Abstract Four cobalt(II) compounds, [Co(Bim)(IA)(H2O)2]n·0.5nH2O (1), [Co(Bim)(MA)(H2O)2]n (2), [Co2(Bim)2(MA)2]n·nH2O (3), and [Co3(Bim)4(TA)2(H2O)2]n·2.5nH2O (4), have been synthesized by solvothermal reactions of cobalt(II) salts with 1,1′-(5-methyl-1,3-phenylene)bis(1H-imidazole) [Bim] and aromatic polycarboxylic acids (H2IA = isophthalic acid, H2MA = 5-methylisophthalic acid, and H3TA = trimesic acid) as coligands. The four complexes were characterized by IR and UV−vis spectra, elemental analyses, X-ray powder and single-crystal diffractions, and thermogravimetric analyses (TGAs). 1 features a zigzag polymeric macrocycle chain containing a nanotubular channel, which is constructed by bridging the folded 20-membered macrocyclic [Co2(Bim)2] subunits with IA ligands. 2 represents a double-chain structure containing 18-membered macrocyclic [Co2(Bim)(MA)] subunits. Both 3 and 4 are 2-D porous coordination polymers but have different architectures. In 3, cage-like [Co4(Bim)2(MA)4] subunits are 4-connected nodes that are further bridged by another half-set of Bim ligands to form a 2-D helical structure containing one-dimensional achiral channels and alternately arranged left- and right-handed helical tubular channels. In 4, Bim ligands bridge three crystallographically independent Co centers into sharply distorted left- and right-handed helices which are further connected by TA ligands to form a meso layer about 3.0 nm monolayer thickness with a unique (3,4)-connected topology. The structural diversities of coordination polymers 1–4 are tuned by the flexible coordination number of Co and coligand polycarboxylates. Thermal analyses show that the main frameworks of all compounds remain stable to 352 °C. Moreover, the interesting color changes of crystals 1–4, varying from pink to purple and dark blue, result from the d → d* transitions of chromophoric Co2+ in different coordination geometries as determined by the UV–vis spectra in combination with crystal structure analyses.

中文翻译：

---

以 1,1'-（5-甲基-1,3-亚苯基）双（1H-咪唑）和芳香族羧酸盐作为配体的 Co-MOF：合成、结构、光谱和热表征

摘要 四种钴(II)化合物，[Co(Bim)(IA)(H2O)2]n·0.5nH2O(1)，[Co(Bim)(MA)(H2O)2]n(2)，[Co2( Bim)2(MA)2]n·nH2O (3) 和 [Co3(Bim)4(TA)2(H2O)2]n·2.5nH2O (4)，已通过钴 (II) 的溶剂热反应合成1,1'-(5-甲基-1,3-亚苯基)双(1H-咪唑)[Bim]和芳香族多元羧酸的盐（H2IA = 间苯二甲酸，H2MA = 5-甲基间苯二甲酸，H3TA = 均苯三甲酸）作为配体。这四种配合物通过红外和紫外可见光谱、元素分析、X 射线粉末和单晶衍射以及热重分析 (TGA) 进行表征。图 1 具有包含纳米管通道的锯齿形聚合物大环链，该通道是通过将折叠的 20 元大环 [Co2(Bim)2] 亚基与 IA 配体桥接而成的。图2表示包含18元大环[Co 2 (Bim)(MA)]亚单元的双链结构。3 和 4 都是二维多孔配位聚合物，但具有不同的结构。在 3 中，笼状 [Co4(Bim)2(MA)4] 亚基是 4 个连接的节点，这些节点由另一半组 Bim 配体进一步桥接形成包含一维非手性通道的二维螺旋结构和交替排列的左旋和右旋螺旋管状通道。在 4 中，Bim 配体将三个晶体学独立的 Co 中心桥接成急剧扭曲的左手和右手螺旋，这些螺旋通过 TA 配体进一步连接以形成具有独特 (3,4) 连接拓扑的约 3.0 nm 单层厚度的中间层。配位聚合物 1-4 的结构多样性由 Co 和聚羧酸盐的灵活配位数调节。热分析表明，所有化合物的主要骨架在 352 °C 下保持稳定。此外，晶体 1-4 有趣的颜色变化，从粉红色到紫色和深蓝色，是由紫外-可见光谱结合晶体结构分析确定的不同配位几何中发色 Co2+ 的 d → d* 跃迁引起的.