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Photochemical Insights on Intramolecular Dye‐Sensitized Free‐Radical Processes with a Quinoline Antenna
Author(s) -
Akari Aviya S.,
Hodgson Gregory K.,
Golian Karol P.,
Impellizzeri Stefania
Publication year - 2021
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202100027
Subject(s) - photochemistry , quinoline , chemistry , moiety , radical , quenching (fluorescence) , nitroxide mediated radical polymerization , intramolecular force , chromophore , fluorescence , excited state , antenna effect , hydroxylamine , polymer , radical polymerization , monomer , materials science , organic chemistry , luminescence , physics , quantum mechanics , optoelectronics , nuclear physics
Organic fluorophores containing paramagnetic nitroxides covalently tethered to the chromophoric core show a dramatic reduction in fluorescence due to intramolecular quenching of their excited states. Nonetheless, trapping of hydrogen atoms or carbon‐centered radicals by the nitroxide suppresses the quenching pathway and restores the fluorescence, an effect that can be used to monitor radical scavenging processes. Herein, we synthesized a prefluorescent radical probe in which a 2,2,6,6‐tetramethylpiperidine‐ N ‐oxyl (TEMPO) moiety was chemically coupled to a quinoline chromophore, which can directly sensitize TEMPO via energy transfer following low‐intensity ultraviolet illumination. In this design, the quinoline dye effectively acts as molecular ‘antenna’ to promote the reactivity of TEMPO toward H abstraction to form the corresponding N ‐hydroxylamine. The excited TEMPO can also abstract a hydrogen from a polymeric matrix, enabling the photochemical modification of the polymer with concomitant fluorescence activation and patterning. In addition, the patterning process can be thermally reverted (‘erased’) by heating the film above the glass transition temperature of the polymer.