Preparation of gold nanoparticles modified with tetrathiafulvalene via direct sulfur bridge

A new tetrathiafulvalene-modified gold colloid was prepared. The modification or coordination of 2-[4,5-ethylenedisulfanyl-1,3-dithiol-2-ylidene]-1,3-dithiole-4-thiolate to the surface of gold nanoparticles was characterized by UV-Vis and Raman spectra, and cyclic voltammograms. The most valuable point of the modified gold nanoparticles is their redox activities. The cyclic voltammogram of the tetrathiafulvalene-modified gold colloid on a Pt electrode showed two pair of redox peaks, at E1/2 = +0.67 V and at +0.87 V (vs. a saturated calomel electrode, in MeCN-0.1 M Bu4NClO4), corresponding to TTF/TTF*+ and TTF*+/TTF2+, respectively. A gold electrode modified with a self-assembled monolayer of the tetrathiafulvalene was also prepared and its cyclic voltammogram behaviors were in accordance with those of the nano-Au system. The E1/2 data are higher than those of the neutral mother precursor and the separation of E1/2(1) to E1/2(2) becomes very narrow. The data of E1/2 also revealed that electrochemical behavior of the no-spacer system (TTF-S-Au) are different from that of a spacer system (TTF-S-(CH2)n-Au).