Magnesium and zinc complexes of azaphthalocyanines (AzaPc) with eight peripheral aromatic (phenyl) or heteroaromatic (pyridyl, thienyl, furyl) substituents are studied from the point of view of their singlet oxygen (Φ Δ ) and fluorescence (Φ F ) quantum yields, and UV-vis absorption spectra. Zn complexes have higher Φ ∆ than Mg complexes by a factor of two, whereas the Mg complexes have higher Φ F than Zn complexes, also by a factor of two. Thienyl AzaPc have the highest Φ ∆ among all studied substances (0.635 for Zn complex) followed by phenyl and pyridyl derivatives. The order of Φ F values is then reversed -the highest values were reached for pyridyl and phenyl derivatives followed by thienyl AzaPc. Both furyl AzaPc were unstable towards light and decomposed giving very low Φ ∆ and Φ F . The Q-bands of the furyl and thienyl AzaPc were red-shifted for approx. 20 nm compared to phenyl and pyridyl derivatives indicating lower sterical hindrance between five-membered rings and thus allowing better conjugation of π-systems. Pyridyl-, thienyl-and furylsubstituted pyrazino[2,3-b]pyrazine-2,3-dicarbonitriles were also prepared but decomposed during attempted cyclotetramerizations.

The Zn ( quinoline )2 Cl 2 complex is found to be a convenient reagent for the direct synthesis of amino-substituted, zinc azaphthalocyanines. Octa(4-thiomorpholinyl)- and octa(1-pyrazolyl)- substituted zinc azaphthalocyanines were synthesized from pyrazines, 5,6-bis(4-thiomorpholinyl)pyrazine-2,3-dicarbonitrile and 5,6-bis(1-pyrazolyl)pyrazine-2,3-dicarbonitrile, respectively and dry Zn ( quinoline )2 Cl 2. Two zinc azaphthalocyanines, both mixtures of four constitutional isomers, were synthesized by the same method, from 6-(2-thienyl)-5-(4-thiomorpholinyl)pyrazine-2,3-dicarbonitrile and from 6-(2-thienyl)-5-(1-pyrazolyl)pyrazine-2,3-dicarbonitrile respectively. The octa(4-thiomorpholinyl)- and octa(1-pyrazolyl)-substituted zinc azaphthalocyanines and the zinc azaphthalocyanines with mixed substituents were characterized by elemental analyses, TOF-SIMS, 1 H and 13 C NMR, and UV-vis spectroscopic methods. Q-bands for octa(4-thiomorpholinyl)- and octa(1-pyrazolyl)-substituted zinc azaphthalocyanines and the zinc azaphthalocyanines with mixed substituents are found at respectively 655 and 670 nm (ɛ: 100 000-180 000 M-1.cm-1).

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