Surface-Enhanced Raman Spectra of the Reduction Product of 4-Cyanopyridine on Copper Colloids

Surface-enhanced Raman spectra of 4-cyanopyridine in a copper collotion solution were collected and showed no signal due to the C≡N stretching normal mode. [¹⁵N]-4-Cyanopyridine was prepared and similar results were obtained. The spectra of these molecules on gold colloids contain a signal attributed to this mode. These data were interpreted as being due to a transition metal-assisted reduction of the nitrile group with the product 4-aminomethylpyridine being adsorbed on the copper surface. The surface-enhanced Raman spectrum of 4-aminomethylpyridine on a copper colloid is nearly identical with the spectrum collected for 4-cyanopyridine with the copper colloid.