Cheng Fei, Marshall Ellis S, Young Adam J, Robinson Peter J, Bouillard Jean-Sebastien G, Adawi Ali M, Vermeulen Nicolaas A, Farha Omar K, Reithofer Michael R, Chin Jia Min
Gray Centre for Advanced Materials, School of Mathematics and Physical Sciences, University of Hull, Cottingham Road, Hull, East Riding of Yorkshire, HU6 7RX, United Kingdom.
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
Chemistry. 2017 Nov 7;23(62):15578-15582. doi: 10.1002/chem.201703812. Epub 2017 Oct 4.
Most metal-organic frameworks (MOFs) possess anisotropic properties, the full exploitation of which necessitates a general strategy for the controllable orientation of such MOF crystals. Current methods largely rely upon layer-by-layer MOF epitaxy or tuning of MOF crystal growth on appropriate substrates, yielding MOFs with fixed crystal orientations. Here, the dynamic magnetic alignment of different MOF crystals (NH -MIL-53(Al) and NU-1000) is shown. The MOFs were magnetized by electrostatic adsorption of iron oxide nanoparticles, dispersed in curable polymer resins (Formlabs 1+ clear resin/ Sylgard 184), magnetically oriented, and fixed by resin curing. The importance of crystal orientation on MOF functionality was demonstrated whereby magnetically aligned NU-1000/Sylgard 184 composite was excited with linearly polarized 405 nm light, affording an anisotropic fluorescence response dependent on the polarization angle of the excitation beam relative to NU-1000 crystal orientation.
大多数金属有机框架材料（MOF）具有各向异性特性，要充分利用这些特性，就需要一种用于可控定向此类MOF晶体的通用策略。目前的方法很大程度上依赖于逐层MOF外延生长或在合适的衬底上调节MOF晶体生长，从而得到具有固定晶体取向的MOF。在此，展示了不同MOF晶体（NH -MIL-53(Al)和NU-1000）的动态磁取向。通过氧化铁纳米颗粒的静电吸附使MOF磁化，将其分散在可固化聚合物树脂（Formlabs 1+透明树脂/西尔加德184）中，进行磁取向，并通过树脂固化固定。证明了晶体取向对MOF功能的重要性，即通过用线偏振405 nm光激发磁取向的NU-1000/西尔加德184复合材料，可产生依赖于激发光束相对于NU-1000晶体取向的偏振角的各向异性荧光响应。
