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

Abstract

The first photophysical studies of a member of the family of subnaphthalocyanines are described. The cone-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.