The synthesis and physical-chemical characterization of the metal-ligand complex [Os(bpy)2(CO)(enIA)][OTf]2 (where
enIA ) ethylenediamine iodoacetamide) with a sulfhydryl-specific functional group is described. The UV and visible
absorption and luminescence emission, including lifetime and steady-state anisotropy, are reported for the free
probe and the probe covalently linked to two test proteins. The spectroscopic properties of the probe are unaffected
by chemical modification and subsequent covalent linkage to the proteins. The luminescence lifetime in aqueous
buffer is approximately 200 ns and the limiting anisotropy is greater than 0.125, suggesting a potentially useful
probe for biophysical investigations
