A Series of Zinc(II) 3D → 3D Interpenetrated Coordination Polymers Based On Thiophene-2,5-dicarboxylate and Bis(Imidazole) Derivative Linkers

Six coordination polymers of Zn(II) ions and three organic linkers namely, [Zn(μ 4 -tdc)(μ-bmeib) 0.5 ] n ( 1 ), [Zn(μ 4 -tdc)(μ-betib) 0.5 ] n ( 2 ), [Zn(μ 4 -tdc)(μ-bisopib) 0.5 ] n ( 3 ), [Zn(μ 4 -tdc)(μ-pbmeix) 0.5 ] n ( 4 ), [Zn(μ 4 -tdc)(μ-pbetix) 0.5 ] n ( 5 ), [Zn(μ 4 -tdc)(μ-pbisopix) 0.5 ] n ( 6 ), bisopib, pbetix, and pbisopix, where H 2 tdc = thiophene-2,5-dicarboxylic acid, bmeib = 1,4-bis(2-methyl-1 H -imidazol-1-yl)butane, betib = 1,4-bis(2-ethyl-1 H -imidazol-1-yl)butane, bisopib = 1,4-bis(2-isopropyl-1 H -imidazol-1-yl)butane, pbmeix = 1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, pbetix = 1,4-bis((2-ethyl-1 H -imidazol-1-yl)methyl)benzene, pbisopix = 1,4-bis((2-isopropyl-1 H -imidazol-1-yl)methyl)benzene, have been synthesized and structurally characterized by elemental analysis, IR spectra, NMR spectra and single-crystal and powder X-ray diffractions. Compounds 1–6 are isostructural and display a 3D cubic structure with 2-fold interpenetrated nets. Two crystallographically independent Zn(II) ions are bridged by four different thiopehene-2,5-dicarboxlylate linkers adopting a bis(monodentate) coordination mode to form a paddle-wheel unit forming two-dimensional layers. These 2D layers containing paddle-wheel unit are further pillared by bridging bis(imidazole) derivative linkers forming a 3D framework. Moreover, topological analyses show that two 3D frameworks are interlocked with each other to give a 2-fold interpenetrating pcu net with 4 12 .6 3 topology. Interestingly, compound 3 is a 2-fold heterointerpenetrating 2(1 + 1) three-dimensional (3D) framework. In addition, photoluminescence properties, thermal stabilities and Cu(II) ion exchange properties of the compounds were also investigated.