Impact of fluorination on the photophysics of the flavin chromophore: a quantum chemical perspective

Bracker, Mario; Dinkelbach, Fabian; Weingart, Oliver; Kleinschmidt, Martin

doi:10.1039/c9cp00805e

Cited by 18 publications

(52 citation statements)

References 61 publications

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“…Further screening was therefore undertaken on various commercially available as well as synthesized acridone derivatives (for structures see Figure ). Inspired by a recent study on the impact of fluorination on the photophysics of the flavine chromophore, , fluorine-substituted acridone derivatives such as NMA-dF were synthesized as described in the Supporting Information (SI). Regarding fluorescence quantum yields and emission ranges, it turned out that NMA-dF is the most promising chromophore tested (Figure , right).…”

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confidence: 99%

Acridones: Strongly Emissive HIGHrISC Fluorophores

Thom

Wieser

Diestelhorst

et al. 2021

J. Phys. Chem. Lett.

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An acridone derivative (N-methyl-difluoro-acridone, NMA-dF) is characterized with respect to its utility as an emitter in organic light emitting diodes (OLEDs). Using steadystate and time-resolved spectroscopy as well as quantum chemistry, its ability to convert singlet and triplet excitons into light was scrutinized. NMA-dF emits in the deep blue range of the visible spectrum. Its fluorescence emission occurs with quantum yields close to 1 and a radiative rate constant of ≈5 × 10 8 s −1 . So, it processes singlet excitons very efficiently. Using 1,4-dichlorobenzene as a sensitizer, it is shown that NMA-dF also converts triplet excitons into light. With the aid of quantum chemistry, this is related to a reverse intersystem crossing starting from a higher triplet state (HIGHrISC).

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confidence: 99%

Acridones: Strongly Emissive HIGHrISC Fluorophores

Thom

Wieser

Diestelhorst

et al. 2021

J. Phys. Chem. Lett.

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“…This trend propagates through the optimization of the S 1 excited state and relaxation to the ground state. The low-lying T 2 state has been hypothesized to influence the rate and quantum yield of intersystem crossing (ISC). , It is prudent to compare the energy of the Frank–Condon (FC) S 1 states to the T 2 states since the T 2 states were computed using the vertical excitation method. The T 2 states are lower in energy than the FC S 1 states for both 1AB and 6AB, implying that the potential for intersystem crossing from S 1 to T 2 is possible for both derivatives.…”

Section: Resultsmentioning

confidence: 99%

“…and Bracker et al . evaluated the impact of monofluorination at the C6-C9 positions of methylisoalloxazine. , Furthermore, Salzmann et al . synthetically and computationally studied the photochemical properties of deazaflavin derivatives and investigated the influence of solvation effects on the photophysics of deazaflavins. , Photophysical properties have also been investigated in the context of catalysis.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Photochemistry of C7 and C8 Functionalized N(5)-Ethyl-flavinium Cation: A Computational Study

2020

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Flavins are a diverse set of compounds with a wide variety of biological and nonbiological applications. Applications of flavins receiving attention recently consist of electro- and photocatalytic oxidation of substrates for organic synthesis, bioengineered nanotechnology, and water splitting catalysts, among others. While there is vast knowledge regarding the structure–property relationships of flavins and their electrochemistry, there is much less work elucidating the structure property relationships as they pertain to flavinium photochemistry. Herein, we report the effect of molecular tailoring on the molecular properties of N(5)-ethyl-flavinium cation (Et-Fl+), a derivative of the biocatalytic coenzyme riboflavin, by incorporating electron withdrawing and donating groups at the C7 and C8 position of the isoalloxazine ring. The presence of electron withdrawing groups at the C8 position caused a red shift in the absorption spectrum, while the electron donating groups caused a blue shift. Functionalization at the C7 position had the opposite effect on the absorption spectrum. The effects of single substitution were relatively negated with simultaneous functionalization at both the C8 and C7 positions. Difference density plots indicate no change in the nature of the S1 excited state, which was confirmed by optimization of the excited state geometries. The results presented in this study indicate that functionalization of the isoalloxazine unit affects the photophysical properties of N(5)-ethyl-flavinium cations.

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“…The ISC channels of naturally occurring flavins have been analyzed in several previous studies, either linked to the mechanism of photoreception [13,15,25] or describing the isolated chromophore [24,26,27] . In this study we focus on the core ring (MIA, see Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Computer‐Aided Design of Fluorinated Flavin Derivatives by Modulation of Intersystem Crossing and Fluorescence

et al. 2022

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This study aims at finding fluorinated flavin derivatives with modified intersystem crossing (ISC) and fluorescence properties. In total, photophysical properties of 8 derivatives were investigated computationally using combined density functional theory and multireference configuration interaction methods. On top of a screening procedure, the excited‐state decay mechanisms of selected chromophores were investigated in detail. Kinetic schemes including fluorescence, ISC as well as internal conversion (IC) channels were set up to unravel the complex excited‐state decay kinetics. We find two chromophores that exhibit promising properties with respect to fluorescence microscopy. Distinctive stabilization of the bright S1 ππ* state results in absorption in the green wavelength region and emission of (infra‐)red light. The 1(πHπL)⤳3(πH–1πL) ISC channel of the flavin chromophore was found to be deactivated upon both modifications, but nonradiative deactivation of the fluorescence by IC appears to be a problem. Alternative modifications of the pteridine dione moiety were found to result in a marked stabilization of nπ* states along with activation of El‐Sayed allowed ISC channels. For the latter two compounds, we predict fluorescence to be quenched by ISC followed by efficient population of the long‐lived T1 state via IC.

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Impact of fluorination on the photophysics of the flavin chromophore: a quantum chemical perspective

Abstract: 10-Methylisoalloxazine (MIA) and its fluorinated derivatives (6-9F-MIA) were investigated by means of quantum chemistry, looking into the influence of fluorination on fluorescence, absorption and inter-system crossing (ISC) in vacuum and in aqueous solution.

Cited by 18 publications

References 61 publications

Acridones: Strongly Emissive HIGHrISC Fluorophores

Acridones: Strongly Emissive HIGHrISC Fluorophores

Investigating the Photochemistry of C7 and C8 Functionalized N(5)-Ethyl-flavinium Cation: A Computational Study

Computer‐Aided Design of Fluorinated Flavin Derivatives by Modulation of Intersystem Crossing and Fluorescence

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