Electrodeposition of Oligothiophene-Linked Gold Nanoparticle Films

The electrodeposition and characterization of conducting thin films of gold nanoparticles bridged with oligothiophene linkers are reported. Gold nanoparticles capped with the conjugated phosphines 5 -diphenylphosphino-2,2ʹ:5ʹ,2ʹ ʹ-terthiophene (dcore = 1.7 (plus_minus) 0.3 nm) and 5-diphenylphosphino-3ʹ,4ʹethylenedioxy-2,2ʹ:5ʹ,2ʹ ʹ-terthiophene (dcore = 1.8 (plus_minus) 0.4 nm) have been prepared. Electrochemical oxidation of these particles results in the deposition of thin films consisting of intact nanoparticles linked by oligothiophene moieties, in which the (pi)-(pi)* absorption of both the conjugated linker and the plasmon band are red-shifted relative to individual nanoparticles. Conductivities of both the unlinked and linked particles are measured and the latter are shown to have substantially higher conductivities than unlinked particles or gold nanoparticles linked by saturated alkyl chain linkers.