Li-Hua He

Luminescent monometallic Cu(I) triphenylphosphine complexes based on methylated 5-trifluoromethyl-3-(2′-pyridyl)-1,2,4-triazole ligands

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.

Synthesis and characterization of emissive mononuclear Cu(I) complexes with 5-tert-butyl-3-(pyrimidine-2-yl)-1H-1,2, 4-triazole

A new series of mononuclear copper(I) halide complexes possessing 5-tert-butyl-3-(pyrimidine-2-yl)-1H-1,2,4-triazole (bpmtzH) and PPh3, Cu(bpmtzH)(PPh3)X (X = I (1); Br (2); Cl (3)), have been synthesized and characterized. As revealed via X-ray crystallography, 1–3 show a chiral, distorted tetrahedral N2PX arrangement, in which bpmtzH is a neutral bidentate chelating ligand using the 4-N of the 1,2,4-triazolyl ring and one N donor from the 2-pyrimidyl ring, consistent with the computational results. A comparatively weak low-energy absorption tail is observed between 320 and 450 nm for CH2Cl2 solutions of 1–3 at room temperature, ascribing to charge-transfer transitions with appreciable metal-to-ligand charge transfer (MLCT) character. Complexes 1–3 in the solid state have good luminescence at ambient temperature, although they are non-emissive in solution. The solid-state emission, most likely originating from both 3MLCT and 3XLCT transitions, can be modulated via alteration of the halide bound to {Cu(bpmtzH)(PPh3)} motif. Graphical Abstract

Emissive mononuclear Eu(III) and Tb(III) complexes bearing deprotonated 2,2′-bipyridyl-1,2,4-triazole terdentate ligands

Abstract A series of new emissive mononuclear Ln(III) complexes with deprotonated 2,2ʹ-bipyridyl-1,2,4-triazole terdentate ligands, [Ln(L)(DMF)2(NO3)2]∙n(solvent) (Ln = Eu (1 and 2), Tb (3 and 4), HL = 6-(5-trifluoromethyl-1,2,4-triazol-3-yl)-2,2′-bipyridine, 6-(5-trifluoromethyl-1,2,4-triazol-3-yl)-4,4′-dimethyl-2,2′-bipyridine), have been synthesized and characterized. As revealed by X-ray crystallography, each Ln(III) has a distorted tricapped trigonal prism generated by three nitrogens from one 2,2ʹ-bipyridyl-1,2,4-triazolate chelate and six oxygens from two DMF molecules and two chelating nitrates, where 2,2ʹ-bipyridyl-1,2,4-triazole serves as a mono-anionic tridentate chelate via deprotonation of the 1,2,4-triazolyl-NH. Complexes 1–4 are all emissive at room temperature in solution and solid states, and the introduction of two methyl groups into the 2,2ʹ-bipyridyl ring is efficient in enhancing luminescence efficiencies of Ln(III) complexes.

Emissive mononuclear Cu(I) triphenylphosphine complexes with functionalized 6-tert-butoxycarbonyl-2,2′-bipyridine

Two new emissive mononuclear copper(I) triphenylphosphine complexes with functionalized 6-tert-butoxycarbonyl-2,2′-bipyridine chelating ligands were prepared and characterized. Each Cu(I) cation has a markedly distorted P2N2 tetrahedral array with two different Cu—N bond distances, due to the addition of the bulky tert-butoxycarbonyl group at the 6-position of the 2,2′-bipyridyl ring. A weak low-energy broad absorption band appears at 330—500 nm in their CH2Cl2 solutions, which is influenced by the methylation of the 2,2′-bipyridyl ring. At room temperature, the photoluminescence can be clearly observed both in degassed CH2Cl2 solution and in the solid state, because of the introduction of the bulky tert-butoxycarbonyl substituent, and the emission properties are remarkably affected by both the methylation and the alkoxycarbonyl variation of the 2,2′-bipyridyl ring. It is shown that the introduction of the bulky tert-butoxycarbonyl group is favorable for improving the emission properties of the 6-alkoxycarbonyl-2,2′-bipyridine-based cuprous complexes.