Nucleophilic aromatic substitution chemistry on perfluorophthalocyanines was used to develop facile synthetic methods for generating Pc derivatives with near IR absorption. The photophysics of these molecules can be fine-tuned via simple click-type substitution chemistry resulting in a decrease in the HOMO-LUMO gap for each substitution. This leads to a red-shifted absorbance that should be ideal for various biomedical and materials applications. A commercially available, cost effective surfactant, isodecyloxypropyl-1,3-diaminopropane (tomamine®), is appended onto zinc 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluorophthalocyanine (ZnF<sub>16</sub>Pc). This substitution red-shifts the UV-vis absorbance and helps in solubility. Varying the equivalents of tomamine, we were able to isolate mono, di, tri and tetra-substituted products with UV-visible absorbance, lowest energy Q bands, at ca. 748, 765, 786 and 805 nm respectively. An unexpected discovery showed that addition of a 7-membered ring on the outside of ZnF<sub>16</sub>Pc induces steric interactions that cause the otherwise planar Pc macrocycle to twist and distort. This distortion results in an unexpectedly large shift in the UV-visible spectral peaks. The resulting peak is also much broader because of flexibility in the macrocycle. These compounds are highly soluble in organic and aqueous solvents and showed high photoacoustic and photothermal conversions for photoacoustic imaging and photothermal therapy of cancers.

Distorted phthalocyanines via click-chemistry: Synthesis, photoacoustic, photothermal and cell studies

256th National Meeting (2018)

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