Abstract

COMPUTATIONAL STUDY ON THE ELECTRONIC STRUCTURE OF METHICILLIN ZWITTERIONS BY AUSTIN MODEL-1 METHOD

B. Mahipal Reddy1, G. V. R. Saimadhukar, T. Karunakar and B. Rajeshwar Rao*

ABSTRACT

The electronic structure and conformational analysis of methicillin zwitterions have been optimized and calculated in the gas phase, usually considering an isolated molecule surrounded in a vacuum by using semi-empirical molecular orbital AM1 method. Further, the mechanism of formation of zwitterions has been studied. In this connection, the heats of formation (ΔHf o), dipole moment (μ), ionization potential (IP), Electron affinity (eV) (A), Chemical hardness (ƞ), Chemical potential (μ0), Electronegativity (χ), Global softness (S), full atomic charges and energies of frontier molecular orbitals (EHOMO and ELUMO) have been calculated and discussed. The effects of conformational changes and electronic properties have also been discussed for stable conformations. The stability is observed in the increased order of 2 < 3 < 1.

Keywords: Methicillin, AM1, zwitterions, induction effect, frontier molecular orbital.