Photodynamical behaviour of MOFs and related composites: Relevance to emerging photon-based science and applications

Abstract Metal-organic frameworks (MOFs) are porous materials that are extraordinarily suitable for numerous applications such as gas separation and storage, chemical sensing, bioimaging, drug delivery, optoelectronic devices, and catalysis. MOFs are created from the connection of metal ions or clusters with organic or organometallic linkers through coordination bonds. They offer exceptional flexibility in terms of pore volume, shape, and dimensions by adequate choice of the constituents. The rigid structure of these hybrid compounds makes them accessible to several potential guests, which are able to interact with the inorganic/organic parts. As a consequence, a vast number of fast (ps) and ultrafast (fs) processes occur within the cavities of these complexes. An imperative requisite to study the photodynamics of MOF-based host-guest systems is the use of advanced laser-based spectroscopy and microscopy techniques. The recent development of ultrafast (spectroscopy and imaging) tools has allowed the scientific community to investigate the photodynamics of these composites at intimate levels. This Review aims to provide a comprehensive overview of the latest (since 2005) fast and ultrafast experimental studies on the photodynamics of MOFs and related composites. The MOFs are classified in different families based on the nature of the metal, thus allowing the reader to gain a concise understanding of the related photoinduced processes within each family. We discuss the different processes taking place upon photoexcitation such as: excimer formation, energy- and electron/charge- and proton-transfer, LMCT, MLCT, and interparticles interaction. We also summarize the relevant applications of MOFs and related composites in modern science and technology using light.