The Effect of Ligand-to-Metal Energy Transfer on the Photooxidation Performance of an Isostructural Series of Pyrene-Based Rare-Earth Metal–Organic Frameworks

Abstract

The rectangular tetratopic linker, 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) along with rare-earth (RE) ions is used for the synthesis of 9 isostructures of a metal–organic framework (MOF) with shp topology, named RE-CU-10 (RE = Y(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III) and Lu(III)). The synthesis of each RE-CU-10 analogue requires different reaction conditions to achieve high quality phase pure products. Single crystal X-ray diffraction indicates the presence of a RE9-cluster in Y- to Tm-CU-10, while a unique RE11-cluster is observed for Yb- and Lu-CU-10. The photooxi-dation performance of the reported RE-CU-10 analogues is evaluated, giving insight into the competitive process of ligand-to-metal energy transfer versus the generation of singlet oxygen by RE-CU-10. The singlet oxygen produced is used to detoxify a mustard gas simulant 2-chloroethylethyl sulfide (2-CEES) to 2-chloroethyl ethyl sulfoxide (2-CEESO), with half-lives ranging from 4.0 to 5.8 min, some of the fastest reported to date using UV-irradiation and < 1 mol% catalyst, in methanol under O2 saturation.