Significant Positional Isomeric Effect on Structural Assemblies of Zn(II) and Cd(II) Coordination Polymers Based on Bromoisophthalic Acids and Various Dipyridyl-Type Coligands

Seven Zn(II) and Cd(II) coordination polymers, formulated as {[Zn2(5-Br-ip)2(bpy)(H2O)]·2H2O}n (1), {[Zn(5-Br-ip)(bpa)(H2O)]}n (2), {[Cd(5-Br-ip)(bpp)(H2O)]}n (3), {[Zn(5-Br-ip)(bpe)]}n (4), {[Zn2(4-Br-ip)2(bpy)]·H2O}n (5), {[Zn(4-Br-ip)(bpa)(H2O)]}n (6), and {[Cd(4-Br-ip)(bpp)]}n (7), were prepared by hydrothermal reactions based on 4-bromo- or 5-bromoisophthalic acid (4-Br-H2ip or 5-Br-H2ip) and different dipyridyl-type coligands 4,4′-bipyridyl (bpy), 1,2-bi(4-pyridyl)ethane (bpa), 1,3-di(4-pyridyl)propane (bpp), and 1,2-di(4-pyridyl)ethene (bpe). All complexes 1−7 were characterized by elemental analysis, IR spectra, and X-ray single-crystal diffraction. Complex 1 is a 2D (6,3) coordination network and further assembled into a 3D framework via π−π stacking interactions. Complex 2 shows a 1D coordination array and further forms a 2D supramolecular network via H-bonding interactions. Complex 3 has a 2-fold interpenetrating 3D diamond framework. Complex 4 is a 3-fold interpenetrating 3D network with CdSO4 topology, constructed from alternately left- and right-handed helical arrays. Complex 5 has a 3D (3,4)-connected network with (4·82)(4·82·103) topology. Complex 6 features a 1D coordination chain and further forms a 2D helical supramolecular pattern by H-bonding. Complex 7 exhibits a (3,5)-connected 2D layer with the Schläfli symbol of (42·6) (42·67·8). The results reveal that the diverse coordination networks of 1−7 can be adjusted by the different dispositions of the -Br substituent of isophthalate building blocks, as well as the metal ions and the dipyridyl coligands. Moreover, the luminescent properties of the complexes have been investigated.

以4-溴间苯二甲酸（4-Br-H₂ip）或5-溴间苯二甲酸（5-Br-H₂ip）与不同联吡啶类共配体（dipyridyl-type coligands）：4,4'-联吡啶（4,4′-bipyridyl, bpy）、1,2-二(4-吡啶基)乙烷（1,2-bi(4-pyridyl)ethane, bpa）、1,3-二(4-吡啶基)丙烷（1,3-di(4-pyridyl)propane, bpp）和1,2-二(4-吡啶基)乙烯（1,2-di(4-pyridyl)ethene, bpe）为原料，通过水热反应合成了7种Zn(II)与Cd(II)配位聚合物，其化学式分别为{[Zn₂(5-Br-ip)₂(bpy)(H₂O)]·2H₂O}ₙ（1）、{[Zn(5-Br-ip)(bpa)(H₂O)]}ₙ（2）、{[Cd(5-Br-ip)(bpp)(H₂O)]}ₙ（3）、{[Zn(5-Br-ip)(bpe)]}ₙ（4）、{[Zn₂(4-Br-ip)₂(bpy)]·H₂O}ₙ（5）、{[Zn(4-Br-ip)(bpa)(H₂O)]}ₙ（6）以及{[Cd(4-Br-ip)(bpp)]}ₙ（7）。所有配合物1~7均通过元素分析、红外光谱（infrared spectroscopy, IR）和X射线单晶衍射（X-ray single-crystal diffraction）进行了结构表征。配合物1为二维(6,3)拓扑配位网络，进一步通过π-π堆积作用（π-π stacking interactions）组装为三维骨架。配合物2呈现一维配位阵列，并通过氢键（hydrogen bonding, H-bonding）作用进一步构筑为二维超分子网络。配合物3具有二重互穿的三维金刚石骨架。配合物4为具有CdSO₄拓扑的三重互穿三维网络，由交替的左手和右手螺旋阵列构筑而成。配合物5为三维(3,4)连接网络，其拓扑符号为(4·8²)(4·8²·10³)。配合物6为一维配位链，并通过氢键作用进一步形成二维螺旋超分子结构。配合物7为(3,5)连接的二维层状结构，其施莱夫利符号（Schläfli symbol）为(4²·6)(4²·6⁷·8)。研究结果表明，通过改变间苯二甲酸配体上溴取代基的取代位置、金属离子种类以及联吡啶类共配体，可以调控配合物1~7的多样化配位网络结构。此外，本文还对所有配合物的发光性能进行了研究。