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 <i>ab initio </i>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 with formamide as a test case using the molecular electrostatic potential (MESP) as a tool for probing weak interactions. The present work

is based on mapping of MESP topography followed by the application of an electrostatics-based model, viz., electrostatic potential for intermolecular complexation (EPIC), for obtaining the structures 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 <i>ab initio</i> optimization. Also, the EPIC structures when

subjected to <i>ab initio</i> optimization are found to converge faster. This highlights the utility of MESP for investigating the hydration patterns at molecular level by understanding lock-and-key mechanism in such processes. The patterns found in the present study could be gainfully employed further for probing the complete first and second hydration shells of small- and medium-sized molecules.