UC Berkeley

The supramolecular capsule Ga4L612- has been found to catalyze a number of important chemical reactions, but the close proximity of a poorly organized external solvent environment can serve as an impediment to the reaction chemistry. Using ab initio molecular dynamic calculations and electric field analyses, we find that metal substitution of indium for gallium lowers the total and electrostatic activation barriers by ∼3-4 kcal/mol in water solvent. Using an energy decomposition analysis of the interaction of water solvent with the metal vertices, we find that Pauli repulsion between the metal and water decreases, allowing the water coordination with the metal to increase, upon substitution of In for Ga. We therefore determine that the stabilization of the transition state is due to a better arrangement of water molecules around the metal vertices of In4L612- and provides a proof of concept of how to redesign the nanocage scaffold in order to reduce the solvent reorganization energy.