AM1 study on the conformations of alpha-methyldopa

摘要

The geomtry and electronic structure of alpha-methyldopa molecule having various reaction centers have been fully optimized by semi-empirical molecular orbital AM1 calculations. Furthermore, the effect of conformational changes on the electronic properties have been studied. In this connection, the heats of formation, dipole moments, ionization potentials, full atomic charges, and energies of frontier molecular orbital (E_(HOMO) and E_(LUMO)) have been calculated and discussed. The mechanism of protonation in alpha-methyldopa has been studied by using the comparison of net charges on nitrogen and oxygen atoms in the different positions of the molecule. The conformational analyses of protonated species and zwitterion have also been performed by AM1 method and their stable conformations determined.