Bringing 5-(3, 4-dicarboxylphenyl)picolinic acid to crystal engineering research: hydrothermal assembly, structural features, and photocatalytic activity of Mn, Ni, Cu, and Zn coordination polymers. Issue 7 (24th January 2018) - Gu, Jin-Zhong
Abstract : A novel tricarboxylic acid block with phthalate and picolinate functionalities was applied for the assembly of a new series of coordination polymers with interesting structural features and functional properties. Abstract : 5-(3, 4-Dicarboxylphenyl)picolinic acid (H3 dppa) was applied as a novel tricarboxylic acid block with phthalate and picolinate functionalities for the aqueous-medium assembly of seven new coordination compounds, namely, [Mn2 (μ-Hdppa)2 (phen)2 (H2 O)2 ] (1 ), {[Mn(μ-Hdppa)(2, 2′-H2 biim)(H2 O)]·H2 O} n (2 ), [Ni(Hdppa)(phen)2 ]·4H2 O (3 ), {[Ni(μ-Hdppa)(μ-4, 4′-bipy)(H2 O)]·H2 O} n (4 ), {[Cu3 (μ3 -dppa)(μ-Hdppa)(phen)4 ]2 [Cu(μ-Hdppa)2 ]·10H2 O} n (5 ), {[Ni3 (μ-dppa)2 (μ-1, 4-bpb)2 (H2 O)6 ]·4H2 O} n (6 ), and {[Zn3 (μ4 -dppa)2 (phen)2 (H2 O)2 ]·4H2 O} n (7 ). These products1–7 represent the first structurally characterized examples of the coordination compounds derived from H3 dppa. Compounds1–7 were assembled in the presence of various N-donor supporting ligands acting as crystallization mediators, which were selected from 1, 10-phenanthroline (phen), 2, 2′-biimidazole (H2 biim), 4, 4′-bipyridine (4, 4′-bipy), or 1, 4-bis(pyrid-4-yl)benzene (1, 4-bpb). Full characterization of1–7 by IR spectroscopy, thermogravimetric (TGA), elemental, and topological analyses, as well as powder (PXRD) and single-crystal X-ray diffraction, was performed. The structural types range from the discrete 0D complexes (1 and3 ) and 1D coordination polymers with a2C1 topology (2, 5, and6 ) to the 2D metal–organic layers with ansql topology (4 and7 ). The structural diversity of1–7 is driven by various factors, including the metal(ii ) node nature, deprotonation degree of H3 dppa, or type of crystallization mediator. The magnetic properties of1, 2, 4, and6 were studied and modeled, revealing antiferromagnetic (in1, 2, and6 ) or ferromagnetic (in4 ) interactions between adjacent metal(ii ) centers. The luminescence of7 was also investigated. Moreover, the photocatalytic activity of1–7 was studied for the degradation of methylene blue as a model dye pollutant, disclosing that the nickel(ii ) coordination polymer4 is the most active catalyst. The observed catalytic activity of1–7 correlates well with their band gap energies determined by the UV-diffuse reflectance method.