Substituent screening effect on single-molecule photostability: comparison of three differently substituted porphycenes.

Autor:	Bednarz A; Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Kasprzaka 44/52, Poland., Kamińska I; Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Kasprzaka 44/52, Poland., Jamrozik A; Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Kasprzaka 44/52, Poland., Zielonka K; Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Kasprzaka 44/52, Poland., Listkowski A; Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Kasprzaka 44/52, Poland.; Faculty of Mathematics and Science, Cardinal Stefan Wyszyński University, Dewajtis 5, 01-815 Warsaw, Poland., Waluk J; Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Kasprzaka 44/52, Poland.; Faculty of Mathematics and Science, Cardinal Stefan Wyszyński University, Dewajtis 5, 01-815 Warsaw, Poland.
Jazyk:	angličtina
Zdroj:	Methods and applications in fluorescence [Methods Appl Fluoresc] 2021 May 12; Vol. 9 (3). Date of Electronic Publication: 2021 May 12.
DOI:	10.1088/2050-6120/abfcac
Abstrakt:	Photobleaching of single molecules has been studied using confocal fluorescence microscopy for porphycene, a porphyrin isomer, and its two derivatives. Fourfold substitution of porphycene with bulky tert -butyl groups leads to the enhancement of photostability, even though the spectral, photophysical, and redox parameters remain similar. We attribute this effect to the increase of the efficiency of physical quenching of the chromophore triplet state by oxygen, compared with the yield of chemical reaction that leads to photobleaching. Analysis of the observed photon fluxes from single emitters embedded in a polymer film shows that the experiment based on fluorescence is biased towards detection of molecules which have oxygen-the triplet quencher-in their vicinity. The distribution of the measured photodegradation quantum yields is very heterogeneous, suggesting that physical and chemical quenching rates exhibit different distance and orientation dependences. (© 2021 IOP Publishing Ltd.)
Databáze:	MEDLINE
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