Synthesis, electrochemical, spectral and DFT study of novel thiazole-annelated subphthalocyanines with inherent chirality

• Subphthalocyanines (SubPcs) with annelated thiazole rings were synthesized.
• SubPcs with C3-symmetry were resolved to enantiomers.
• Electrochemical and spectral experiments correlate well with DFT calculations.
• All novel SubPcs exhibit high quantum yields of singlet oxygen production.

Five-membered thiazole-annelated subphthalocyanine derivatives have been prepared for the first time. Both regioisomers with C3 and C1 molecular symmetry have been isolated and optical resolution of C3 enantiomers was achieved. Heterocycle annelation resulted in red shifted long wave Q-band with regard to the unsubstituted subphthalocyanines, in the case of linear annelated compounds it is more red shifted (603, 615 nm) than the corresponding band in angular annelated derivatives (590, 594 nm). Analysis of fluorescence quantum yields revealed the heavy atom effect of bromine. Irrespective of the present bromine atom, all complexes were characterized by high singlet oxygen production with quantum yields ranging from 0.62 to 0.80. The HOMO and LUMO energy levels (DFT calculated and electrochemically determined) showed that frontier orbital energies can be effectively tuned by different type of annelation.

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