A Cationic Metal-Organic Framework Consisting of Nanoscale Cages: Capture, Separation, and Luminescent Probing of Cr2O72- through a Single-Crystal to Single-Crystal Process
A Cationic Metal-Organic Framework Consisting of Nanoscale Cages: Capture, Separation, and Luminescent Probing of Cr2O72- through a Single-Crystal to Single-Crystal Process
复制标题
由纳米级笼组成的阳离子金属有机框架：通过单晶到单晶过程捕获、分离和发光探测 Cr2O72-
DOI：
10.1002/anie.201307650
复制
发表时间：
2013-12-16
影响因子：
16.6
通讯作者：
Wang, Ruihu
中科院分区：
文献类型：
--
作者：
Li, Xinxiong;Xu, Hongyan;Wang, Ruihu
随着现代工业的发展，重金属污染已成为一个越来越严重的问题。在常见的重金属污染物中，六价铬（CrVI）因对人体健康和环境造成严重危害而备受关注CrVI已广泛应用于镀铬、冶金、颜料制造、皮革制革、木材防腐等领域从工业废水中捕获和分离CrVI是非常重要的。虽然吸附剂、[3]树脂、[4]和[5]膜已经被用于去除CrVI和其他污染物，但它们固有的缺点，如选择性差和过程动力学慢，限制了它们的进一步发展和应用。因此，探索高效捕获和分离CrVI的新材料具有十分重要的意义。金属有机骨架（MOFs）作为一类新兴的多孔材料，因其具有比表面积大、孔径均匀、结构可控、功能易于定制等特点，近年来受到了广泛的关注阳离子mof是一种很有吸引力的亚类，可以用中性含氮有机配体和金属离子来构建。电荷平衡的阴离子通常占据骨架空隙，有时与金属中心的配位很弱，甚至不配位，这可能使阴离子通过阴离子交换被捕获和分离。近年来，一些阳离子MOFs已被用于交换和去除重金属污染物阴离子，如ReO4 À， CrO4 2À和TcO4 À，[7]，但Cr2O7 2À阴离子交换在MOFs中尚未见报道，尽管该物种具有强大的致癌性和广泛的应用。本文报道了一种前所未有的由[Ag2-(btr) 2]·2ClO4·3h2o (ABT·2ClO4;（btr= 4,4 ' -bis（1,2,4 -三唑））组成的纳米笼组成的三维阳离子MOF，该笼对水中Cr2O7 2À的捕获和分离具有快速交换、高捕获能力和良好的选择性。有趣的是，Cr2O7 2À在abt·2clo4中的交换是通过单晶到单晶（SC-SC）过程进行的。将AgClO4和btr溶液在水和乙腈中缓慢蒸发，得到无色ABT·2ClO4晶体。单晶x射线衍射分析表明ABT·2ClO4在立方空间群Fd”3c中结晶。如图1所示，两个独立的AgI离子采用扭曲的
With the development of modern industry, heavy-metal contamination has become a more and more severe problem. Among common heavy-metal pollutants, hexavalent chromium [CrVI] has been a focus of concern because it causes serious damage to human health and the environment.[1] CrVI has been widely used in the field of chromium plating, metallurgy, pigment manufacturing, leather tanning, and wood preservation.[2] The capture and separation of CrVI from industrial waste water is extremely important. Although adsorbents,[3] resins,[4] and membranes [5] have been introduced to remove CrVI and other pollutants, their inherent drawbacks, such as poor selectivity and slow process kinetics, limit their further development and application. Therefore, the exploration of new materials for the efficient capture and separation of CrVI is highly important. As an emerging class of porous materials, metal–organic frameworks (MOFs) have recently attracted considerable attention owing to their high surface area, uniform pore size, controllable structures, and readily tailorable functions.[6] Cationic MOFs are an appealing subclass and can be constructed by using neutral nitrogen-containing organic ligands and metal ions. The charge-balancing anions usually occupy the framework voids and are sometimes just weakly coordinated or even uncoordinated to the metal centers, potentially allowing the capture and separation of anions through anion exchange. Recently, a few cationic MOFs have been used for exchange and removal of heavy-metal pollutant anions, such as ReO4 À, CrO4 2À, and TcO4 À,[7] but there has been no report of Cr2O7 2À anion exchange in MOFs despite the powerful carcinogenicity and extensive application of this species. Herein, we report an unprecedented 3D cationic MOF consisting of nanoscale cages composed of [Ag2-(btr) 2]· 2 ClO4· 3 H2O (ABT· 2ClO4;(btr= 4, 4’-bis (1, 2, 4-triazole)), which shows fast exchange, high trapping capacity, and good selectivity for the capture and separation of Cr2O7 2À in water. Interestingly, the exchange of Cr2O7 2À inABT· 2 ClO4 was performed through a single-crystal to single-crystal (SC–SC) process. Colorless crystals of ABT· 2ClO4 were obtained by slow evaporation of a solution of AgClO4 and btr in water and acetonitrile. Single-crystal X-ray diffraction analysis revealed that ABT· 2ClO4 crystallizes in the cubic space group Fd" 3c. As shown in Figure 1, two independent AgI ions adopt a distorted