Electrocrystallization of Monolayer-Protected Gold Clusters : Opening the Door to Quality, Quantity, and New Structures

摘要

Thiolate-protected metal clusters are materials ofever-growing importance in fundamental and applied research.Knowledge of their single-crystal X-ray structures has beeninstrumental to enable advanced molecular understanding oftheir intriguing properties. So far, however, a general, reliable,chemically clean approach to prepare single crystals suitable foraccurate crystallographic analysis was missing. Here we show thatsingle crystals of thiolate-protected clusters can be grown in largequantity and very high quality by electrocrystallization. Thismethod relies on the fact that charged clusters display a highersolubility in polar solvents than their neutral counterparts.Nucleation of the electrogenerated insoluble clusters directlyonto the electrode surface eventually leads to the formation of a dense forest of millimeter-long single crystals.Electrocrystallization of three known Au25(SR)180 clusters is described. A new cluster, Au25(S-nC5H11)18, was also preparedand found to crystallize by forming bundles of millimeter-long Au25 polymers.