Incumbent of the Falk Chair in Laser Phototherapy.
Enhanced Acidity, Photophysical Properties and Liposome Binding of Perfluoroalkylated Phthalocyanines Lacking C-H Bonds
Article first published online: 30 APR 2007
Photochemistry and Photobiology
Volume 82, Issue 2, pages 593–599, March 2006
How to Cite
Minnes, R., Weitman, H., Lee, H.-J., Gorun, S. M. and Ehrenberg, B. (2006), Enhanced Acidity, Photophysical Properties and Liposome Binding of Perfluoroalkylated Phthalocyanines Lacking C-H Bonds. Photochemistry and Photobiology, 82: 593–599. doi: 10.1562/2005-11-08-RA-732
- Issue published online: 30 APR 2007
- Article first published online: 30 APR 2007
- Received 8 November 2005; accepted 7 December 2005; published online 8 December 2005
The acid-base, spectroscopic, photophysical and liposome-binding properties of the recently synthesized free base, 29H,31H,1,4,8,11,15,18,22,25-octafluoro-2,3,9,10,16,17,23, 24-octakisperfluoro(isopropy1) phthalocyanine, F64PcH2, are reported. The perfluoroalkylation of the phthalocyanine core renders the hydrogen atoms acidic, with a pKa= 6. The F64Pc-2 dianion is detected already at pH 3, by singular-value decomposition analysis of electronic spectra. F64Pc-2 generates 1O2 with quantum yields ΦΔ= 0.252 (in MeOH) and 0.019 in liposomes. Metallation of the Pc macrocycle to yield F64PcZn increases ΦΔ to 0.606 and 0.126 in MeOH and liposomes, respectively. Surprisingly, F64Pc-2 (but not F64PcH2 or F64PcZn) binds strongly to liposomes, with a binding constant Kb= 25 (mg/mL)-1. The fully protonated F64PcH2, but not the zwitterionic F64Pc-2, might favor hydrogen bonding, thus reducing its lipophilicity. Similarly, the Lewis acidity of Zn in F64PcZn, and thus its ability to bind water within a hydrophobic perfluoroalkyl pocket, is significantly enhanced by the fluorinated substituents.