6-Phenyl-3-(4-pyridyl)-1,2,4-triazolo-[3,4-b][1,3,4]thiadiazole: synthesis, experimental, theoretical characterization and biological activities.

The molecular geometry, vibrational frequencies, and gauge including 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 Hartree-Fock (HF) and density functional theory (DFT) methods with 6-31G(d) basis sets, and compared with the experimental data. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters and the theoretical vibrational frequencies, and (1)H and (13)C NMR chemical shift values show good agreement with experimental data. To determine conformational flexibility, molecular energy profile of the title compound was obtained by HF/6-31G(d) and (DFT/B3LYP) calculations with respect to selected degree of torsional freedom, which was varied from -180° to +180° in steps of 10°.

4-Allyl-5-pyridin-4-yl-2,4-dihydro-3H-1,2,4-triazole-3-thione: synthesis, experimental and theoretical characterization.

The title molecule, 4-allyl-5-pyridin-4-yl-2,4-dihydro-3H-1,2,4-triazole-3-thione (C(10)H(10)N(4)S), was synthesized and characterized by IR-NMR spectroscopy and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group is P2(1)/c, a=8.006(5)Å, b=15.

6-phenyl-3-(4-pyridyl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole.

The title compound, C(14)H(9)N(5)S, has been synthesized and characterized both spectroscopically and structurally. The triazolo-thiadiazole system, the pyridine ring and the phenyl ring are all planar. The plane of the triazolo-thiadiazole system forms dihedral angles of 1.