Boosting the singlet oxygen photosensitization abilities of Zn(ii) phthalocyanines through functionalization with bulky fluorinated substituents

In-depth, systematic photophysical studies have been performed on a series of ABAB, A3B and A4 ZnPcs functionalized with a varying number of bis(trifluoromethyl)phenyl units (i.e. at the B isoindoles) and other electron-withdrawing/electron-donating moieties (i.e. at the A isoindoles), to determine the influence of the susbtitution pattern on the aggregation features, fluorescence quantum yields and singlet oxygen (1O2) generation abilities of these molecules. As a general trend, the larger the number of bis(trifluoromethyl)phenyl units (i.e.ABAB crosswise functionalized ZnPcs), the lower the fluorescence quantum yield and the higher the 1O2 photosensitization. On the other hand, the electronic character of the substituents at the A isoindoles do not seem to have a clear effect on the photophysical properties of these ABAB ZnPcs. Overall, 1O2 quantum yields determined by the direct observation of the 1O2 phosphorescence are very high, with values ranging from 1 to 0.74 in THF solutionsThis work was supported by MINECO (CTQ2017-85393-P and CTQ2016-78454-C2-1-R) and ERA-NET/MINECO EuroNanoMed2017-191/PCIN-2017-04

Crosswise Phthalocyanines with Collinear Functionalization: New Paradigmatic Derivatives for Efficient Singlet Oxygen Photosensitization

This is the peer reviewed version of the following article: Revuelta‐Maza, M. A., Hally, C., Nonell, S., de la Torre, G., & Torres, T. (2019). Crosswise Phthalocyanines with Collinear Functionalization: New Paradigmatic Derivatives for Efficient Singlet Oxygen Photosensitization. ChemPlusChem, 84(6), 673-679, which has been published in final form at https://doi.org/10.1002/cplu.201800631. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsSupporting information for this article is available on the WWW under https://doi.org/10.1002/cplu.201800631We describe here the preparation of a series of trans-ABAB Zn(II) phthalocyanines (ZnPcs, which combine several interesting features. First, these compounds present high solubility and hindered aggregation, due to the functionalization of two facing isoindole constituents (B) of the ZnPc with bis(trifluoromethylphenyl) units. Second, the other two isoindoles (A) bear extra-annulated phthalimide units containing different substituents in the nitrogen positions, this feature results in a collinear arrangement of a variety of functional groups. Some of these collinearly functionalized ZnPcs are interesting building blocks for constructing either homo- or heteroarrays containing ZnPc units. Furthermore, the amphiphilic nature of some members of the series renders them interesting candidates for photosensitization of singlet oxygen. Photophysical studies on a model compound of the series have shown that these molecules are efficient singlet oxygen photosensitizers in both polar and apolar media, with 1O2 quantum yields (φΔ) as high as 0.74This work has been supported by MINECO, Spain (CTQ2017‐85393‐P and CTQ2016‐78454‐C2‐1‐R). C. H. thanks the European Social Funds and the SUR del DEC de la Generalitat de Catalunya for his predoctoral fellowships (Grant No. 2017 FI_B 00617 and 2018 FI_B1 00174