Aerobic Photodegradation of Pyrene-Based Metal-Organic Framework NU-1000 to Terephthalic Acid

NU-1000, a pyrene-containing benchmark metal-organic framework (MOF), is well-known for its utility and potential across a wide range of applications. Although the extended π-systems in NU-1000 confer favorable properties for diverse photochemical applications, they also increase the susceptibility of the MOF to photodegradation. However, the photostability of NU-1000 has yet to be systematically studied and remains poorly understood. Herein, we report that in the presence of oxygen, water, and light of appropriate energy, extensive oxidation of the pyrene linkers of NU-1000 can occur to yield terephthalic acid as the major decomposition product. Through extensive mechanistic studies, we show that the open framework structure of NU-1000 greatly facilitates linker oxidation, with more than 25-fold greater linker decomposition from the MOF within 3 h of photoirradiation compared to a homogeneous solution of the linker, brought about by rapid generation of pyrene-centred holes. By determining the specific conditions under which the MOF remains stable, our findings offer not just valuable strategies for preserving the integrity of NU-1000 for controlled applications but also reveal its ability to decompose into benign products under ambient light and oxygen, which could provide an eco-friendly route for avoiding environmental accumulation of MOF materials for various applications.