FTIR study of pi-stacking effects in (eta(6)-arene)tricarbonylchromium complexes: Application as a molecular sensor for aromatic analytes

FTIR spectra of (eta(6)-benzene)tricarbonylchromium (1) in cyclohexane solutions containing aromatic substrates have been measured. From a study of the nu(CO) modes, it is shown that at least two distinct species are present, free 1, and an adduct in which 1 and a molecule (or molecules) of the substrate are associated via a rr-stacking interaction between the exo-face of the eta(6)-benzene ligand and the substrate. Changes in the nu(CO) region of the spectrum can be correlated with substrate concentration. The incorporation of (eta(6)-arene)tricarbonylchromium moieties as spectroscopic reporting groups into molecular receptors for aromatic analytes is discussed, and a simple illustrative example is described.