Efficient singlet oxygen photogeneration by zinc porphyrin-dimers upon one- and two-photon excitation
Abstract
The development of photodynamic therapy at depth requires photosensitizers which have both sufficient quantum yield for singlet oxygen generation and strong two photon absorption. Here we show that this can be achieved by conjugated linkage of zinc porphyrins to make dimers. We determined the quantum yield of generation of 1O2, φΔ , by measuring emission at 1270 nm using a near infra-red streak camera and found it to increase from 15% for a single porphyrin unit to 27 47% for the dimers with a conjugated linker. Then, we measured the spectra of two-photon absorption cross section, σ2, by a focus-tunable Z scan method, which allows for nondestructive investigation of light-sensitive materials. We observed a strong enhancement of the two photon absorption coefficient in the dimers, especially those with an alkyne linker. These results lead to an excellent figure of merit for two photon production of singlet oxygen (expressed by the product σ2xφΔ) in the porphyrin dimers, of around 3700 GM, which is very promising for applications involving treatment of deep tumors by photodynamic therapy.
Citation
Mazur , L M , Roland , T , Leroy-Lhez , S , Sol , V , Samoc , M , Samuel , I D W & Matczyszyn , K 2019 , ' Efficient singlet oxygen photogeneration by zinc porphyrin-dimers upon one- and two-photon excitation ' , Journal of Physical Chemistry B , vol. 123 , no. 19 , pp. 4271-4277 . https://doi.org/10.1021/acs.jpcb.8b12561
Publication
Journal of Physical Chemistry B
Status
Peer reviewed
ISSN
1520-6106Type
Journal article
Description
Funding: UK EPSRC (EP/L017008/1), IDWS acknowledges a Royal Society Wolfson Research Merit Award. This work is a part of the ITN-EJD-2017 project POLYTHEA which has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement 764837.Collections
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