-45 K mixture with the mass ratio of 1:2:1: w/w/w was selected as the suitable sorbent. The effective parameters influencing the method's efficiency were investigated and optimized. Based on the figure of merit for the developed method, the calibration curves were linear in the concentration range of 0.76–1000 ng mL–1 and limits of detection were from 0.09 to 0.19 ng mL–1. The method repeatability was investigated at three concentrations as inter- and intra-day precisions and the obtained data showed that they were in the ranges of 5.2–9.1 and 4.2–8.9%, respectively. The enrichment factors were in the range of 88–100. The developed method was successfully employed in the analysis of the surfactants in the exhaled breath samples of three premature infants collected from the expiratory circuits of the mechanical ventilators. The nature of the chemical interactions with PMMA-PS complex system of the surfactants was investigated through Density Functional Theory calculations. Calculated binding energies showed that PMMA-PS complex system exhibit high performance in the extraction of lung surfactants. The most powerful interaction is between PMMA-PS complex system and 1-palmitoyl-2-oleoylsn‑glycero-3-phosphocholine. [ABSTRACT FROM AUTHOR]

SCHIFF bases, ESCHERICHIA coli, NUCLEAR magnetic resonance spectroscopy, METAL complexes, MYCOBACTERIUM tuberculosis, DENSITY functional theory, SILVER, and PEPTIDE antibiotics

This article describes the in vitro antibacterial and β-lactamase inhibition of a novel silver(I) complex with the sulfonamide probenecid (Ag-PROB). The formula Ag 2 C 26 H 36 N2O 8 S 2 ·2H 2 O for the Ag-PROB complex was proposed based on elemental analysis. High-resolution mass spectrometric studies revealed the existence of the complex in its dimeric form. Infrared, nuclear magnetic resonance spectroscopies and Density Functional Theory calculations indicated a bidentate coordination of probenecid to the silver ions by the oxygen atoms of the carboxylate. In vitro antibacterial activities of Ag-PROB showed significant growth inhibitory activity over Mycobacterium tuberculosis , S. aureus , and P. aeruginosa PA01biofilm-producers, B. cereus , and E. coli. The Ag-PROB complex was active over multi-drug resistant of uropathogenic E. coli extended spectrum β-lactamases (ESBL) producing (EC958 and BR43), enterohemorrhagic E. coli (O157:H7) and enteroaggregative E. coli (O104:H4). Ag-PROB was able to inhibit CTX-M-15 and TEM-1B ESBL classes, at concentrations below the minimum inhibitory concentration for Ag-PROB, in the presence of ampicillin (AMP) concentration in which EC958 and BR43 bacteria were resistant in the absence of Ag-PROB. These results indicate that, in addition to ESBL inhibition, there is a synergistic antibacterial effect between AMP and the Ag-PROB. Molecular docking results revealed potential key residues involved in interactions between Ag-PROB, CTX-M-15 and TEM 1B, suggesting the molecular mechanism of the ESBL inhibition. The obtained results added to the absence of mutagenic activity and low cytotoxic activity over non-tumor cell of the Ag-PROB complex open a new perspective for future in vivo tests demonstrating its potential of use as an antibacterial agent. Ag-Probenecid complex was active on biofilm-producing multidrug-resistant bacteria and Mycobacterium tuberculosis and was capable to inhibit extended spectral β-lactamase classes produced by Escherichia coli EC958 and BR43 with synergistic antibacterial effect with ampicillin. Ag-PROB was active on biofilm-producing MDR bacteria and Mycobacterium tuberculosis and was capable to inhibit extended spectral β-lactamase classes produced by E. coli EC958 and BR43 with synergistic antibacterial effect with ampicillin. [Display omitted] • Broad spectrum of Ag-Probenecid complex antibacterial activity. • Extend spectrum β-lactamase inhibition. • Mycobacterium tuberculosis growth inhibition. • Absence of mutagenic activity. [ABSTRACT FROM AUTHOR]

REGIOSELECTIVITY (Chemistry), METHYLTRANSFERASES, SUPPLY & demand, BIOMOLECULES, and METHIONINE

Methyltransferases provide excellent specificity in late-stage alkylation of biomolecules. Their dependence on S-adenosyl- L -methionine (SAM) mandates efficient access to SAM analogues for biocatalytic applications. We directly compared halide methyltransferase (HMT) and methionine adenosyltransferase (MAT) to access SAM analogues and explored their utility in cascade reactions with NovO for regioselective, late-stage Friedel-Crafts alkylation of a coumarin. The HMT cascade efficiently provided SAM for methylation, while the MAT cascade also supplied high levels of SAM analogues for alkylation reactions. [ABSTRACT FROM AUTHOR]

DRUG resistance, APOPTOSIS, LEUKEMIA, GOLD compounds, REACTIVE oxygen species, and MITOCHONDRIAL pathology

Gold complexes could be promising for tumor therapy because of their cytotoxic and cytostatic properties. We present novel gold(I) complexes and clarify whether they also show antitumor activity by studying apoptosis induction in different tumor cell lines in vitro, comparing the compounds on resistant cells and analyzing the mechanism of action. We particularly highlight one gold complex that shows cytostatic and cytotoxic effects on leukemia and lymphoma cells already in the nanomolar range, induces apoptosis via the intrinsic signaling pathway, and plays a role in the production of reactive oxygen species. Furthermore, not only did we demonstrate a large number of resistance overcomes on resistant cell lines, but some of these cell lines were significantly more sensitive to the new gold compound. Our results show promising properties for the gold compound as anti-tumor drug and suggest that it can subvert resistance mechanisms and thus targets resistant cells for killing. [Display omitted] • Novel Au(I)-complexes show cytostatic and cytotoxic activity on tumor cells in vitro. • Apoptosis induction studied functions via the intrinsic apoptosis pathway. • Effect reduction by antioxidants indirectly indicates ROS formation. • Au-compound overcomes a variety of multidrug resistances and sensitizes to apoptosis. [ABSTRACT FROM AUTHOR]

QUINAZOLINONES, CHEMICAL stability, ANTI-infective agents, CHEMICAL structure, CHEMICAL processes, DNA topoisomerase I, and VAN der Waals forces

The review characterizes the role of the basic targets of antibacterial agents: efflux pumps, enzymes (DNA gyrases as a subclass of topoisomerases, homoserine transacetylase, various classes of sortases, aromatase, lipoteichoic synthase, polyketide synthase, pantothenate synthetase, acetyl-CoA carboxylase, sensory histidine kinase, kinase, cyclooxygenase, etc.), penicillin-binding protein, quorum sensing systems, and adhesins in significant biochemical processes of pathogen maintenance and virulence manifestation. It has been demonstrated that a chemical can exhibit the antimicrobial effect when it binds to protein molecules responsible for pathogenicity of a microorganism. The role of quinazolinone derivatives exhibiting high reactivity and stability in chemical processes and characterized by a wide spectrum of pharmacological activity, including antimicrobial activity with respect to various Gram-positive and Gram-negative bacteria, has been determined. It has been shown that structural changes induced by introducing various substituents contribute to a change in the degree of hydrophilicity and, as a result, determine a different degree of penetration of the drug through the cell membrane, the ability to form intermediate complex compounds stabilized by a system of hydrogen bonds, as well as by van der Waals and stacking interactions, with enzymatic targets, receptor regulatory proteins, and signaling systems of pathogen cells. The results of mathematical modeling of the mechanism of action of the compounds synthesized by the authors of the article are discussed. The possibility of creating a pharmaceutical with a pronounced antimicrobial activity by combining the quinazolinone core with various heterocyclic derivatives is assessed. The considered regularities are of practical importance for the researchers in the field of medicinal chemistry, organic synthesis, biotechnology, clinical pharmacology, and pharmaceutical chemistry and technology, whose efforts are aimed at designing a new drug. [ABSTRACT FROM AUTHOR]

PYRIMIDINES, ANAPLASTIC lymphoma kinase, GLIOBLASTOMA multiforme, and EPIDERMAL growth factor receptors

Glioblastoma multiforme (GBM) is a highly‐aggressive, dreadful disease with poor prognosis and disappointing clinical success. There is an unmet medical need of molecularly‐targeted therapeutics for GBM treatment. In the present work, a series of novel 2‐phenyl‐substituted 4‐amino–6,7‐dihydro‐5H‐cyclopenta[d]pyrimidines was designed, synthesized, purified, characterized, and evaluated for cytotoxicity against glioblastoma cell line U87‐MG. The design process (virtual library enumeration around the core, physicochemical and molecular property prediction/calculation of the designs, filtering the undesirable ones, and the diversity analyses of the lead‐like designs), was carefully curated so as to obtain a set of structurally‐diverse, novel molecules (total 20), with a particular focus on the relatively unexplored core structure, 6,7‐dihydro‐5H‐cyclopenta[d]pyrimidine. The preliminary screening was done using MTT assay at 10 and 100 μM concentrations of the title compounds F1−F20 and positive control cisplatin, which yielded six hits (% inhibition at 10 μM: ~50%)—F2, F3, F5, F7, F15, and F20, which were taken up for IC50 determination. The top hits F2 and F7 (IC50 < 10 μM) were further used for computational studies such as target prediction, followed by their molecular docking in the binding sites of the top‐3 predicted targets (epidermal growth factor receptor kinase domain, cyclin‐dependent kinase 2 [CDK2]) /cyclin E, and anaplastic lymphoma kinase [ALK]). The docking pose analyses revealed interesting trends. The relatively planar core structure, presence of favorable hinge‐binding substructures, basic groups, all added up, and culminated in appreciable cytotoxicity against GBM cell line. [ABSTRACT FROM AUTHOR]

ENDOPHYTIC fungi, ARTEMIA, ASPERGILLUS, ETHYL acetate, CELL lines, FLAVONOIDS, and ANTI-inflammatory agents

A new unsaturated aliphatic anhydride derivative (Z)-(12Z)-heptadec-12-enoic-2′-hydroxypropanoic anhydride (1) and ten known compounds, three flavonoids (2–4), two terphenyllins (5-6), four triterpenoids (7-8, 10-11), and one n-fatty acid (9), were isolated from the EtOAc extract of Aspergillus candidus T1219W1, an endophytic fungus, inhabiting Pittosporum mannii. All the isolated compounds were characterized using 1D- and 2D-NMR and HR-EI experiments together with the reported literature. p-terphenyls are suggested to be the chemophenetic marker of the genus Aspergillus. The ethyl acetate crude extract as well as some isolated compounds of A. candidus was assayed for antibiofilm activity, anti-inflammatory (ROS) activity, and cytotoxicity on brine shrimps and the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cytotoxicity assay on 3T3 cell lines. The tested sample showed good antibiofilm activity with the lowest MBEC50 obtained at 64 μg/mL. Compounds showed low anti-inflammatory activity even at high concentration (250 μg·mL−1 with an IC50 of 59.6 ± 0.1 μg·mL−1) with moderate cytotoxicity on brine shrimps at high concentration (1000 μg·mL−1, with 46.67% mortality). However, no cytotoxic activity was observed against 3T3 cell lines. [ABSTRACT FROM AUTHOR]

MOLYBDATES, CATALYSTS, LAYERED double hydroxides, CATALYTIC activity, GRAPHENE oxide, OXIDATION, and KEGGIN anions

This paper is focused on the utilization of hybrid catalysts obtained from layered double hydroxides containing molybdate as the compensation anion (Mo-LDH) and graphene oxide (GO) in advanced oxidation using environmentally friendly H2O2 as the oxidation agent for the removal of indigo carmine dye (IC) from wastewaters at 25 °C using 1 wt.% catalyst in the reaction mixture. Five samples of Mo-LDH-GO composites containing 5, 10, 15, 20, and 25 wt% GO labeled as HTMo-xGO (where HT is the abbreviation used for Mg/Al in the brucite type layer of the LDH and x stands for the concentration of GO) have been synthesized by coprecipitation at pH 10 and characterized by XRD, SEM, Raman, and ATR-FTIR spectroscopy, determination of the acid and base sites, and textural analysis by nitrogen adsorption/desorption. The XRD analysis confirmed the layered structure of the HTMo-xGO composites and GO incorporation in all samples has been proved by Raman spectroscopy. The most efficient catalyst was found to be the catalyst that contained 20%wt. GO, which allowed the removal of IC to reach 96.6%. The results of the catalytic tests indicated a strong correlation between catalytic activity and textural properties as well as the basicity of the catalysts. [ABSTRACT FROM AUTHOR]

