Supporting Information For: Nitrile Bonds as Infrared Probes of Electrostatics in Ribonuclease S

The spectroscopic responses to environmental changes (e.g. different solvents or temperatures) of the nitrile stretching transition of small molecule-nitriles or unstructured peptides were explored to better understand the observations of the nitrile-modified RNase complexes. In general, when solvated by a polar solvent, it is expected that the large ground state dipole moment of nitrile-containing molecules will exert an orienting force on the nearby solvent dipoles. These oriented dipoles will exert an electrostatic force on ground state dipole