Electroreduction of Bi(III) Ions at a Cyclically Renewable Liquid Silver Amalgam Film Electrode in the Presence of Methionine

The catalytic influence of methionine (Mt) on the electroreduction of Bi(III) ions on the novel, cyclically renewable liquid silver amalgam film electrode (R–AgLAFE) in a non-complexing electrolyte solution was examined. The presence of methionine leads to a multistep reaction mechanism, where the transfer of the first electron is the rate limiting step, which is the subject of catalytic augmentation. The catalytic activity of methionine is a consequence of its ability to remove water molecules from the bismuth ion coordination sphere, as well as to form active complexes on the electrode surface, facilitating the electron transfer process.

Tetraphenylethylene AIEgen bearing thiophenylbipyridine receptor for selective detection of copper(II) ion

Highly emissive tetraphenylethylene (TPE) chromophore appended thiophenylbipyridine pendant as a receptor (1) site has been successively synthesized via multistep reaction pathway. The synthesized chromophore 1 was been well characterized by...

Synthesis, Characterization and Preliminary Anti-inflammatory Evaluation of New Fenoprofen Hydrazone Derivatives

New hydrazone derivatives of Fenoprofen were synthesized and evaluated for their anti-inflammatory activity by means of egg white induced paw edema method. All the synthesized target compounds were characterized by FT-IR spectroscopy, 1HNMR analysis and by measure of their physical properties. The synthesis of the target compounds(H1-H4) was accomplished by multistep reaction procedures. The synthesized target compounds were show activity in reducing paw edema thickness and their anti-inflammatory effect was comparable to that of the standard (Fenoprofen) except for compound H3 which show anti-inflammatory activity higher than Fenoprofen.

Synthesis of sandwich type acyclic tetra-nuclear silver(I)-N-heterocyclic carbene complexes for wound healing applications

Two meta-xylyl linked tetrakis-benzimidazolium salts (L1-L2) as multidentate ligands and two respective silver complexes (C1 and C2) were synthesized. A multistep reaction was done at room temperature, starting with simple benzimidazole and alkyl halides, going through precursors and salt formation by reflux and finally in situ deprotonation of tetrabenzimidazolium salts with Ag2O to yield respective tetra-nuclear Ag(I)-N-heterocyclic Carbene (NHC) complexes. Propyl and butyl groups were bonded at the terminal positions of tetra-azolium open chain salts. Characterization of compounds was done by analytical and spectroscopic techniques. On the basis of spectroscopic data, a chemical structure with open chains having four Ag(I) ions sandwiched between NHC layers was established. Potential of synthesized complexes (C1 & C2) for wound contraction was evaluated and compared with standard wound contraction gel. Percentage wound contraction of both complexes was found very close to that of standard drug used in parallel.

Computational generation of an annotated gigalibrary of synthesizable, composite peptidic macrocycles

Peptidomimetic macrocycles have the potential to regulate challenging therapeutic targets. Structures of this type having precise shapes and drug-like character are particularly coveted, but are relatively difficult to synthesize. Our laboratory has developed robust methods that integrate small-peptide units into designed scaffolds. These methods create macrocycles and embed condensed heterocycles to diversify outcomes and improve pharmacological properties. The hypothetical scope of the methodology is vast and far outpaces the capacity of our experimental format. We now describe a computational rendering of our methodology that creates an in silico three-dimensional library of composite peptidic macrocycles. Our open-source platform, CPMG (Composite Peptide Macrocycle Generator), has algorithmically generated a library of 2,020,794,198 macrocycles that can result from the multistep reaction sequences we have developed. Structures are generated based on predicted site reactivity and filtered on the basis of physical and three-dimensional properties to identify maximally diverse compounds for prioritization. For conformational analyses, we also introduce ConfBuster++, an RDKit port of the open-source software ConfBuster, which allows facile integration with CPMG and ready parallelization for better scalability. Our approach deeply probes ligand space accessible via our synthetic methodology and provides a resource for large-scale virtual screening.

