DESIGN OF NOVEL MOLECULAR WIRES FOR REALIZING LONG-DISTANCE ELECTRON-TRANSFER

Novel heteroarene oligomers, consisting of two pyridinium groups, link ed by thiophene units of variable length, ''thienoviologens'', are des cribed as promising candidates for molecular wires. Two representative thienoviologens were coated by adsorption from micromolar concentrati ons in ethanol onto octadecylmercaptan (ODM)-coated gold electrodes an d induced a gradual restoration of the electrochemistry with hexacyano ferrate as a function of molecular wire concentration. Glucose oxidase and choline oxidase showed strong adsorption to these conductive laye rs, but showed striking differences in adsorption to the different thi enoviologen layers. The measurements support the hypothesis that the m olecules are incorporated in the ODM layer in a different fashion. Als o the complex formation of an engineered azurin redox protein with wat er-soluble pyridyl ligands is presented in relation to a possible appl ication of the thienoviologens as conductive spacers, in which the con tact with the redox protein is achieved via complex formation with a f ree pyridine nitrogen. (C) 1997 Elsevier Science S.A.