Differences in hydration between cis- and trans-platin: Quantum insights by ab initio fragment molecular orbital-based molecular dynamics (FMO-MD)

Differences in hydration between cis- and trans-platin were investigated using ab initio fragment molecular orbital-based molecular dynamics (FMO-MD) simulations. Analyzing quantum charge fluctuation in water, we found that the Pt–Cl bond fluctuation of cis/trans-platin, which is important for activating their anticancer functions, was induced by charge transfer interaction between an anti-bonding π(Pt–Cl) orbital of platin complex and unoccupied orbital of solvent water molecules. The hydration number of Cl ligand in the first hydration shell was found to be larger for cis-platin than for trans-platin due to their difference in charge distribution. Our FMO-MD simulations showed that the amplitude of the Pt–Cl bond fluctuation is larger in hydrated cis-platin than in hydrated trans-platin.