Hydrothermal Generation, Crystal Structures, and Catalytic Performance of Mn(II), Cu(II), and Ni(II) Coordination Polymers Based on a Pyridine-Tricarboxylate Ligand

A pyridine-tricarboxylic acid, 4-(6-carboxy-pyridin-3-yl)-isophthalic acid (H3cpia), was used as a versatile building block to synthesize three novel coordination polymers under hydrothermal conditions and formulated as [Mn8(mu 3-Hcpia)2 (mu 6-cpia)4(Hbiim)2(H2O)6]n<middle dot>6nH2O (1), [Cu3(mu 4-cpia)2(bipy)2(H2O)2]n<middle dot>4nH2O (2), and [Ni3(mu 3-cpia)2(dpe)3(H2O)2]n<middle dot>4nH2O (3). Three supporting ligands, 2,2 '-biimidazole (H2biim), 2,2 '-bipyridine (bipy), and 1,2-di(4-pyridyl)ethane (dpe), were used in the synthesis. The structures of the studied products 1-3 varied significantly, ranging from a 1D chain (2) to 2D sheets (1 and 3). Furthermore, these compounds were evaluated as heterogeneous catalysts for the Henry reaction, achieving high product yields under optimized conditions. In addition, we investigated various reaction parameters and substrate scopes, and assessed the feasibility of catalyst recycling. This thorough investigation's results highlight the versatility of H3cpia as a tricarboxylate building block in the formation of functional coordination polymers.