Multifunctional Supramolecular Hybrid Materials Constructed from Hierarchical Self-Ordering of In Situ Generated Metal-Organic Framework (MOF) Nanoparticles.
Multifunctional Supramolecular Hybrid Materials Constructed from Hierarchical Self-Ordering of In Situ Generated Metal-Organic Framework (MOF) Nanoparticles.
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DOI：
10.1002/adma.201501448
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发表时间：
2015-08
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影响因子：
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通讯作者：
Tan JC
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作者：
Chaudhari AK;Han I;Tan JC
DOI：10.1002/ADMA。201501448高度一致的光纤网络脚手架。金属有机骨架(MOF)[11]是一类发展迅速的晶态纳米多孔材料，其三维骨架由有序的金属离子单元或通过有机键连接的团簇组成。MOF提供了丰富的化学功能和巨大的结构多样性。[12]MOF晶体的高度均匀和3D微孔结构可以为共生效应提供独特的平台，产生以实现超分子自组装为中心的正交相互作用[13]。值得注意的是，尽管金属-有机凝胶(MOGS)[14]是一种非常相似的自组装杂化化合物，但它们包含通过有机连接物随机交联的金属离子(没有形成有序骨架)，随后捕获溶剂分子以形成更传统的凝胶网络材料。被命名为HKUST-1[15]的微孔材料因其广泛的潜在应用而成为当今研究最深入的MOF之一。通常，它可以通过铜(II)和BTC 3−(1，3，5-苯三甲酸)之间的溶剂热反应获得，生成热力学上最有利的结晶HKUST-1[Cu3(BTC)2]。[16]事实上，HKUST-1以其易于合成而闻名，除了膜、中空胶囊和由此衍生的超结构外，它还易于使用不同的溶剂、温度或碱[17]。[18]在这里，我们证明，通过在相对少量的溶剂中使用高浓度的HKUST-1标准反应物，产生以前未报道的凝胶状杂化材料，表现出违反直觉的化学物理特性。在目前的工作中，我们发现在三乙胺碱(NET3)的作用下，Cu(NO3)2溶液与去质子化的BTC在室温下反应，可以容易地形成一种非传统的凝胶状超分子自组装。有趣的是，上述反应可以在极性-质子型和极性-非质子型溶剂中完成，从而形成了一种全新的基于MOF的超分子杂化材料体系(见支持资料中的图S1)，我们将其命名为：G⊃ACN、G⊃DMF、G⊃DMSO、G⊃ETH和g⊃MEH(其中G表示使用以下溶剂获得的凝胶：ACN：乙腈；DMF：N，N-二甲基甲酰胺；DMSO：二甲基亚砜；乙H：乙醇；MEH：甲醇；见图S2和支持资料中的表S1)。用不同的溶剂研究了杂化材料的形成机理，使我们能够研究这些新型杂化材料丰富的形态和结构多样性。我们发现，使用不同的溶剂可以产生具有不同结构、机械、化学和电学性质的杂化材料。值得注意的是，只有在G⊃的情况下才发生溶胶-凝胶转变，而粘弹性相转变(从软网络到刚性网络)仅在G⊃ACN中明显。此外，详细的
DOI: 10.1002/adma. 201501448 highly aligned fiber network scaffolding. Metal-organic framework (MOF)[11] is a rapidly expanding class of crystalline nanoporous materials, whose 3D framework consists of ordered units of metal ions or clusters bridged by organic linkages. MOFs offer rich chemical functionalities combined with vast structural versatility.[12] The high uniformity and 3D microporous architecture of MOF crystals could provide the unique platform for symbiotic effects, yielding orthogonal interactions [13] central to achieve supramolecular self-assembly. It is worth noting that, although metal-organic gels (MOGs)[14] are a very similar type of self-assembled hybrid compound, they comprise randomly cross-linked metal ions by organic linkers (without forming an ordered framework), subsequently trapping solvent molecules to form a more conventional gel network material. The microporous material designated as HKUST-1 [15] represents one of the most intensely studied MOFs today due to its wide-ranging potential applications. Typically, it can be obtained via solvothermal reactions between Cu (II) and BTC 3−(1, 3, 5-benzene tricarboxylic acid), yielding crystalline HKUST-1 [Cu 3 (BTC) 2] as the most thermodynamically favorable product.[16] In fact, HKUST-1 is renowned for its ease of synthesis using different solvents, temperatures, or bases,[17] in addition to membranes, hollow capsules, and superstructures derived from it.[18] Herein, we demonstrate that, by employing a high concentration of standard reactants of HKUST-1 in a relatively small quantity of solvents, yields previously unreported gel-like hybrid materials that exhibit counterintuitive chemico-physical properties. In the present work, we discovered that room-temperature reaction between Cu (NO 3) 2 solution and deprotonated BTC, using triethylamine base (NEt 3), yields facile formation of an unconventional gel-like supramolecular self-assembly. Interestingly, the aforementioned reactions can be accomplished in both polar-protic and polar-aprotic solvents, resulting in an entirely new system of MOF-based supramolecular hybrid materials (see Figure S1 in the Supporting Information), which we termed: G⊃ ACN, G⊃ DMF, G⊃ DMSO, G⊃ ETH, andG⊃ MEH (where G denotes gel obtained using solvent: ACN: acetonitrile; DMF: N, N-dimethyl formamide; DMSO: dimethyl sulfoxide; ETH: ethanol; MEH: methanol; see Figure S2 and Table S1 in the Supporting Information). The formation mechanism was investigated utilizing different solvents, which allowed us to study the rich morphological and structural diversity of these novel hybrid materials. We found that the use of different solvents yields hybrid materials that exhibit distinct structural, mechanical, chemical, and electrical properties. Noteworthy, sol–gel transitions occur only in the case of G⊃ DMSO, while viscoelastic phase conversion (from soft to rigid network) is evident only in G⊃ ACN. Moreover, detailed