Competitie hydrogen bonding in aspirin-aspirin and aspirin-leucine interactions

Abstract

Aspirin-aspirin and aspirin-leucine interactions are studied by the density functional theory (DFT) and high leel ab initio calculations with second order Moller-Plesset perturbation theory (MP2). The rotational isomers of aspirin are identified by their relatie stability both in gaseous phase and in water using the polarizable continuum method (PCM). Local minima of aspirin monomers in water are found to be all highly populated compared to the gas phase behaior. Homodimers of aspirin form hydrogen bonds with bond energies of 10 kcal/mol. Weak hydrogen bonds utilizing phenyl and methyl groups are also found. The interaction between aspirin and leucine is stronger with relatiely short bond lengths compared to homodimeric aspirin interactions. The potential energy surface has seeral minima with comparable stability. This study shows the significance of dierse bonding schemes, which are important for understanding complete interaction mechanisms of aspirin. © TÜBITAK.