Quasi-Isomeric Anion-Templated Silver Nanoclusters: Effect of Bulkiness on Luminescence

Anion-templated silver nanoclusters are fascinating to study because of their diverse structures, which are dictated by the nature of both anions and ligands. Here, we used the bulky 1-ethynyladamantane as one of the protecting ligands alongside trifluoracetate to successfully synthesize a chlorine-templated silver nanocluster─Cl@Ag19(C12H15)11(C2O2F3)7. Elucidation of its structure by single crystal X-ray diffraction revealed the structure to be a chlorine-centered Ag19 cage with protection by alkynyl and carboxylic ligands. This cluster is non-emissive at room temperature and showed green emission with a large Stokes shift at low temperature. The crystal structure was found to be quasi-isomeric with a previously reported Ag19 cluster protected by tert-butyl acetylene, which is emissive at room temperature. Detailed photoluminescence studies and structure–property correlation revealed that the arrangement of the silver skeleton which is influenced by the bulky substituent of the ligand might be responsible for the difference in emission properties.