title: Octa-alkyl zinc phthalocyanines: potential photosensitizers for use in the photodynamic therapy of cancer.
abstract: The synthesis, characterization and electronic spectra of a series of nine 1,4,8,11,15,18,22,25-octa-alkyl zinc phthalocyanines (ZnPc), potential photosensitizers for the photodynamic therapy of cancer, are described. The substituents on the phthalocyanine (Pc) macrocycle "red-shift" the absorbance maximum, in cyclohexane, of all nine members of this series to a value of 703 +/- 2 nm, with a corrected fluorescence emission maximum for the octadecyl derivative of 715 nm. The solubilities and degree of aggregation of six examples in cyclohexane have been measured. The highest homologue, the octadecyl derivative, remains essentially unaggregated to a concentration of 1.5 x 10(-4) mol dm-3. the photostability of this Pc has been examined and the compound shown to be sensitive to photooxidation processes which lead to its decomposition to 3,6-bis-decylphthalimide. Known singlet oxygen quenchers inhibit the photodecomposition. In a comparative study, the octadecyl ZnPc underwent a more rapid photodecomposition than the corresponding metal-free derivative.
authors.affiliation: School of Chemical Sciences, University of East Anglia, Norwich, Norfolk, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Cook
authors.forename: I
authors.initials: I
authors.lastname: Chambrier
authors.forename: S J
authors.initials: SJ
authors.lastname: Cracknell
authors.forename: D A
authors.initials: DA
authors.lastname: Mayes
authors.forename: D A
authors.initials: DA
authors.lastname: Russell
mesh_terms: D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D054833:Isoindoles; D009369:Neoplasms / Q000188:drug therapy; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D015032:Zinc / Q000737:chemistry / Q000494:pharmacology; D017967:Zinc Compounds
chemical_list: D007211:Indoles; D054833:Isoindoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D017967:Zinc Compounds; C052159:Zn(II)-phthalocyanine; D015032:Zinc