SEIRA and SERS Effects in Cyclopentabithiophenethiol-Capped Gold Nanoparticles

Gold nanoparticles capped with cyclopentadithiophene via hexylsulfide bridges have undergone FUR and Raman analysis, before and after dithiophene oxidative coupling, with the support of DFT calculations. A strong SEIRA effect has revealed an almost parallel disposition of the oligothiophene ring plane in respect to the gold surface, enhanced by polymerization. An unusual SERS enhancement of the oligothiophene ring stretching band has been assigned to coordination of the gold surface of neighboring particles via the thiophene sulfur atoms.