Molecular dynamics of a vanadate-dipeptide complex in aqueous solution

Static geometry optimizations and Car-Parrinello molecular dynamics simulations with the BP86 density functional, as well as NMR chemical shift calculations at the GIAO-B3LYP level, have been used to assess structure, speciation, and dynamics of aqueous solutions of the vanadate-glycylglycine complex. According to the simulations, this complex should be formulated as five-coordinate, anionic [VO2(GlyGly')]- (GlyGly' = H2N-CH2-C(O)-N-CH2-CO2). The neutral conjugate acid is unstable in water, where it is deprotonated within a few picoseconds. Six-coordinate structural alternatives, [VO(OH)2(GlyGly')]-, are disfavored energetically and/or entropically. The hydration shell around [VO2(GlyGly')]- in water is characterized in terms of suitable pair correlation functions.