Synthesis, optical absorption and photophysical properties of cone-shaped subnaphthalocyanine

The first photophysical studies of a member of the family of subnaphthalocyanines are described. The one-shaped unsubstituted subnaphthalocyanine, synthesized in 35% yield, provides it with distinctive photophysical properties that are better than those of the related planar phthalo- and naphthalocyanines. SubNc absorbs in the red part of the spectrum, has substantial fluorescence, φ_F = 0.22, and, significantly for photodynamic therapy applications, triplet and singlet oxygen quantum yields, φ_T = φ_Δ = 0.68, that are substantially higher than those of the related phthalo and naphthalocyanines. These results, together with their synthetic availability, high solubility, and low tendency to aggregate, make this new class of sensitisers amenable to being further studied with a view to finding photodynamic therapy applications.