Photoconversion of Ag31 to Ag42 Initiated by Solvated Electrons

Light-matter interactions, especially in atomically precise nanomaterials, belong to an unexplored realm of research with potential benefits for the synthesis of materials. Here, we present an interesting light-activated expansion process of an Ag31 nanocluster to an Ag42 analogue, both clusters being protected with 6-(dibutylamino)-1,3,5-triazine-2, 4-dithiol (shortly, TRZ-H2) ligands. The conversion process was initially monitored through UV–vis, revealing that the violet-colored Ag31 got converted to greenish Ag42, exhibiting their characteristic absorption features. High-resolution mass spectrometric studies confirmed that the as-synthesized [Ag31(TRZ)10] with coexisting di- and monoanionic charged species in dichloromethane solution got converted to [Ag42(TRZ)13] with a dipositive charge state. Electrochemical studies revealed the photoresponsive nature of Ag31, and light illumination resulted in transient intermediate clusters covered with solvated electrons, which contributed to the core expansion. Ag31 is NIR-emitting, while Ag42 is red-emitting. The ultrafast transient absorption studies reveal that Ag42 has strikingly short excited-state carrier dynamics than Ag31. The stable excited-state carriers for Ag31 upon photoexcitation also underline the unique electronic characteristics responsible for such light-activated structural evolution.