A chiral mixed metal–organic framework based on a Ni(saldpen) metalloligand: synthesis, characterization and catalytic performances

Abstract

A three-dimensional (3D) chiral mixed metal-organic framework [Cd4Cl(Ni-L)3(Ni-HL)(H2O)6(DMF)]·4DMF (CMOF 1) based on a new enantiopure dicarboxyl-functionalized Ni(saldpen) metalloligand Ni-H2L and a novel tetranuclear cadmium cluster [Cd4Cl(CO2)7(CO2H)] has been synthesized and characterized by elemental analyses, IR and UV-vis spectra, thermogravimetric analysis, nitrogen and carbon dioxide adsorption, powder and single-crystal X-ray diffractions. Each tetranuclear-cadmium cluster in 1 is linked by eight Ni-L ligands, and each Ni-L ligand is linked by two tetranuclear-cadmium clusters to generate a 3D framework with 1D open channels (∼1.1 × 0.9 nm(2)) along the b-axis. Based on its good stability, permanent porosity, Lewis acid sites and moderate uptake for CO2, 1 can be used as a self-supported heterogeneous catalyst for the synthesis of optically active propylene carbonate by asymmetric cycloaddition of CO2 with racemic propylene oxide under relatively mild conditions.

Synthesis of Chiral Cyclic Carbonates via Kinetic Resolution of Racemic Epoxides and Carbon Dioxide

“…The best result was obtained using a combination of (R)-(+)-binaphthol in conjunction A novel three-dimensional chiral mixed metal-organic framework (MOF) based on an enantiopure nickel(II)(salen) metalloligand and a tetranuclear cadmium cluster was reported by Jiang and co-workers in 2013 [29]. With each cadmium cluster linked by eight nickel complexes and each nickel complex surrounded by two cadmium clusters, a three-dimensional structure which displayed both high porosity and stability was generated.…”

“…This showed that chloride or tosylate counterions on the chromium centre gave enantioselective catalysts though with low s values (1.1-2.2). Subsequently, the effect of the co-catalyst was studied and the results showed that a combination of chromium(III)(salen) acetate and PPNCl [(bis-(triphenylphosphoranylidene)ammonium chloride)] was the most efficient catalyst for the kinetic resolution of phenyl glycidyl ether 1c, achieving 84% conversion and a s value of 3.1 at 25 °C and one atmosphere of carbon dioxide pressure for 24 h. Similarly, the use of N-(2,3-epoxypropyl)diphenylamine 1b gave a s value of 7.3 when the reaction was carried out at 25 °C and one atmosphere of carbon dioxide pressure for 3 h. A novel three-dimensional chiral mixed metal-organic framework (MOF) based on an enantiopure nickel(II)(salen) metalloligand and a tetranuclear cadmium cluster was reported by Jiang and co-workers in 2013 [29]. With each cadmium cluster linked by eight nickel complexes and each nickel complex surrounded by two cadmium clusters, a three-dimensional structure which displayed both high porosity and stability was generated.…”

A heterometal (Pd–Pb) organic framework: synthesis, structure and heterogeneous catalytic application

“…Metal–organic frameworks (MOFs) have attracted tremendous interests and an enormous amount of MOFs have been designed and synthesized for energy‐, environment‐ and medicine‐relevant applications, such as gas sorption, luminescence, sensors and so on. Especially, MOFs used as heterogeneous catalysts have been developed dramatically during the past decade and many MOF‐based catalysts containing various types of catalytic sites have been reported . Among them, the most intensively investigated topic is MOF‐based Lewis acid catalysts that utilize the coordinatively unsaturated metal centers in MOFs.…”

“…However, these MOF catalysts often suffer from the possible collapse of frameworks after catalytic reaction since the coordinatively unsaturated metal centers are also responsible for the stability of the frameworks. To overcome this problem, a more rational strategy is to utilize metalloligands involving well‐defined catalytic sites rather than pure organic ligands to construct MOF catalysts . For example, we have reported two Ni(salen)‐based MOFs that could be used as efficient and recyclable heterogeneous catalysts for the synthesis of cyclic carbonates by the cycloaddition of CO 2 with epoxides using the Ni(salen) moieties as Lewis acid catalytic sites .…”

High Temperature Postsynthetic Rearrangement of Dimethylthiocarbamate-Functionalized Metal–Organic Frameworks

“…Metal-organic frameworks (MOFs) have seen a huge increase in interest in recent years, due to their potential as porous materials for a wide variety of applications, such as gas sorption and storage, 1-5 catalysis [6][7] and in separations. [8][9][10] Reasons MOFs are so attractive for such a wide variety of applications include their crystalline nature, their high porosity and their potential for controlled modifications of their structures and pore surfaces.…”