Luminescent heteroleptic copper(I) complexes with polydentate benzotriazolyl-based ligands

Bis(benzotriazol-1-yl)phenylmethane CHPh(btz)2 and tris(benzotriazol-1-yl)methane CH(btz)3 were used as N-donor ligands to prepare luminescent heteroleptic copper(I) complexes. [Cu{CHPh(btz)2}(PPh3)2][BF4] and [Cu{CHPh(btz)2}(DPEphos)][BF4] (DPEphos = bis[(2-diphenylphosphino)phenyl] ether) were obtained from the corresponding borohydride complexes [Cu(BH4)(PPh3)2] and [Cu(BH4)(DPEphos)] and tetrafluoroboric acid. [Cu{CH(btz)3}(PPh3)][BF4] and [Cu{CH(btz)3}(PiPr3)][BF4] were prepared from the acetonitrile complex [Cu(NCCH3)4][BF4]. The complexes exhibited bright yellow or orange emissions upon excitation with near-UV and violet light. The photoluminescent properties were attributed to metal-to-ligand charge transfer transitions on the basis of experimental data and DFT calculations.