SPECTROMETRY, INFRARED spectra, and BIOMACROMOLECULES

Carbohydrates constitute one of the four key classes of biomacromolecules but have not been studied by 2D-IR spectroscopy so far. Similarly as for proteins, a lack of native vibrational reporter groups, combined with their huge structural diversity, leads to spectrally congested infrared spectra already for single carbohydrates. Biophysical studies are further impeded by the strong overlap between water modes and carbohydrate modes. Here, we demonstrate the application of the known vibrational reporter group thiocyanate (SCN) as a label in glucose. In this first study, we are able to perform IR and 2D-IR spectroscopy of β-glucose with SCN at the C2 position in chloroform. Upon improved synthesis and the removal of all protecting groups, we successfully performed 2D-IR spectroscopy of β-glucose in H2O. All experimental results are compared to those of methyl-thiocyanate as a reference sample. Overall, we show that the concept of using site-specific vibrational reporter groups can be transferred to carbohydrates. Thus, biophysical studies with 2D-IR spectroscopy can now expand to glycoscience. [ABSTRACT FROM AUTHOR]

ORGANIC chemistry, COMPUTATIONAL chemistry, SUPRAMOLECULAR chemistry, COLLECTIONS, and PERIODICAL editors

Organic chemistry, computational chemistry, supramolecular chemistry, synthetic methods, young researchers Keywords: computational chemistry; organic chemistry; supramolecular chemistry; synthetic methods; young researchers EN computational chemistry organic chemistry supramolecular chemistry synthetic methods young researchers 1 1 1 04/11/23 20230406 NES 230406 Guest Editor Prof. Stefano Protti introduces the #NextGenOrgChem special collection, which includes original research papers, reviews and concept articles by young organic chemists (post-doctoral and early-career researchers) nominated by the EurJOC advisory and editorial board members. [Extracted from the article]

MOLECULAR docking, ELECTRIC potential, DENSITY of states, AZEPINES, and CANCER cells

In this strategy, we attempt to design various novel nitrogen-rich heterocycles in one molecule. Green, simple, and efficient aza-annulations of an active, versatile building block, 1-amino-4-methyl-2-oxo-6-phenyl-1,2-dihydropyridine-3-carbonitrile (1), with different bifunctional reagents were developed under solvent-free conditions, resulting in the bridgehead tetrazines and azepines (triazepine and tetrazepines). Pyrido[1,2,4,5]tetrazines have been synthesized through two pathways; [3 + 3]- and [5 + 1]-annulations. In addition, pyrido-azepines have been developed by applying [4 + 3]-and [5 + 2]-annulations. This protocol establishes an efficient technique for synthesizing essential biological derivatives of 1,2,4,5-tetrazines, 1,2,4-triazepines, and 1,2,4,5-tetrazepine, tolerating a diverse variety of functionalities without the need for catalysis and fast reaction rates in high yields. The National Cancer Institute (NCI, Bethesda, USA) examined twelve compounds produced at a single high dosage (10−5 M). Compounds 4, 8, and 9 were discovered to have potent anticancer action against certain cancer cell types. To explain NCI results, the density of states was calculated to conduct a better description of the FMOs. The molecular electrostatic potential maps were created to explain a molecule's chemical reactivity. In silico ADME experiments were performed to better understand their pharmacokinetic characteristics. Finally, the molecular docking investigations on Janus Kinase-2 (PDB ID: 4P7E) were carried out to study the binding mechanism, binding affinity, and non-bonding contacts. [ABSTRACT FROM AUTHOR]

INDUCTIVELY coupled plasma mass spectrometry, PORITES, X-ray spectroscopy, CORALS, INDUCTIVELY coupled plasma atomic emission spectrometry, and BIOGEOCHEMICAL cycles

Coral skeletal P/Ca ratio has been developed as an indicator of temporal seawater dissolved inorganic phosphorus (DIP). The use of coral P/Ca proxy helps to assess oceanographic and climatic impacts such as upwelling, circulation, and continent runoffs on marine biogeochemical cycles. However, factors controlling skeletal P incorporation and elemental partitioning between seawater and coral skeletons remain elusive. We conducted temperature-controlled (∼21 to 29 °C) aquaria culture experiments using two colonies of Porites australiensis corals (here refer to B and C) with the only difference in zooxanthellae density (B > C). The coral growth rate ranges from 9.4 to 19.4 mg/day (B) and 0.7 to 14.1 mg/day (C). Only the growth rate of colony C significantly correlates to temperature, potentially reflecting physiological controls on the two colonies given the difference in the zooxanthellae density. We measured coral P/Ca ratios by Inductively coupled plasma mass spectrometry and determined skeletal P speciation through a synchrotron-based spectroscopic approach. Coral P/Ca ratio ranges from 6.5 to 18.6 μmol/mol (B) and 7.2 to 19.8 μmol/mol (C). The dominance of organic-P is confirmed, and the presence of inorganic-P cannot be excluded. Only colony C has a strong P/Ca dependence on temperature and both colonies show strong correlations between P/Ca and growth rate. Although growth rate and temperature are intercorrelated, the growth rate is more likely the direct controlling factor on coral P/Ca in our experiments. Combined laboratory data with field observations, we suggest that the validity of the Porites P/Ca proxy may be influenced by seawater DIP, coral species, and growth rate. • Cultured coral P/Ca ratio can be variable with relatively constant seawater chemistry. • Organic phosphorus is widely present in coral skeletons despite oxidative cleaning. • The validity of the P/Ca proxy could be influenced by seawater DIP, coral species, and growth rate. [ABSTRACT FROM AUTHOR]

CONFERENCES & conventions, ANTIVIRAL agents, CAREER development, VACCINE development, SCIENTIFIC community, and INFORMATION sharing

The 35th International Conference on Antiviral Research (ICAR), sponsored by the International Society for Antiviral Research (ISAR), was held in Seattle, Washington, USA, on March 21–25, 2022 and concurrently through an interactive remote meeting platform. This report gives an overview of the conference on behalf of the society. It provides a general review of the meeting and awardees, summarizing the presentations and their main conclusions from the perspective of researchers active in many different areas of antiviral research and development. Through ICAR, leaders in the field of antiviral research were able to showcase their efforts, as participants learned about key advances in the field. The impact of these efforts was exemplified by many presentations on SARS-CoV-2 demonstrating the remarkable response to the ongoing pandemic, as well as future pandemic preparedness, by members of the antiviral research community. As we address ongoing outbreaks and seek to mitigate those in the future, this meeting continues to support outstanding opportunities for the exchange of knowledge and expertise while fostering cross-disciplinary collaborations in therapeutic and vaccine development. The 36th ICAR will be held in Lyon, France, March 13–17, 2023. • This report summarizes presentations at the 35th International Conference on Antiviral Research. • This meeting used a hybrid model with in-person sessions in Seattle, WA, USA, and concurrent live virtual sessions. • Meeting sessions covered the treatment of a wide variety of viruses, pandemic preparedness, and other topics. • Plenary lectures focused on the role of foundations in antiviral development, pandemic preparedness and other key concepts. • The meeting also featured special sessions and events, late-breaking oral presentations, and a career development workshop. [ABSTRACT FROM AUTHOR]

HETEROGENEOUS catalysts, UNSATURATED compounds, DECOMPOSITION method, ETHANOL, AROMATIC aldehydes, CALCITE, and OXINDOLES

[Display omitted] • CaCO 3 nanoflowers (NFs) were synthesized by the thermal decomposition method. • Knoevenagel condensation of 2-oxindole has been investigated using Calcite NFs first time. • The higher catalytic activity of NFs is due to the size, surface area, and hollow, sheet-like structures of flower petals. • According to the findings, the technique is far more cost-effective and has a lower environmental toxicity impact. • The catalyst could be recycled without significantly decreasing reactivity until five cycles. α-β unsaturated heterocyclic compounds such as C3-arylidene-oxindoles, with five-member rings containing nitrogen, have an important role in the realm of medicine. This study aims to synthesize the C3-arylindene-oxindoles derivative compounds using calcite nanoflowers (CaCO 3 NFs) as a heterogeneous catalyst for the first time. These CaCO 3 NFs prepared by the thermal decomposition method, which is an active and reusable catalyst for stereospecific Knoevenagel condensation reaction between 2-oxindole and aromatic aldehyde under different solvent conditions like water, ethyl alcohol, and 50 % aqueous ethyl alcohol. This catalytic method is employed with a wide range of aromatic aldehydes to produce high yields of C3-arylidene-oxindoles (93–99 %), with stereo-specifically E -isomers (100 %) for 50 % alcohol and alcohol as a solvent. [ABSTRACT FROM AUTHOR]

SMALL molecules, STYRENE, ALKENES, FATTY acids, and ALCOHOL

Enantioselective synthesis of chiral alcohols through asymmetric addition of water across an unactivated alkene is a highly sought‐after transformation and a big challenge in catalysis. Herein we report the identification and directed evolution of a fatty acid hydratase from Marinitoga hydrogenitolerans for the highly enantioselective hydration of styrenes to yield chiral 1‐arylethanols. While directed evolution for styrene hydration was performed in the presence of heptanoic acid to mimic fatty acid binding, the engineered enzyme displayed remarkable asymmetric styrene hydration activity in the absence of the small molecule activator. The evolved styrene hydratase provided access to chiral alcohols from simple alkenes and water with high enantioselectivity (>99 : 1 e.r.) and could be applied on a preparative scale. [ABSTRACT FROM AUTHOR]

ENZYME stability, THERAPEUTIC immobilization, AMINOTRANSFERASES, KINETIC resolution, BIOCATALYSIS, ENZYMES, and AMINE oxidase

Biocatalytic syntheses often require unfavorable conditions, which can adversely affect enzyme stability. Consequently, improving the stability of biocatalysts is needed, and this is often achieved by immobilization. In this study, we aimed to compare the stability of soluble and immobilized transaminases from different species. A cysteine in a consensus sequence was converted to a single aldehyde by the formylglycine-generating enzyme for directed single-point attachment to amine beads. This immobilization was compared to cross-linked enzyme aggregates (CLEAs) and multipoint attachments to glutaraldehyde-functionalized amine- and epoxy-beads. Subsequently, the reactivity and stability (i.e., thermal, storage, and solvent stability) of all soluble and immobilized transaminases were analyzed and compared under different conditions. The effect of immobilization was highly dependent on the type of enzyme, the immobilization strategy, and the application itself, with no superior immobilization technique identified. Immobilization of HAGA-beads often resulted in the highest activities of up to 62 U/g beads, and amine beads were best for the hexameric transaminase from Luminiphilus syltensis. Furthermore, the immobilization of transaminases enabled its reusability for at least 10 cycles, while maintaining full or high activity. Upscaled kinetic resolutions (partially performed in a SpinChemTM reactor) resulted in a high conversion, maintained enantioselectivity, and high product yields, demonstrating their applicability. [ABSTRACT FROM AUTHOR]

HYDROGELS, ELASTICITY, INCLUSION compounds, CHEMICAL structure, POLYMER networks, DOUBLE bonds, MACROMONOMERS, and POLYACRYLAMIDE

Smart hydrogels are interesting materials as they can change their dimensions upon an external trigger. Herein, a photoresponsive double cross‐linked hydrogel system based on polyacrylamide (AAm) with grafted poly(2‐methyl‐2‐oxazoline) (PMOXA) chains with a α‐cyclodextrin/azobenzene host–guest complex is present. Switching azobenzene from the trans to the cis‐conformation through irradiation with UV light breaks the complex reversibly. Well‐defined PMOXA macromonomers have been synthesized and functionalized with the respective host and guest functionalities as well as double bonds for the incorporation into the polymer network as grafted side chains. The chemical structure of the macromonomers and the complex is confirmed by 1H NMR, 2D NOESY NMR, GPC, and UV–VIS measurements. Hydrogels with different ratios of permanent and photoresponsive cross‐linkers as well as different chain lengths of the PMOXA macromonomers are analyzed toward differences in their swelling/deswelling and elastic properties. Successive irradiation of supramolecular hydrogels with UV and VIS light allowed for a repeated swelling and de‐swelling of the hydrogels. This system is studied at both macro and micro scales, showing similar swelling tendencies. The tuned properties of photoresponsive double cross‐linked hydrogel makes this system a promising tool for various applications, for example, as in situ controllable valves in microfluidic flow cells. [ABSTRACT FROM AUTHOR]

