Solvent-Induced Modulation in the Optical Properties of Copper Nanoclusters and Revealing the Isomeric Effect of Templates.

The solvent plays an influential role in controlling the nucleation process of Metal Nanoclusters (MNCs) and thereby significantly modulates their optical signatures. Herein, we have demonstrated the solvent-induced modulation in the optical properties of copper nanoclusters (CuNCs), primarily governed by the solvent polarity. During the preparation of para-mercaptobenzoic acid (p-MBA)-templated CuNCs, the simultaneous formation of blue-emitting CuNCs (B-CuNCs) and red-emitting CuNCs (R-CuNCs) were observed up to 7 h of reaction time, reflected from the systematic increment in the photoluminescence (PL) intensity at 420 nm and 615 nm, respectively. However, after 7 h of reaction time, the exclusive formation of B-CuNCs was observed. Such simultaneous growth and depletion dynamics of CuNCs result in a significant modulation in their optical properties. The variation of the solvent from water to less polar solvents such as DMSO and DMF restricts this inter-cluster dynamics by stabilizing both the CuNCs (B-CuNCs and R-CuNCs). Thereby, a single-component White Light Emission (WLE) was realized in DMSO with CIE coordinates (0.37, 0.36). The isomeric effect of the templates has also been investigated which extensively controls the optical and catalytic properties of the CuNCs.