Photoinduced reversible phase transition in a phenothiazine-based metal-organic framework

Abstract

Photoinduced phase transitions in metal-organic frameworks are provoked by structural changes of photoresponsive linkers within the framework under light irradiation. These transitions are rare but fundamentally important as they can bring about light-switchability on a variety of properties of the materials. In this work, phenothiazine as a photoresponsive unit with distinctive photochemical properties is incorporated into a Zn-based metal-organic framework, PCN-401. The structural characterization of PCN-401 revealed a reversible structural transition upon light irradiation. The mechanisms behind the photoinduced phase transition are studied systematically by spectrometric methods and structural stability characterization. Our mechanistic studies successfully showcased how the phenothiazine unit in the framework undergoes structural transformation under light irradiation and how the reversible phase transition leads to the property changes. The findings have emphasized the significance of phenothiazine in photoresponsive materials and can serve as inspiration for the design and understandings of next-generation photoresponsive metal-organic materials. • PCN-401 can go through a light-induced reversible phase transition • The oxygen content can tune the nucleation of PCN-401 • The CO 2 adsorption changes drastically as it transitions between phases • Inter-ligand electron transfer under light was revealed as the mechanism Xiao et al. report a photoresponsive MOF, PCN-401, which undergoes a structural change and radical formation upon light radiation. The photoresponsive behavior, caused by electron transfer among the phenothiazine-based ligands within the framework, brings about drastic property changes.