A chemopalette strategy for white light by modulating monomeric and excimeric phosphorescence of a simple Cu(i) cyclic trinuclear unit.

Room-temperature white phosphorescence with a quantum yield (QY) of 35.6% and a CIE coordinate of (0.33, 0.37) is observed for Cl-α, the crystal of cyclic Cu3(4-chloropyrazolate)3. Its white light consists of comparably uncommon monomeric blue and common excimeric yellow phosphorescence associated with Cu3(pyrazolate)3, achieved by multiple non-covalent interactions involving chlorine.