Aulakh Darpandeep, Varghese Juby R, Wriedt Mario
Department of Chemistry & Biomolecular Science, Clarkson University , 8 Clarkson Avenue, Potsdam, New York 13699, United States.
Inorg Chem. 2015 Feb 16;54(4):1756-64. doi: 10.1021/ic5026813. Epub 2015 Feb 4.
Two isostructural microporous zwitterionic metal-organic frameworks (ZW MOFs), {[M(bdcbpy)(OH2)4]·4H2O}n with M = Mn (1) and Ni (2), were synthesized by the rational design of the flexible anionic viologen derivate, 1,1'-bis(3,5-dicarboxybenzyl)-4,4'-bipyridinium dibromide dihydrate solvate (H4bdcbpyBr2·2H2O), and its self-assembly with metal(II) acetates in an aqueous medium. Single-crystal structure analyses revealed that both compounds exhibit three-dimensional hydrogen-bonded supramolecular frameworks with one-dimensional channel pores. Significantly, the pore surfaces are lined with charge gradients employed by the ZW ligand bdcbpy(2-) leading to the adsorption of hydrogen attributed to polarization effects. The thermostabilty and activation conditions were systematically investigated by thermogravimetric analysis, differential scanning calorimetry, and powder X-ray diffraction experiments. Furthermore, repeating cycles of reversible color changes are observed in air upon irradiation with UV light attributed to the formation of viologen radicals via an intermolecular electron transfer. This work also contains an in-depth literature analysis on ZW MOFs, which shows the need for the development of alternative routes for the rational design of new porous ZW MOFs.
通过合理设计柔性阴离子紫精衍生物二水合二溴化1,1'-双(3,5-二羧基苄基)-4,4'-联吡啶二水合物溶剂化物(H4bdcbpyBr2·2H2O)，并使其与金属(II)乙酸盐在水介质中自组装，合成了两种同构的微孔两性离子金属有机骨架(ZW MOFs)，{[M(bdcbpy)(OH2)4]·4H2O}n，其中M = Mn (1)和Ni (2)。单晶结构分析表明，两种化合物均呈现具有一维通道孔的三维氢键超分子骨架。值得注意的是，孔表面排列着ZW配体bdcbpy(2-)产生的电荷梯度，由于极化效应导致氢的吸附。通过热重分析、差示扫描量热法和粉末X射线衍射实验系统地研究了热稳定性和活化条件。此外，在空气中用紫外光照射时，观察到可逆颜色变化的重复循环，这归因于通过分子间电子转移形成紫精自由基。这项工作还包含对ZW MOFs的深入文献分析，表明需要开发新的多孔ZW MOFs合理设计的替代路线。
