Counterion‐Assisted Shaping of Nanocluster Supracrystals. Issue 1 (5th November 2014) - Yao, Qiaofeng
Abstract: Ag44 ( p ‐MBA)30 4− ( p ‐MBA= para ‐mercaptobenzoic acid) nanocluster (NC) supracrystals (SCs) with customizable shapes can be obtained by simply altering the type and concentration of the counterions of the p ‐MBA ligands in the dimethylsulfoxide (DMSO)/water crystallization system. Changing the counterion of the p ‐MBA ligand from H + to Cs + eliminates the directional hydrogen bonds in the SCs, resulting in the packing of deprotonated Ag44 ( p ‐MBA)30 4− NCs into octahedral SCs, which is in stark contrast to the rhombohedral SCs that were formed by the packing of protonated Ag44 ( p ‐MBA)30 4− NCs in previous studies. Furthermore, the double layer of deprotonated Ag44 ( p ‐MBA)30 4− NCs is sensitive to charge screening induced by increasing the Cs + concentration, thereby providing a means to regulate the precipitation kinetics of the Ag44 ( p ‐MBA)30 4− NCs for SC shape engineering. Slow precipitation kinetics was found to favor over‐growth at the corners and edges of the octahedral SC nuclei, shaping the SCs into concave octahedra. Abstract : Nanocluster supracrystals : By replacing the H + counterions with Cs + ions, octahedral Ag44 nanocluster supracrystals are obtained instead of the previously reported rhombohedra. The faces of the octahedral supracrystals can be further customized to be convex or concave simply by adjusting the Cs + concentration.