RESUMEN
The cyclization reactions of propargylic alcohols and propargylic amines with CO2 are important in industrial applications, but it was a great challenge that non-noble-metal catalysts catalyzed both reactions under mild conditions. Herein, the catalyst Cu2 O@ZIF-8 was prepared by encapsulating Cu2 O nanoparticles into robust ZIF-8, and it can effectively catalyze the cyclization of both propargylic alcohols and propargylic amines with CO2 into valuable α-alkylidene cyclic carbonates and oxazolidinones with turnover numbers (TONs) of 12.1 and 19.6, which can be recycled at least five times. The mechanisms were further uncovered by NMR, FTIR, 13 C isotope-labeling experiments and DFT calculations, in which Cu2 O and DBU can synergistically activate the C≡C bond and the hydroxy/amino group of substrates. Importantly, it is the first example of a noble-metal-free catalyst that can catalyze both propargylic alcohols and propargylic amines with CO2 simultaneously.
RESUMEN
The coupling reaction of propargylic amines and carbon dioxide (CO2) to synthesize 2-oxazolidinones is an important reaction in industrial production, and yet harsh reaction conditions and noble-metal catalysts are often required to achieve high product yields. Herein, one novel noble-metal-free three-dimensional framework, [Mg3Cu2I2(IN)4(HCOO)2(DEF)4]n (1), assembled by magnesium and copper clusters was synthesized and applied to this reaction. Compound 1 displays excellent solvent stability. Importantly, 1, acting as heterogeneous catalyst, can highly catalyze the cyclization of propargylic amines with CO2 under atmospheric pressure at room temperature, which can be recycled at least five times without an obvious decrease of the catalytic activity. NMR spectroscopy, coupled with 13C-isotope- and deuterium-labeling experiments, clearly clarifies the mechanism of this catalytic system: CO2 was successfully captured and converted to the product of 2-oxazolidinones, the C≡C bond of propargylic amines can be effectively activated by 1, and proton transfer was involved in the reaction process. Density functional theory calculations are further conducted to uncover the reaction path and the crucial role of compound 1 during the reaction.
RESUMEN
A new porous copper-organic framework assembled from 12-nuclear [Cu12] nanocages {[Cu2(L4-)(H2O)2]·4DMA·2H2O}n (1) (H4L = 5,5'-(butane-1,4-diyl)-bis(oxy)-diisophthalic acid) was successfully prepared and structurally characterized. Compound 1 feathering of a 3D framework with two types of 1D nanotubular channels and a large specific surface area can effectively enrich various harmful dyes. Additionally, due to the carbon dioxide (CO2) interactions with open Cu(II) sites and the electron-rich ether oxygen atoms of ligand in 1, it exhibits a highly selective CO2 uptake. Interestingly, 1 can effectively catalyze the cycloaddition reaction of CO2 with various epoxides under mild conditions, which is ascribed to the Lewis acid Cu(II) sites in the framework of 1. Importantly, 1 acting as a heterogeneous catalyst can be recycled at least 10 times without an obvious loss of catalytic activity, and the CO2 cycloaddition mechanism was further uncovered by density functional theory (DFT) calculations. This study can greatly enrich the MOF catalysts system of CO2 conversion and also provide a valuable guidance for the design of efficient MOFs catalysts.
RESUMEN
Two structurally similar metal-organic frameworks (MOFs) [Dy2Cu4I3(IN)7(DMF)2]·DMF (1) and [Dy2Cu4I3(IN)7(DMA)2]·DMA (2) (HIN = isonicotinic acid) feathering different coordinated solvent molecules were successfully isolated by tuning the types of solvents in the reaction system. Structural tests indicate that 1 and 2 are both built from 1D Dy(III) chains and copper iodide clusters [Cu4I3], generating into three-dimensional frameworks with an open 1D channel along the a axis. 1 and 2 display extensive and excellent solvent stability. Magnetic studies of 1 and 2 indicate that they exhibit interesting solvent-dependent magnetization dynamics. Importantly, 1 and 2 can act as highly effective catalysts for the carboxylic cyclization of propargyl alcohols with carbon dioxide (CO2) under ambient operating conditions. Additionally, the substrate scope was further explored over compound 1 based on the optimal conditions, and it exhibits efficient cyclic carboxylation of various terminal propargylic alcohols with CO2. This research offers an effective approach for the solvent-guided synthesis of MOFs materials and also presents the great application value of MOFs in CO2 chemical conversion.
RESUMEN
OBJECTIVE: To observe and compare the curative effect of pingyangmycin and sodium morrhuae respectively in the treatment of oral and maxillofacial venous malformation. METHODS: Forty cases of oral and maxillofacial venous malformation were induced in this study, 20 of which were given local injection of low dose of pingyangmycin, and 20 given local injection of 5% sodium morrheate. The therapeutic effects were observed. RESULTS: The effective cases of pingyangmycin was 19, and the effective cases of sodium morrhuate was 12. The side effect was found in 10 cases of, and in 15 cases sodium morrhuate group, the former was mainly pingymangmycin group systemic, the later was mainly local. The difference was significant between the two groups (P < 0.05). CONCLUSIONS: Pingyangmycin is more effective in effective rate and side effect treatment of venous hemangioma than sodium morrhuate.