Metal-organic frameworks : from molecules/metal ions to crystals to superstructures

Metal-organic frameworks (MOFs) are among the most attractive porous materials known today, exhibiting very high surface areas, tuneable pore sizes and shapes, adjustable surface functionality, and flexible structures. Advances in the formation of MOF crystals, and in their subsequent assembly into more complex and/or composite superstructures, should expand the scope of these materials in many applications (e.g., drug delivery, chemical sensors, selective reactors and removal devices, etc.) and facilitate their integration onto surfaces and into devices. This Concept article aims to showcase recently developed synthetic strategies to control the one-, two- and three-dimensional (1-, 2- and 3D) organisation of MOF crystals. Superstructures: Recent developments are described for the construction of the first-ever MOF superstructures, all of which entail control over MOF crystallisation and/or the subsequent spatial layout of the resulting crystals. These methods are characterised as 1) spontaneous higher-order assembly, 2) self-assembly using hard templates, 3) self-assembly using soft templates and 4) self-templated synthesis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.