BRONSTED acids, PHOSPHORIC acid, PHASE-transfer catalysis, COVALENT bonds, QUINOLINE, ACIDS, FLUORINATION, and CATALYSIS

The linking of phosphoric acids via covalent or mechanical bonds has proven to be a successful strategy for the design of novel organocatalysts. Here, we present the first systematic investigation of singly‐linked and macrocyclic bisphosphoric acids, including their synthesis and their application in phase‐transfer and Brønsted acid catalysis. We found that the novel bisphosphoric acids show dramatically increased enantioselectivities in comparison to their monophosphoric acid analogues. However, the nature, length and number of linkers has a profound influence on the enantioselectivities. In the asymmetric dearomative fluorination via phase‐transfer catalysis, bisphosphoric acids with a single, rigid bisalkyne‐linker give the best results with moderate to good enantiomeric excesses. In contrast, bisphosphoric acids with flexible linkers give excellent enantioselectivities in the transfer‐hydrogenation of quinolines via cooperative Brønsted acid catalysis. In the latter case, sufficiently long linkers are needed for high stereoselectivities, as found experimentally and supported by DFT calculations. [ABSTRACT FROM AUTHOR]

POLYMERIZATION, RENEWABLE natural resources, MONOMERS, DEPOLYMERIZATION, PETROLEUM, LIGNINS, and AMMONIA

The complete utilization of all lignin depolymerization streams obtained from the reductive catalytic fractionation (RCF) of woody biomass into high-value-added compounds is a timely and challenging objective. Here, we present a catalytic methodology to transform beech lignin-derived dimers and oligomers (DO) into well-defined 1,4-cyclohexanediol and 1,4-cyclohexanediamine. The latter two compounds have vast industrial relevance as monomers for polymer synthesis as well as pharmaceutical building blocks. The proposed two-step catalytic sequence involves the use of the commercially available RANEY® Ni catalyst. Therefore, the first step involves the efficient defunctionalization of lignin-derived 2,6-dimethoxybenzoquinone (DMBQ) into 1,4-cyclohexanediol (14CHDO) in 86.5% molar yield, representing a 10.7 wt% yield calculated on a DO weight basis. The second step concerns the highly selective amination of 1,4-cyclohexanediol with ammonia to give 1,4-cyclohexanediamine (14CHDA) in near quantitative yield. The ability to use RANEY® Ni and ammonia in this process holds great potential for future industrial synthesis of 1,4-cyclohexanediamine from renewable resources. [ABSTRACT FROM AUTHOR]

SULFUR compounds, SOLIDS, DIPYRRINS, SULFUR, COMPUTATIONAL chemistry, and ETHERS

In this contribution, we describe a set of three chlorinated bridged ethers with varying numbers of sulfur and oxygen atoms. The substitution leads to highly emissive compounds with tunable photophysical properties in relationship to their state of aggregation, i. e. in solution, as aggregates and in the solid state. Additionally, an in‐depth X‐ray diffractometric analysis supported by a Hirshfeld study of non‐covalent interactions and quantum chemical simulations was carried out. As the outcome, it was found that the content of sulfur in the compounds regulates the tuning of emission in solution as well as in the aggregated states as a consequence of their variation of planarity. [ABSTRACT FROM AUTHOR]

ANTIFUNGAL agents, CHITIN, MOLECULAR docking, AMINES, TACROLIMUS, and ASPERGILLUS nidulans

Agents with antifungal activity play a vital role as therapeutics in health care, as do fungicides in agriculture. Effectiveness, toxicological profile, and eco-friendliness are among the properties used to select suitable substances. Furthermore, a steady supply of new agents with different modes of action is required to counter the well-known potential of human and phyto-pathogenic fungi to develop resistance against established antifungals. Here, we use an in vitro growth assay to investigate the activity of the calcineurin inhibitor tacrolimus in combination with the commercial fungicides cyproconazole and hymexazol, as well as with two earlier reported novel {2-(3-R-1H-1,2,4-triazol-5-yl)phenyl}amines, against the fungi Aspergillus niger, Colletotrichum higginsianum, Fusarium oxysporum and the oomycete Phytophthora infestans, which are notoriously harmful in agriculture. When tacrolimus was added in a concentration range from 0.25 to 25 mg/L to the tested antifungals (at a fixed concentration of 25 or 50 mg/L), the inhibitory activities were distinctly enhanced. Molecular docking calculations revealed triazole derivative 5, (2-(3-adamantan-1-yl)-1H-1,2,4-triazol-5-yl)-4-chloroaniline), as a potent inhibitor of chitin deacetylases (CDA) of Aspergillus nidulans and A. niger (AnCDA and AngCDA, respectively), which was stronger than the previously reported polyoxorin D, J075-4187, and chitotriose. The results are discussed in the context of potential synergism and molecular mode of action. [ABSTRACT FROM AUTHOR]

ACID derivatives, ELLAGIC acid, COLUMN chromatography, METABOLITES, ANTI-infective agents, ETHYL acetate, and FLAVONOIDS

Medicinal plants are known as sources of potential antimicrobial compounds belonging to different classes. The aim of the present work was to evaluate the antimicrobial potential of the crude extract, fractions, and some isolated secondary metabolites from the leaves of Macaranga occidentalis, a Cameroonian medicinal plant traditionally used for the treatment of microbial infections. Repeated column chromatography of the ethyl acetate and n-butanol fractions led to the isolation of seventeen previously known compounds (1−17), among which three steroids (1−3), one triterpene (4), four flavonoids (5−8), two stilbenoids (9 and 10) four ellagic acid derivatives (11−14), one geraniinic acid derivative (15), one coumarine (16), and one glyceride (17). Their structures were elucidated mainly by means of extensive spectroscopic and spectrometric (1D and 2D NMR and, MS) analysis and comparison with the published data. The crude extract, fractions, and isolated compounds were all screened for their antimicrobial activity. None of the natural compounds was active against Candida strains. However, the crude extract, fractions, and compounds showed varying levels of antibacterial properties against at least one of the tested bacterial strains, with minimal inhibitory concentrations (MICs) ranging from 250 to 1000 μg/mL. The n-butanol (n-BuOH) fraction was the most active against Escherichia coli ATCC 25922, with an MIC value of 250 μg/mL. Among the isolated compounds, schweinfurthin B (10) exhibited the best activity against Staphylococcus aureus NR 46003 with a MIC value of 62.5 μg/mL. In addition, schweinfurthin O (9) and isomacarangin (6) also exhibited moderate activity against the same strain with a MIC value of 125 μg/mL. Therefore, pharmacomodulation was performed on compound 6 and three new semisynthetic derivatives (6a–c) were prepared by allylation and acetylation reactions and screened for their in vitro antimicrobial activity. None of the semisynthetic derivatives showed antimicrobial activity against the same tested strains. The chemophenetic significance of the isolated compounds is also discussed in this paper. [ABSTRACT FROM AUTHOR]

NICOTINIC acetylcholine receptors, NICOTINIC receptors, LIGAND-gated ion channels, CHOLINERGIC receptors, LIGANDS, CONOTOXINS, PROTEIN-ligand interactions, ALZHEIMER'S disease, and DRUG design

The neuronal nicotinic acetylcholine receptors (nAChRs) belong to the ligand-gated ion channel (GLIC) group, presenting a crucial role in several biological processes and neuronal disorders. The α4β2 and α7 nAChRs are the most abundant in the central nervous system (CNS), being involved in challenging diseases such as epilepsy, Alzheimer's disease, schizophrenia, and anxiety disorder, as well as alcohol and nicotine dependencies. In addition, in silico-based strategies may contribute to revealing new insights into drug design and virtual screening to find new drug candidates to treat CNS disorders. In this context, the pharmacophore maps were constructed and validated for the orthosteric sites of α4β2 and α7 nAChRs, through a docking-based Comparative Intermolecular Contacts Analysis (dbCICA). In this sense, bioactive ligands were retrieved from the literature for each receptor. A molecular docking protocol was developed for all ligands in both receptors by using GOLD software, considering GoldScore, ChemScore, ASP, and ChemPLP scoring functions. Output GOLD results were post-processed through dbCICA to identify critical contacts involved in protein-ligand interactions. Moreover, Crossminer software was used to construct a pharmacophoric map based on the most well-behaved ligands and negative contacts from the dbCICA model for each receptor. Both pharmacophore maps were validated by using a ROC curve. The results revealed important features for the ligands, such as the presence of hydrophobic regions, a planar ring, and hydrogen bond donor and acceptor atoms for α4β2. Parallelly, a non-planar ring region was identified for α7. These results can enable fragment-based drug design (FBDD) strategies, such as fragment growing, linking, and merging, allowing an increase in the activity of known fragments. Thus, our results can contribute to a further understanding of structural subunits presenting the potential for key ligand-receptor interactions, favoring the search in molecular databases and the design of novel ligands. [ABSTRACT FROM AUTHOR]

SUSTAINABILITY, COVID-19 pandemic, SUSTAINABLE chemistry, UNDERGRADUATES, PHYSICAL constants, and CHEMICAL laboratories

In this section of Resonance, we invite readers to pose questions likely to be raised in a classroom situation. We may suggest strategies for dealing with them, or invite responses, or both. "Classroom" is equally a forum for raising broader issues and sharing personal experiences and viewpoints on matters related to teaching and learning science. Amidst the Covid-19 pandemic, we have planned a strategy for our institution which aims towards reuse and reduce principles of Green Chemistry. Organic preparations in the undergraduate curriculum can be utilized for other sister laboratory experiments such as recrystallization, determination of physical constants (m.pt) and detection of extra elements, detection of functional group and in qualitative analysis. The product of preparation can also be subjected to a second synthesis. This approach will reduce the amount of chemicals needed for carrying out experiments other than organic preparations. This paper illustrates a few organic preparations which can be reused for other companion laboratory exercises. This approach may set a model towards sustainability for other undergraduate laboratories. [ABSTRACT FROM AUTHOR]

HETEROCYCLIC compounds, INDAZOLES, ETHYLATION, METHYLTRANSFERASES, BIOCATALYSIS, and IMIDAZOLES

Methods for regioselective N‐methylation and ‐alkylation of unsaturated heterocycles with "off the shelf" reagents are highly sought‐after. This reaction could drastically simplify synthesis of privileged bioactive molecules. Here we report engineered and natural methyltransferases for challenging N‐(m)ethylation of heterocycles, including benzimidazoles, benzotriazoles, imidazoles and indazoles. The reactions are performed through a cyclic enzyme cascade that consists of two methyltransferases using only iodoalkanes or methyl tosylate as simple reagents. This method enables the selective synthesis of important molecules that are otherwise difficult to access, proceeds with high regioselectivity (r.r. up to >99 %), yield (up to 99 %), on a preparative scale, and with nearly equimolar concentrations of simple starting materials. [ABSTRACT FROM AUTHOR]

CATALYSIS, ORGANIC chemistry, FLOW chemistry, and METAL catalysts

Fine chemical industry, flow chemistry, organic process, single-atom catalysis Keywords: fine chemical industry; flow chemistry; organic process; single-atom catalysis EN fine chemical industry flow chemistry organic process single-atom catalysis 1 1 1 11/11/22 20221108 NES 221108 B The Cover Feature b shows a flow reactor employing a single-atom catalyst schematically represented. Cover Feature: Continuous Flow Single-Atom Catalysis: A Viable Organic Process Technology?. [Extracted from the article]

AROMATIC amines, AMINES, HYDROGEN peroxide, METALS, DEAMINATION, and FUNCTIONAL groups

A new and green strategy to synthesize α‐aminophosphonates has been developed using benzyl amines as carbonyl alternates. The method involves oxidative deamination of benzyl amines to produce in situ aldehyde intermediate which is then directly converted into aminophosphonates by coupling with aryl amines and trialkylphosphite. The synthesis offers a green alternative strategy which involves benzyl amines as useful carbonyl surrogate and their possible application in multicomponent reactions to synthesize value added products like aminophosphonates. The methodology has a wide substrate scope and functional group compatibility. Further, the synthesis uses aqueous hydrogen peroxide (H2O2) as a green oxidant and enables to synthesize these products under mild and metal‐free conditions in water as a medium. [ABSTRACT FROM AUTHOR]

