A series of ((pyridinyl)-1H-pyrazolyl)pyridine (pypzpy) ligands in which the pyrazolyl ring at 1- and 3-positions is modified by two 2-, 3-, or 4-pyridyl groups were prepared. Reaction of CuI with 2-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (2,2′-pypzpy) in MeCN at room temperature or solvothermal reaction of the same components at 120 °C afforded one binuclear complex [{(2,2′-pypzpy)Cu}(μ-I)]2 (1). Treatment of CuI with 3-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (3,2′-pypzpy) at room temperature or at 120 °C produced one-dimensional (1D) polymer [{Cu3(μ3-I)3}(μ-3,2′-pypzpy)] n (2) and one two-dimensional (2D) polymer [{Cu2(μ-I)(μ3-I)}2(3,2′-pypzpy)2] n (3), respectively. Similar reactions of CuI with 4-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (4,2′-pypzpy) at room temperature or at 150 °C yielded one 1D polymeric complex [{Cu(μ3-I)}2(4,2′-pypzpy)2{Cu(μ-I)}2] n (4). Complexes [{Cu3(μ3-I)3}(μ-2,3′-pypzpy)] n (5), [(CuI)(μ-2,3′-pypzpy)]2 (6), [(Cu2I2)(3,3′-pypzpy)] (7), [(CuI)(4,3′-pypzpy)] (8), [{Cu(μ3-I)}2(μ-2,4′-pypzpy)2{Cu(μ-I)}2] n (9), [(CuI)(3,4′-pypzpy)] (10), and [(CuI)(μ-4,4′-pypzpy)] n (11) could be isolated by solution reactions or solvothermal reactions of CuI with 2-, 3-, 4-(1-(pyridin-3-yl)-1H-pyrazolyl)pyridine (2,3′-, 3,3′-, 4,3′-pypzpy), or 2-, 3-, 4-(1-(pyridin-4-yl)-1H-pyrazolyl)pyridine (2,4′-, 3,4′-, 4,4′-pypzpy). Compounds 1–11 were characterized by IR, elemental analysis, powder X-ray diffraction, and single-crystal X-ray crystallography. Complex 1 contains a normal [Cu(μ-I)]2 dimeric structure. Complexes 2 and 5 consist of a unique displaced staircase chain [Cu2(μ3-I)2] n . Complex 3 has a 2D network formed by linking chairlike [Cu2(μ-I)(μ3-I)]2 units with two pairs of 3,2′-pypzpy bridges. Complexes 4 and 9 have a rare 1D triple chain, in which one internal 1D ladder-like chain [Cu2(μ3-I)2] n is connected with two zigzag chains [Cu(μ-I)] n via 4,2′-pypzpy or 2,4′-pypzpy ligands. Compound 6 consists of two [CuI] units interconnected by two 2,3′-pypzpy ligands. Compound 11 contains a 1D chain assembled by monomeric [CuI] units and 4,4′-pypzpy ligands. The luminescence properties of 1–11 in solid state were also investigated at room temperature. These results offer an interesting insight into how the coordination sites of the pypzpy ligands do exert great impact on their coordination modes, the coordination spheres of the Cu(I) centers, the formation of the [Cu n I n ] motifs and the topological structures of the final complexes.
Reactions of a pincer ligand 2-(1H-pyrazol-1-yl)-6-(1H-pyrazol-3-yl)pyridine (pzpypzH) with Cu(NO3)2, Cu(ClO4)2, CuSO4, CuCl2 or CuI produced three dinuclear Cu(ii) complexes [{Cu(NO3)}(μ-pzpypz)]2 (1), [{Cu(ClO4)}(μ-pzpypz)]2 (2), [Cu2(μ-SO4)(μ-pzpypz)2]·2MeOH (3·2MeOH), one mononuclear Cu(ii) complex [CuCl2(pzpypzH)] (4) and one trinuclear Cu(i)/Cu(ii) complex [(ICu)(μ-I)2Cu2(μ-pzpypz)2] (5), respectively. Treatment of 4 with two equiv. of AgNO3 in DMF also gave rise to 1. Complexes 1-5 were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 or 2 has a dimeric structure in which two {Cu(X)} (X = NO3, ClO4) fragments are interconnected by two μ-pzpypz(-) ligands. 3 also adopts a dimeric structure in which two Cu(ii) centers are interconnected by a pair of μ-pzpypz(-) ligands and one μ-SO4(2-) ion. The Cu(ii) center in 4 is five-coordinated by three N atoms of the pzpypzH ligand and two Cl atoms. In 5, two Cu(ii) centers are bridged by two μ-pzpypz(-) ligands and one CuI3(2-) unit, forming a unique trinuclear structure. Complexes 1-5 displayed high catalytic activity toward the ammoxidation of alcohols to nitriles and the aerobic oxidation of alcohols to aldehydes in H2O. The nitrile or aldehyde products could be readily separated from the catalytic system by extraction and the residual aqueous solution containing 1 retained good activity for several cycles.
Herein, we report a facile and efficient synthetic method to construct azepino[1,2-a]indoles through a novel gold(I)-catalyzed intramolecular hydroarylation of alkynylindoles. A wide range of functional groups can be well tolerated in this transformation, and the corresponding highly functionalized azepino[1,2-a]indole skeletons were obtained in moderate to excellent yields. Subsequent oxidation of the products gave the interesting and valuable polycyclic carbazoles, which were widely used as the key building blocks in materials science. Letter pubs.acs.org/OrgLett
Introduction Metabolic-associated fatty liver disease (MAFLD) has been found to be strongly linked to several diseases. Although previous studies have explored the association between MAFLD and extrahepatic cancers, research on the relationship between MAFLD and gastric carcinoma (GC) and esophageal carcinoma (EC) is relatively scarce and requires updating. Therefore, the objective of this study is to conduct a comprehensive investigation into the association between MAFLD and GC or EC. Material and methods We conducted a comprehensive search for relevant studies published up to 5 August 2022, using the PubMed, Embase and Web of Science databases. To estimate the risk ratio (RR) and the 95% confidence interval (CI), we employed a random-effects model. We also conducted subgroup analyses based on study characteristics. The protocol for this systematic review is registered in the Prospero database under the registration number CRD42022351574. Results Our analysis included eight eligible studies, comprising a total of 8 629 525 participants. We found that the pooled RR values for the risk of GC in patients with MAFLD were 1.49 (95%CI: 1.17–1.91), whereas the pooled RR values for the risk of EC in patients with MAFLD were 1.76 (95%CI: 1.34–2.32). Conclusions Based on our meta-analysis, we conclude that there is a significant association between the presence of MAFLD and the development of GC and EC.
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