Quantum chemical study of some candidate for molecular photo switches

In general, a molecule that can be reversibly shifted between two or more stable states named molecular switching compound. The molecules may be shifted between the states in response to environmental stimuli, such as changes in pH, light, temperature, an electrical current, microenvironment, or in the presence of a compound. The oldest forms of synthetic molecular switches are pH indicators, which display distinct colors as a function of pH. Currently synthetic molecular switches are of interest in the field of nanotechnology for application in molecular computers. Molecular switches are also important to in biology because many biological functions are based on it. They are also one of the simplest examples of machines. Up to now, almost all of the organic molecules investigated for the second-order nonlinear optical materials contain electron-donating and withdrawing groups being linking through an intervening π-backbone has been calculated by the Restricted Density Functional Theory (DFT) methods with the basis set B3LYP/6-311G**[1-2]. The major purpose of this work is to calculate the molecular geometry of above compound and to theoretically study structural and electrical properties. Geometry optimization and calculation of the structural and electronic properties of (E)-N-(2-methyl-5-nitrobenzylidene)-3-chloropropan-1-amine compound have been carried out at DFT/B3LYP level of theory with 6-31G** basis set using Gaussian 03 program package [3]. All geometry parameters like bond lengths, bond angles, dipolmoment, energy of HOMO and LUMO levels, gap between the HOMO and LUMO levels, heat of formation and hyperpolarazibilty data were obtained.