SINGLE molecules, AMMONIA, CATALYSTS, LIGNOCELLULOSE, DIAMINES, and GLYCOLS

Diamines are important industrial chemicals. In this paper we outline the feasibility of lignocellulose as a source of diol‐containing molecules. We also illustrate the possibility of turning these diols into their diamines in good to excellent yields. Central to these transformations is the use of commercially available Raney Ni. For diol formation, the Raney Ni engages in hydrogenation and often also demethoxylation, that way funneling multiple components to one single molecule. For diamine formation, Raney Ni catalyzes hydrogen‐borrowing mediated diamination in the presence of NH3. [ABSTRACT FROM AUTHOR]

CHALCONE, PHARMACEUTICAL chemistry, ANTI-infective agents, CHALCONES, COMPLEMENT activation, and ORGANIC synthesis

Chalcones have been well examined in the extant literature and demonstrated antibacterial, antifungal, anti-inflammatory, and anticancer properties. A detailed evaluation of the purported health benefits of chalcone and its derivatives, including molecular mechanisms of pharmacological activities, can be further explored. Therefore, this review aimed to describe the main characteristics of chalcone and its derivatives, including their method synthesis and pharmacotherapeutics applications with molecular mechanisms. The presence of the reactive α,β-unsaturated system in the chalcone's rings showed different potential pharmacological properties, including inhibitory activity on enzymes, anticancer, anti-inflammatory, antibacterial, antifungal, antimalarial, antiprotozoal, and anti-filarial activity. Changing the structure by adding substituent groups to the aromatic ring can increase potency, reduce toxicity, and broaden pharmacological action. This report also summarized the potential health benefits of chalcone derivatives, particularly antimicrobial activity. We found that several chalcone compounds can inhibit diverse targets of antibiotic-resistance development pathways; therefore, they overcome resistance, and bacteria become susceptible to antibacterial compounds. A few chalcone compounds were more active than conventional antibiotics, like vancomycin and tetracycline. On another note, a series of pyran-fused chalcones and trichalcones can block the NF-B signaling complement system implicated in inflammation, and several compounds demonstrated more potent lipoxygenase inhibition than NSAIDs, such as indomethacin. This report integrated discussion from the domains of medicinal chemistry, organic synthesis, and diverse pharmacological applications, particularly for the development of new anti-infective agents that could be a useful reference for pharmaceutical scientists. [ABSTRACT FROM AUTHOR]

CYCLODEXTRINS, ISOTHERMAL titration calorimetry, PHOSPHORESCENCE, COMPLEX compounds, MASS spectrometry, and INCLUSION compounds

We present an in‐depth investigation of cyclodextrin complexes with guest compounds featuring complexation‐induced room temperature phosphorescence (RTP) in aqueous solution. Very interestingly, only the complexed regioisomers bearing lateral substituents on meta‐position show RTP, whereas the stronger host‐guest systems with para‐substituted dyes show no RTP features. The reported systems were investigated regarding their complexation behavior in water using isothermal titration calorimetry and mass spectrometry. In the case of γ‐CD very strong 1 : 1 inclusion complexes (Ka up to 5.13×105 M−1) were unexpectedly observed. It was found that not only a strong binding to the cyclodextrin cavity is needed to restrict motion, inducing the emission, but also the conformation inside the cavity plays a pivotal role – as supported by an extensive NMR study and MD simulations. [ABSTRACT FROM AUTHOR]

ORGANIC solvents, PEPTIDES, POISONS, RESEARCH teams, ORGANIC synthesis, and SOLVENTS

Dihydrolevoclucosenone (Cyrene is its market name) is a biomass-derived solvent that can be produced in only two steps from biomass, while being biodegradable, non-mutagenic and non-toxic. Its "green" profile combined with its physical properties makes Cyrene a plausible substitute for a number of widely used toxic organic solvents. The first attempt to assess Cyrene as a solvent dates back to 2014 and since then, numerous research groups have opted for this promising alternative. Cyrene has successfully been employed as a solvent in materials chemistry, peptide chemistry, organic synthesis and many more research fields, which are going to be discussed in the context of this review. [ABSTRACT FROM AUTHOR]

DIAMINES, MOLECULAR docking, CYTOCHROME c, SCHIFF bases, PEROXIDASE, ESCHERICHIA coli, and DENSITY functional theory

• Synthesis of symmetrical bis-benzoxazines. • Density Functional Theory (DFT) estimation was disclosed for compound 5e. • A Molecular docking study was carried out against Cytochrome c Peroxidase (2 × 08). • Compounds 3 g, 4 g, 5c, and 5 g showed remarkable antimicrobial activity. • Compounds 3b, 3c, 3 g, 4c, 5b, & 5f displayed good antioxidant activity. We herein report the efficient synthesis of symmetrical bis-benzoxazines by substituted salicylaldehydes and alkyl diamines. The substituted salicylaldehydes (1a-d) and alkyl diamines (2a-b) on reaction synthesize Schiff's bases 3a-h. These compounds on reduction with NaBH4 in dry methanol yielded 2,2′-((alkyl-1,2-diylbis (azanediyl)) bis(methylene))disubstituted phenol, 4a-h in good yield. The preferable 1,2-bis(6-substituted-2 H -benzo[ e ][1,3]oxazin-3(4 H)-yl)ethanes, 5a-h formed when the compounds 4a-h undergo an internal Mannich reaction with formaldehyde. Different spectroscopic methods prove the formation of all the compounds. The compounds 3 g, 4 g, 5c, and 5 g showed excellent antibacterial activity against S. aureus, E. coli, S. Typhi, and B. subtilis , antifungal activity against A. flavus, C. Albicans, A. niger, and C. oxysporum with MIC values of 6.25 µg/ml and anti-TB activity against M. tuberculosis for which is equivalent to the standard drug. Furthermore, studies on the antioxidant activity of the compounds 3b, 3c, 3 g, 4c, 5b, and 5f revealed that they have excellent antioxidant activity. To comprehend the electronic behavior of compound 5e, Density Functional Theory estimations at the DFT/B3LYP level via 6–31G++ (d, p) replicate the structure and geometry. The first-order hyperpolarizability calculation finds the non-linear visual feature of compound 5e. Finally, HOMO and LUMO analysis were used for the charge transfer interface between the structures. Against Cytochrome c Peroxidase (2 × 08), the compounds 3c and 4c exhibited good docking properties in Molecular docking studies. [Display omitted] [ABSTRACT FROM AUTHOR]

ALBIZIA, NORMAL-phase chromatography, ANTI-infective agents, LEGUMES, FRUIT, and COLUMN chromatography

Twenty-two compounds were isolated from the fruit of Albizia lebbeck including one unprecedented, rare amino acid-derived zwitterionic and one new flavone derivative. The isolation was performed on repeated column chromatography over silica gel and their structures were determined by 1D-, 2D-NMR and HR-ESI-MS spectra together with reported data in the literature. The chemophenetic significance is also discussed. Some isolated compounds were reported for the first time to be found in the species. Additionally, compound 2 showed antibacterial activity and compounds 1 and 2 revealed moderate cytotoxic activity against the Raw 264.7 cancer cell line with IC50 values of 37.19 µM and 29.36 µM, respectively. Furthermore, a proposed biosynthetic pathway of compound 1 is described. [ABSTRACT FROM AUTHOR]

AMINO acids, COLLOIDAL gels, CATALYST supports, LIGHT beating spectroscopy, and TRANSMISSION electron microscopy

Polyacrylamide-based waterborne microgels were prepared with copolymerized carboxylic acid and tertiary amine moieties. The colloidal gels were loaded with palladium nanoparticles and utilized for the Suzuki–Miyaura cross-coupling of amino acids and peptides. The thermoresponsive properties of the prepared microgels were characterized by means of photon correlation spectroscopy (PCS) at solvent conditions of the catalytic reaction. The localization and morphology of the incorporated nanoparticles were characterized with transmission electron microscopy (TEM). Palladium-catalyzed Suzuki–Miyaura cross-coupling of N α-Boc-4-iodophenylalanine and N α-Boc-7-bromotryptophan with phenylboronic acid was carried out under ambient atmosphere in water at 20, 37, and 60 °C, respectively. The properties of the thermoresponsive microgel showed a strong influence on the reactivity and selectivity towards the respective substrate. For the amine containing microgels, a recyclability for up to four cycles without loss in activity could be realized. Furthermore, the systems showed good catalytic activity regarding Suzuki–Miyaura cross-coupling of halogenated amino acids in selected tri- and tetrapeptides. [ABSTRACT FROM AUTHOR]

IODINE, CHEMICAL synthesis, HYDRAZONES, POTASSIUM carbonate, HETEROCYCLIC compounds, OXIDATION, and HYDRAZONE derivatives

An oxidative cyclization of 2‐arenoxybenzaldehyde N‐acyl hydrazones 3 a–o was employed to synthesize new 2,5‐disubstituted 1,3,4‐oxadiazole compounds 4 a–d, 4 f–i, 4 k–n. This method involves oxidative cyclization of 2‐arenoxybenzaldehyde N‐acyl hydrazones 3 a–o with molecular iodine mediated catalysis in which potassium carbonate served as a base. Characterization of all the synthesized novel compounds involved, proton and carbon NMR, mass spectrometry, and CHN elemental analysis. The synthesis of novel 2,5‐disubstituted 1,3,4‐oxadiazoles may display potential to provide pharmacologically important heterocyclic compounds. [ABSTRACT FROM AUTHOR]

CHEMICAL processes, ORGANIC acids, AMIDES, ENANTIOMERIC purity, ENZYMES, AMIDATION, ACYL chlorides, and ORGANIC solvents

Efficient amide formation is of high importance for the chemical and pharmaceutical industry. The direct biocatalytic one-pot transformation of acids into amides without substrate activation is a highly desirable but highly challenging reaction; this is why in general the acid is activated using additional reagents before amide formation occurs. In particular, amidation of α-amino acids is challenging and in general requires protection strategies for the amino functionality. A further challenge is the low solubility of the unprotected amino acids in organic solvents. Furthermore, the amidation process is prone to racemisation as observed for the acyl chloride derivative. These three challenges may be addressed using biocatalysis. Here the enzyme catalyzed, racemization-free amidation of unprotected L-proline with ammonia in an organic solvent is described. Comprehensive reaction, solvent and enzyme engineering allowed obtaining high L-prolinamide concentrations. For instance at 145 mM substrate concentration, 80% conversion was achieved employing an immobilized CalB variant and ammonia in 2-methyl-2-butanol at 70 °C. A twofold increase in L-prolinamide formation was achieved employing the immobilized and engineered enzyme variant CalBopt-24 T245S compared to wild type CalB. In contrast to chemical processes, racemization, halogenated solvents and waste are avoided/minimized and atom efficiency is significantly improved from 45.5% to 86.4%. The excellent optical purity of the obtained product (ee >99%) and the stability of immobilized CalB pave the way for an innovative industrial process to produce L-prolinamide, a key intermediate in drug synthesis. [ABSTRACT FROM AUTHOR]

DOSAGE forms of drugs, FREE groups, VITAMIN C, FLAVONOIDS, HYDROXYL group, and PLANT species

Biflavonoids are C-C or C-O-C linked flavonoid dimers with highly restricted presence in plant species. They are extensively reported to possess interesting pharmacological properties. The chromatographic fractionation and purification of CH2Cl2/MeOH (1:1) extract of the root of Rhus ruspolli led to the isolation of a new biflavonoid (1) along with four other known biflavonoids (2-5). The structure of the compounds were identified based on the analysis of NMR spectroscopic and mass spectrometric data and also in comparison with reported literature data. Compounds 2-5 were assayed for their antioxidant activity using DPPH and displayed potent in vitro antioxidant activities. The percentage radical scavenging activities were 78.32, 68.90, 93.22 and 92.00 for compounds 2-5, respectively. The highest activity was observed for compound 4 and 5 with IC50 values of 7.90 and 8.40, respectively, which are even greater than that of ascorbic acid (IC50 9.90). The high antioxidant activity of the compounds could be due to the presence of free hydroxyl groups in the flavonoids. The antioxidant activities of these compounds support the traditional uses of the plant in treatment of wound, ectoparasite and as antibacteria and indicates the potential use of these compounds as drug lead candidates. [ABSTRACT FROM AUTHOR]

