Hydrothermal syntheses, structures and luminescent properties of Zn(ii) coordination polymers assembled with benzene-1,2,3-tricarboxylic acid involving in situ ligand reactions

Abstract

Five Zn(II) coordination polymers, [Zn(1,2,3-Hbtc)(1,4-bix)]·0.5(1,4-bix)·H2O (1), [Zn(mocip)(1,4-bix)] (2), [Zn3(1,2,3-btc)2(4,4′-bpy)2(H2O)2]2·7H2O (3), [Zn3(1,2,3-btc)2(bbi)3]2·3H2O (4) and [Zn(dmcaip)(1,3-bix)]·DMF (5), were prepared by hydro(solvo)thermal reactions of ZnO with 1,2,3-H3btc (1,2,3-H3btc = 1,2,3-benzenetricarboxylic acid) in the presence of different N-donor ligands (1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, 4,4′-bpy = 4,4′- bipyridine, bbi = 1,1′-(1,4-butanediyl)bis(imidazole), 1,3-bix = 1,3-bis(imidazol-1-ylmethyl)benzene, H2mocip = 2-(methoxycabonyl)isophthalic acid and H2dmcaip = 2-(dimethylcarbamoyl)isophthalic acid). Their crystal structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses and IR spectra. Complex 1 has a one-dimensional (1D) infinite tubular structure, whereas 2 exhibits two-dimensional (2D) supramolecular networks assembled from 1D chains and 1,4-bix. The three-dimensional (3D) framework of 3 can be described as a trinodal 4-connected (42·64)2(65·8)(42·64)2 topology, which consists of 2D [Zn3(1,2,3-btc)2] layers and 4,4′-bpy pillars. Complex 4 features a 5-nodal (3,4)-connected 3D coordination net with a (6·74·8)2(62·72·82)(6·72)2 topology. Complex 5 has a rare 1D double meso-helical supramolecular structure. Interestingly, in the complexes 2 and 5, the starting 1,2,3-H3btc reagents are converted into new ligands (mocip2− in 2 and dmcaip2− in 5) under solvothermal conditions via in situ ligand reactions. Moreover, thermal stabilities, X-ray powder diffraction and the fluorescent properties of complexes 1–5 have been investigated.