Homonuclear and Heteronuclear Cluster Compounds of Gold

Hydrophobic Anchoring of Monolayer-Protected Gold Nanoclusters to Carbon Nanotubes

“…Figure shows UV−visible absorption spectra of OT-capped gold nanoclusters before and after attachment onto acetone-treated carbon nanotubes. The Au−OT clusters exhibit a strong surface plasmon peak at ∼400 nm, in contrast with the well-known 520 nm peak characteristic of >3 nm nanoclusters. − We attribute this result to surface plasmon excitation from ∼1−3 nm-diameter gold nanoclusters consisting of AuCl 3 complexes and/or 3−13 Au atoms, consistent with previous reports. , The small peak at ∼310 nm corresponds to the ligand-to-metal charge-transfer absorption band of AuCl 4 - . Both these peaks remain, albeit at a decreased intensity, in acetone-treated MWNTs mixed with OT-capped Au nanoclusters, even after repeated (6 times) washing and vigorous ultrasonication.…”

“…To determine the mechanism by which the Au clusters were attached to the nanotubes, we carried out transmissionmode FTIR measurements. Our results, shown in Figure 3 and Table 1 and described below, indicate that the nanoclusters are attached to nanotubes via hydrophobic interactions 27 between CH 3 groups in acetone (on MWNTs) and the alkyl chains in OT molecules (on the nanoclusters). Both pristine and acetone-activated MWNTs, prior to cluster attachment, show no observable absorption signatures corresponding to carbonyl groups >CdO (e.g., at 1750 cm -1 ).…”

“…[24][25][26] We attribute this result to surface plasmon excitation from ∼1-3 nm-diameter gold nanoclusters consisting of AuCl 3 complexes and/or 3-13 Au atoms, consistent with previous reports. 27,28 The small peak at ∼310 nm corresponds to the ligand-to-metal charge-transfer absorption band of AuCl 4 -. 29 Both these peaks remain, albeit at a decreased intensity, in acetone-treated MWNTs mixed with OT-capped Au nanoclusters, even after repeated (6 times) washing and vigorous ultrasonication.…”