SERS and DFT study of nitroarenes adsorbed on metal nanoparticles

A combined SERS and DFT investigation has been performed for 2-amino,5-nitropyridine (ANP) adsorbed on silver colloidal nanoparticles in order to get a better insight into the adsorption mechanism of ANP on the silver surface. Both B3LYP and B3PW91 functionals were used in the DFT calculations on ANP in the anionic form (ANP−) and on different models of ANP−/silver surface complexes. A mixed basis set 6-311++G**/LANL2DZ was used in the case of the ANP−/Ag+ complexes. From the comparison between the experimental and the computational data, it was evinced that ANP is adsorbed on the silver surface in the anionic form with a quinonoid electronic structure through the nitrogen atom of the imino group.