Quantum chemical and experimental studies on polymorphism of antiviral drug Lamivudine.

Lamivudine, is chemically known as [4-amino-1-[(2R,5S)-2-(hydroxymethyl)-1,3-oxathiolan-5-yl]-1,2-dihydropyrimidin-2-one], is an anti-HIV agent belonging to the class of the non-nucleoside inhibitors of the HIV-1 virus reverse transcriptase. Spectral characteristics of Lamivudine have been studied by methods of FTIR, NMR and quantum chemistry. The FTIR and spectra of Lamivudine was recorded in the regions 4000-400 cm(-1). The thermal stability of Lamivudine was studied by the thermogravimetric analysis (TGA). The isotropic (13)C-nuclear magnetic shielding constants of this compound were calculated by employing the direct implementation of the gauge including-atomic-orbital (GIAO) method at the HF and B3LYP density functional theory using 6-31G(d,p) basis set. The optimized molecular geometry, bond orders, harmonic vibrational spectrum of anhydrous and hydrated Lamivudine were calculated by restricted Hartree Fock and density functional B3LYP method with the 6-31G(d,p) basis set using Gaussian 03W program.