Studies on Structure and Conformational Stability of Free Canonical 2'-Deoxyribonucleosides: Approximate SCC-DFTB and LMP2 Methods

摘要

The molecular structure of free canonical 2'-deoxyribonucleosides have been studied by applying the electron-correlated local second-order M011er-Plesset perturbation theory (LMP2) and self-consistent-charge density-functional tight-binding (SCC-DFTB) methods. The variation of structural parameters for C2, C3 endo and exo conformations, and anti, syn orientation of the base unit with furanose ring have been discussed. The relative energies have been calculated for the anti and syn conformations of dT, dC, dG, and dA. Conformational analysis has been performed using the results of the LMP2 and SCC-DFTB methods. Chemical hardness and chemical potential have been used to study the Conformational stability of the conformers. The maximum hardness principle is obeyed for the furanose ring conformations and not for the nucleosides.