Electrochemical Synthesis of Very Stable Photoluminescent Copper Clusters

Small fluorescent atomic copper clusters, stabilized by tetrabutylammonium nitrate, have been synthesized by a simple electrochemical technique. These small clusters (CuN, N < ≈14) show photoluminescence in the visible range with unusual high quantum yields (13%) and were characterized by UV−vis and fluorescence spectroscopies, LDI-TOF (laser desorption/ionization time-of-flight) mass spectroscopy, XPS (X-ray photoelectron spectroscopy), and TEM/HRTEM (high-resolution/transmission electron microscopy). Cu clusters are very stable and can be dispersed in both apolar and polar solvents, which makes them useful as very small building blocks, bringing new possibilities to construct novel nano/microstructures, with potential applications in fields such as biosensors, biomedicine, etc.