Enhanced acidity, photophysical properties and liposome binding of perfluoroalkylated phthalocyanines lacking C-H bonds

Document Type

Article

Publication Date

3-1-2006

Abstract

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(isopropyl) phthalocyanine, F 64PcH 2, are reported. The perfluoroalkylation of the phthalocyanine core renders the hydrogen atoms acidic, with a pK a = 6. The F 64Pc -2 dianion is detected already at pH 3, by singular-value decomposition analysis of electronic spectra. F 64Pc -2 generates 1O 2 with quantum yields Φ Δ = 0.252 (in MeOH) and 0.019 in liposomes. Metallation of the Pc macrocycle to yield F 64PcZn increases Φ Δ to 0.606 and 0.126 in MeOH and liposomes, respectively. Surprisingly, F 64Pc -2 (but not F 64PcH 2 or F 64PcZn) binds strongly to liposomes, with a binding constant K b = 25 (mg/mL) -1. The fully protonated F 64PcH 2, but not the zwitterionic F 64Pc -2, might favor hydrogen bonding, thus reducing its lipophilicity. Similarly, the Lewis acidity of Zn in F 64PcZn, and thus its ability to bind water within a hydrophobic perfluoroalkyl pocket, is significantly enhanced by the fluorinated substituents. © 2006 American Society for Photobiology.

Identifier

33646255904 (Scopus)

Publication Title

Photochemistry and Photobiology

External Full Text Location

https://doi.org/10.1562/2005-11-08-RA-732

ISSN

00318655

First Page

593

Last Page

599

Issue

2

Volume

82

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