Affiliation:
1. Institut für Organische Chemie und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
2. Institut für Physikalische Chemie Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
3. Institut für Theoretische Chemie und Computerchemie Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
Abstract
AbstractA previous quantum chemical study (M. Bracker et al., Phys. Chem. Chem. Phys. 2019, 21, 9912–9923) on the excited state properties of fluorinated derivatives of the flavin chromophore promised an increased fluorescence performance of the derivative 7,8‐difluoro‐10‐methyl‐isoalloxazine (7,8‐dF‐MIA). Here, we describe the synthesis of 7,8‐dF‐MIA, its ribityl derivative, and for reason of comparison 9‐F‐MIA. The compounds dissolved in water (H2O and D2O) were characterized by steady state, time resolved, and fluorescence correlation spectroscopy. The experiments confirm the increase of the fluorescence quantum yield of 7,8‐dF‐MIA (0.42 in H2O) compared to MIA (0.22) predicted by quantum chemistry. The anticipated reduction of the fluorescence quantum yield for 9‐F‐MIA is also confirmed experimentally. The quantum chemical computations as well as the spectroscopic observations attribute the increased fluorescence quantum yield of 7,8‐dF‐MIA predominantly to a decrease of the rate constant of intersystem crossing. Switching from H2O to D2O as a solvent is shown to increase fluorescence quantum yields (0.53 for 7,8‐dF‐MIA) and lifetimes of all fluorinated MIA derivatives. This can be attributed to a Förster type energy transfer from the excited chromophore to vibrational overtones of water and further water‐mediated deactivation processes.
Funder
Deutsche Forschungsgemeinschaft
Subject
Organic Chemistry,Physical and Theoretical Chemistry,Analytical Chemistry
Cited by
1 articles.
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