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摘要
A highly stable chiral salen-based metal-organic framework [(Cu4I4)(2)L-4]center dot 20DMF center dot 3CH(3)CN (1) [L = (R,R)-N, N'-bis(3-tert-butyl-5-(4-pyridyl) salicylidene)-1,2-diphenylethylenediamine nickel(II)] has been synthesized and characterized by single crystal X-ray diffraction and other physicochemical methods. 1 exhibits a rare 8-fold interpenetrated 3D framework constructed by a 4-connecting Cu4I4 cluster and a 2-coordinating L ligand. Remarkably, in spite of 8-fold interpenetration, 1 still possesses two types of 1D chiral hydrophobic channels with pore window sizes of 6.77 x 8.64 angstrom(2) and 6.09 x 10.96 angstrom(2) along the crystallographic a axis. All Ni(salen) moieties of L lie inside the 1D channels and the empty coordination sites of Ni2+ are oriented to the cavities. PXRD and N-2 adsorption measurements confirmed that 1 is extremely stable under high temperature (>400 degrees C), in water vapor (90% relative humidity), in acid/base aqueous solution (pH 0-14), and in saturated NaOH solution at 100 degrees C, as well as in 30 wt% H2O2 and 70 wt% tert-butyl hydroperoxide solution. 1 was proved to be an excellent recycled heterogeneous catalyst for the conversion of simulated industrial CO2 (that is, involving tiny amounts of water vapor and other acidic gases) with epoxides into cyclic carbonates under mild conditions for the first time. The synthesis of beta-hydroxy-1,2,3-triazoles from the same epoxides, alkyne and sodium azide was also catalyzed by 1 in aqueous solution with high yield. Interestingly, the cycloaddition reaction of CO2 to bulky epoxides shows a decrease in the activity with an increase in the alkyl chain length of the substrate because of confinement of the channel size of 1, showing size-dependent selectivity. The plausible catalytic mechanisms for these two reactions have also been proposed.
- 出版日期2017-6-28
- 单位华南理工大学
