Journal of the American Chemical Society
Journal of the American Chemical Society
5 years ago

Redox-Based Photostabilizing Agents in Fluorescence Imaging: The Hidden Role of Intersystem Crossing in Geminate Radical Ion Pairs

Redox-Based Photostabilizing Agents in Fluorescence Imaging: The Hidden Role of Intersystem Crossing in Geminate Radical Ion Pairs
Viktorija Glembockyte, Gonzalo Cosa
Here we report transient absorption studies on the ground-state recovery dynamics of the single-molecule fluorophore Cy3B in the presence of four different photostabilizing agents, namely β-mercaptoethanol (β-ME), Trolox (TX), n-propyl gallate (n-PG), and ascorbic acid (AA). These are triplet-state quenchers that operate via photoinduced electron transfer (PeT). While quantitative geminate recombination was recorded following PeT for β-ME (∼100%), for Trolox, n-propyl gallate, and ascorbic acid the extent of geminate recombination was >48%, >27%, and >13%, respectively. The results are rationalized in terms of the rates of intersystem crossing (ISC) in the newly formed geminate radical ion pairs (GRIPs). Rapid spin relaxation in the radicals formed accounts for quantitative geminate recombination with β-ME and efficient geminate recombination with TX. Our results illustrate how the interplay of PeT quenching efficiency and geminate recombination dynamics may lead to improved photostabilization strategies, critical for single-molecule fluorescence and super-resolution imaging.

Publisher URL: http://dx.doi.org/10.1021/jacs.7b08134

DOI: 10.1021/jacs.7b08134

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