Chiral Recognition Via a Stereodynamic Vanadium Probe Using ECD-ROA Interference

Intermolecular interactions sensitive to chirality occur in many biological events. We report a complex formation between a versatile vanadium-based probe and a chiral co-ligand monitored through the interference of electronic circular dichroism (ECD) and Raman optical activity (ROA). Simulated ECD-ROA interference spectra based on experimental ECD and degree of circularity (DOC) values agree with the observed ones. Sensitive recognition of the chiral enantiopure co-ligand is thus enabled by a combination of resonance of the excitation light with the diastereoisomeric complex, co-ligand complexation, circular dichroism, and polarized Raman scattering from the achiral solvent. Relatively diluted solutions could be detected (10-4 mol·dm-3), which is about 1000x less than is necessary for conventional ROA detection of the pure co-ligand. The results indicate that the ECD/ROA method can be conveniently used to monitor molecular interactions and molecular spectroscopic properties.