Microporous Metal–Organic Frameworks: Structures, in Situ Formation of Ligand, and Crystal-to-Crystal Transformations

Among these new microporous metal–organic frameworks (MOFs) {[CuI17(L1)12X2]X3(H2O)n}∞ (1, X = Cl, 1a, n = 6; 1b, 1c, n = 5, 1d, n = 3; 2, X = Br, 2a, n = 5; 2b, n = 3; L1 = 3,5-bis(4-aminophenyl)-1,2,4-triazolate), 1a and 2a were obtained through in situ copper-mediated ring conversion of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole into L1 under hydrothermal conditions, while the others were generated through interesting single-crystal-to-single-crystal transformations with an accompanying color change from red to black. In the process of synthesis, when CuII salt was used as starting reactant, the CuI complex 1a was obtained; so the redox reaction clearly took place under this condition. The fascinating features of these structures are the double-stranded helical chains and the largest metallamacrocycle based on triazolate ever reported. These isomorphous complexes adopt the rare binodal six-connected networks. In the solid state at low temperature (∼273 K), the red crystal sample 1b displays an emission band at ∼585 nm upon photoexcitation at 467 nm.

在这类新型微孔金属有机框架（metal–organic frameworks, MOFs）{[Cu(I)₁₇(L¹)₁₂X₂]X₃(H₂O)ₙ}∞（其中1系列：X=Cl，1a的n=6；1b、1c的n=5，1d的n=3；2系列：X=Br，2a的n=5；2b的n=3；L¹=3,5-双(4-氨基苯基)-1,2,4-三唑负离子）中，1a与2a是在水热条件下，通过铜介导的原位环转化反应，将2,5-双(4-氨基苯基)-1,3,4-噁二唑转化为配体L¹后得到的；其余产物则通过极具趣味的单晶到单晶转变（single-crystal-to-single-crystal transformation）制备得到，过程中伴随红色至黑色的颜色变化。合成过程中，当以二价铜盐（CuII salt）作为起始反应物时，得到了一价铜配合物1a，由此可见该条件下确实发生了氧化还原反应。这类配合物的结构特色在于其包含双链螺旋链，以及迄今为止报道过的基于三唑配体的最大金属大环（metallamacrocycle）。这些同构配合物采用了罕见的双节点六连接网络拓扑结构。在低温（约273 K）的固态条件下，红色晶体样品1b经467 nm光激发后，于约585 nm处呈现出发射谱带。