Preparation and Thermochromic Switching between Phosphorescence and Thermally Activated Delayed Fluorescence of Mononuclear Copper(I) Complexes

Instructive, inexpensive, and environmentally friendly laboratory syntheses of two highly luminescent copper(I) complexes CuI(PPh[subcript 3])[subscript 2](py[superscript R]) (py[superscript R] = pyridine, 4-cyanopyridine) are described for second-year/upper-division undergraduate inorganic chemistry students. Both complexes exhibit bright thermally activated delayed fluorescence (TADF) at ambient temperature and phosphorescence at low temperature. The laboratory experiments familiarize the students with mechanochemical syntheses, cluster and complex formation, ligand substituent effects, and the fascinating phenomenon of luminescence thermochromism.