Two Stable Heterometal-MOFs as Highly Efficient and Recyclable Catalysts in the CO2 Coupling Reaction with Aziridines.

Two stable heterometal-organic frameworks, {Na[LnCo(DATP)2 (Ac)(H2 O)](NO3 )⋅DMA⋅11 H2 O}n (Ln=Er(1) and Yb(2)), have been prepared with H2 DATP (4'-(3,5-dicarboxyphenyl)-2,2':6',2'''-terpyridine) as organic building block. These two isostructural compounds featuring two-dimensional layer architectures possess outstanding thermal stabilities and excellent chemical stabilities in common organic solvents and different acid/base solutions with pH range changing from 1 to 13. Moreover, compounds 1 and 2 serving as heterogeneous catalysts can efficiently catalyse the CO2 fixation reaction with various aziridines to result in corresponding oxazolidinones at 70 °C. Importantly, a good recyclable performance of 1 for at least 10 cycles is observed based on the experimental results, which are further confirmed by PXRD, TGA and ICP analyses.

Solvent-dependent variations of both structure and catalytic performance in three manganese coordination polymers.

Three new manganese 4'-(3,5-dicarboxyphenyl)-2,2':6',2'''-terpyridine (H2DATP) metal-organic framework materials have been generated through regulating the ratios of a binary solvent mixture (DMA/H2O) under solvothermal conditions. Compound 1 {[Mn2(DATP)(HDATP)(H2O)4](OH)·10H2O}n displaying a one-dimensional (1D) chainlike structure was crystallized from the DMA/H2O mixture with a molar ratio of 1 : 1, while the two-dimensional (2D) layer species, {[Mn(DATP)(H2O)]·2H2O}n (2) was produced by increasing the ratio of DMA/H2O to 5 : 1. Interestingly, the crystallization in pure DMA yields a three-dimensional (3D) interpenetrating network {[Mn(DATP)]·4H2O}n (3), featuring higher solvent stability and pH stability than compounds 1 and 2. It is proved that solvent not only influences the structural transformation process of crystals but also has a significant effect on their properties. These three compounds present different catalytic performances in the CO2 cycloaddition to epoxides with various substituent groups into corresponding cyclic carbonates, and only 3 can serve as an efficient and recyclable catalyst at mild temperature.