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Four coordination polymers (CPs) based on H 2 tbta ligand, namely, [Zn(tbta) (bmbp)] n (1), {[Cd 0.5 (tbta) (H 2 O)] n ·(Hbia) (H 2 O)} (2), [Cu 1.5 (tbta) (OH) (bi) (H 2 O)] n (3) and [Cd(tbta) (ei) 2 ] n (4) have been synthesized and characterized (H 2 tbta = 2,3,5,6-tetrabromoterephthalic acid, bmbp = 4,4'-dimethyl-2,2'-bipyridine, bia = 1H-benzo[d]imidazol-2-amine, bi = 1H-benzo[d]imidazole, ei = 2-ethyl-1H-imidazole). Single-crystal X-ray diffraction analyses illustrate 1 and 4 exhibit 1D chains, and compound 1 and 4 are hydrogen-bonded into a 2D layer to form a 3D supramolecular structure. Compounds 2 and 3 show 2D layered structures and further expand to 3D supramolecular structures through hydrogen bonds. Structural comparisons indicate that the position of coordination sites and substituent groups plays a crucial role in the control of the final structures. Besides, the photoluminescence properties of compounds 1 , 2 , 4 and UV–vis spectra of 3 have been investigated in the solid state at room temperature. Image 1 • Four CPs based on H 2 tbta ligand were synthesized and structurally characterized. • The auxiliary ligands drastically affect the formation of low-dimensional structures. • The UV–vis spectrum and luminescence properties were studied. [ABSTRACT FROM AUTHOR]

Four coordination polymers, namely, [Zn (DBT) (4,4′-dmbpy) (H 2 O)] n (1), [Co(DBT) (2,2′-bpy) (H 2 O)] n (2), [Zn (DBT) (2,2′-bpy)] n (3), [Zn (DBT) 0.5 (2,2′-bpy) 2 ·(HDBT−)] n (4) (H 2 DBT ​= ​2,5-dibromoterephthalic acid, 4,4′-dmbpy ​= ​4,4′-dimethyl-2,2′-bipyridyl and 2,2′-bpy ​= ​2,2′-bipyridyl) have been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR and thermogravimetric (TG) analysis. These four compounds remained stable until 150 ​°C, and the major quality loss (83–90%) occurred between 150 and 700 ​°C. In mixed ligands system, the main ligand H 2 DBT exhibits monodentate or bidentate bridging coordination modes and the auxiliary ligands 4,4′-dmbpy and 2,2′-bpy both possess bidentate chelate coordination modes. An objective of this study was to investigate the pivotal role of chelating ligands in the formation of low dimensional structures. As the bipyridyl ligands occupy the coordination site, compounds 1 – 3 all display two dimensional structures and 4 shows 1D chains, of which compounds 1 and 2 are isomorphic. The hydrogen bonds and π-π stacking work together in the formation of 3D supramolecular structure of these four compounds. Besides, we investigated their photoluminescence properties in the solid state at room temperature. The compounds 1 , 3 and 4 exhibited good fluorescence performance, and their strong emission peaks were located at 447 ​nm (λex ​= ​285 ​nm) for 1 , 427 ​nm (λex ​= ​330 ​nm) for 3 , and 412 ​nm (λex ​= ​310 ​nm) for 4. Image 1 • Four CPs based on H 2 DBT ligand were synthesized and structurally characterized. • Low-dimensional crystals were obtained by changing experimental conditions. • The luminescence properties were studied. [ABSTRACT FROM AUTHOR]

Four coordination polymers (CPs) based on bis-imidazole ligands (1,2-bimb and 1,2-bmimb), namely, {[Zn(1,2-bimb)(2,5-dtpa)] H2O}n (1), {[Cd2(1,2-bimb)2(5-hipa)2] 2H2O} (2), {Zn2(1,2-bimb)(L)(CH3COO) DMF·2H2O}n (3) and {Cd(1,2-bmimb)(3-npa)}n (4), have been synthesized by solvothermal reactions (1,2-bimb = 1,2-bis((1H-imidazol-1-yl)methyl)benzene, 1,2-bmimb = 1,2-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, 2,5-H2dtpa = 2,5-diaminoterephthalic acid, 5-H2hipa = 5-hydroxyisophthalic acid, H3L= 3,3′,3′′-(2,4,6-trioxo-1,3,5-triazinane-1,3,5-triyl)tripropanoic acid, 3-H2npa = 3-nitrophthalic acid) and structurally verified by single-crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD), elemental analyses and infrared spectroscopy (IR). Complex 1 and 2 show a dinuclear 2D layered structure. Complex 4 exhibits a two-dimensional network consisting of [Cd(3-npa)]n and [Cd(1,2-bmimb)]n chains. Both 1,2 and 4 display a 4-connected sql topology sheet, which can be further expanded into a 3D supramolecular network through π···π interaction between layers. Complex 3 features a 3D (3,6)-connected {42·6}·{44·610·8}-3,6T24 topology structure consisting of 2D bilayers. Structural comparison reveals that it is not only the substituents at different positions of ancillary ligands and the primary bis(imidazole) linkers that play crucial roles in the control of the final structures. Besides, the photoluminescence properties of 1–4 have been investigated in the solid state at room temperature. [ABSTRACT FROM AUTHOR]