Highly Luminescent Gold Nanocluster Frameworks

Abstract

Metal nanoclusters (NCs) are being intensely pursued as prospective luminophores because of their tunable electronic and optical properties. Among the various fluorescent NCs, gold nanoclusters (GNCs) are attractive due to their biocompatibility and excellent photostability, even if so far, they have had limited application potential due to poor quantum yield (QY). In this context, a facile route is demonstrated to tune up the photophysical and photochemical activities of water‐borne luminescent GNCs through the formation of self‐assembled nanocluster superstructures. The approach involves the controlled introduction of Sn2+ ions, directing GNCs from individual particles into 3D spherical gold nanocluster colloidal frameworks (GNCFs). In these, the reduction in the nonemissive relaxation pathways leads to significant enhancement of luminescence signals (QY from ≈3.5% to ≈25%), likely owing to restricted movements of ligands. This approach paves ways for GNCFs as a potent agent for biomedical imaging and therapies, while their high photocatalytic activity is an added advantage