EFFECTS OF STRUCTURAL VARIATIONS ON THE HYDROGEN BOND PAIRING BETWEEN ADENINE DERIVATIVES AND THYMINE

The hydrogen bonding between substituted adenines and thymine was investigated by density functional theory computations at the B3LYP/6-311+G(2d,2p) level. The effect of 20 different polar substituents at position 8 in adenine was examined in detail. Three different theoretical parameters, reflecting the electrostatics at the atoms involved in hydrogen bonding, were applied. An excellent correlation between electrostatic potentials at the bonding atoms in the monomer adenines and interaction energies was derived (Eqn. 2). It can be employed in designing bioactive adenine derivatives that are able to bind with a finely adjusted strength to thymine bioreceptor sites. NBO and Hirshfeld atomic charges are found to be less successful as reactivity predictors in these interactions.