Modulation of the Photophysics of Nucleotide-Functionalized Copper Nanoclusters Using Aqueous Binary Mixtures

Abstract

Nanomaterials have been steadily gaining importance over the past few decades. Metal nanoclusters comprised of gold or silver have been thoroughly studied and well documented. Only recently, the focus has begun to shift to copper nanoclusters (CuNCs). However, there are very few studies that focus on the modulation of the photophysics of metal nanoclusters, especially CuNCs. Dimethyl sulfoxide (DMSO) is an industrially and biologically important solvent. Aqueous DMSO binary mixtures have been frequently used for modulation of excited-state dynamics of many conventional fluorophores. Here, by performing the time-resolved fluorescence spectroscopy of nucleotide-functionalized CuNCs in aqueous DMSO binary mixtures, we have demonstrated that DMSO negatively affects the excited-state decay dynamics of CuNCs by destabilizing the excited state, leading to faster decay dynamics. We have proposed that DMSO disrupts the water-mediated internanocluster (interNC) cuprophilic interactions, which are mostly responsible for stabilization of the CuNC excited state. These results will provide significant physical insight on techniques to modulate the radiative decay dynamics of CuNCs and other nanomaterials.