Synthesis, structural characterization, and investigation on photophysical and photochemical features of new metallophthalocyanines

Abstract In this report, the 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol group was substituted to the peripheral positions of the phthalocyanine macrocycle for obtaining copper (II) 4 , cobalt (II) 5 and zinc (II) 6 phthalocyanine derivatives starting from the phthalonitrile derivative 3 . This group was also axially substituted to the silicon (IV) phthalocyanine for the synthesis of silicon(IV) phthalocyanine 8 starting from silicon(IV) phthalocyanine dichloride 7 (SiPcCl 2 ). The newly synthesized phthalocyanines 4–6 and 8 exhibited good solubility in tetrahydrofuran, ethyl acetate, CH 2 Cl 2 , N,N-dimethylformamide, diethyl ether, CHCl 3 , ethyl alcohol, DMSO, and acetonitrile. The novel compounds were structurally characterized by LC-MS/MS (for the phthalonitrile derivative 3 ), 1 H NMR (for the compounds 3, 6 and 8 ), 13 C NMR (for the compound 3 ), FT–IR, elemental analysis, UV–Vis spectroscopy (for phthalocyanines ) and MALDI–TOF mass spectral data (for phthalocyanines). The aggregation behavior, photophysical and photochemical properties such as fluorescence lifetime and quantum yields, singlet oxygen and photodegradation quantum yields of 6 and 8 were explored in dimethylsulfoxide (DMSO) to the determination of the potential use of these novel phthalocyanines as photosensitizers in photodynamic therapy (PDT) applications. The newly synthesized zinc(II) phthalocyanine ( 6 ) showed high singlet oxygen generation in DMSO when compared to unsubstituted zinc(II) phthalocyanine that used the standard. The studied phthalocyanine complexes 6 and 8 exhibited moderate degradation under light irradiation. These results indicate that the studied phthalocyanines 6 and 8 can be a candidate as photosensitizers for PDT.