Abstract
A(3)B type unsymmetrical magnesium and zinc phthalocyanines with annelated thiazole ring connected to the triphenylamine moiety via ethylene bridge were designed and synthesized. Such tailored molecules showed the typical pattern for phthalocyanines (Soret and Q-band) in their electronic absorption spectra together with an absorption in the region 400-500 nm.
According to the DFT calculations the latter is assigned to the charge-transfer band originating from the triphenylamine-phthalocyanine core transition as a donor-acceptor system. Photophysical properties were affected by the central metal cation, Zn(II) causes an increase in the singlet oxygen quantum yield, reaching a value of 0.68 whereas Mg(II) gives only 0.50.
On the other hand, the fluorescence quantum yield was proportionally higher for magnesium derivative with quantum yield of 0.51 while only 0.32 for the zinc complex. The photophysical and photochemical properties of prepared magnesium and zinc phthalocyanines were compared with the unsubstituted zinc phthalocyanine for determination of the substitution effect.