Open AccessSubstituent screening effect on single-molecule photostability: comparison of three differently substituted porphycenes
Author(s) -
Aleksandra Bednarz,
Izabela Kamińska,
Agnieszka Jamrozik,
Karolina Zielonka,
Arkadiusz Listkowski,
Jacek Waluk
Publication year - 2021
Publication title -
methods and applications in fluorescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 25
ISSN - 2050-6120
DOI - 10.1088/2050-6120/abfcac
Subject(s) - photobleaching , photochemistry , chemistry , quenching (fluorescence) , chromophore , porphyrin , molecule , fluorescence , substituent , photodegradation , structural isomer , quantum yield , oxygen , triplet state , stereochemistry , photocatalysis , organic chemistry , quantum mechanics , catalysis , physics
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.