The CN Stretching Band of Aliphatic Thiocyanate is Sensitive to Solvent Dynamics and Specific Solvation

Infrared absorption spectra in the C[triple bond]N stretching frequency region were collected for methyl thiocyanate, the simplest model aliphatic thiocyanate, in several common solvents to establish the dependence of the C[triple bond]N spectral band of aliphatic thiocyanate on its local solvation environment. Systematic changes in the C[triple bond]N bandwidth indicate that it reports on fast solvation dynamics. Anomalous asymmetry and temperature dependence of the C[triple bond]N band in fluorinated alcohol solvents indicates that these solvents participate in formation of a discrete hydrogen-bonded complex with the C[triple bond]N end of methyl thiocyanate. These observations indicate that the C[triple bond]N band of thiocyanate could be an effective site-specific probe of both specific hydrogen bonding and local dynamics in more complex systems, such as peptides and proteins.