Photocatalysis and self-catalyzed photobleaching with covalently-linked chromophore-quencher conjugates built around BOPHY

Two Chromophore-Quencher Conjugates (CQCs) have been synthesized by covalent attachment of the anti-oxidant dibutylated-hydroxytoluene (BHT) to a pyrrole-BF 2 chromophore (BOPHY) in an effort to protect the latter against photofading. In fluid solution, light-induced intramolecular charge transfer i...

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Bibliographic Details
Published in:Photochemical & photobiological sciences 2018, Vol.17 (6), p.75-762
Main Authors: Sirbu, Dumitru, Woodford, Owen J, Benniston, Andrew C, Harriman, Anthony
Format: Article
Language:English
Subjects:
Autocatalysis
Benzonitrile
Biochemistry
Biomaterials
Bleaching
Charge transfer
Chemistry
Chromophores
Conjugates
Cyclohexane
Damage detection
Dependence
Fluorescence
Light effects
Magnetic resonance spectroscopy
NMR spectroscopy
Photobleaching
Photocatalysis
Photons
Physical Chemistry
Plant Sciences
Solvents
Stoichiometry
Substrates
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Summary:Two Chromophore-Quencher Conjugates (CQCs) have been synthesized by covalent attachment of the anti-oxidant dibutylated-hydroxytoluene (BHT) to a pyrrole-BF 2 chromophore (BOPHY) in an effort to protect the latter against photofading. In fluid solution, light-induced intramolecular charge transfer is favoured in polar solvents and helps to inhibit photo-bleaching of the chromophore. The rate of photo-fading, which scales with the number of BHT residues, is zero-order in polar solvents but shows a linear dependence on the number of absorbed photons. The zero-order rate constant shows an inverse correlation with the fluorescence quantum yield measured in the same solvent. Photo-bleaching in benzonitrile involves autocatalysis while reaction in cyclohexane shows an unexpected stoichiometry. NMR spectroscopy indicates initial damage takes place at the BHT unit and allows identification of a reactive hydroperoxide as being the primary product. In the presence of an adventitious substrate, this hydroperoxide is a photocatalyst for amide formation under mild conditions. Two Chromophore-Quencher Conjugates (CQCs) have been synthesized by covalent attachment of the anti-oxidant dibutylated-hydroxytoluene (BHT) to a pyrrole-BF 2 chromophore (BOPHY) in an effort to protect the latter against photofading.
ISSN:1474-905X
1474-9092
DOI:10.1039/c8pp00162f