Coordination polymers based on amidocarboxylate ligands: Hydrothermal syntheses, structural investigation, and catalytic application

A novel series of ten coordination polymers containing transition metals [M = Co(II), Ni(II), Mn(II), Zn(II) and Cd(II)] were synthesized through hydrothermal methods using 5,5′-azanediyldiisophthalic acid (H4adip) as the primary ligand. Additionally, a variety of auxiliary ligands were also employed, including (phen: 1,10-phenanthroline; 2,2′-bipy: 2,2′-bipyridine; 4,4′-bipy: 4,4′-bipyridine; H2biim: 2,2′-biimidazole or bpb: 1,4-bis(pyrid-4-yl)benzene). The synthesis yielded one 1D, one 2D and eight 3D coordination polymers, which were identified as [M2(μ6-adip)(phen)2]n·5nH2O (M = Co(1), Mn(2)), [Mn2(μ6-adip)(2,2′-bipy)2]n·4nH2O (3), [Ni2(μ6-adip)(2,2′-bipy)2(H2O)]n·5nH2O (4), [Zn2(μ4-adip)(2,2′-bipy)2(H2O)]n·nH2O (5), [Cd2(μ6-adip)(2,2′-bipy)2]n·4nH2O (6), [Ni2(μ4-adip)(μ-4,4′-bipy)1.5(H2O)4]n·4nH2O (7), [Cd2(μ7-adip)(μ-4,4′-bipy)(H2O)2] n·2nH2O (8), [Zn3(μ7-adip)(μ-Hbiim)2]n·2nH2O (9), and [Co2(μ7-adip)(μ-bpb)(H2O)]n·nH2O (10). These coordination polymers were thoroughly analyzed using standard techniques to investigate their topological types of underlying nets and catalytic properties. Remarkably, coordination polymer 9 exhibited significant activity in the Henry reaction with pyridine-4-aldehyde, achieving high yields under optimal conditions. It also demonstrated excellent stability, high efficiency, and reusability as a heterogeneous catalyst. © 2024 Elsevier B.V.