Structurally photo-active metal–organic frameworks: Incorporation methods, response tuning, and potential applications

Abstract

Metal–organic frameworks (MOFs) are an important family of materials due to the properties that make them well suited to a range of applications. This includes structurally photo-active MOFs, which have properties that can be efficiently modulated through controlled light irradiation, making them ideal due to the cost-effectiveness and noninvasive nature of this stimulus. The incorporation of structurally photo-active functional groups into MOFs has occurred through either guest inclusion, as pendant moieties, or as part of a ligand's backbone. While initial studies into the incorporation of these groups focused on prominent photo-switches such as azobenzenes, the literature has expanded to include other classes described in the wider photo-switch literature, most notably spiropyrans (SPs). The incorporation of alternative photo-switching classes has currently benefited the field through tuning the light responsive wavelength. Initial inquiries demonstrated suitable function in gas sorption applications where irradiation could be exploited for inducing adsorption or desorption. Furthermore, the potential applications explored in the literature have also recently expanded to include inquiries into other commercial functions, such as desalination [R. Ou et al., Nat. Sustain. 3, 1052–1058 (2020)], photo-lithography [H. A. Schwartz et al., Inorg. Chem. 56(21), 13100–13110 (2017)], and drug capture/release [X. Meng et al., Sci. Adv. 2(8), 2–8 (2016)].