Divisions of Molecular Physics and Organic Chemistry,Department of Physics,Chemistry and Biology,Linkoping University,SE-581 83 Linkoping,Sweden

摘要

It is very important to understand metal-molecule interface characteristics for the development of efficient molecular wires in molecular electronics.Because isocyanide is potentially a good alligator clip,we have investigated in this work the adsorption characteristics of 2,6-dimethylphenylisocyanide (DMPI) on Au and Pt electrodes by recording the potential-dependent surface-enhanced Raman scattering (SERS) spectra.First of all,we confirmed that Pt nanoaggregate films were efficient SERS-active substrates,not only in ambient conditions,but also in electrochemical environments.Second,we confirmed that aryl isocyanide should adsorb on Au and Pt by forming exclusively metal-CN bonds,via a pure sigma type interaction in the case of gold compared with a sigma/pi synergistic interaction on Pt.This implies that DMPI should adsorb on Au only via the on-top site,whereas not only the on-top site,but also the 2-fold bridge and 3-fold hollow sites,could be used in the surface adsorption of DMPI on Pt.Despite these differences,DMPI was assumed to possess a vertical orientation with respect to the Au and Pt substrates,irrespective of the potential variation between +0.2 and -0.6 V relative to the Ag/AgCl reference electrode.The latter characteristics of the Au-CN and Pt-CN combinations are presumed to be useful in designing molecular-scale wires.