A two-fold interpenetrating metal-organic framework based on [Co4O(COO)6] cluster: Synthesis, crystal structure and catalytic properties

Abstract

One new Metal-Organic Frameworks, [Co₄O(L)₂]·(DMF)₈·(H₂O)₈ (1, H₃L = 4-[N,N-bis(4-methylbenzoic acid)amino]benzoic acid), had been successfully constructed under hydrothermal conditions, which firstly presents the [Co₄O(COO)₆] secondary-building unit similar to the typical [Zn₄O(COO)₆] one via single-crystal X-ray diffraction studies. All of the cobalt ions exhibit the four-coordinate environment, and possess more open metal sites. Heterogeneous catalytic experiments on allylic oxidation of cyclohexene indicate that 1 exhibits high catalytic activity by utilizing the tert-butylhydroperoxide (t-BuOOH) as the oxidant. The activation energy for the whole process of oxidation of cylcohexene had been calculated as 40.6 kJ mol⁻¹, which indicate the important role of the special [Co₄O(COO)₆] cluster in the resulted heterogeneous catalyst.