Derivatives of pyridine and thiazole hybrid: Synthesis, DFT, biological evaluation via antimicrobial and DNA cleavage activity.

A novel series of the 2-pyridine substituted 3a-e and 4-pyridine substituted 4a-e thiazole derivatives were synthesized, characterized, and evaluated for the biological activity. Crystallographic parameters and inter- and intramolecular interactions of 3a and 3c single crystals were examined through XRD analysis. The chemical reactivity potentials of the compounds were evaluated, by comparing with a theoretical approach based on DFT. The biological activity properties of synthesized compounds were determined by antimicrobial activity with Gram positive, Gram negative, Yeast via minimal inhibitory concentration (MIC) method and DNA cleavage activity studies. The most obvious findings to emerge from this study are that on the basis of both biological activity and chemical reactivity 4-pyridine thiazole hybrid compounds 4a-e showed more potent activity than 3a-e. In general, the antimicrobial activity of synthesized compounds follows the Bacillus cereus > Staphylococcus aureus > Candida albicans > Escherichia coli > Pseudomonas aeruginosa. The most potent compound 4c (MIC values 0.02 mM) exhibited antimicrobial activity against Staphylococcus aureus and Bacillus cereus. Furthermore, this compound has a good electrophilicity index value (4.56 eV).

Synthesis, spectroscopic (FT-IR/NMR) characterization, X-ray structure and DFT studies on (E)-2-(1-phenylethylidene) hydrazinecarboximidamide nitrate hemimethanol.

The title molecular salt, (E)-2-(1-phenylethylidene) hydrazinecarboximidamide nitrate hemimethanol C9H13N4(+)·NO3(-)·0.5CH4O, was synthesized and characterized by elemental analysis, FT-IR and NMT spectroscopies, and single-crystal X-ray diffraction technique. Quantum chemical calculations were performed to study the molecular and spectroscopic properties of the title compound, and the results were compared with the experimental findings. The calculated results show that the optimized geometry can well reproduce the crystal structure parameters, and the theoretical vibrational frequencies and GIAO (1)H and (13)CNMR chemical shifts show good agreement with experimental values. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. On the basis of the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between standard heat capacities (C) standard entropies (S), and standard enthalpy changes (H) and temperatures.

Synthesis, spectroscopic and structural characterization of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine with theoretical calculations using density functional theory.

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameters (FT-IR, (1)H NMR, (13)C NMR) of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine. The compound crystallizes in the triclinic space group P-1 with Z=2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) and 6-311++G(d,p) basis sets in ground state and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential (ESP). Also, non-linear optical properties of the title compound were performed at B3LYP/6-311++G(d,p) level. The theoretical results showed an excellent agreement with the experimental values.

1-(3-methyl-3-mesityl)-cyclobutyl-2-(5-pyridin-4-yl-2H-[1,2,4]triazol-3-ylsulfanyl)-ethanone: X-ray structure, spectroscopic characterization and DFT studies.

The triazole compound 1-(3-Methyl-3-mesityl)-cyclobutyl-2-(5-pyridin-4-yl-2H-[1,2,4]triazol-3-ylsulfanyl)-ethanone, (C23H26N4OS), was characterized by X-ray single crystal diffraction technique, IR NMR spectroscopy and quantum chemical computational methods as both experimental and theoretically. The compound crystallizes in the monoclinic space group P2(1)/c with Z=4. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) basis set in ground state and compared with the experimental data. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Data of the title compound display significant structure correlation and provide the basis for future design of efficient materials having the derivatives of 1,2,4-triazole. From the optimized geometry of the molecule, vibrational frequencies, gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values, molecular electrostatic potential (MEP) distribution, non-linear optical properties and frontier molecular orbitals (FMOs) of the title compound were performed at B3LYP/6-311G(d,p). On the basis of theoretical vibrational analyses, the thermodynamic properties (standard heat capacities, standard entropies, and standard enthalpy changes) of the title compound at different temperatures have been calculated, revealing the correlations between Cp,m0, Sm0, ΔHm0 and temperatures. The predicted non-linear optical properties of the title compound are much greater than those of urea. Data of the title compound display significant structure-correlation and provide the basis for future design of efficient materials having the derivatives of 1,2,4-triazole.

Synthesis, spectroscopic characterization, X-ray structure and DFT studies on 2,6-bis(1-benzyl-1H-benzo[d]imidazol-2-yl)pyridine.

The title molecule, 2,6-bis(1-benzyl-1H-benzo[d]imidazol-2-yl)pyridine (C(33)H(25)N(5)), was synthesized and characterized by elemental analysis, FT-IR spectroscopy, one- and two-dimensional NMR spectroscopies, and single-crystal X-ray diffraction. In addition, the molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) (1)H and (13)C NMR chemical shift values of the title compound in the ground state have been calculated using the density functional theory at the B3LYP/6-311G(d,p) level, and compared with the experimental data. The complete assignments of all vibrational modes were performed by potential energy distributions using VEDA 4 program. The geometrical parameters of the optimized structure are in good agreement with the X-ray crystallographic data, and the theoretical vibrational frequencies and GIAO (1)H and (13)C NMR chemical shifts show good agreement with experimental values. Besides, molecular electrostatic potential (MEP) distribution, frontier molecular orbitals (FMO) and non-linear optical properties of the title compound were investigated by theoretical calculations at the B3LYP/6-311G(d,p) level. The linear polarizabilities and first hyper polarizabilities of the molecule indicate that the compound is a good candidate of nonlinear optical materials. The thermodynamic properties of the compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures.

2-Chloro-N-[4-(3-methyl-3-phenyl-cyclo-but-yl)-1,3-thia-zol-2-yl]-N'-(naphthalen-1-yl-methyl-idene)acetohydrazide.

In the mol-ecular structure of the title hydrazide derivative, C(27)H(24)ClN(3)OS, the acetohydrazide group is approximately planar, with a maximum deviation of 0.017 (3) Å. The dihedral angle between the naphthyl-ene system and the phenyl ring is 78.91 (18)°. The crystal structure is stabilized by one weak inter-molecular C-H⋯O hydrogen bond and two aliphatic C-H⋯π hydrogen-bonding associations.

2-Chloro-N'-[4-(dimethyl-amino)-benzyl-idene]-N-[4-(3-methyl-3-phenyl-cyclo-but-yl)-1,3-thia-zol-2-yl]acetohydrazide.

The mol-ecular conformation of the title compound, C(25)H(27)ClN(4)OS, is stabilized by an intra-molecular benzyl-idine C-H⋯N(thia-zole) hydrogen bond. The thiazole ring makes dihedral angles of 12.0 (3) and 20.4 (2)°, respectively, with the phenyl and benzene rings, while the phenyl and benzene rings make a dihedral angle of 22.6 (2)°. The crystal packing involves weak inter-molecular thia-zole C-H⋯O(carbon-yl) and methyl C-H⋯π hydrogen-bonding associations.