Theoretical Spectroscopic Study for a Series of 1,3,4-Oxadiazole Derivatives

In recent years the computational chemistry becomes of great importance in many chemical and pharmaceutical scientific fields. Since many of the oxadiazole derivatives have a wide range in biological, and pharmacological activities.Therefore this work involves a theoretical study for two series of oxadiazole derivatives. Series one contains oxadiazole molecules which are substitute by electron donating or electron with drawing groups [1,3,4-oxadiazole (OD), 1,3,4oxadiazole-2-amine (ODA), 1,3,4-oxadiazole-2,5-diamine (ODDA), 5-chloro1,3,4-oxadiazole-2-amine (CODA), 2-amino-1,3,4-oxadiazole-5-carbonitrile (AODCN), 5-nitro-1,3,4-oxadiazole-2-amine(NODA)]. Series two consist the following oxadiazole derivatives which obtain by substituting electron donating or electron with drawing as well as phenyl groups [2-phenyl-1,3,4-oxadiazoles (POD), 5-phenyl-1,3,4-oxadiazole-2-thiol (PODT), 5-phenyl-1,3,4-oxadiazole-2amine (PODA), 5-(4-chlorophenyl)-1,3,4-oxadiazole-2-amine (CPODA), 2,5diphenyl-1,3,4-oxadiazole(DPOD)] molecules.The theoretical study is done by employing the density functional theory DFT with B3LYP / high basis set 6-311++G(2d,2p), using  Gaussian program 09.In few cases, Avogadro program is used to assist and view the electronic orbitals or molecular electrostatic potentials.For the above mentioned two series molecules, the calculations are done to evaluate several physical properties such as:- equilibrium optimize geometry,vibrational spectra, electronic properties (electronic absorption spectra, energy of molecular orbital, molecular electrostatic potential [in gas phase and in water solution]), and nuclear magnetic resonance spectra [in gas phase and in Dimethyl sulfoxide solution]. Then a comparison is done between their different states.