Ten new coordination polymers based on 3-carboxy-1-(4′-carboxybenzyl)-2-oxidopyridinium and different N-donor ligands: syntheses, structures, and photoluminescent properties

Abstract

Ten new coordination polymers, namely, [Zn(L)(H₂O)] (1), [Zn(L)(biim-4)_0.5]·2H₂O (2), [Zn(L)(biim-6)_0.5]·2H₂O (3), [Zn(L)(BTE)_0.5(H₂O)]·H₂O (4), [Zn(L)(phen)]·H₂O (5), [Cu(L)(phen)]·H₂O (6), [Cd(L)(phen)] (7), [Cd₅(L)₅(biim-4)_2.5]·5H₂O (8), [Co(L)(biim-4)_0.5(H₂O)]·H₂O (9), and [Ni(L)(biim-4)_0.5(H₂O)]·2H₂O (10), where H₂L = 3-carboxy-1-(4′-carboxybenzyl)-2-oxidopyridinium, biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole), biim-6 = 1,1′-(1,6-hexanedidyl)bis(imidazole), BTE = 1,1′-(2,2′-oxybis(ethane-2,1-diyl))bis(1H-1,2,4-triazole), and phen = 1,10-phenanthroline, have been synthesized under hydrothermal conditions. These complexes were structurally characterized by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Compound 1 displays a 2D undulated layer structure. Compounds 2 and 3 exhibit the similar 1D chain structures. In 2, the adjacent chains are extended into a 3D supramolecular architecture via hydrogen-bonding interactions and π–π interactions. In 3, the adjacent chains are extended into a 3D supramolecular architecture via hydrogen-bonding interactions. Compound 4 shows a 1D chain structure. The adjacent chains are further extended into a 3D supramolecular architecture through π–π interactions. Compounds 5 and 6 are isomorphous, and show the same 1D chain structures. The chains are linked by hydrogen-bonding interactions into a 3D supramolecular architecture. Compound 7 shows a 1D chain structure. The chains are arranged on parallel levels in two directions, resulting in a plywood-like structure. Compound 8 displays an unusual 2D 2-fold parallel interpenetrating network with both polyrotaxane and polycatenane characters. Compound 9 shows a 2D 3-connected 6³ network. The structure of compound 10 is an intriguing 2D self-penetrating network. In addition, the photoluminescent properties of 1–5, 7 and 8 have also been investigated in detail.