Structure Prediction of Bis(amino acidato)copper(II) Complexes with a New Force Field for Molecular Modeling

This article presents a new force field whose parameterization was based on experimental crystal data and quantum chemically obtained vacuum structures of a series of copper(II) complexes with aliphatic alpha-amino acids and their N-alkyl derivatives, along with the SPC/E water model. The ability of the new force field to reproduce and predict the structural properties of the copper(II) complexes in the gas phase, in simulated crystalline surroundings, and solvated in water is examined. Molecular dynamics (MD) simulations with the new force field yielded time-average structural coordinates of bis(glycinato)copper(II) [the only one of 25 modeled bis(amino acidato)copper(II) systems with published experimental structural data in aqueous solution at room temperature] within the experimental error values. The study of the cis-trans isomerization of bis(glycinato)copper(II) in aqueous medium at 300 K using the quantum chemical polarized continuum model revealed a small energy difference (5 kJ mol(-1)) between the solvated cis and trans minima, in line with the MD energy estimations. The new force field proved promising in predicting the association of the complexes in aqueous solution and formation of a nucleus of crystallization.