AM1 study of the electronic structure of benzylpenicillin

The geometry, conformation and electronic structure 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. Further, the mechanism of protonation in 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 (∆Hf o ), dipole moment (µ), ionization potential (IP), full atomic charges and energies of frontier molecular orbitals (EHOMO and ELUMO) have been performed and discussed. The conformational analyses of mono- and di-protonated species and their stable conformations have also been performed. © 2011 Universal Research Publications. All rights reserved