TITANIUM catalysts, ALLYL alcohol, HYDROGEN peroxide, EPOXIDATION, ALCOHOL oxidation, ALCOHOL drinking, and TETRAHYDROFURAN

In the Sharpless asymmetric epoxidation of chiral secondary allylic alcohols, one substrate enantiomer is predominantly converted to the anti‐epoxy alcohol. We herein report the first highly syn‐selective epoxidation of terminal allylic alcohols using a titanium salalen complex as catalyst, at room temperature, and aqueous hydrogen peroxide as oxidant. With enantiopure terminal allylic alcohols as substrates, the epoxy alcohols were obtained with up to 98 % yield and up to >99 : 1 dr (syn). Catalyst loadings as low as 1 mol % can be applied without eroding the syn‐diastereoselectivity. Modification of the allylic alcohol to an ether does not affect the diastereoselectivity either [>99 : 1 dr (syn)]. Inverting the catalyst configuration leads to the anti‐product, albeit at lower dr (ca. 20 : 1). The synthetic potential is demonstrated by a short, gram‐scale preparation of a tetrahydrofuran building block with three stereocenters, involving two titanium salalen catalyzed epoxidation steps. [ABSTRACT FROM AUTHOR]

Depressants are critical reagents for the selective separation of minerals in froth flotation. They serve a vital role in preferentially making the gangue minerals hydrophilic and prevent them from reporting to the mineral-rich froth phase. Current practice involves the use of inorganic depressants, which are toxic and non-biodegradable. Environmentally friendly, flexible and affordable flotation depressants are needed due to the depletion of easy-to-process high-grade ores as well as sustainability and environmental concerns. This paper discusses various organic depressants that have been adopted for selective depression of unwanted minerals in chalcopyrite flotation. The origin and chemistry, organic depressant-gangue minerals interaction mechanism, and the use of organic depressants in the most common chalcopyrite-flotation instances, including chalcopyrite separation from galena, molybdenite, sphalerite, pyrite, pyrrhotite, talc, serpentine and carbonaceous materials, are discussed. This review shows that organic depressants can partially or fully replace current inorganic depressants used in suppressing both sulfide and non-sulfide gangue minerals in chalcopyrite flotation. In this review, a well-detailed and well-referenced discussion is provided for the current state of organic depressants in chalcopyrite flotation, as well as a valuable discussion is provided to comparatively evaluate the depression performance of the various reported organic depressants. Finally, suggestions are made regarding future research challenges and directions. The recent advancements, developing features, and research prospects discussed in this article will provide a helpful reference for academics who want to delve deeper into the greening of chalcopyrite flotation process. [ABSTRACT FROM AUTHOR]

ORGANIC synthesis, ALKYNES, HYDROXYLATION, ALUMINUM oxide, and SUPERHEAVY elements

The discovery and development of new synthetic methods exploiting earth-abundant-element-based catalysts is an important goal in contemporary synthetic organic chemistry, which faces increasingly stringent requirements of sustainability. In this work, we disclose alumina-mediated propargylic C–H activation inducing a challenging transformation of readily available alkynes into a valuable 1,3-diene moiety under unprecedentedly mild conditions. Combining DFT-investigation and synthetic observations, we demonstrate that partial hydroxylation of alumina's surface might play an essential role in this process. [ABSTRACT FROM AUTHOR]

SOLAR cells, PYRENE, SURFACE interactions, THIOPHENES, and SELENOPHENE

A new class of polymeric hole‐transport materials (HTMs) are explored by inserting a two‐dimensionally conjugated fluoro‐substituted pyrene into thiophene and selenophene polymeric chains. The broad conjugated plane of pyrene and "Lewis soft" selenium atoms not only enhance the π–π stacking of HTM molecules greatly but also render a strong interaction with the perovskite surface, leading to an efficient charge transport/transfer in both the HTM layer and the perovskite/HTM interface. Note that fluorine substitution adjacent to pyrene boosts the stacking of HTMs towards a more favorable face‐on orientation, further facilitating the efficient charge transport. As a result, perovskite solar cells (PSCs) employing PE10 as dopant‐free HTM afford an excellent efficiency of 22.3 % and the dramatically enhanced device longevity, qualifying it among the best PSCs based on dopant‐free HTMs. [ABSTRACT FROM AUTHOR]

METALS, CYCLOPROPANE, DIOLEFINS, MOIETIES (Chemistry), INDUSTRIAL applications, and ALLYLIC amination

Biologically potent and synthetically significant 1,2‐dihydronaphthalene derivatives have gained considerable attention due to their wide applications in industrial as well as in medicinal fields also. A mild and efficient metal‐free protocol via the rearrangement of cyclopropylcarbinols has been reported to construct these 1,2‐dihydronaphthalene skeletons utilizing cyclopropane ring as the scaffold. We obtained conjugated dienes and, in some cases, homoallylic chlorides as major products in good to excellent yields. They have no literature precedence till date. The fate of this rearrangement depends on the substituent patterns of the cyclopropane bearing aryl moiety. Besides the synthetic studies, to get deep insight into the electronic transitions, time dependent DFT studies have also been performed. [ABSTRACT FROM AUTHOR]

AUTOCATALYSIS, KINETIC isotope effects, ALDEHYDES, and ZWITTERIONS

Under aprotic conditions, the stoichiometric reaction of N‐heterocyclic carbenes (NHCs) such as imidazolidin‐2‐ylidenes with aldehydes affords Breslow Intermediates (BIs), involving a formal 1,2‐C‐to‐O proton shift. We herein report kinetic studies (NMR), complemented by DFT calculations, on the mechanism of this kinetically disfavored H‐translocation. Variable time normalization analysis (VTNA) revealed that the kinetic orders of the reactants vary for different NHC‐to‐aldehyde ratios, indicating different and ratio‐dependent mechanistic regimes. We propose that for high NHC‐to‐aldehyde ratios, the H‐shift takes place in the primary, zwitterionic NHC‐aldehyde adduct. With excess aldehyde, the zwitterion is in equilibrium with a hemiacetal, in which the H‐shift occurs. In both regimes, the critical H‐shift is auto‐catalyzed by the BI. Kinetic isotope effects observed for R‐CDO are in line with our proposal. Furthermore, we detected an H‐bonded complex of the BI with excess NHC (NMR). [ABSTRACT FROM AUTHOR]

ALDEHYDES

Keywords: Autocatalysis; Breslow Intermediate; Carbenes; NMR; Reaction Mechanisms EN Autocatalysis Breslow Intermediate Carbenes NMR Reaction Mechanisms 1 1 1 06/01/22 20220607 NES 220607 B Breslow intermediates b (BIs) are pivotal species in Umpolung catalysis effected by N-heterocyclic carbenes (NHCs). Inside Back Cover: Formation of Breslow Intermediates from N-Heterocyclic Carbenes and Aldehydes Involves Autocatalysis by the Breslow Intermediate, and a Hemiacetal (Angew. Autocatalysis, Breslow Intermediate, Carbenes, NMR, Reaction Mechanisms. [Extracted from the article]

LEWIS acidity, CORANNULENE, POLYCYCLIC aromatic hydrocarbons, HELICENES, and ACENAPHTHENE

We have discovered a dual (i. e., soft and hard) Lewis acidity of alumina that enables rapid one‐pot π‐extension through the activation of terminal alkynes followed by C−F activation. The tandem reaction introduces an acenaphthene fragment – an essential moiety of geodesic polyarenes. This reaction provides quick access to elusive non‐alternant polyarenes such as π‐extended buckybowls and helicenes through three‐point annulation of the 1‐(2‐ethynyl‐6‐fluorophenyl)naphthalene moiety. The versatility of the developed method was demonstrated by the synthesis of unprecedented structural fragments of elusive geodesic graphene nanoribbons. [ABSTRACT FROM AUTHOR]

LEWIS acidity, CORANNULENE, and HELICENES

Keywords: alkyne activation; alumina; buckybowls; C-F activation; geodesic nanoribbons EN alkyne activation alumina buckybowls C-F activation geodesic nanoribbons 1 1 1 06/06/22 20220601 NES 220601 B Tandem bond activation b : The dual Lewis acidity of alumina has been discovered and employed to activate C-F and triple C C bonds in a tandem manner to provide rapid access to elusive nonplanar PAHs such as -extended helicenes, buckybowls and fragments of geodesic nanoribbons. Alkyne activation, alumina, buckybowls, C-F activation, geodesic nanoribbons. [Extracted from the article]

BIOSYNTHESIS, POSITRON emission tomography, HIPPOCAMPUS (Brain), SEROTONIN receptors, CENTRAL nervous system, LAMOTRIGINE, and RISPERIDONE

Efforts are underway to improve the diagnosis and treatment for neurological disorders like depression, anxiety, epilepsy, and schizophrenia. The G‐protein‐coupled receptors (GPCRs) 5‐HT7 receptor, the most recently identified member of 5‐HT receptor family dysregulation has an association with various central nervous system (CNS) disorders and its ligands have an edge as potential therapeutics. Here, we report the synthesis, characterization, and biological evaluation of diversely substituted methoxy derivatives of 2‐benzoxazolone arylpiperazine for targeting 5‐HT7 receptors. Out of all derivatives, only C‐2 substituted derivative, 3‐(4‐(4‐(2‐methoxyphenyl)piperazin‐1‐yl)butyl)benzoxazol‐2(3H)‐one/ABO demonstrate a high affinity for human 5‐HT7 receptors. [11C]ABO was obtained by O‐methylation of desmethyl‐precursor using [11C]CH3OTf in the presence of NaOH giving a high radiochemical yield of 25 ± 12% (decay‐corrected, n = 7) with stability up to 1.5 h postradiolabeling. In vitro autoradiography displays binding of [11C]ABO in accordance with 5‐HT7 distribution with a decrease of approximately 80% and 40% activity in the hippocampus and cerebellum brain region when administered with 10 µM cold ligand. Prefatory positron emission tomography scan results in Sprague‐Dawley (SD) rat brain revealed fast and high radioactivity build‐up in 5‐HT7 receptor‐rich regions, namely, the hippocampus (2.75 ± 0.16 SUV) and the cerebral cortex (2.27 ± 0.02 SUV) establishing selective targeting of [11C]ABO. In summary, these pieces of data designate [11C]ABO as a promising 5‐HT7 receptor ligand that can have possible roles in clinics after its further optimization on different animal models. [ABSTRACT FROM AUTHOR]

ORGANOSELENIUM compounds, POLYMERIZATION, and SELENIUM

The one-pot multicomponent synthetic strategy of organoselenium compounds represents an alternative and robust protocol to the conventional multistep methods. During the last decade, a potential advance has been made in this domain. This review discusses the latest advances in the polymerization, metal, and metal-free one-pot multicomponent synthesis of organoselenium compounds. [ABSTRACT FROM AUTHOR]

PARACYCLOPHANES, IONS, FLUOROPHORES, FLUORESCENCE, SKELETON, and MACROCYCLIC compounds

Transformation of [15]paracyclophanes ([15]PCP) into fluorophores has been achieved by embedding tetraphenylethene (TPE) units into their skeletons at the meso-positions. The obtained two hosts demonstrated distinct aggregation-induced emission (AIE) properties and their fluorescence could be selectively quenched by Ni2+ ions. [ABSTRACT FROM AUTHOR]

LIGNINS, MOLECULAR motor proteins, LIGNOCELLULOSE, TARGETED drug delivery, DRUG delivery systems, SOFT robotics, MOLECULAR switches, and LIGNIN structure

Lignin is the largest natural source of functionalized aromatics on the planet, therefore exploiting its inherent structural features for the synthesis of aromatic products is a timely and ambitious goal. While the recently developed lignin depolymerization strategies gave rise to well-defined aromatic platform chemicals, the diversification of these structures, especially toward high-end applications is still poorly addressed. Molecular motors and switches have found widespread application in many important areas such as targeted drug delivery systems, responsive coatings for self-healing surfaces, paints and resins or muscles for soft robotics. They typically comprise a functionalized aromatic backbone, yet their synthesis from lignin has not been considered before. In this contribution, we showcase the synthesis of a novel light-driven unidirectional molecular motor from the specific aromatic platform chemical 4-(3-hydroxypropyl)-2,6-dimethoxyphenol (dihydrosynapyl alcohol) that can be directly obtained from lignocellulose via a reductive catalytic fractionation strategy. The synthetic path takes into account the principles of green chemistry and aims to maintain the intrinsic functionality of the lignin-derived platform molecule. [ABSTRACT FROM AUTHOR]

