Metal(II) Coordination Polymers Derived from Bis-pyridyl-bis-amide Ligands and Carboxylates: Syntheses, Topological Structures, and Photoluminescence Properties

Using bis-pyridyl-bis-amide ligands N,N′-bis-(4-pyridyl)phthalamide (L1), N,N′-bis-(4-pyridyl)iso -phthalamide (L2), hexanedioic acid bis-pyridin-4-ylamide (L3), and carboxylates, six metal(II) complexes formulated as Cd2(1,4-chdc)(L1)2·4H2O (1,4-H2chdc = 1,4-cyclohexanedicarboxylic acid) (1), Cd2(L1)2(in)4·3DMF (Hin = isonicotinic acid) (2), Zn(L1)(1,4-bdc) (1,4-H2bdc = 1,4-benzenedicarboxylic acid) (3), Cd(L2)(1,4-chdc) (4), Zn2(L2)2(tdc)2·DMF (H2tdc = thiophene-2,5-dicarboxylic acid) (5), and Zn(2,6-ndc)0.5(L3)0.5(SO4)·(CH3NHCH3) (2,6-H2ndc = 2,6-naphthalene- dicarboxylic acid) (6) have been hydro(solvo)thermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 is a uninodal 6-connected noninterpenetrated three-dimensional (3D) network with {44.610.8}-mab topology, complex 2 exhibits a uninodal 6-connected 2-fold interpenetrated 3D framework with {412.63}-pcu topology, complex 3 shows a uninodal 8-fold interpenetrated 3D diamondoid framework, complexes 4 and 5 possess similar uninodal 2D layer with 44-sql topology, and complex 6 shows a framework of 2D → 3D inclined polycatenation based on 44-sql layer. The six complexes show different thermal stability and photoluminescence properties. The emission band of complex 1 becomes strong after dehydration, and water can reduce the emission intensities of the six complexes to some extents.

本研究以双吡啶双酰胺类配体N,N′-双(4-吡啶基)邻苯二甲酰胺（N,N′-bis-(4-pyridyl)phthalamide, L1）、N,N′-双(4-吡啶基)间苯二甲酰胺（N,N′-bis-(4-pyridyl)iso-phthalamide, L2）、己二酸双(4-吡啶基)酰胺（hexanedioic acid bis-pyridin-4-ylamide, L3）以及羧酸盐类配体为构筑单元，成功合成了六种金属(II)配合物，其化学式分别为：Cd₂(1,4-chdc)(L1)₂·4H₂O (1)（其中1,4-H₂chdc=1,4-环己二甲酸，1,4-cyclohexanedicarboxylic acid）、Cd₂(L1)₂(in)₄·3N,N-二甲基甲酰胺（DMF）(2)（其中Hin=异烟酸，isonicotinic acid）、Zn(L1)(1,4-bdc) (3)（其中1,4-H₂bdc=1,4-苯二甲酸，1,4-benzenedicarboxylic acid）、Cd(L2)(1,4-chdc) (4)、Zn₂(L2)₂(tdc)₂·N,N-二甲基甲酰胺（DMF）(5)（其中H₂tdc=噻吩-2,5-二甲酸，thiophene-2,5-dicarboxylic acid）、Zn(2,6-ndc)₀.₅(L3)₀.₅(SO₄)·(CH₃NHCH₃) (6)（其中2,6-H₂ndc=2,6-萘二甲酸，2,6-naphthalenedicarboxylic acid）。上述配合物均通过水热（溶剂热）法合成，并借助单晶X射线衍射完成结构表征。配合物1为单节点6连接非穿插三维（3D）骨架，具有{4⁴.6¹⁰.8}-mab拓扑结构；配合物2呈现单节点6连接二重穿插三维骨架，具有{4¹².6³}-pcu拓扑结构；配合物3为单节点8重穿插三维类金刚石骨架；配合物4与5均为具有4⁴-sql拓扑的单节点二维（2D）层状结构；配合物6则展现出基于4⁴-sql层的二维→三维倾斜多穿插骨架结构。该六种配合物展现出各不相同的热稳定性与光致发光性能，其中配合物1经脱水处理后发射谱带强度显著增强，而水分子可在一定程度上降低六种配合物的发射强度。