SYNTHESIS OF NANOPOROUS HOMOCHIRAL METAL-ORGANIC FRAMEWORKS AND THEIR APPLICATION IN ENANTIOSELECTIVE CATALYSIS

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Publications

A copper-amidocarboxylate based metal organic macrocycle and framework: synthesis, structure and catalytic activities towards microwave assisted alcohol oxidation and Knoevenagel reactions

Publication . Karmakar, Anirban; Soliman, Mohamed Mostafa Aboelhassan; Alegria, Elisabete; Rubio, Guilherme; Guedes Da Silva, M. Fátima C.; Pombeiro, Armando

Reactions of 3,3 '-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L) with copper(ii) nitrate were studied and the obtained compounds [Cu-2(1:2 kappa(OO2)-O-1,2:3 kappa(OO4)-O-3-L)(mu-NO3)(mu(3)-OH)(MeOH)(2)](2)center dot 2MeOH center dot 1DMF (1) and [Cu(mu-1 kappa O-1:2 kappa O-2,3 kappa O-3:4 kappa O-4-L)(DMF)](n)center dot 4n(DMF) (2) were characterized by elemental analysis, FT-IR spectroscopy, and single-crystal and powder X-ray diffraction. Compound 1 is a macrocyclic tetranuclear Cu(ii) complex possessing a central, quasi-planar rhomboid shaped {Cu-4} cluster, which is the first example of a Cu(ii) based macrocyclic tetranuclear complex using such a linker. Compound 2 is a 2D metal organic framework having dinuclear paddlewheel type Cu(ii) assemblies that act as secondary building blocks. The topological analysis of framework 2 revealed that it has a 2,4-connected binodal net. Both compounds act as heterogeneous, easily recovered and reusable catalysts (the catalysts could be reused at least four times without significant loss of activity) for the microwave-assisted oxidation of several alcohols, as well as for the Knoevenagel condensation reaction of various aldehydes. The effect of reaction parameters such as temperature, time and type of oxidant was investigated. This study demonstrates that compound 1 can act as an efficient catalyst for the conversion of secondary alcohols (1-phenylethanol) to the corresponding ketones with high selectivity and yields up to 93% after 1 h of reaction at 120 degrees C and using t-BuOOH as an oxidant. Moreover, these compounds effectively catalyze the Knoevenagel condensation reactions of aldehydes with malononitrile and produce reaction yields between 64 and 99% within a very short period (10 min) under low power microwave irradiation. Furthermore, we have also studied the effectiveness of our catalyst 1 towards peroxidative oxidation/Knoevenagel condensation cascade reactions under microwave conditions.

2019-07-07Journal article

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Metal-organic frameworks with pyridyl-based isophthalic acid and their catalytic applications in microwave assisted peroxidative oxidation of alcohols and Henry reaction

Publication . Karmakar, Anirban; Martins, Luisa; HAZRA, SUSANTA; Guedes Da Silva, M. Fátima C.; Pombeiro, Armando

Reactions of 5-{(pyridin-4-ylmethyl)amino} isophthalic acid (H(2)L1) with copper(II), zinc(II), and cadmium(II) were studied, and the obtained metal organic frameworks (MOFs) [{Cu(L1)(DMF)}center dot DMF center dot H2O](n) (1), [Zn(L1)(H2O)(n) (2), and [Cd(L1)](n) (3) were characterized by elemental analysis, Fourier transform infrared spectroscopy, and X-ray single-crystal diffraction. As shown by X-ray crystallography, novel hybrid organic inorganic coordination-driven assemblies were obtained which exhibit different two- and three-dimensional (2D and 3D) polymeric architectures. Compounds 1 and 2 have 2D structures, whereas compound 3 features a 3D network type polymer with a dimetallic core acting as a secondary building unit. These frameworks act as heterogeneous polymeric solid catalysts (the most effective one being the copper MOF 1) for solvent-free microwave assisted peroxidative oxidation of primary and secondary alcohols. They also effectively catalyze the nitroaldol (Henry) reaction of different aldehydes with nitroalkanes in water. These MOF-based heterogeneous catalysts can be easily recovered and reused, at least for a few consecutive cycles, without losing activity.

2016-04Journal article

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