Decoding the Kinetic Limitations of Plasmon Catalysis: The Case of 4-Nitrothiophenol Dimerization

Plasmon-mediated chemistry presents an intriguing new approach to photocatalysis. However, the reaction enhancement<br>mechanism is not well understood. In particular, the relative importance of plasmon-generated hot charges and<br>photoheating are strongly debated. In this article, we evaluate the influence of microscopic photoheating on the kinetics of<br>a model plasmon-catalyzed reaction: the light-induced 4-nitrothiophenol (4NTP) to 4,4’-dimercaptoazobenzene (DMAB)<br>dimerization. Direct measurement of the reaction temperature by nanoparticle Raman-thermometry demonstrated that<br>the thermal effect plays a dominant role in the kinetic limitations of this multistep reaction. On the same time, no reaction<br>is possible by dark heating to the same temperature. This shows that plasmon nanoparticles have the unique ability to<br>enhance several steps of complex tandem reactions simultaneously. These results provide insight into the role of hot<br>electron and thermal effects in plasmonic catalysis of complex organic reactions, which highly important for the ongoing<br>development of plasmon based photosynthesis. <br>

Decoding the Kinetic Limitations of Plasmon Catalysis: The Case of 4-Nitrothiophenol Dimerization

Plasmon-mediated chemistry presents an intriguing new approach to photocatalysis. However, the reaction enhancement<br>mechanism is not well understood. In particular, the relative importance of plasmon-generated hot charges and<br>photoheating are strongly debated. In this article, we evaluate the influence of microscopic photoheating on the kinetics of<br>a model plasmon-catalyzed reaction: the light-induced 4-nitrothiophenol (4NTP) to 4,4’-dimercaptoazobenzene (DMAB)<br>dimerization. Direct measurement of the reaction temperature by nanoparticle Raman-thermometry demonstrated that<br>the thermal effect plays a dominant role in the kinetic limitations of this multistep reaction. On the same time, no reaction<br>is possible by dark heating to the same temperature. This shows that plasmon nanoparticles have the unique ability to<br>enhance several steps of complex tandem reactions simultaneously. These results provide insight into the role of hot<br>electron and thermal effects in plasmonic catalysis of complex organic reactions, which highly important for the ongoing<br>development of plasmon based photosynthesis. <br>

Structure of the 4-hydroxy-tetrahydrodipicolinate synthase from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV and the phylogeny of the aminotransferase pathway

The enzyme 4-hydroxy-tetrahydrodipicolinate synthase (DapA) is involved in the production of lysine and precursor molecules for peptidoglycan synthesis. In a multistep reaction, DapA converts pyruvate and L-aspartate-4-semialdehyde to 4-hydroxy-2,3,4,5-tetrahydrodipicolinic acid. In many organisms, lysine binds allosterically to DapA, causing negative feedback, thus making the enzyme an important regulatory component of the pathway. Here, the 2.1 Å resolution crystal structure of DapA from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV is reported. The enzyme crystallized as a contaminant of a protein preparation from native biomass. Genome analysis reveals that M. fumariolicum SolV utilizes the recently discovered aminotransferase pathway for lysine biosynthesis. Phylogenetic analyses of the genes involved in this pathway shed new light on the distribution of this pathway across the three domains of life.

An Improved Synthesis of Key Intermediate to the Formation of Selected Indolin-2-Ones Derivatives Incorporating Ultrasound and Deep Eutectic Solvent (DES) Blend of Techniques, for Some Biological Activities and Molecular Docking Studies

We have developed a new idea to synthesize a key intermediate molecule by utilizing deep eutectic solvent (DES) and ultrasound in a multistep reaction to ensure process cost-effectiveness. To confirm the stability of reagents with DES, electronic energies were calculated at the B3LYP/6-31+G(d,p) level of theory. DES stabilized the reagents mainly due to strong intermolecular hydrogen bonding. Key intermediate (3) and final compounds (4a–n) were synthesized in a higher yield of 95% and 80%–88%, respectively. Further, final compounds (4a–n) were assessed for their anti-inflammatory, analgesic, ulcerogenic, and lipid peroxidation. The compounds 4f, 4g, 4j, 4l, and 4m showed good anti-inflammatory activity, while 4f, 4i, and 4n exhibited very good analgesic activity as compared to the standard drug. The ulcerogenicity of selected compounds was far less than the indomethacin. The ligands had also shown a good docking score (4f = −6.859 kcal/mol and 4n = −7.077 kcal/mol) as compared to control indomethacin (−6.109 kcal/mol) against the target protein COX-2. These derivatives have the potential to block this enzyme and can be used as NSAID. The state-of-art DFT theory was used to validate the lipid peroxidation mechanism of the active compounds which was in good agreement with the variations of BDEs and IP of the tested compounds.