The azido-tetrazole tautomerism in azoles and its relationships with aromaticity and NMR properties

The properties of 41 neutral molecules (azoles) together with 13 transition states as well as of 16 anions (azolates) with seven transition states belonging to the series of azido/azoles, have been calculated at the B3LYP/6-31G(d) and at the G3B3 levels. Energies, NICS, and bond critical points are used to discuss the ring-chain tautomerism of these compounds in relation with the magnetic aromaticity of the azoles (imidazoles, benzimidazoles, pyrazoles, indazoles, 1,2,4-triazoles, 1,2,3-triazoles and tetrazoles). The removal of the N–H proton has a considerable effect on the azido/tetrazole equilibrium and corresponds to a large stabilization (73 kJ mol^?1 in average) of the tetrazoles. Cioslowski’s exothermicity is related to the energy barriers (TSs). A study of the E/Z isomerism of the azides, determination of NICS(1) values and AIM analysis were also carried out.     

Coumarin-1,2,3-triazole hybrid derivatives: Green synthesis and DFT calculations

A series of new 1,2,3-triazole-coumarin hybrid system are synthesized from the click reaction between 3-azido coumarin and different aromatic terminal alkyne derivatives in a green manner. All compounds are characterized by IR, NMR and UV–VIS spectroscopy. The experimental observations are further supported by DFT computational studies to investigate the effect of substituents at para position in these compounds.     

Computational study of new 1,2,3-triazole derivative of lithocholic acid: Structural aspects,non-linear optical properties and molecular docking studies as potential PTP 1B enzyme inhibitor

We have reported synthesis of a novel 1,2,3-triazole conjugate of lithocholic acid by 1,3-dipolar cycloaddition reaction. The molecular properties such as geometry, conformations, bond lengths and dihedral angles were investigated theoretically. The bond order analysis was performed using Wiberg bond order (WBO), Fuzzy bond order (FBO) and Laplacian bond order (MBO) method. Electronic properties of molecule such as electrostatic surface potential analysis, frontier molecular orbital analysis, reduced density gradient, total density of states, and global chemical reactivity indices have been investigated. The nonlinear optical properties were also investigated. Total dipole moment, mean polarizability and hyperpolarizability were found to be much higher than standard urea molecule which suggests that it could act as potential NLO material. The molecular docking calculations are also performed to investigate its potential as PTP 1B enzyme inhibitor.     

1,2,3-triazole derivative: Synthesis,characterization, DFT,molecular docking study and antibacterial-antileishmanial activities

In this study, 4-((1-(4-chlorobenzyl)-1H-1,2,3-triazole-4-yl)methoxy)-3-methoxybenzaldehyde (I) was synthesized and molecular structure of compound I was confirmed by FTIR and NMR (¹H and ¹³C NMR) spectroscopic methods. The geometric structure of compound I was optimized by DFT/B3LYP method using 6–311++G(d, p) basis set. The molecular docking study was carried out against six different proteins. The antibacterial and antileishmanial activities of compound I were tested by microdilution broth with Alamar blue method and minimum inhibitor concentrations (MIC) were determined. According to the test results, it was found to be effective against eleven types of bacteria at different concentrations (MIC: 312–5000 ​μg/mL). In addition, compound I was not effective against leishmania species at the concentrations that were examined.     

The structure of azines derived from C‐formyl‐1H‐imidazoles in solution and in the solid state: tautomerism,configurational and conformational studies

The structures of three azines derived from 2‐formylimidazole, 4(5)‐formylimidazole, and 4(5)‐formyl‐5(4)‐methylimidazole have been determined in solution and in the solid state. Density Functional Theory (DFT) Polarizable Continuum Model (PCM) calculations (geometries, energies, and chemical shifts), NMR [solution and cross polarization magic‐angle spinning (CPMAS)], and X‐ray crystallography [azine of 4(5)‐formylimidazole] have been used. The configuration around the central C = N bonds has been determined and some insights about prototropic tautomerism and conformation have been gained. Copyright © 2013 John Wiley & Sons, Ltd.     

DFT calculations of amine‐imine tautomerism in some pyrimidine derivatives and their 1:1 and 1:2 complexes with water

Amine‐Imine tautomerization in 2‐amino‐pyrimidine (I), 2‐amino‐4,6‐dichloropyrimidine (II), 2‐amino‐4,6‐dimethylpyrimidine (III), and 2‐amino‐4,6‐dimethoxypyrimidine (IV) and their 1:1 and 1:2 H‐bonded complexes with water have been studied using the B3LYP/6‐31++G** method. Optimum molecular geometries, electronic properties, and energetics of these systems have been discussed. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Identification of the monoanions and of their complexes with lithium salts possibly formed in solution during the alkylation of lithiated phenylacetonitrile dianions: infrared spectroscopy and density functional theory calculations

The carbanionic species possibly formed during the first alkylation step of phenylacetonitrile lithiated anion by CH(3)I and PhCH(2)Cl in THF-hexane solution and their complexes with the lithium salt formed have been observed by infrared spectrometry and characterized by density functional theory calculations. The spectra of alkylated phenylacetonitrile lithiated anion monomers and dimers have been identified in good agreement with calculations. The wave numbers of the vibrational modes of the alkylated species differ significantly from those of PhCHCNLi species, but do not depend appreciably on the substituent nature. Nevertheless with the methyl substituent, the isomerization equilibrium of the monomer is noticeably shifted toward the bridged (C-lithiated) species. The formation of a heterodimer at the expense of the dimer after addition of LiCl has been confirmed by experiment.