An Unusual Luminescent Anionic Copper(I) System: Dicyanocuprate(I) Ion in Nano and Bulky States

Abstract

Anionic dicyanocuprate(I) ions in nano and bulky crystals have been investigated. The doped nanosystems show unusual photophysical properties such as multiple emission bands, thermochromism, and optical memory. In contrast, NaCu(CN)2 and KCu(CN)2 have different polymeric structures and exhibit only a single emission peak. This was confirmed by infrared, Raman, and reflectance spectroscopy results. The emission peaks of these doped systems show tunability over a wide wavelength interval, indicating the existence of different {[Cu(CN)2]}n nanoclusters. The thermochromism and optical memory phenomena are due to the population changes of these different-sized nanoclusters. Ab initio DFT calculations for the impurity copper(I) ion in different alkali halides show that the {[Cu(CN)2]}n nanoclusters are examples of excimers and exciplexes. Atomistic modeling describes how the distribution of different nanoclusters varies with the alkali halide hosts.