Hexaphenylbenzene-Stabilized Luminescent Silver Nanoclusters: A Potential Catalytic System for the Cycloaddition of Terminal Alkynes with Isocyanides.

A hexaphenylbenzene (HPB)-based derivative bearing thiol groups has been designed and synthesized that undergoes aggregation-induced emission enhancement in mixed aqueous media to form rodlike fluorescent aggregates. These rodlike aggregates behave as a "not quenched" probe for the detection of silver ions and further act as reactors and stabilizers for reducing-agent-free preparation of blue luminescent silver nanoclusters at room temperature. The utilization of fluorescent supramolecular aggregates for the preparation of Ag NCs in mixed aqueous media is unprecedented in the literature. Moreover, the wet chemical method that we are reporting in the present paper for the preparation of luminescent silver nanoclusters is better than the other methods reported in the literature. Further, these in situ generated Ag NCs showed exceptional catalytic activity in the preparation of pyrroles involving cocyclization of isocyanides and terminal alkynes. Interestingly, the catalytic efficiency of in situ generated Ag NCs was found to be better than the other catalytic systems reported in the literature.