Preparation and Luminescence Thermochromism of Tetranuclear Copper(I)–Pyridine–Iodide Clusters

A simple and straightforward synthesis of a tetranuclear copper(I)–pyridine–iodide cluster is described as a laboratory experiment for advanced inorganic chemistry undergraduate students. The product is used to demonstrate the fascinating and visually impressive phenomenon of luminescence thermochromism: exposed to long-wave UV light, the crystalline solid shows a bright yellow fluorescence at room temperature and an equally intense blue-violet fluorescence when cooled in liquid nitrogen. The procedure was also extended to several other pyridine ligands to allow students to synthesize different clusters and compare their photophysical behavior.