Benzotriazole maleimide as a bifunctional reactant for SERS

The synthesis of a benzotriazole maleimide is reported and its use as a bifunctional compound demonstrated. The triazole moiety of the compound complexes strongly with metals such as copper and silver and can be used to form monolayers on metal surfaces. The maleimide acts as a dienophile and reacts with dienes to produce cycloadducts. We report the selective reaction of the benzotriazole maleimide with seven different dienes to produce a range of cycloadducts. These cycloadducts were then adsorbed onto a metal surface via the triazole group. The presence on the metal surface was confirmed by surface enhanced Raman scattering, SERS. SERS is a vibrational spectroscopy and as such provides a fingerprint of each compound examined. The cycloadducts all gave different spectra that allowed identification of each diene that had cyclised. The dienes did not produce SERS on their own and had to be reacted with the bifunctional benzotriazole maleimide prior to examination. This provides an illustration of the use of bifunctional reactants specifically designed to produce SERS active products and also provides an example of an efficient derivatisation chemistry for copper and silver metal surfaces.