Ag₅₀(Dppm)₆(SR)₃₀ and Its Homologue Au_<i>x</i>Ag_{50–<i>x</i>}(Dppm)₆(SR)₃₀ Alloy Nanocluster: Seeded Growth, Structure Determination, and Differences in Properties

Abstract

A large thiolate/phosphine coprotected Ag₅₀(Dppm)₆(SR)₃₀ nanocluster was synthesized through the further growth of Ag₄₄(SR)₃₀ nanocluster and characterized by X-ray photoelectron spectroscopy (XPS), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray analysis. This new nanocluster comprised a 32-metal-atom dodecahedral kernel and two symmetrical Ag₉(SR)₁₅P₆ ring motifs. The 20 valence electrons correspond to shell closure in the Jellium model. Moreover, this nanocluster could be alloyed by templated/galvanic metal exchange to the homologue Au_xAg_50-x(Dppm)₆(SR)₃₀ nanocluster; the latter showed much higher thermal stability than the Ag₅₀(Dppm)₆(SR)₃₀ nanocluster. Further experiments were conducted to study the optical, electrical, and photoluminescence properties of both nanoclusters. Our work not only reports two new larger size nanoclusters but also reveals a new way to synthesize larger size silver and alloy nanoclusters, that is, controlled growth/alloying.