-[MoO]-based multifunctional hybrid material for high catalytic performance on the cycloaddition of CO, esterification and knoevenagel condensation.

Developing materials with excellent properties has become the norm in the field of basic research, prompting us to explore highly robust hybrid materials based on electron-rich POMs and electron-deficient MOFs. Herein, a -[MoO]-based hybrid material of [Cu(BPPP)]{-[MoO]} (NUC-62) with excellent physicochemical stability was self-assembled under acidic solvothermal conditions from NaMoO and CuCl in the presence of a designed chelated ligand of 1,3-bis(3-(2-pyridyl)pyrazol-1-yl)propane (BPPP), which has sufficient coordination sites, spatial self-regulation and great deformation ability. In NUC-62, each of two tetra-coordinated Cu ions and two BPPP are unified into one dinuclear unit serving as the cation, which is interactively linked to -[MoO] anions rich hydrogen bonds of C-H⋯O. Because of the unsaturated Lewis acidic Cu sites, NUC-62 exhibits high catalytic performance on the cycloaddition reactions of CO with epoxides under mild conditions with a high turnover number and turnover frequency. Furthermore, NUC-62, as a recyclable heterogeneous catalyst, shows high catalytic activity for the esterification of aromatic acid under refluxing, which is much better than the inorganic acid catalyst of HSO in terms of turnover number and turnover frequency. Moreover, because of open metal sites and rich terminal oxygen atoms, NUC-62 shows high catalytic activity for Knoevenagel condensation reactions of aldehydes and malononitrile. Hence, this study lays the groundwork for constructing heterometallic cluster-based microporous MOFs with excellent Lewis acidic catalysis and chemical stability. Therefore, this study lays a foundation for the construction of functional polyoxometalate complexes.