Synthesis of Metallomacrocycle and Coordination Polymers with Pyridine-Based Amidocarboxylate Ligands and Their Catalytic Activities towards the Henry and Knoevenagel Reactions.

The reactions of 3,3'-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2 L) with zinc(II), cadmium(II), and samarium(III) nitrates were studied, and the obtained compounds, [Zn(1κ O :2κ O' -L)(H2 O)2 ] n ( 1 ), [Cd(1κ O 2 :2κ O 2 -L)(H2 O)2 ]2 ⋅ 6 n  H2 O ⋅ n  C4 H8 O2 ⋅ 1.5 n  DMF ( 2 ), and [Sm(1κ O :2κO ' O '' :3κ O''' -L)(NO3 )(H2 O)(dmf)] n ⋅ n  DMF ( 3 ), were characterized by elemental analysis, FTIR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction. Compounds 1 and 3 have 1D zigzag- and double-chain-type structures, respectively, whereas 2 features a dinuclear metallomacrocyclic complex. The ligand (L2- ) orients in different conformations, that is, syn-syn for 1 and anti-anti for 2 and 3 . Compound 1 is the first example in which the syn-syn conformation for this ligand has been observed. These compounds act as heterogeneous catalysts for the nitroaldol (Henry; in water medium) and Knoevenagel condensation reactions of different aldehydes, and the most effective is zinc coordination polymer 1 . Recyclability, heterogeneity, and size-selectivity tests were performed, which showed that the catalyst was highly active over at least four recycling runs.