Abstract

AM1 STUDY ON THE CONFORMATIONS OF ZWITTERIONS OF BENZYLPENICILLIN

Mandla Venugopal*, P. Raveendra Reddy and B. Rajeshwar Rao

Abstract

The conformation and electronic structure of zwitterions of benzylpenicillin have been optimized and calculated in the gas phase by semi-empirical molecular orbital AM1 method usually considering an isolated molecule surrounded by vacuum. The formation of zwitterions of benzylpenicillin has been studied by comparison of the different positions of net charges on nitrogen atoms in the molecule. In this connection, the heats of formation (ΔHf o), dipole moment (μ), full atomic charges and energies of frontier molecular orbitals (EHOMO and ELUMO) have been performed and discussed. The effect of conformational changes and their stabilities have been determined.

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