3-Methylthio-4-phenyl-5-phenylamino-1,2,4-triazole hexabromotellurate:X-ray and computational study

Theoretical study on charge distribution in cetylpyridinium cationic surfactant

Here, we report the electrostatic potential maxima and partial atomic charges evaluated on cetylpyridinium cation. The Hartree-Fock method and six DFT functionals (namely, PBE, TPSS, B3LYP, PBE0, M06, and wB97) were used to calculate partial atomic charges via CHELPG, Mulliken, Löwdin, Hirshfeld, and natural population schemes. Calculations were performed for the gas phase and for the CPCM water solvated cation, resulting in a set of 70 types of partial atomic charges. The main tendencies in charge deviations were discussed. In comparison with the electrostatic potential-based CHELPG partial charges, Hirshfeld, Mulliken, Löwdin, and NPA partitioning schema lead to an almost steady decrease in the partial charges in the cetyl chain. This agreed closely with the redistribution of electrostatic potential mapped onto the 0.002 e/Bohr³ isodensity surface.

A DFT study of fulvic acid binding with bivalent metals: Cd, Cu, Mg, Ni, Pb, Zn

3,7,8-Trihydroxy-3-methyl-10-oxo-4,10-dihydro-1H,3H-pyrano [4,3-b]chromene-9-carboxylic acid is a structurally well-characterized fulvic acid (FA) capable to act as a polyfunctional bidentate ligand in the complexes with metal ions. Investigations of the formation mechanisms and structure of the above-mentioned FA complexes with bivalent metals [Cd(II), Cu(II), Mg(II), Ni(II), Pb(II) and Zn(II)] are presently an actual and trending topic in the modern chemistry of humic and fulvic acids. Furthermore, the importance of the theoretical DFT investigations of binding of metals with fulvic acids is stipulated by the lack of the relevant experimental structural data for such complexes. The quantum chemical calculations have shown that, of the four possible FA tautomers, the two FA forms are more stable. The wavefunction analysis and computed reactivity descriptors (electrostatic potential, Hirshfeld surface analysis, natural population analysis charges, and condensed Fukui indexes) give the insight on the properties and reactive ability of these two different forms of the FA. The computed thermochemical parameters of the ion-exchange reaction explain the metal binding affinity and selectivity of the FA forms.

[1,3]Thiazolo[3,2-b][1,2,4]triazol-7-ium salts: synthesis, properties and structural studies

The reactions of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium salts with nucleophiles were investigated. Theoretical investigation of reactivity descriptors and structural parameters of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium cation was carried out, and the reactivity centers of the model salts were located. An efficient general method for the synthesis of novel poly-functional derivatives of symmetric triazoles from [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium halides was developed. The structures of the synthesized compounds were confirmed using proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), Fourier-transform infrared spectroscopy (FTIR) and single-crystal X-ray analysis.