Improvement of the Thermal Stability of Self-Assembled Monolayers of Isocyanide Derivatives on Gold

Abstract

We report that the thermal stability of self-assembled monolayers (SAMs) of two isocyanide derivatives (1-pentyl isocyanide and benzyl isocyanide) on a gold surface was drastically improved by their preparation at high temperature (373 K). In the case of conventionally prepared isocyanide SAMs, thermal desorption spectroscopy revealed that the isocyanides changed their adsorption states with corresponding increase in binding energy. The results of surface-enhanced Raman scattering spectroscopy measurements also clearly indicated the change in adsorption states at 373 K during heating. Theoretical calculations using density functional theory revealed that there are two stable adsorption states (atop and adatom configurations) and that the calculated vibrational energies are in good agreement with those observed in Raman spectra.