Sulfonated Ionic Covalent Organic Frameworks With Dual-State Activation for Synergistic Photodynamic-Ferroptosis...

Conventional photocatalysis is fundamentally constrained by the competitive nature of excited-state dynamics, which typically restricts utilization to a single excitonic channel. Consequently, simultaneously harvesting both excitons to maximize reactive oxygen species (ROS) generation remains a formidable challenge in cancer theragnostic. Herein, an ionic engineering strategy is developed to overcome this excitonic bottleneck by constructing sulfonated covalent organic frameworks (BD-SO₃-COF) via backbone quaternization. This specific ionic modulation imparts a strong push-pull electronic landscape that fundamentally reshapes excited-state dynamics. Mechanistically, the sulfonate moieties suppress the parasitic radiative recombination of singlet excitons (S₁) to boost superoxide anion (O₂ ^•-) generation specifically at the electron-deficient quaternized pyridine rings (redox sites), while simultaneously populating long-lived triplet excitons (T₁) on the porphyrin macrocycles that activate molecular oxygen via an efficient Dexter energy transfer pathway to produce singlet oxygen (¹O₂). Capitalizing on this site-specific dual-state activation, the engineered COF triggers robust photodynamic therapy (PDT) and induces catastrophic lipid peroxidation, effectively driving cancer cells into ferroptosis. In vivo assessments confirm that this synergistic PDT-ferroptosis strategy achieves potent tumor regression with minimal systemic toxicity. This work elucidates the critical role of specific active-site engineering in ionic COFs and provides a paradigm for designing molecular photosensitizers for multi-modal cancer therapy.