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