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PUBLISHED ONLINE: 19 FEBRUARY 2012 | http://www.nature.com/doifinder/10.1038/nchem.1272
Web End =DOI: 10.1038/NCHEM.1272
Imparting functionality to a metalorganic framework material by controlled nanoparticle encapsulation
Guang Lu1, Shaozhou Li1, Zhen Guo2, Omar K. Farha3, Brad G. Hauser3, Xiaoying Qi1, Yi Wang2, Xin Wang2, Sanyang Han4, Xiaogang Liu4,5, Joseph S. DuChene6, Hua Zhang1, Qichun Zhang1, Xiaodong Chen1, Jan Ma1, Say Chye Joachim Loo1,7, Wei D. Wei6, Yanhui Yang2, Joseph T. Hupp3*
and Fengwei Huo1*
Microporous metalorganic frameworks (MOFs) that display permanent porosity show great promise for a myriad of purposes. The potential applications of MOFs can be developed further and extended by encapsulating various functional species (for example, nanoparticles) within the frameworks. However, despite increasing numbers of reports of nanoparticle/MOF composites, simultaneously to control the size, composition, dispersed nature, spatial distribution and connement of the incorporated nanoparticles within MOF matrices remains a signicant challenge. Here, we report a controlled encapsulation strategy that enables surfactant-capped nanostructured objects of various sizes, shapes and compositions to be enshrouded by a zeolitic imidazolate framework (ZIF-8). The incorporated nanoparticles are well dispersed and fully conned within the ZIF-8 crystals. This strategy also allows the controlled incorporation of multiple nanoparticles within each ZIF-8 crystallite. The as-prepared nanoparticle/ZIF-8 composites exhibit active (catalytic, magnetic and optical) properties that derive from the nanoparticles as well as molecular sieving and orientation effects that originate from the framework material.
Metalorganic frameworks (MOFs)13 are permanently micro-porous materials synthesized by assembling metal ions with organic ligands in appropriate solvents. MOFs have crystal
line structures and typically are characterized by large internal surface areas, uniform but tunable cavities and tailorable chemistry. These characteristics make them very promising for a variety of applications, including gas storage4,5, chemical separation6, catalysis7,8, sensing9 and drug delivery10. By serving as unique host matrices for various functional species, MOFs also offer the opportunity to develop new types of composite materials that display enhanced (gas storage) or new (catalytic, optical and electrically conductive) behaviours1118
in comparison to the parent MOF counterparts.
In particular, the incorporation of nanoparticles in MOFs attracts much attention because of the benets of novel chemical and physical properties exhibited by certain classes of nanoparticles1922. Nanoparticle/MOF composites can be prepared either by using MOFs as templates to generate nanoparticles within their cavities2332 or by encapsulating presynthesized...