Regulating the Arrangement of Planar Ligands in Lanthanide Metal–Organic Framework Photosensitizers to Induce a Photocatalytic Reactive Oxygen Species Storm for Sewage Purification and Photodynamic Sterilization

Abstract

Constructing lanthanide metal–organic frameworks (Ln-MOFs) that are both water-stable and capable of efficiently generating reactive oxygen species (ROS) remains a significant challenge in the field of photocatalytic water remediation. In this study, two structurally robust and water-stable Ln-MOFs (Eu-MOF and Gd-MOF) were synthesized by assembling the ligand 4,4′-(anthracene-9,10-diyl)dibenzoic acid (H2ADBA) with Eu2O17 and Gd2O16 secondary building units, respectively. The deprotonated ADBA2– ligands adopt a Z+-shaped arrangement with a dihedral angle of 52.71° between adjacent anthracene rings; this configuration suppresses interligand π–π stacking and reduces radiative transition losses, thereby significantly enhancing ROS generation efficiency. Fluorescence probe and electron paramagnetic resonance (EPR) analyses confirmed that both Ln-MOFs could generate Type I and Type II ROS under irradiation from a low-power (60 mW/cm2) xenon lamp. These Ln-MOFs achieved near-complete degradation of 10 mg/L Rhodamine B and Methylene Blue within 30 and 90 min, respectively; furthermore, they demonstrated excellent performance in antibiotic degradation and antibacterial activity against Escherichia coli and Staphylococcus aureus. This work offers a strategy for the rational design of high-performance Ln-MOF photosensitizers for wastewater purification and sterilization.