Molecular electrostatics for exploring hydration patterns of molecules: 2 - Formamide

Abstract

Hydration of various molecular species is of great importance in chemical and biological sciences. Several studies dealing with hydration of molecules by ab initio methods, density functional formalism as well as molecular dynamics/molecular mechanics calculations have been reported in the literature. This article reports an attempt to explore the stepwise hydration patterns of molecules wirh formamide as a test case using the molecular elestrostatic potential (MESP) as a tool for probing weak interactions. The present work is based on mapping of MESP topography followed by the applications of an electrosattics-based model, viz.., electrostatic potential for intermolecular complexation (EPIC), for obtaining the structrres and trends in energetics in different hydrated species, viz.., HCONH₂···n(H₂O), 1≤ n≤ 8. These EPIC calculations are followed up by RHF/6-31G investigations. The structures predicted by EPIC are generally found to be qualitatively similar to those obtained by ab initio optimization. Also the EPIC structures wheb subjected to ab initio optimization are found to converge faster. This highlights the utility of MESP for investigating the hydration patterns at molecular level ny understanding lock-and-key mechanism in such processes. The patterns found in the persent study could be gainfully employed further for probing the complete first and second hydration shells of small-and medium-sized molecules.