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ISSN 1998-9539

Azaphthalocyanines Containing Pyrazine Rings with Focus on the Alkylheteroatom, Aryl and Heteroaryl Substitution and Properties Important in Photodynamic Therapy

Petr Zimcik,@ Veronika Novakova, Miroslav Miletin, and Kamil Kopecky


Department of Pharmaceutical Chemistry and Drug Control, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, Hradec Kralove, 50005, Czech Republic

@ Corresponding author E-mail:


Macrogeterocycles, 2008 1(1) 21-29


In this work, we summarize the recent knowledge about the syntheses, UV-vis absorption properties, aggregation, protonation and deprotonation of macrocycle and singlet oxygen and fluorescence quantum yields in the group of azaphthalocyanines bearing pyrazine rings in their conjugated system. Precursors (pyrazine-2,3-dicarbonitriles) for tetramerization are usually built up by condensation from aliphatic starting materials thus enabling peripheral substitutions sometimes not available for phthalocyanines (Pc). Conditions of tetramerizations are discussed in the article too. Although tetrapyrazinoporphyrazines (TPyzPA) suffer from the hypsochromic shift comparing to corresponding Pc, several types of peripheral substituents can induce important bathochromic shift and eliminate this disadvantage. TPyzPA macrocycle tends to higher aggregation comparing to Pc molecules and a lot of aggregation inhibiting substituents have been developed. Protonation of the TPyzPA macrocycle in acidic media starts on azomethine nitrogens and at higher concentrations of acid also pyrazine nitrogens accept the proton. The central hydrogens in metal-free compounds are acidic (N-acids) and the macrocycle can be deprotonated in basic solutions. Singlet oxygen production as well as fluorescence emission are strongly dependent on peripheral substituents, namely on the heteroatoms connecting the core with the substituents.


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