ETHYL acetate, CERVICAL cancer, GRISEOFULVIN, CELL lines, XANTHONE, and CANCER cells

Chromatographic separation of the ethyl acetate extract of the root bark of Securidaca longipedunculata led to the isolation of one new xanthone derivative (1) along with nine known compounds (2-10). The structure of the isolated compounds were identified by NMR, mass spectrometric analyses, and comparison with the reported literature data. The isolates were evaluated for their cytotoxic activity with compounds 5 (IC50 = 0.38 µM) and 6 (IC50 = 52 µM) showed significant inhibitory activities against the human cervical cancer KB-3-1 cell line. Compound 5 displayed superior activity, which is even better than one of the reference drugs (griseofulvin, IC50 = 17 µM), whereas the rest showed little or none inhibitory activities. [ABSTRACT FROM AUTHOR]

ARGININE, DENSITY functional theory, FLUORESCENCE spectroscopy, ELECTROMAGNETIC spectrum, CARBOXYLATES, and SUPRAMOLECULAR chemistry

In this article, we present fluorescent guanidiniocarbonyl-indoles as versatile oxo-anion binders. Herein, the guanidiniocarbonyl-indole (GCI) and methoxy-guanidiniocarbonyl-indole (MGCI) were investigated as ethylamides and compared with the well-known guanidiniocarbonyl-pyrrole (GCP) concerning their photophysical properties as well as their binding behavior towards oxo-anions. Hence, a variety of anionic species, such as carboxylates, phosphonates and sulfonates, have been studied regarding their binding properties with GCP, GCI and MGCI using UV-Vis titrations, in combination with the determination of the complex stoichiometry using the Job method. The emission properties were studied in relation to the pH value using fluorescence spectroscopy as well as the determination of the photoluminescence quantum yields (PLQY). Density functional theory (DFT) calculations were undertaken to obtain a better understanding of the ground-lying electronic properties of the investigated oxo-anion binders. Additionally, X-ray diffraction of GCP and GCI was conducted. We found that GCI and MGCI efficiently bind carboxylates, phosphonates and sulfonates in buffered aqueous solution and in a similar range as GCP (Kass ≈ 1000–18,000 M−1, in bis-tris buffer, pH = 6); thus, they could be regarded as promising emissive oxo-anion binders. They also exhibit a visible fluorescence with a sufficient PLQY. Additionally, the excitation and emission wavelength of MGCI was successfully shifted closer to the visible region of the electromagnetic spectrum by introducing a methoxy-group into the core structure, which makes them interesting for biological applications. [ABSTRACT FROM AUTHOR]

QUINONE derivatives, MELTING points, INDOLE, THIN layer chromatography, and ORGANIC synthesis

12-Ethyl-6-methyliden-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indole-3-one (4) Methyllithium (10 mL, 3.0 M MeLi solution in THF) was added to a solution of compound B 3 b (1.5 g, 5.2 mmol) in 30 mL of anhydrous THF under a nitrogen atmosphere at 0 SP ° sp C and the mixture was stirred at 0 SP ° sp C for 1 h. The organic layer was dried over magnesium sulfate, filtered, and the solvent was evaporated to give an oil, which was purified by column chromatography (silica gel, ethyl acetate:acetone:triethylamine, 4:1:1). Finally, compound B 4 b was reduced with tris(triphenylphosphine)rhodium(I) carbonyl hydride in THF to give (±)-noruleine B 5 b in four steps, with an over-all yield of 41% and also obtained as yellow oil.[21],[22],[28] All of the component compounds in the preparative sequence were rigorously characterized (see Experimental section). The uleine alkaloids (Figure 1) have remarkable biological activities and have attracted much interest from synthetic organic chemists. [Extracted from the article]

ACIDOLYSIS, CHEMICAL kinetics, ETHYLENE glycol, DEPOLYMERIZATION, ACTIVATION energy, LIGNIN structure, LIGNINS, and PHENOL content of food

The product selectivity, production rates and the required process conditions are important for technology development. Selective lignin depolymerisation on the prime β-O-4 motif provides an opportunity to obtain valuable functionalized phenolic monomers. Diol-stabilized acidolysis of lignin with sulfuric acid, triflic acid or triflate salts is a proven β-O-4 cleavage methodology that forms acetals by trapping of released reactive aldehydes. For future scale-up, a better understanding of the prime reaction pathways and how these can be controlled upon changing reaction parameters is required. By using β-O-4 model compounds and ytterbium(III) triflate as catalyst, starting material conversion and product formation including two key intermediates, the diol adducts (in this study, ethylene glycol as the diol) and the vinyl ethers, were accurately monitored, allowing for detailed kinetic modelling. Over the selected temperature range (80-150 °C), higher temperatures led to higher overall carbon balance and selectivity for the main desired acetal product. The kinetic modelling allowed for establishing a detailed reaction network with activation energies and rate constants. These collectively led to new insights into the key steps involved in the diol-stabilized β-O-4 motif acidolysis and how the reaction selectivity can be manipulated by controlling the reaction temperature, and the ethylene glycol and water content. The elucidation on reaction kinetics and networks constitutes a further step in the design of a diol-stabilized lignin acidolysis process. [ABSTRACT FROM AUTHOR]

NANOFIBERS, NERVOUS system regeneration, REGENERATION (Biology), NATURAL fibers, BONE cells, and EXTRACELLULAR matrix

Electrospun techniques are promising and flexible technologies to fabricate ultrafine fiber/nanofiber materials from diverse materials with unique characteristics under optimum conditions. These fabricated fibers/nanofibers via electrospinning can be easily assembled into several shapes of three-dimensional (3D) structures and can be combined with other nanomaterials. Therefore, electrospun nanofibers, with their structural and functional advantages, have gained considerable attention from scientific communities as suitable candidates in biomedical fields, such as the regeneration of tissues and organs, where they can mimic the network structure of collagen fiber in its natural extracellular matrix(es). Due to these special features, electrospinning has been revolutionized as a successful technique to fabricate such nanomaterials from polymer media. Therefore, this review reports on recent progress in electrospun nanofibers and their applications in various biomedical fields, such as bone cell proliferation, nerve regeneration, and vascular tissue, and skin tissue, engineering. The functionalization of the fabricated electrospun nanofibers with different materials furnishes them with promising properties to enhance their employment in various fields of biomedical applications. Finally, we highlight the challenges and outlooks to improve and enhance the application of electrospun nanofibers in these applications. [ABSTRACT FROM AUTHOR]

QUANTUM dots, NONIONIC surfactants, ORGANIC synthesis, IONIC surfactants, SEMICONDUCTOR nanoparticles, ORGANIC semiconductors, and PHOSPHINES

Efficient conversion of light from short wavelengths to longer wavelengths using color conversion layers (CCLs) underpins the successful operation of numerous contemporary display and lighting technologies. Inorganic quantum dots, based on CdSe or InP, for example, have received much attention in this context, however, suffer from instability and toxic cadmium or phosphine chemistry. Organic nanoparticles (NPs), though less often studied, are capable of very competitive performance, including outstanding stability and water-processability. Surfactants, which are critical in stabilizing many types of nano-structures, have not yet been used extensively in organic NPs. Here we show the utility of surfactants in the synthesis and processing of organic NPs by thoroughly characterizing the effect of ionic and non-ionic surfactants on the properties of fluorescent organic NPs. Using this information, we identify surfactant processing conditions that result in nearly 100 % conversion of organic fluorophores into sub-micrometer particles, or nano-dots, with outstanding performance as CCLs. Such water dispersions are environmentally benign and efficiently convert light. They can be used for a range of fluorophores covering a full spectral gamut, with excellent color purity, including full-width at half-maximum (FWHM) values as low as 21 nm. Compared to inorganic (InP) reference CCLs, the organic nano-dot based CCLs show superior color conversion efficiency and substantially improved long-term stability. Compared to inorganic nanoparticles, organic nanoparticles aren't as well understood. Here the authors explore the use of surfactants to prepare organic semiconductor nanoparticles with outstanding photophysical properties. [ABSTRACT FROM AUTHOR]

SURFACE analysis, ACETAMIDE, HYDROGEN bonding, NUCLEOPHILIC reactions, CRYSTAL structure, DENSITY functional theory, and CHALCOGENS

N-(4-((3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl)selanyl)phenyl)acetamide (5), C19H15NO3Se, was prepared in two steps from 4,4′-diselanediyldianiline (3) via reduction and subsequent nucleophilic reaction with 2-methyl-3-bromo-1,4-naphthalenedione, followed by acetylation with acetic anhydride. The cytotoxicity was estimated against 158N and 158JP oligodendrocytes and the redox profile was also evaluated using different in vitro assays. The technique of single-crystal X-ray diffraction is used to confirm the structure of compound 5. The enantiopure 5 crystallizes in space group P21 with Flack parameter 0.017 (8), exhibiting a chiral layered absolute structure. Molecular structural studies showed that the crystal structure is foremost stabilized by N-H···O and relatively weak C-H···O contacts between molecules, and additionally stabilized by weak C-H···π and Se···N interactions. Hirshfeld surface analysis is used to quantitatively investigate the noncovalent interactions that stabilize crystal packing. Framework energy diagrams were used to graphically represent the stabilizing interaction energies for crystal packing. The analysis of the energy framework shows that the interactions energies of and C-H···π and C-O···π are primarily dispersive and are the crystal's main important forces. Density functional theory (DFT) calculations were used to determine the compound's stability, chemical reactivity, and other parameters by determining the HOMO-LUMO energy differences. The determination of its optimized surface of the molecular electrostatic potential (MEP) was also carried out. This study was conducted to demonstrate both the electron-rich and electron-poor sites. [ABSTRACT FROM AUTHOR]

ANTIBACTERIAL agents, MESQUITE, GALLIC acid, TROPICAL dry forests, ETHYL acetate, SKIN infections, and TREE growth

Prosopis africana (G. &Perr.) Taub (Mimosaceae) is a large tree native to dry tropical Africa and characteristic of dry leguminous forests. Different parts of this plant are used to treat wounds, skin infection, and to fight against cancer. Literature review indicated various pharmacological properties. Despite these medicinal properties, the chemical composition studies remain limited. This study aims to isolate and characterize secondary metabolites from P. africana leaves and evaluate their antibacterial and antioxidant properties. Air-dried powdered leaves of P. africana were macerated in methanol at room temperature and partitioned with ethyl acetate. The EtOAc extract was subjected successively to flash and column chromatographies in order to isolate compounds. The structure of the isolates was determined with help of spectroscopic data including 1D and 2D NMR experiments and comparison with literature data. The antibacterial activities were evaluated via determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antioxidant activities were evaluated via gallic acid equivalent antioxidant capacity (GEAC) and diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The chemical investigation of the EtOAc extract led to the isolation of seven compounds: (2E, 6E) farnesylamine (1), myricetin-3-O-rhamnoside (2), bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3), lupeol (4), ß-sitosterol (5), stigmasterol glycoside (6), and a mixture of bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3) and bis(2-ethylhexyl) benzene-1,4-dicarboxylate (7) in ratio 1 : 2. Compound 1 is described here for the first time as a natural product with complete 1H and 13C assignments. Compounds 3 and 7 were identified as artefacts from dichloromethane. Sesquiterpene amine (1) is reported in Prosopis genus for the first time. Antibacterial and antioxidant activities of isolated compounds were investigated. Among the tested samples, the EtOAc extract and compound 2 exhibited the highest antioxidant (EC50 = 5.67–77.56 μg/mL; GEAC = 36.58–89.28 μg/mL) and antibacterial (MIC = 8–64 μg/mL) activities against gram-negative and gram-positive bacteria. The EtOAc extract and compound 2 from P. africana exhibited antibacterial activity through bacteriolytic effects and reduction of the antioxidant defenses in the bacterial cells. Furthermore, the chemotaxonomic significance of isolated compounds was discussed. The antibacterial and antioxidant activities of ethyl acetate extract and compound 2 can justify the traditional uses of P. africana leaves for the treatment of diseases related to bacterial infections. The presence of compounds 1, 2, and 4 in this plant should also be considered as valuable chemotaxonomic features. [ABSTRACT FROM AUTHOR]

