OLIGOIMIDE MONOLAYERS COVALENTLY ATTACHED TO GOLD

Three soluble, thiophenol-terminated oligoimides, e.g. HSPh-A-B-A-B-A-B-A-B, where Ph = phenyl, A = naphthalene-1,4,5,8-tetracarboxylic dianhydride, and B = 3,3'-dimethoxybenzidine, were prepared. Vapor-deposited gold and bulk gold were modified with these oligomers. X-ray photoelectron spectra confirmed the structure. Grazing angle infrared spectra were used to demonstrate that the molecules were attached intact in one monolayer and that they were tilted up from the surfae at an angle of about 30-degrees. The integrated peak currents from cyclic voltammetry in DMF show that each oligomer forms a dense monolayer (GAMMA = 1 x 10(-10) mol cm2) and that each A unit in an oligomer is electroactive, so that as many as eight electrons can be added to each molecule. In DMF or aqueous solution the layer is permeable to ions and incorporates counterions when it is reduced electrochemically.