CHEMICALLY-MODIFIED ELECTRODES BY NUCLEOPHILIC-SUBSTITUTION OF CHLOROSILYLATED PLATINUM OXIDE SURFACES

Chlorosilylated platinum oxide electrode surfaces can be generated by reaction of SiCl4 vapor with an electrochemically prepared monolayer o f platinum oxide. A variety of nucleophilic agents (such as alcohols, amines, thiols, and Grignard reagents) can be used to displace chlorid e and thereby functionalize the metal surface. Electroactive surfaces prepared with ferrocene methanol as the nucleophile show that derivati zation by small molecules can achieve coverages on the order of a full monolayer. Surfaces modified with long-chain alkyl groups efficiently block electrode reactions of redox probes dissolved in the contacting solution, but other electrochemical (double layer capacitance and sur face coverage) and contact angle measurements suggest that these molec ule films are not highly ordered, self-assembled monolayers.