Eight Zn(ii) coordination networks based on flexible 1,4-di(1H-imidazol-1-yl)butane and different dicarboxylates: crystal structures, water clusters, and topologies

Abstract

Eight new Zn(II) coordination polymers based on flexible 1,4-di(1H-imidazol-1-yl)butane and different dicarboxylates, [Zn(dimb)(suc)·2DMF]_n (1), [Zn(dimb)(mbda)·3H₂O]_n (2), [Zn(dimb)(adip)·DMF·2H₂O]_n (3), [Zn(dimb)(pma)·2.5H₂O]_n (4), [Zn₂(dimb)(tha)₂(H₂O)]_n (5), [Zn(dimb)(chda)·2H₂O]_n (6), [Zn(dimb)(obda)·DMF]_n (7), [Zn(dimb)(tdga)·CH₃OH]_n (8) (dimb = 1,4-di(1H-imidazol-1-yl)butane, H₂suc = succinic acid, H₂mbda = m-benzenediacetic acid, H₂adip = adipic acid, H₂pma = pimelic acid, H₂tha = thiophene-2,5-dicarboxylic acid, H₂chda = 1,4-cyclohexanedicarboxylic acid, H₂obda = o-benzenediacetic acid, H₂tdga = thiodiglycolic acid; DMF = N,N′-dimethylformamide), have been synthesized and structurally characterized by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffractions (PXRD) and thermogravimetric analyses (TGA). Single-crystal X-ray diffraction analysis reveals that 1, 2, 4, 7 and 8 are 2D wavy 4⁴-sql networks with different dimensions of quadrilateral window units, depending on the conformation and length of dimb and dicarboxylates. Complex 3 is a 2D a 6³-hcb network incorporating a [Zn₂(dimb)₂] cyclic subunit. In complex 5, Zn(II) centers as 3-connected node are linked by dimb and tha to form a 3D 8-fold interpenetrating ThSi₂2 network. Complex 6 is a 4-connected noninterpenetrating cds network. Interestingly, an infinite T4(2)6(2) water tape and a D_2h cyclic water tetramer are also found in complexes 2 and 3, respectively. In 1–8, all Zn(II) centers are located in a four-coordinated environment, and dimb and dicarboxylates are 2-connected linkers, but networks with diverse topologies are built, which indicates the linkage of central metal ion, the conformation of dimb and dicarboxylate have important influences on the resulting structures. Furthermore, the solid-state photoluminescence properties of the 1–8 were investigated at 298 and 77 K.