A new family of five new mononuclear Cu(I) triphenylphosphine complexes derived from methylated 5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands has been synthesized and well characterized. They all show an N2P2 distorted tetrahedral geometry and the methylated 5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands display the mono-anionic η2(N1,N2) and charge-neutral η2(N1,N4) chelating coordination modes, along with the 1,2,4-triazolyl ring inversion induced by the NH ↔ N− transformation. These Cu(I) complexes are all emissive in solution and solid states at ambient temperature, which can be well modulated by changing the methyl position on the pyridyl ring and regulating the NH ↔ N− conversion of the 1,2,4-triazolyl ring. It is also shown that the deprotonation of 1,2,4-triazolyl-NH can markedly improve the luminescence properties of Cu(I) complexes.
