Oxidative polymerization of a carbazole-substituted perfluorinated trans-A₂B₂ porphyrin as potential photodynamic agent

Porphyrin-based polymers have emerged as promising photosensitizers owing to their enhanced structural stability and potential for photodynamic applications. In this work, a new conjugated porphyrin polymer (P TPPF₁₀CBZ) was synthesized through the oxidative polymerization of the carbazolyl substituents of the 5,15-di(4-(9-carbazolylphenyl))-10,20-di(pentafluorophenyl)porphyrin (TPPF₁₀CBZ). The reaction proceeded efficiently in chloroform using FeCl₃ as the oxidizing agent under an argon atmosphere at room temperature. Oxidative coupling between carbazolyl units generated a conjugated polymeric network while preserving the integrity of the porphyrin macrocycles. Reaction progress was monitored by TLC. The resulting polymer was isolated by centrifugation and washed several times with methanol, affording the desired product in high yield. The polymer was characterized by NMR and UV–visible spectroscopy. P-TPPF₁₀CBZ revealed the typical absorption and fluorescence emission profiles of free-base porphyrins. The absorption spectrum in dimethylformamide (DMF) exhibited an intense Soret band at 418 nm and four characteristic Q bands between 500 and 700 nm, closely resembling those of the monomer. Furthermore, fluorescence measurements presented two emission bands at 645 and 710 nm, with a slight decrease in fluorescence quantum yield (Φ_F = 0.034), while time-resolved fluorescence showed biexponential decay behavior attributed to different local environments within the polymeric matrix. Photodynamic studies demonstrated that P-TPPF₁₀CBZ efficiently generated singlet oxygen, reaching a singlet oxygen quantum yield of F_Δ = 0.87. In addition, the polymer exhibited remarkable photostability, supporting its potential as a robust porphyrin-based photosensitizer for future photodynamic applications.