HEPATITIS B virus, DNA replication, DNA viruses, HEPATITIS B, VIRAL replication, VIRAL mutation, and VIRAL hepatitis

Hepatitis B virus infection (HBV) is one of the most common causes of hepatitis, and may lead to cirrhosis or hepatocellular carcinoma. According to the World Health Organization (WHO), approximately 296 million people worldwide are carriers of the hepatitis B virus. Various nucleos(t)ide analogs, which specifically suppress viral replication, are the main treatment agents for HBV infection. However, the development of drug-resistant HBV strains due to viral genomic mutations in genes encoding the polymerase protein is a major obstacle to HBV treatment. In addition, adverse effects can occur in patients treated with nucleos(t)ide analogs. Thus, alternative anti-HBV drugs of plant origin are being investigated as they exhibit excellent safety profiles and have few or no side effects. In this study, phytomedicines/phytochemicals exerting significant inhibitory effects on HBV by interfering with its replication were reviewed based on different compound groups. In addition, the chemical structures of these compounds were developed. This will facilitate their commercial synthesis and further investigation of the molecular mechanisms underlying their effects. The limitations of compounds previously screened for their anti-HBV effect, as well as future approaches to anti-HBV research, have also been discussed. [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic, various drug candidates have been developed, molnupiravir (MK-4482 and EIDD-2801), which is a new orally anti-viral agent under development for the treatment of COVID-19, is under study in the final stage of the clinical trial. Molnupiravir enhances the replication of viral RNA mutations in animals and humans. Due to the high demand for the synthesis of this drug, it was essential to develop an efficient and suitable synthetic pathway from raw material. In this study, molecular docking analysis on molnupiravir is examined also, the mechanism of action (MOA) and the recent synthetic pathway is reported. This review will be helpful to different disciplines such as medicinal chemistry, organic chemistry, biochemistry, and pharmacology. [ABSTRACT FROM AUTHOR]

PALETTE (Color range), VISIBLE spectra, PHOSPHORESCENCE, ELECTROMAGNETIC spectrum, EXCITON theory, and PHOTOLUMINESCENCE

We mapped the entire visible range of the electromagnetic spectrum and achieved white light emission (CIE: 0.31, 0.34) by combining the intrinsic ns‐fluorescence with ultralong ms‐phosphorescence from purely organic dual emitters. We realized small molecular materials showing high photoluminescence quantum yields (ΦL) in the solid state at room temperature, achieved by active exploration of the regioisomeric substitution space. Chromophore stacking‐supported stabilization of triplet excitons with assistance from enhanced intersystem crossing channels in the crystalline state played the primary role for the ultra‐long phosphorescence. This strategy covers the entire visible spectrum, based on organic phosphorescent emitters with versatile regioisomeric substitution patterns, and provides a single molecular source of white light with long lifetime (up to 163.5 ms) for the phosphorescent component, and high overall photoluminescence quantum yields (up to ΦL=20 %). [ABSTRACT FROM AUTHOR]

SMALL molecules, PROTEINS, PEPTIDES, ANTIBODY-drug conjugates, AMINATION, and ALDEHYDES

The aldehyde tag is appropriate to selectively label proteins, prepare antibody‐drug conjugates or to immobilize enzymes or antibodies for biotechnological and medical applications. The cysteine within the consensus sequence CxPxR of the aldehyde tag is specifically oxidized by the formylglycine‐generating enzyme (FGE) to the non‐canonical and electrophilic amino acid Cα‐formylglycine (FGly). Subsequent reductive amination is a common method for site‐directed immobilization, which usually results in poor immobilization efficiency due to the reaction conditions. Here, we introduce a new solid support like agarose modified with an aryl substituted pyrazolone (Knoevenagel reagent) that was obtained in a facile and efficient 2‐step synthesis. The modified agarose allowed the site‐selective and efficient immobilization of aldehyde‐containing small molecules, peptides and proteins – in particular enzymes – at physiological pH (6.2–8.2) without any additive or catalyst needed. In comparison to reductive amination, higher loadings and activities were achieved in various buffers at different concentrations and temperatures. [ABSTRACT FROM AUTHOR]

BIOACTIVE compounds, ENERGY dispersive X-ray spectroscopy, FOURIER transform infrared spectroscopy, SCANNING electron microscopes, and CATALYSTS recycling

A green and efficient method for the synthesis of chromene derivatives using TiO2 doped Ag as a photocatalyst under visible light irradiation at room temperature is reported. The advantages of our method are clean reaction condition, easy workup procedure, use of eco-friendly solvent, and recyclable catalyst and most importantly higher yield of the product. The photocatalyst was found to be highly efficient for the synthesis of chromene derivatives within a short reaction time. The photocatalyst was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and powder XRD technique and thermogravimetric analysis (TGA). In addition, the in-vitro study of helminths against S. obvelata were investigated and it was found that chromene derivatives were active against S. obvelata and showed no sign of acute toxicity in mice. [ABSTRACT FROM AUTHOR]

ANTIFUNGAL agent synthesis, STRUCTURE-activity relationships, ORGANIC chemistry, RUTHENIUM catalysts, BIOACTIVE compounds, PHARMACEUTICAL chemistry, and HETEROCYCLIC compounds

A pharmacophore system has been found as 1,2,3-triazole, a five-membered heterocycle ring with nitrogen heteroatoms. These heterocyclic compounds can be produced using azide-alkyne cycloaddition processes catalyzed by ruthenium or copper. The bioactive compounds demonstrated antitubercular, antibacterial, anti-inflammatory, anticancer, antioxidant, antiviral, and antidiabetic properties. This heterocycle molecule, in particular, with one or more 1,2,3-triazole cores has been found to have the most powerful antifungal effects. The goal of this review is to highlight recent developments in the synthesis and structure-activity relationship (SAR) investigation of this prospective fungicidal chemical. Also there have been explained drugs and mechanism of action of a triazole compound with antifungal activity. This review will be useful in a variety of fields, including medicinal chemistry, organic chemistry, mycology, and pharmacology. [ABSTRACT FROM AUTHOR]

BORONIC acids, NATURAL products, MOIETIES (Chemistry), and QUINOLINE

A polyprenyl side chain could be introduced into the heterocyclic quinoline moiety through Suzuki‐Miyaura coupling of the corresponding quinoline‐N‐oxide with a polyprenyl boronic acid. This tool could be utilized for the synthesis of the natural product Aurachin B from the myxobacterium Stigmatella aurantiaca. This prenylated quinoline could then be transformed into the related Aurachin A through an epoxidation‐ring opening cascade. [ABSTRACT FROM AUTHOR]

SOLID oxide fuel cells, CATHODES, MATERIALS science, SOLID electrolytes, HIGH temperatures, and OXYGEN reduction

Development of new functional materials with improved characteristics for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) is one of the most important tasks of modern materials science. High electrocatalytic activity in oxygen reduction reactions (ORR), chemical and thermomechanical compatibility with solid electrolytes, as well as stability at elevated temperatures are the most important requirements for cathode materials utilized in SOFCs. Layered oxygen-deficient double perovskites possess the complex of the above-mentioned properties, being one of the most promising cathode materials operating at intermediate temperatures. The present review summarizes the data available in the literature concerning crystal structure, thermal, electrotransport-related, and other functional properties (including electrochemical performance in ORR) of these materials. The main emphasis is placed on the state-of-art approaches to improving the functional characteristics of these complex oxides. [ABSTRACT FROM AUTHOR]

PEPTIDE synthesis, TRYPTOPHAN, ALKYL iodide, and AMINO acids

Mild transition‐metal catalysed cross‐couplings enable direct functionalisation of biocatalytically halogenated tryptophans with alkyl iodides, representing a new alternative for late‐stage derivatisations of halogenated aromatic amino acids. Moreover, this strategy enables preparation of (homo)tryptophan regioisomers in a simple two‐step synthesis using a Pd‐catalysed Negishi cross coupling. This method provides access to non‐canonical constitutional surrogates of tryptophan, ready for use in peptide synthesis. [ABSTRACT FROM AUTHOR]

POLYCYCLIC aromatic compounds and PERYLENE

Front Cover: Domino Dehydrative -Extension: A Facile Path to Extended Perylenes and Terrylenes (Chem. Eur. J. 69/2021) Keywords: domino reactions; perylenes; pi-extension; polycyclic aromatic compounds; terrylenes EN domino reactions perylenes pi-extension polycyclic aromatic compounds terrylenes 17264 17264 1 12/13/21 20211209 NES 211209 B Selective activation of identical functional groups b is one of the most challenging tasks in the realm of organic chemistry. Domino reactions, perylenes, pi-extension, polycyclic aromatic compounds, terrylenes. [Extracted from the article]

TEXT files and PERYLENE

Invited for the cover of this issue is the group of Konstantin Amsharov at Martin Luther University Halle–Wittenberg and Friedrich Alexander University Erlangen–Nürnberg. The image depicts tribenzoterrylene synthesized via the domino‐DPEX reaction. Read the full text of the article at10.1002/chem.202103098. [ABSTRACT FROM AUTHOR]

CELIAC disease, GLIADINS, CELL junctions, CHEMOKINE receptors, COCCIDIA, and JOINTS (Engineering)

Zonulin is a physiological modulator of intercellular tight junctions, which upregulation is involved in several diseases like celiac disease (CeD). The polyQ gliadin fragment binds to the CXCR3 chemokine receptor that activates zonulin upregulation, leading to increased intestinal permeability in humans. Here, we report a general hypothesis based on the structural connection between the polyQ sequence of the immunogenic CeD protein, gliadin, and enteric coccidian parasites proteins. Firstly, a novel interaction pathway between the parasites and the host is described based on the structural similarities between polyQ gliadin fragments and the parasite proteins. Secondly, a potential connection between coccidial infections as a novel environmental trigger of CeD is hypothesized. Therefore, this report represents a promising breakthrough for coccidian research and points out the potential role of coccidian parasites as a novel trigger of CeD that might define a preventive strategy for gluten‐related disorders in general. Also see the video abstract here: https://youtu.be/oMaQasStcFI [ABSTRACT FROM AUTHOR]

CRYSTAL structure

C27H21N3OS2Sn, triclinic, P 1 ‾ $P‾{1}$ (no. 2), a = 11.064(3) Å, b = 11.538(3) Å, c = 12.257(3) Å, V = 1258.2(6) Å3, Z = 2, Rgt(F) = 0.0316, wRref(F2) = 0.0664, T = 298 K. [ABSTRACT FROM AUTHOR]

COORDINATION polymers, TERPHENYL, SPIN crossover, IRON, SPINE, and LIGANDS

A Schiff base‐like ligand H2LTerPh featuring a para‐terphenyl backbone was synthesized and converted in two steps to an octahedral iron(II) coordination polymer with 1,2‐bis‐(4‐pyridyl)‐ethylene as bridging ligand. Single crystal X‐ray structure analysis was possible for the free ligand and the two octahedral iron(II) complexes. The Schiff base‐like ligand features a [N2O2]2− coordination sphere for the metal center and the para‐terphenyl backbone introduces intrinsic steric constraint. Characterization of the coordination polymer with an N4O2 coordination sphere around the iron center via magnetic measurements (SQUID) and room temperature Mössbauer spectroscopy revealed HS character in the entire temperature range investigated. Structure modelling with DFT calculations supports the findings, but support also the possibility of spin crossover in solution. [ABSTRACT FROM AUTHOR]

TETRAPHENYLETHYLENE, THERAPEUTICS, LUMINOPHORES, ORGANIC electronics, and SUPRAMOLECULAR chemistry

