New Fluorinated Phenoxy-Containing Zinc (II) Phthalocyanine; Synthesis, Aggregation Behavior, and Singlet Oxygen Production Capacity

Photodynamic therapy has been considered a suitable alternative to chemotherapy in recent years. In this method, a photosensitizing agent is activated by light, converting triplet oxygen molecules into singlet oxygen, which is required for the elimination of cancerous tissues. This study reports the synthesis of a new phthalonitrile derivative (1), namely 4-chloro-5-(4-(trifluoromethoxy)phenoxy)phthalonitrile. Its structural characterization was performed using 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy. Zinc (II) phthalocyanine (ZnPc) was synthesized by cyclotetramerization of compound (1) in the presence of the zinc ion. Its characterization was performed using ¹H NMR, FT-IR, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF), and ultraviolet-visible (UV-vis) spectroscopy. The electronic absorption spectra of the macromolecule (ZnPc) were recorded at different concentrations in various solvents to study the effects of concentration and solvent nature on its aggregation behavior. The efficiency of zinc (II) phthalocyanine in photodynamic therapy was evaluated by measuring its singlet-oxygen quantum yield. The macromolecule exhibited high solubility at the studied concentration in ethanol, dichloromethane, and dimethyl sulfoxide. Additionally, its singlet-oxygen quantum yield was calculated to be 0.81, higher than that of the unsubstituted zinc (II) phthalocyanine.