A new series of bimetallic Cu(I) complexes 1–5 triply bridged by a monoanionic or charge-neutral functionalized 3-(2′-pyridyl)-1,2,4-triazole in a μ–η1(N),η2(N,N) tridentate binding mode and two bis(diphenylphosphino)methane (dppm) ligands have been synthesized. Complexes 1–5 are singly or doubly charged dinuclear Cu(I) species with an eight-membered Cu2C2P4 ring of {Cu(μ-dppm)2Cu} unit, in which 3 and 4 adopt the boat–boat conformation, while 1, 2, and 5 display the chair–boat form. In these dimeric copper(I) complex cations, one of the two Cu(I) ions is four-coordinated, in a highly distorted N2P2 tetrahedral environment and the other is three-coordinated, in a distorted NP2 trigonal planar arrangement. All these Cu(I) complexes exhibit a comparatively weak low-energy absorption in CH2Cl2 solution, ascribed to the charge-transfer transitions with appreciable 1MLCT contribution, as suggested by time-dependent density functional theory (TDDFT) analyses. Complexes 1–5 display good emission properties in both solution and solid states at ambient temperature, which are well-modulated via structural modification of 3-(2′-pyridyl)-1,2,4-triazole, including the alteration of the substituent type (−CF3, −H, −CH3, and −C(CH3)3) and position (ortho-, meta-, and para-position). Furthermore, the variation of the substituent (−CF3 and −C(CH3)3) on the 5-site of the 1,2,4-triazolyl ring markedly influences the proton activity of the 1,2,4-triazolyl-NH, thus leading to the formation of both singly and doubly charged bimetallic Cu(I) species regulated by the NH ↔ N– conversion, resulting from NH deprotonation of the 1,2,4-triazolyl ring.

1,2-Bis[[(diphenylphosphino)methyl](phenyl)phosphino]ethane (dpmppe) was prepared as a new tetraphosphine, and the corresponding rac and meso stereoisomers were successfully separated in view of their solubility difference in acetone. The substitution of PPh3 into Pt(PPh3)2(C≡CR)2 (R = aryl) with rac- or meso-dpmppe gives Pt(rac-dpmppe)(C≡CR)2 or Pt(meso-dpmppe)(C≡CR)2, respectively. Using Pt(rac-dpmppe)(C≡CR)2 or Pt(meso-dpmppe)(C≡CR)2 as a precursor, PtAg2 heterotrinuclear cluster complexes were synthesized and characterized by X-ray crystallography. Depending on the conformations of tetraphosphine, the structures of PtAg2 complexes supported with rac- and meso-dpmppe are quite different. The higher molecular rigidity of rac-dpmppe-supported PtAg2 complexes results in stronger phosphorescent emission than that of PtAg2 species with meso-dpmppe. The high phosphorescent quantum yields (as high as 90.5%) in doping films warrant these PtAg2 complexes as excellent phosphorescent dopants in organic light-emitting diodes (OLEDs). The peak current and external quantum efficiencies in solution-processed OLEDs are 61.0 cd A–1 and 18.1%, respectively. Electroluminescence was elaborately modulated by modifying the substituent in aromatic acetylide and the conformations in tetraphosphine so as to achieve cyan, green, green-yellow, yellow, and orange-red emission.

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.

A new series of mononuclear copper(I) complexes (1–9) with functionalized 3-(2′-pyridyl)-1,2,4-triazole chelating ligands, as well as the halide and/or phosphine ancillary ligands, have been synthesized. Complexes 1–9 were fully characterized by elemental analysis, NMR spectroscopy, mass spectroscopy, electronic absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and X-ray crystallography (1–8). They adopt a distorted tetrahedral configuration, and are considerably air-stable in solid state and in solution. All these Cu(I) complexes display a comparatively weak low-energy absorption in CH2Cl2 solution, assigned to charge-transfer transitions with appreciable MLCT character, as supported by TD-DFT studies. Cu(I) halide complexes 1–4 each shows bright solid-state emission at room temperature, although they are nonemissive in fluid solutions, in which the emission markedly depends on the halide and the substituent on the 2-pyridyl ring. Complexes 5–9 bearing 2-pyridyl functionalized 1,2,4-triazole and phosphine exhibit good photoluminescence properties in solution and solid states at ambient temperature, which are well-modulated via the alteration of the auxiliary phosphine ligand and the structural modification of 3-(2′-pyridyl)-1,2,4-triazole. Interestingly, cationic complex 6 and neutral derivative 7 can readily be interconverted through the ring inversion of the 1,2,4-triazolyl regulated by the NH ↔ N– transformation.