Hypso- or bathochromic phosphorescent mechanochromic mononuclear Cu(i) complexes with a bis(2-diphenylphosphinophenyl)ether auxiliary ligand

Abstract

Six phosphorescence-emitting metal–organic mononuclear Cu(I) complexes, namely four quinoline-containing three-coordinate Cu(I) complexes and two N-heterocyclic carbene-containing four-coordinate Cu(I) complexes, have been successfully developed and fully characterized. All these Cu(I) complexes include the same bis(2-diphenylphosphinophenyl)ether bidentate auxiliary ligand. Significantly, four-coordinate Cu(I) complexes 1 and 2 display typical aggregation-induced emission phenomena. Their solid samples of luminogenic complexes 1–6 emit a variety of different phosphorescence. Furthermore, solid-state phosphorescence of these Cu(I) complexes can be effectively manipulated by external mechanical force. Remarkably, luminophores 1, 2 and 5 exhibit blue-shifted mechanoluminochromism responses, while luminophores 3, 4 and 6 present red-shifted mechanoluminochromism characteristics. All of the observed mechano-responsive phosphorescence changes of solids 1–6 are reversible by the method of solvent fuming. Powder X-ray diffraction results confirm that the reversible mechanically induced phosphorescence changes of complexes 1–6 are due to the mutual transformation of ordered crystalline and metastable amorphous states.