[Display omitted] • Various luminogens with AIE property (AIEgens) have been broadly utilized in biomedical field. • Tetraphenylethylene derivatives have demonstrated as most promising AIEgen due to their capability of self-organization and conjugation. • They are used in different fields including organic and therapeutic science, supramolecular chemistry, organic electronics and cancer therapy. • This review encompasses the recent advances of TPE based AIE-active luminophores and their potential applications in biomolecular science. The development of aggregation-induced emission (AIE) has received extreme considerations from basic and clinical researches. To date, various luminogens with AIE property (AIEgens) have been broadly utilized in optoelectronic devices, fluorescent bio-probes, drug delivery, anticancer and chemosensors and many more. Scientists have likewise dedicated to investigating the possibilities of AIEgens in the biomedical field. Among the various AIE luminophores studied, tetraphenylethylene (TPE) derivatives have demonstrated as most promising AIEgen, owing to their capacity in self-organization and conjugation with aggregation-caused quenching (ACQ) fluorophores to form larger multi-component assemblies. It likewise generally utilized in different fields, like organic and therapeutic science, supramolecular chemistry, organic electronics, cancer therapy, apoptosis and inflammation, microorganism imaging therapy etc. This review encompasses the recent advances of TPE based AIE-active luminophores and their potential applications in biomolecular science. [ABSTRACT FROM AUTHOR]

RESEARCH protocols, ANIMAL feeds, PLANT residues, SPRINTING, AGRICULTURAL climatology, BATS, FIELD research, and AQUATIC invertebrates

Current farm systems rely on the use of Plant Protection Products (PPP) to secure high productivity and control threats to the quality of the crops. However, PPP use may have considerable impacts on human health and the environment. A study protocol is presented aiming to determine the occurrence and levels of PPP residues in plants (crops), animals (livestock), humans and other non-target species (ecosystem representatives) for exposure modelling and impact assessment. To achieve this, we designed a cross-sectional study to compare conventional and organic farm systems across Europe. Environmental and biological samples were/are being/will be collected during the 2021 growing season, at 10 case study sites in Europe covering a range of climate zones and crops. An additional study site in Argentina will inform the impact of PPP use on growing soybean which is an important European protein-source in animal feed. We will study the impact of PPP mixtures using an integrated risk assessment methodology. The fate of PPP in environmental media (soil, water and air) and in the homes of farmers will be monitored. This will be complemented by biomonitoring to estimate PPP uptake by humans and farm animals (cow, goat, sheep and chicken), and by collection of samples from non-target species (earthworms, fish, aquatic and terrestrial macroinvertebrates, bats, and farm cats). We will use data on PPP residues in environmental and biological matrices to estimate exposures by modelling. These exposure estimates together with health and toxicity data will be used to predict the impact of PPP use on environment, plant, animal and human health. The outcome of this study will then be integrated with socio-economic information leading to an overall assessment used to identify transition pathways towards more sustainable plant protection and inform decision makers, practitioners and other stakeholders regarding farming practices and land use policy. [ABSTRACT FROM AUTHOR]

PHTHALOCYANINE derivatives, ANTINEOPLASTIC agents, ANTI-infective agents, ZINC, PHTHALOCYANINES, and HYDROPHILIC compounds

In this contribution we report on the synthesis, characterization and application of water‐soluble zinc(II) phthalocyanines, which are decorated with four or eight umbelliferone moieties for photodynamic therapy (PDT). These compounds are linked peripherally to zinc(II) phthalocyanine by a triethylene glycol linker attached to pyridines, leading to cationic pyridinium units, able to increase the water solubility of the system. Beside their photophysical properties they were analyzed concerning their cellular distribution in human hepatocyte carcinoma (HepG2) cells as well as their phototoxicity towards HepG2 cells, Gram‐positive (S. aureus strain 3150/12 and B. subtilis strain DB104) and Gram‐negative bacteria (E. coli strain UTI89 and E. coli strain Nissle 1917). At low light doses and concentrations, they exhibit superb antimicrobial activity against Gram‐positive bacteria as well as anti‐tumor activity against HepG2. They are even capable to inactivate Gram‐negative bacteria, whereas the dark toxicity remains low. These unique water‐soluble compounds can be regarded as all‐in‐one type photosensitizers with broad applications ranges in the future. [ABSTRACT FROM AUTHOR]

ACENES, DUMBBELLS, DIMERIZATION, POLYCYCLIC aromatic hydrocarbons, and DIMERS

Two‐dimensional acenes are promising candidates for applications in single‐molecule spectroscopy due to the electronic properties caused by their zig‐zag periphery. However, synthetic access to their dimers remains unexplored because of low solubility and reduced stability. Herein we report a facile approach towards two‐dimensional acenes dimers on the example of 2.3,8.9‐dibenzanthanthrene (DBATT) connected via rigid linker. The exploitation of dehydrative π‐extension on the last step of the synthesis allows avoiding difficulties connected with cumbersome purification of low soluble products. The technique was shown to be applicable for the synthesis of DBATT dimers connected rigidly with conjugated and non‐conjugated linkers, containing alternating para‐phenylene and bicyclo[2.2.2]octane moieties. [ABSTRACT FROM AUTHOR]

TITANIUM dioxide, SURFACE coatings, COMPOSITE coating, ELECTROPLATING, PROTECTIVE coatings, LINEAR polarization, and IMPEDANCE spectroscopy

In this work, Cu–Sn–TiO2 composite coatings were electrochemically obtained from a sulfate bath containing 0–10 g/L of TiO2 nanoparticles. The effect of TiO2 particles on kinetics of cathodic electrodeposition has been studied by linear sweep voltammetry and chronopotentiometry. As compared to the Cu–Sn alloy, the Cu–Sn–TiO2 composite coatings show rougher surfaces with TiO2 agglomerates embedded in the metal matrix. The highest average amount of included TiO2 is 1.7 wt.%, in the case of the bath containing 5 g/L thereof. Composite coatings showed significantly improved antibacterial properties towards E. coli ATCC 8739 bacteria as compared to the Cu–Sn coatings of the same composition. Such improvement has been connected with the corrosion resistance of the composites studied by linear polarization and electrochemical impedance spectroscopy. In the bacterial media and 3% NaCl solutions, Cu–Sn–TiO2 composite coatings have lower corrosion resistance as compared to Cu–Sn alloys, which is caused by the nonuniformity of the surface. [ABSTRACT FROM AUTHOR]

MOLECULES, SUPRAMOLECULAR chemistry, and ANTINEOPLASTIC agents

Keywords: Antitumor agents; Rotaxanes; Sensors; Supramolecular chemistry; Theranostics EN Antitumor agents Rotaxanes Sensors Supramolecular chemistry Theranostics 5104 5104 1 10/19/21 20211007 NES 211007 B The Front Cover b shows an artistic rendition of a cell culture incorporating mechanically interlocked molecules (MIMs), illustrating different strategies in which they have been applied for biological and medical functions. Front Cover: Mechanically Interlocked Molecules for Biomedical Applications (Eur. J. Org. Antitumor agents, Rotaxanes, Sensors, Supramolecular chemistry, Theranostics. [Extracted from the article]

TARGETED drug delivery and MOLECULES

Mechanically interlocked molecules (MIMs) carry great potential in different fields of chemistry, based on their specific structures, their internal dynamics, their stimuli‐responsive behavior, and other unique features of the mechanical bond. This minireview presents some of the most recent developments in their use for medical and biological applications. For example, they have been used to influence, enhance or block the action of therapeutic agents to enable targeted drug delivery. The dynamic structural properties have been used to generate switches and transporters, as well as sensors for various medically relevant species. Building MIMs by incorporating biomolecules like DNA and proteins has served as a novel way to control their properties. [ABSTRACT FROM AUTHOR]

ACIDS

A double-helical supramolecular structure was formed by self-assembly of 1,1′-binaphthyl-based bisguanidines and bisphosphoric acids. Interestingly the homochiral (S,S) + (S,S)-pair forms a left-handed double-helix, while the heterochiral (S,S) + (R,R)-pair forms a non-helical dimer. [ABSTRACT FROM AUTHOR]

VIBRIO cholerae, TRANSCRIPTION factors, PROTEIN-protein interactions, INFORMATION organization, ORGANIZATIONAL behavior, and GENETIC regulation

ToxR represents an essential transcription factor of Vibrio cholerae, which is involved in the regulation of multiple, mainly virulence associated genes. Its versatile functionality as activator, repressor or coactivator suggests a complex regulatory mechanism, whose clarification is essential for a better understanding of the virulence expression system of V. cholerae. Here, we provide structural information elucidating the organization and binding behavior of the cytoplasmic DNA-binding domain of ToxR (cToxR), containing a winged helix-turn-helix (wHTH) motif. Our analysis reveals unexpected structural features of this domain expanding our knowledge of a poorly defined subfamily of wHTH proteins. cToxR forms an extraordinary long α-loop and furthermore has an additional C-terminal beta strand, contacting the N-terminus and thus leading to a compact fold. The identification of the exact interactions between ToxR and DNA contributes to a deeper understanding of this regulatory process. Our findings not only show general binding of the soluble cytoplasmic domain of ToxR to DNA, but also indicate a higher affinity for the toxT motif. These results support the current theory of ToxR being a "DNA-catcher" to enable binding of the transcription factor TcpP and thus activation of virulence-associated toxT transcription. Although, TcpP and ToxR interaction is assumed to be crucial in the activation of the toxT genes, we could not detect an interaction event of their isolated cytoplasmic domains. We therefore conclude that other factors are needed to establish this protein-protein interaction, e.g., membrane attachment, the presence of their full-length proteins and/or other intermediary proteins that may facilitate binding. [ABSTRACT FROM AUTHOR]

MACROCYCLIC compounds, DENSITY functional theory, SUPRAMOLECULAR chemistry, MOLECULES, PHOSPHORESCENCE, BLUE light, and FUNCTIONAL analysis

Construction of synthetic macrocyclic host that can bind with neutral molecules and anions has potential applications in supramolecular chemistry. Herein, we have designed and synthesized blue light emitting an unsymmetrical neutral bis‐urea macrocyclic host. This macrocycle can bind with neutral DMF molecule (1:1) as well as Cl− ion (1:1) through noncovalent interactions. X‐Ray crystal structure, 1H NMR titrations with Job's Plot, HRMS with isotropic distribution pattern, FT‐IR, and density functional theory analysis revealed the binding of bis‐urea macrocyclic host with the guest molecule. [ABSTRACT FROM AUTHOR]

GOLD nanoparticles, TEMPERATURE control, HIGH temperatures, PYRROLES, and NANOPARTICLES

We report a pH‐ and temperature‐controlled reversible self‐assembly of Au‐nanoparticles (AuNPs) in water, based on their surface modification with cationic guanidiniocarbonyl pyrrole (GCP) and zwitterionic guanidiniocarbonyl pyrrole carboxylate (GCPZ) binding motifs. When both binding motifs are installed in a carefully balanced ratio, the resulting functionalized AuNPs self‐assemble at pH 1, pH 7 and pH 13, whereas they disassemble at pH 3 and pH 11. Further disassembly can be achieved at elevated temperatures at pH 1 and pH 13. Thus, we were able to prepare functionalized nanoparticles that can be assembled/disassembled in seven alternating regimes, simply controlled by pH and temperature. [ABSTRACT FROM AUTHOR]

NON-equilibrium reactions

Dissipative systems, nonequilibrium processes, reaction mechanisms Keywords: dissipative systems; nonequilibrium processes; reaction mechanisms EN dissipative systems nonequilibrium processes reaction mechanisms 1 1 1 09/17/21 20210915 NES 210915 B The way chemical transformations b are described by models based on microscopic reversibility does not take into account the irreversibility of natural processes, and therefore, in complex chemical networks working in open systems, misunderstandings may arise about the origin and causes of the stability of non-equilibrium stationary states, and general constraints on evolution in systems that are far from equilibrium. [Extracted from the article]

CHEMICAL systems, CHEMICAL amplification, CHEMICAL plants, and EQUILIBRIUM

The way chemical transformations are described by models based on microscopic reversibility does not take into account the irreversibility of natural processes, and therefore, in complex chemical networks working in open systems, misunderstandings may arise about the origin and causes of the stability of non‐equilibrium stationary states, and general constraints on evolution in systems that are far from equilibrium. In order to be correctly simulated and understood, the chemical behavior of complex systems requires time‐dependent models, otherwise the irreversibility of natural phenomena is overlooked. Micro reversible models based on the reaction‐coordinate model are time invariant and are therefore unable to explain the evolution of open dissipative systems. The important points necessary for improving the modeling and simulations of complex chemical systems are: a) understanding the physical potential related to the entropy production rate, which is in general an inexact differential of a state function, and b) the interpretation and application of the so‐called general evolution criterion (GEC), which is the general thermodynamic constraint for the evolution of dissipative chemical systems. [ABSTRACT FROM AUTHOR]