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A range of novel simple gold(III) compounds has been synthesized in their monocrystalline form, including two previously unknown chloro-complexes of Au3+ with 2-cyanopyridine or 3-cyanopyridine, respectively. Our investigations have revealed the intricate nature of the reaction between 2-cyanopyridine and tetrachloroauric acid, yielding at least three distinct products. The main product, obtained in high yield, is a salt featuring a tetrachloroauric anion and a pyridinium cation stabilized by a hydrogen bond to a further 2-cyanopyridine molecule. Moreover, we observed the in-situ formation of a 2-cyanopyridine-AuCl 3 complex, which undergoes hydrolysis of the nitrile bond to yield a picolinamide-Au(III) complex. The complexes were characterized by IR and Raman spectroscopies, NMR spectroscopy, and single-crystal XRD studies. Additional computational studies were conducted to explain unusual spectral features, the observed disparities in the complexation reactions of the three isomeric cyanopyridine ligands and the distinct reactivity of the complex with 2-cyanopyridine. Based on these studies, we propose a mechanism for the catalyzed hydrolysis of the nitrile bond within the Au(III) complex. Finally, we assessed the antimicrobial efficacy of the synthesized gold(III) complexes against a spectrum of bacteria and fungi. [ABSTRACT FROM AUTHOR]

[Display omitted] • The production of antioxidative mineral-binding peptides (AMBPs) is described. • Factors that contribute to the effectiveness of AMBPs are presented. • Description of AMBPs' mechanisms provided. • Bioavailability and intestinal absorption of AMBPs are discussed. The discovery of food-derived biopeptides is becoming increasingly prevalent in the scientific community. Some peptides possess multiple biological functions that can confer health benefits through various mechanisms following ingestion. The present review targets food-derived antioxidant and mineral-binding peptides (AMBPs) including their production procedure i.e., enzymolysis, separation, and purification (through membrane separation, gel filtration, ion exchange chromatography, and high-performance liquid chromatography), followed by mass spectrometry for identification. The most effective AMBPs exhibit radical scavenging activity, detoxification of excess metals, and reduction of lipid peroxidation to facilitate mineral bioavailability. The metal complexation of AMBPs necessitates an optimal metal-to-peptide ratio, specific ligands, precursors, and complexation reactions. The bioavailability and absorbability mechanisms of AMBPs are also elucidated, encompassing gastrointestinal stability, binding mode, and cell absorption machinery. Ultimately, further considerations regarding additional research on AMBPs are provided, which will assist researchers in conducting more comprehensive studies to promote the effective and safe use of AMBPs. [ABSTRACT FROM AUTHOR]

The current study focuses on the molecular behavior of the azobenzene-4,4'-dicarboxylate/ α -CD pseudorotaxane and how it is affected by changes in pH. A combination of experimental measurements and molecular simulations were used, including different computational calculations, to evaluate the kinetic and thermodynamic aspects of the formation of this mechanically bound architecture. The research involved determining the formation rate constants for these complexes at different pH values and conducting a comprehensive kinetic study. Additionally, the binding affinity and complexation reaction was analyzed using free energy profiles derived from umbrella sampling in molecular dynamics simulations. To gain a better understanding of the energetic and structural aspects of the complexes, hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) calculations were employed. The intermolecular interactions that stabilize the pseudorotaxanes were characterized using quantum theory of atoms in molecules (QTAIM) and Molecular Electrostatic Potentials (MEPs)   • Pseudorotaxane formation occurs simultaneously via two competitive pathways. • Azobenzene spontaneously forms a pseudorotaxane with neutral α -CD through the Tail side. • Azobenzene forms a less stable pseudorotaxane with charged α -CD. • MD simulations and QM calculations are in complete agreement with experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new ligand (2a) was synthesized by using a coupling agent N,N′- dicyclohexylcarbodiimide. • The geometry of a new mononuclear Zn(II) complex (3a) is tetrahedral. • 2a and 3a emitted a blue and a strong greenish-blue fluorescent, respectively in pure DMSO. • This fluorescence displayed very low emission efficiency in aqueous and acidic DMSO–H 2 O. • 1a–3a have weaker DPPH radical scavenging activity than ascorbic acid. Novel amido-Schiff base 3,5-bis((2-hydroxybenzylidene)amino)- N -(2-hydroxyphenyl)benzamide (2a) has been obtained by the reaction of Schiff base 1a with 2-hydroxyaniline in the presence of coupling agent N,N′- dicyclohexylcarbodiimide. Schiff base (1a) which serves as the starting compound in amide synthesis was produced from the condensation of 3,5-diaminobenzoic acid with salicylaldehyde in a 1:2 mol ratio. Tetrahedral geometry with 1:1 [M:L] stoichiometry Zn(II) complex (3a) was newly synthesized by the complexation reaction of ligand 2a with zinc(II) nitrate. 1a and 2a displayed a broad emission band at λ em = 456 and 472 nm with a blue fluorescent in pure DMSO, while 3a emitted a strong greenish-blue fluorescent with the λ em = 485 nm (λ exc = 365 nm). The fluorescence efficiency of 1a was poor compared to the others. The λ em in aqueous DMSO solution (v/v, 1:1) had ∼8–33 nm red-shift with respect to that of pure solution. The λ em gave ∼1–15 nm red-shift with very low emission efficiency in acidic DMSO media. The results suggested that the aggregation caused quenching properties of 1a–3a in pure, aqueous, and acidic DMSO system with a 50 % water fraction. The fluorescence of the compounds appeared to be visibly very bright in basic DMSO media. All the compounds were also screened for antioxidant activity using UV–Vis spectroscopy. They were found to be not effective DPPH radical scavengers in DMSO. [ABSTRACT FROM AUTHOR]