Metal-Organic Framework Nanocomposite Materials
Abstract: Metal-organic frameworks (MOFs) have crystalline structures and are typically characterized by large internal surface areas, uniform but tunable cavities, and tailorable chemistry. MOFs have shown great promise for a variety of applications, including gas storage, chemical separation, catalysis, and sensing. Particularly, the incorporation of nanoparticles in MOFs has attracted great attention because of the benefits of the novel chemical and physical properties exhibited by certain classes of nanoparticles.
Recently, we developed an encapsulation strategy that allows any of several types of nanoparticles to be fully incorporated within crystals of a readily synthesized zeolitic imidazolate framework material, ZIF-8, in a well-dispersed fashion. Our strategy relies on the successive adsorption of nanoparticles onto the continuously forming surfaces of the growing MOF crystals. This allows ready control over the spatial distribution of nanoparticles within ZIF-8 crystals by adjusting the time of nanoparticle addition during the MOF-formation reaction. The as-prepared hybrid materials exhibit both active (catalytic, magnetic, and optical) properties deriving from the incorporated nanoparticles and size- and alignment-selective behavior (i.e., molecular sieving and regioselective guest reactivity) originating from the well-defined microporous nature of the MOF component.