Phthalocyanines possess similar structure of natural chromophore porphyrins. The phthalocyanines are known to utilize in important functional colorants for many fields. The phthalocyanines are especially expected to use photosensitizers for both dye-sensitized solar cells and photodynamic therapy of cancer. In the present study, novel non-peripheral substituted thio-alkyl zinc phthalocyanines were synthesized in order to develop second-generation photosensitizer for photodynamic therapy of cancer. In order to evaluate the influence of heteroatom existence and chain length, synthesized non-peripheral substituted thio-alkyl phthalocyanines were reported photoexcited triplet lifetime using laser-flash photolysisand singlet oxygen quantum yields by 1,3-diphenylbenzofuranemethod. Of synthesized non-peripheral substituted phthalocyanines, ultraviolet-visible spectra showed around 780 nm, photoexcited triplet lifetimes were estimated around 1 as and singlet oxygen quantum yields. It is thought that synthesized non-peripheral hetero-alkyl substituted phthalocyaines had enough ability for photodynamic therapy of cancer.

Eight strongly electron-donating alkylthio- or arylthio-groups have been introduced to a strongly electron-withdrawing pyrazinoporphyrazine (PyZ) core, to form the Zn complexes of octadecylthiolated ZnPyZ, (SDc)[Formula: see text]ZnPyZ, and octaphenylthiolated ZnPyZ, (S[Formula: see text])[Formula: see text]ZnPyZ, and their electronic structures studied by 1H NMR and electronic absorption spectroscopy. The strength of the ring current, aromaticity, and flow of charge were discussed by calculating the ring current, nucleus-independent chemical shift (NICS), and anisotropy of the current-induced density (ACID), respectively. Good agreement was seen for the results of these three calculations, demonstrating that a strong ring current of the macrocycle is produced when the aromatic ring fused to the tetraazaporphyrin core has a weaker diamagnetic ring current, [Formula: see text]. weaker aromaticity (negatively smaller NICS values). TD-DFT molecular orbital (MO) calculations succeeded in explaining the differences of the absorption spectra between these octathiolated ZnPyZs and those without thiolated groups. The singlet oxygen quantum yield in pyridine (0.62) of (S[Formula: see text])[Formula: see text]ZnPyZ was similar to that (0.61) of normal ZnPc.