A BODIPY-Containing Covalent Organic Framework as a Highly Porous Photosensitizer for Environmental Remediation and Pollutants Adsorption

Abstract

The direct incorporation of borondipyrromethene (BODIPY) subunits into the structural backbone of covalent organic frameworks (COFs) gives facile access to porous photosensitizers but is still a challenging task. Here, we introduce β-ketoenamine-linked BDP-TFP-COF, which crystallizes in AA-stacking mode with hcb topology. A comprehensive characterization reveals high crystallinity and enhanced stability in a variety of solvents, excellent mesoporosity (SA_BET=1042 m² g⁻¹), broad light absorption in the visible region, and red emission upon the exfoliation of few-layer COF nanosheets. The versatility of multifunctional BODIPY-COFs is highlighted in various applications. Pollutants Bisphenol A (BPA, q_max=426 mg g⁻¹) and Methylene Blue (MB, q_max=96 mg g⁻¹) have been efficiently removed from H₂O. Fluorescence quenching or enhancement of exfoliated BDP-TFP-COF nanosheets have been utilized for dual-mode sensing of MB or NEt₃, respectively. Ultimately, the photosensitizing effect of the BODIPY units is retained in the COF. Thus, BPD-TFP-COF was established as a metal-free triplet photosensitizer, which efficiently oxidized a mustard gas simulant under visible light irradiation.