Rosales-Vázquez Luis D, Sánchez-Mendieta Víctor, Dorazco-González Alejandro, Martínez-Otero Diego, García-Orozco Iván, Morales-Luckie Raúl A, Jaramillo-Garcia Jonathan, Téllez-López Antonio
Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón y Paseo Tollocan, Toluca, Estado de México 50120, Mexico.
Dalton Trans. 2017 Sep 26;46(37):12516-12526. doi: 10.1039/c7dt02376f.
Four coordination polymers have been synthesized using self-assembly solution reactions under ambient conditions, reacting Cd(ii) ions with 1,4-cyclohexanedicarboxylic acid in the presence of different 2,2'-bipyridine co-ligands: {[Cd(HO)(e,a-cis-1,4-chdc)(2,2'-bpy)]·HO} (1); [Cd(HO)(e,a-cis-1,4-chdc)(4,4'-dmb)] (2); {[Cd(e,a-cis-1,4-chdc)(5,5'-dmb)]·HO·CHOH} (3) and {[Cd(e,e-trans-1,4-chdc)(4,4'-dtbb)]·CHOH} (4), where 1,4-chdc = 1,4-cyclohexanedicarboxylato, 2,2'-bpy = 2,2'-bipyridine, 4,4'-dmb = 4,4'-dimethyl-2,2'-bipyridine, 5,5'-dmb = 5,5'-dimethyl-2,2'-bipyridine and 4,4'-dtbb = 4,4'-di-tert-butyl-2,2'-bipyridine. Crystallographic studies show that compound 1 has a 1D structure propagating along the crystallographic b-axis; the Cd ion in 1 is six-coordinated with a distorted-octahedral coordination sphere. Compound 2 has two crystallographic different Cd ions and both are six-coordinated with a distorted-octahedral coordination sphere. Compound 3 exhibits a seven-coordinated Cd ion having a distinctive distorted-monocapped trigonal prismatic geometry. In compound 4, the Cd ion is also seven-coordinated in a distorted monocapped octahedral geometry. Compounds 2, 3 and 4 possess rhombic-shaped dinuclear units (CdO) as nodes to generate larger cycles made up of four dinuclear units, a Cd motif, bridged by four 1,4-chdc ligands, accomplishing, thus, 2D structures. Remarkably, in compound 4 the 1,4-chdc ligand conformation changes to the equatorial, equatorial trans, unlike the other compounds where the bridging ligand conformation is the more typical equatorial, axial cis. The solid state luminescence properties of 1-4 were investigated; polymers 3 and 4 exhibited a strong blue emission (λ = 410-414 nm) compared to 1 and 2; structure-related photoluminescence is attributed to the degree of hydration of the compounds. Furthermore, Cd-polymer 3 suspended in acetone allows the fluorescence selective sensing of acetonitrile over common organic solvents such as alcohols and DMF, based on turn-on fluorescence intensity with a limit of 53 μmol L.
在环境条件下，通过自组装溶液反应合成了四种配位聚合物，使镉（Ⅱ）离子与1,4 - 环己烷二甲酸在不同的2,2'-联吡啶共配体存在下反应：{[Cd(HO)(e,a - cis - 1,4 - chdc)(2,2'-bpy)]·HO} (1)；[Cd(HO)(e,a - cis - 1,4 - chdc)(4,4'-dmb)] (2)；{[Cd(e,a - cis - 1,4 - chdc)(5,5'-dmb)]·HO·CHOH} (3) 和 {[Cd(e,e - trans - 1,4 - chdc)(4,4'-dtbb)]·CHOH} (4)，其中1,4 - chdc = 1,4 - 环己烷二甲酸根，2,2'-bpy = 2,2'-联吡啶，4,4'-dmb = 4,4'-二甲基 - 2,2'-联吡啶，5,5'-dmb = 5,5'-二甲基 - 2,2'-联吡啶，4,4'-dtbb = 4,4'-二叔丁基 - 2,2'-联吡啶。晶体学研究表明，化合物1具有沿晶轴b传播的一维结构；化合物1中的镉离子为六配位，配位球为扭曲八面体。化合物2有两个晶体学上不同的镉离子，均为六配位，配位球为扭曲八面体。化合物3呈现出一个七配位的镉离子，具有独特的扭曲单帽三角棱柱几何形状。在化合物4中，镉离子也是七配位，呈扭曲单帽八面体几何形状。化合物2、3和4具有菱形双核单元（CdO）作为节点，以生成由四个双核单元组成的更大环，一个镉基序，由四个1,4 - chdc配体桥连，从而形成二维结构。值得注意的是在化合物4中，1,4 - chdc配体构象变为赤道面、赤道面反式，这与其他化合物中桥连配体构象更典型的赤道面、轴向顺式不同。研究了1 - 4的固态发光性质；与1和2相比，聚合物3和4表现出强烈的蓝色发射（λ = 410 - 414 nm）；与结构相关的光致发光归因于化合物的水合程度。此外，悬浮在丙酮中的镉聚合物3基于荧光强度开启，对乙腈具有荧光选择性传感，相对于常见有机溶剂如醇类和DMF，检测限为53 μmol L。
