Electrostatic insights into the molecular hydration process: A case study of crown ethers

Ab initio quantum chemical methods as well as simulation/dynamics programs have been conventionally used for probing the hydration of molecules, an im portant problem in chemistry and biology. However, very few attempts have a s yet been reported for understanding the stepwise patterns in hydration pr ocesses at the molecular level. The present work investigates the problem o f hydration of the 18-crown-6 (18C6) molecule based on rigorous topography mapping of molecular electrostatic potential (MESP) followed by an applicat ion of a simple electrostatic model (electrostatic potential for intermolec ular complexation) for obtaining trends in energetics. Structures and energ ies of the hydrated species, 18C6 . nH(2)O (n = 1, 2, 3, 4, 6) have been st udied by the EPIC model followed by ab initio HF/6-31G** investigations. Th e remarkable agreement between the model and ab initio results highlights t he utility of MESP topography for exploring the lock-and-key features in a hydration process via cooperative electrostatic effects.