Molecular dynamics of a vanadate-dipeptide complex in aqueous solution.

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Biophysical Chemistry

Background:

• Vanadate complexes are relevant in biological systems and catalysis.
• Understanding the speciation and dynamics of metal-ligand complexes in solution is crucial.

Purpose of the Study:

• To elucidate the structure, speciation, and dynamics of the vanadate-glycylglycine complex in aqueous solution.
• To determine the predominant form of the complex under physiological conditions.

Main Methods:

• Static geometry optimizations using the BP86 density functional.
• Car-Parrinello molecular dynamics simulations.
• Nuclear Magnetic Resonance (NMR) chemical shift calculations at the GIAO-B3LYP level.

Main Results:

• The vanadate-glycylglycine complex exists predominantly as a five-coordinate anionic species, [VO2(GlyGly")]-.
• The neutral conjugate acid of the complex is unstable in water, undergoing rapid deprotonation.
• Six-coordinate structures, such as [VO(OH)2(GlyGly")]-, are energetically and entropically disfavored.
• The hydration shell of the [VO2(GlyGly")]- complex was characterized using pair correlation functions.

Conclusions:

• The anionic five-coordinate [VO2(GlyGly")]- is the stable form of the vanadate-glycylglycine complex in aqueous solutions.
• Computational simulations provide valuable insights into the behavior of metal-ligand complexes in solution.