Highly Effective Generation of Singlet Oxygen by an Imidazole-Linked Robust Photosensitizing Covalent Organic Framework.

Developing effective photosensitizers to initiate the generation of singlet oxygen ( 1 O 2 ) is of great significance in both chemistry and physiology. Herein, linking the photoactive porphyrin moieties by in situ-formed robust imidazole groups, a covalent organic framework (COF), PyPor-COF , was successfully designed and synthesized. Detailed characterizations reveal that it not only possesses high crystallinity, permanent porosity, and robust stability but also shows a semiconductive photoresponse activity. As demonstrated by electron paramagnetic resonance experiments, the COF can initiate the generation of 1 O 2 efficiently under visible-light irradiation, the efficiency of which is higher than that of the pristine porphyrin-based reactant and even higher than some commonly used commercially available photosensitizing agents. Anticancer experiments prove that it can efficiently trigger the production of 1 O 2 in a physiological environment. This work demonstrates that the imidazole-linked porphyrin-incorporated COF is a highly promising photosensitizer that can even be applied in photodynamic therapy.