Defect engineering is a promising approach for constructing highly efficient catalytic activity based on metal-organic frameworks (MOFs).In this study, a defective MOFs, referred to as quasi-MIL-100(Fe), was synthesized by moderate synthesis method and then careful thermal treatment at an atm. ranging from 150 to 450°C, linking crystalline materials and the associated metal oxides.MIL-100(Fe) heat-treated at 250°C (referred to as M-250) partially breaks coordination bonds, resulting in a crystalline-to-amorphous transformation, increased porosity, and elimination of ligands.Compared to pristine MIL-100(Fe), M-250 possessed more reactive sites and exhibited the highest photo-Fenton degradation of ciprofloxacin with 95.6% removal efficiency in 90 min, despite the unfavorable photo properties for photo-Fenton performance due to the destruction of the crystal structure.Addnl., d. functional theory (DFT) calculations, combined with free radical quenching and mass spectrometry anal., elucidated the catalytic mechanism.These findings highlight the significant potential of quasi-MOFs for applications in the photo-Fenton reaction.