U. Michelsen et al., UNSYMMETRICALLY SUBSTITUTED BENZONAPHTHOPORPHYRAZINES - A NEW CLASS OF CATIONIC PHOTOSENSITIZERS FOR THE PHOTODYNAMIC THERAPY OF CANCER, Photochemistry and photobiology, 64(4), 1996, pp. 694-701
Unsymmetrical zinc(II) complexes of benzonaphthoporphyrazines 5a-12a b
earing between one and eight pyridyloxy substituents are synthesized b
y statistical tetramerization of -(1,1-dimethylethyl)-2,3-naphthalened
icarbonitrile (1) with 4-(3-pyridyloxy)- or 4,5-bis-(3-pyridyloxy)-1,2
-benzenedicarbonitrile (2,3). Methylation of 5a-12a leads to the catio
nic pyridyloxybenzonaphthoporphyrazines 5b-12b having between one to e
ight positive charges, The Q-band transition in the visible spectra ex
hibits a bathochromic shift from 680 to 760 mm dependent upon the numb
er of annelated naphthalene rings. The singlet oxygen quantum yields o
f the benzonaphthoporphyrazines determined by the dye-sensitized photo
oxidation of 1,3-diphenylisobenzofurane is surprisingly high (in the r
ange of zinc phthalocyanine). The photooxidative stabilities of the ph
otosensitizers described quantitatively by first-order kinetics decrea
se with the number of annelated naphtho groups, A linear correlation b
etween the logarithm of the decomposition rate constant and the positi
on of the highest occupied molecular orbital (HOMO)-level of the photo
sensitizers is found. Destabilization of the HOMO leads to a decrease
of the photostability. Due to their adjustable long wavelength absorpt
ion, their intramolecular polarity axis and their different hydrophili
c/hydrophohic character, these novel compounds may be suitable photose
nsitizers for the photodynamic therapy of cancer.