Phthalocyanines are an important class of industrial dyes with potential commercial applications ranging from photovoltaics to biomedical imaging and therapeutics. We previously demonstrated the versatility of the commercially available zinc(II) hexadecafluorophthalocyanine (ZnF<sub>16</sub>Pc) as a platform for rapidly developing functional materials for these applications and more. Because this core platform approach to dye development is increasingly common, it is important to understand the photophysical and structural consequences of the substitution chemistry involved. We present a fundamental study of a series of ZnF<sub>16</sub>Pc derivatives in which the aromatic fluorine atoms are progressively substituted with thioalkanes. Clear spectroscopic trends are observed as the substituents change from electron-withdrawing to electron-releasing groups. Additionally, there is evidence for significant structural distortion of the normally planar heterocycle, with important ramifications for the photophysics. These results are also correlated to DFT calculations, which show that the orbital energies and symmetries are both important factors for explaining the excited-state dynamics. One of the most important outcomes of this study is the development of a facile, flexible method for rapidly generating Pcs with tunable properties, using only inexpensive, commodity reagents. Investigating the structure−function relationships in Pcs and other photoactive macrocycles is an active area of research,21 and our results offer a new perspective on the competing mechanisms at play. In particular, we have highlighted a distinct approach to easily manipulating these properties through distortion of the planar Pc structure. These kinds of nonplanar chromophores have found use in a variety of applications such as organic photovoltaics, photodynamic therapy, nonlinear optics, and photoacoustic spectroscopy, all of which underscores the importance of further exploring this pathway.

Tuning the structure and photophysics of a fluorous phthalocyanine platform

253rd National Meeting (2017)

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