Synthesis, Characterization, and Photophysical Properties of Heteroleptic Copper(I) Complexes with Functionalized 3‑(2′-Pyridyl)-1,2,4-triazole Chelating Ligands

A new series of mononuclear copper­(I) complexes (<b>1</b>–<b>9</b>) 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 <b>1</b>–<b>9</b> were fully characterized by elemental analysis, NMR spectroscopy, mass spectroscopy, electronic absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and X-ray crystallography (<b>1</b>–<b>8</b>). 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 <b>1</b>–<b>4</b> 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 <b>5</b>–<b>9</b> 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 <b>6</b> and neutral derivative <b>7</b> can readily be interconverted through the ring inversion of the 1,2,4-triazolyl regulated by the NH ↔ N^– transformation

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

<div><p>A new series of mononuclear copper(I) halide complexes possessing 5-<i>tert</i>-butyl-3-(pyrimidine-2-yl)-1<i>H</i>-1,2,4-triazole (bpmtzH) and PPh₃, Cu(bpmtzH)(PPh₃)X (X = I (<b>1</b>); Br (<b>2</b>); Cl (<b>3</b>)), have been synthesized and characterized. As revealed via X-ray crystallography, <b>1–3</b> 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 <b>1–3</b> at room temperature, ascribing to charge-transfer transitions with appreciable metal-to-ligand charge transfer (MLCT) character. Complexes <b>1–3</b> 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.</p></div

Luminescent Three- and Four-Coordinate Dinuclear Copper(I) Complexes Triply Bridged by Bis(diphenylphosphino)methane and Functionalized 3‑(2′-Pyridyl)-1,2,4-triazole Ligands

A new series of bimetallic Cu­(I) complexes <b>1</b>–<b>5</b> 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 <b>1</b>–<b>5</b> are singly or doubly charged dinuclear Cu­(I) species with an eight-membered Cu₂C₂P₄ ring of {Cu­(μ-dppm)₂Cu} unit, in which <b>3</b> and <b>4</b> adopt the boat–boat conformation, while <b>1</b>, <b>2</b>, and <b>5</b> 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 <b>1</b>–<b>5</b> 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 (<i>ortho</i>-, <i>meta</i>-, and <i>para</i>-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

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<p>Streptococcus agalactiae and Candida albicans often co-colonize the female genital tract, and under certain conditions induce mucosal inflammation. The role of the interaction between the two organisms in candidal vaginitis is not known. In this study, we found that co-infection with S. agalactiae significantly attenuated the hyphal development of C. albicans, and that EFG1-Hwp1 signal pathway of C. albicans was involved in this process. In a mouse model of vulvovaginal candidiasis (VVC), the fungal burden and the levels of pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α showed a increase on co-infection with S. agalactiae, while the level of TH17 T cells and IL-17 in the cervicovaginal lavage fluid were significantly decreased. Our results indicate that S. agalactiae inhibits C. albicans hyphal development by downregulating the expression of EFG1-Hwp1. The interaction between S. agalactiae and C. albicans may attenuate host vaginal mucosal TH17 immunity and contribute to mucosal colonization by C. albicans.</p

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<p>Streptococcus agalactiae and Candida albicans often co-colonize the female genital tract, and under certain conditions induce mucosal inflammation. The role of the interaction between the two organisms in candidal vaginitis is not known. In this study, we found that co-infection with S. agalactiae significantly attenuated the hyphal development of C. albicans, and that EFG1-Hwp1 signal pathway of C. albicans was involved in this process. In a mouse model of vulvovaginal candidiasis (VVC), the fungal burden and the levels of pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α showed a increase on co-infection with S. agalactiae, while the level of TH17 T cells and IL-17 in the cervicovaginal lavage fluid were significantly decreased. Our results indicate that S. agalactiae inhibits C. albicans hyphal development by downregulating the expression of EFG1-Hwp1. The interaction between S. agalactiae and C. albicans may attenuate host vaginal mucosal TH17 immunity and contribute to mucosal colonization by C. albicans.</p

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<p>Streptococcus agalactiae and Candida albicans often co-colonize the female genital tract, and under certain conditions induce mucosal inflammation. The role of the interaction between the two organisms in candidal vaginitis is not known. In this study, we found that co-infection with S. agalactiae significantly attenuated the hyphal development of C. albicans, and that EFG1-Hwp1 signal pathway of C. albicans was involved in this process. In a mouse model of vulvovaginal candidiasis (VVC), the fungal burden and the levels of pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α showed a increase on co-infection with S. agalactiae, while the level of TH17 T cells and IL-17 in the cervicovaginal lavage fluid were significantly decreased. Our results indicate that S. agalactiae inhibits C. albicans hyphal development by downregulating the expression of EFG1-Hwp1. The interaction between S. agalactiae and C. albicans may attenuate host vaginal mucosal TH17 immunity and contribute to mucosal colonization by C. albicans.</p