Nanoarchitectonics of metal-organic frameworks (MOFs) for energy and sensing applications

Abstract

MetalOrganic Frameworks (MOFs) constitute a whole family of emergent materials [1], whichwere first reported a few decades ago and have been intensively employed since then for numerousand shockingly diverse applications [210]. MOFs can be defined as coordination networks assem-bled by noncovalent interactions between metallic ions and multidentate organic linkers featuring per-manent porosity [11]. By combining appropriate building blocks, either resorting to liquid phase, orvia solvent-free (gas or solid phase) synthesis procedures [1214], MOFs nano- or microparticlesconsisting of ordered networks capable of X-ray diffraction can be straightforwardly obtained[1517]. A careful selection of linkers and metallic ions define important features of the particularMOF obtained, such as pore size and pore wall surface chemistry [1821]. Among the unique char-acteristics responsible for the multiplication of MOF-related research projects worldwide, it must bestressed that their relatively high thermal and chemical stability, record-high surface areas and porevolumes, and the possibility of employing them as heterogeneous catalysts are due to the presence of coordinatively unsaturated metal sites or active sites in linkers [2225]. During an incipient development stage, the main drive for the observed bloom was the consideration of MOFs as prospects for next-generation tailored adsorbent materials, both polar and nonpolar (i.e., as replacement for traditionally employed zeolites and carbon-derived materials). MOFs allow an interesting alternative: a “smart” ad hoc predesigned porous material with tunable affinity toward selected adsorbates [2632]. Moreover, slight modification of the common synthesis procedures allows fabrication of MOF nanoparticles with porosity (i.e., both macro-, meso-, and micropores), which in turn can be assembled into films with tunable permeability, a crucial parameter in many technological applications [3336].