| As a new generation of solid-state materials, inorganic-organic hybrid compounds have been greatly developed not only for their various fascinating framework topologies, but also for their potential application in the field of catalysis. Because of the importance of epoxides as key chemical intermediates for a wide variety of industrial and chemical applications, the epoxidation of alkenes is an attractive reaction.This paper mainly focus on the design and synthesis of defferent inorganic-organic hybrid vanadates and their catalytic properties in the olefin epoxidation reactions. The main contents and results are as follows:1. Five inorganic-organic hybrid vanadates based on tetravanadate cores, transition metals and N-donor ligands have been designed and synthesized under hydrothermal conditions, namely, [Zn(e IM)3]2V4O12(1), [Zn(p IM)3]2V4O12?H2O(2), [Zn(ip IM)3]2V4O12(3), [Co(e IM)3]2V4O12?H2O(4), [Cu(e IM)2(H2O)]2V4O12(5)(e IM = 1-ethylimidazole, p IM = 1-propylimidazole, ip IM = isopropylimidazole). All compounds were fully characterized by single-crystal XRD, powder XRD, elemental analyses, TGA, and FT-IR spectroscopy. The hybrid zinc vanadates(1-3) and cobalt vanadate(4) exhibit interesting 2D folded structures and the hybrid copper vanadate(5) presents a 1D chain configuration.2. The epoxidation of cyclooctene was selected as a model reaction to evaluate the catalatic activities of compounds 1-5. They all can efficiently catalyze the epoxidation of cyclooctene to corresponding epoxide with excellent conversion and selectivity, but the catalytic effects is basically the same. Therefore, compound 1 with high yields is selected to examine the long-term stability in a heterogeneous system. The catalyst was recycled for at least three runs and still maintained its conversion and selectivity, besides the strcture of the catalyst remained stable. We also examined on various olefins under optimized conditions. |
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