Six new aluminum and silicon phthalocyanines have been synthesized and their photocytotoxicity toward V79 cells has been studied. The compounds that have been prepared are: A1PcOSi(CH3)2(CH2)3N(CH3)2, I; A1Pc-OSi(CH3)2(CH2)3N(CH3)3+I-, II; CH3SiPcOSi(CH3)2(CH2)3N(CH3)2, III; HOSiPcOSi(CH3)2(CH2)3N(CH3)2, IV; HOSiPcOSi(CH3)2(CH2)3N(CH3)3+I-, V; and SiPc[OSi(CH3)2(CH2)3N(CH3)3+I-]2, VI. Relative growth delay values for compounds I-VI and relative cytotoxicity values for compounds I, II, IV, V and VI have been determined. Compounds I and II have been shown to be comparable in photocytotoxicity to what is presumed to be A1PcOH.xH2O, and compound IV has been shown to have greater activity. The classes of compounds to which these six compounds belong appear to have potential for photodynamic therapy.

The synthesis and photoproperties of six new metal 1,4,8,11,15,18,22,25-octabutoxyphthalocyanines and photoproperties of the known, analogous Zn and metal-free phthalocyanines are described. The new compounds are AlPc(OBu)8OSiEt3, GaPc(0Bu)80SiEt3, GePc(0Bu)8(0SiEt3)2, SnPc(0Bu)8(0SiEt3)2, RuPc(0Bu)8(py)2, and PdPc(OBu)g (where Pc(OBu)8 represents the octabutoxyphthalocyanine ligand). Benzene-zf6 solutions of all eight of the compounds give NMR spectra showing large ring-current effects. Benzene solutions of the compounds give visible spectra with absorption maxima in the 688-779-nm range having extinction coefficients between 1.0 X I05 and 2.2 X 105 M"1 cm'1. The triplet-state properties of the phthalocyanines in benzene solutions have been measured by laser flash photolysis. The triplet states have absorption maxima in the 550-640-nm range, quantum yields in the 0.1-0.9 range, and lifetimes when the solutions are deaerated in the 0.5-150-µ$ range. The rate constants for energy transfer from the triplet states of the compounds to 02 are between 1.3 X 108 and 2.8 X 109 M'1 s'1. Analysis of kinetic data pertaining to the photogeneration of 02 (!Ag) by the main-group compounds shows that the energy gap between their singlet (S,) and triplet (T,) states is 14.9 ± 0.3 kcal/mol. Relationships between the photoproperties of the metal complexes and the position in the periodic chart of the metals they contain are apparent.

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