Anionic passivation layer-assisted trapping of an icosahedral Ag13 kernel in a truncated tetrahedral Ag89 nanocluster

Isolating reductive silver kernel from shell is a challenging task but is quite important to understand the embryonic form during the formation of silver nanoclusters. The intercalation of suitable anionic species may be of benefit for passivating then capturing such highly active kernel. Herein, we successfully isolated a novel silver thiolate nanocluster [Ag13@Ag76S16(CyhS)42(p-NH2-PhAsO3)4]3+ (SD/Ag89a, CyhSH = cyclohexanethiol) that contains a well-isolated icosahedral Ag13 kernel passivated by four AgS47− tetrahedra and four p-NH2PhAsO32− piercing from outer Ag72 shell. Of note, this Ag13 kernel is the largest isolable subvalent silver kernel beneath the silver shell with extremely legible core-shell boundary ever before and represents a precise embryonic model formed in the reducing Ag(I) to Ag(0) followed by aggregating to large silver nanoparticles. The reductive role of DMF and the introduction of anionic passivation layer (APL) synergistically modulate the reduction kinetics, facilitating the capture of ultrasmall subvalent silver kernel. SD/Ag89a emits in near infrared (NIR) region (λem = 800 nm) at low temperature. The synthetic strategy shown in this work opens up new opportunities for precisely capturing and recognizing diverse reductive silver kernels in different systems.