Measuring electronic structure properties of flavins and flavoproteins by electronic Stark spectroscopy

Stanley, Robert J.; Galen, Cornelius J. van

doi:10.1016/bs.mie.2019.03.012

Cited by 7 publications

(9 citation statements)

References 34 publications

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“…The Stark spectrometer has been previously described in detail. , Briefly, emission from a 300 W Xe arc lamp (Oriel) is focused upon the entrance slit of a 1/8 m monochromator (CVI) with a 2 nm bandpass and a wavelength accuracy of ±0.1 nm. Light exiting the monochromator is then coupled into a 1 m long, 1.000 mm diameter solarized fiber optic (Edmund Optics) that projects the beam through an adjustable Glan-Taylor polarizer onto a lens, which in turn focuses the monochromatic light into the Stark cuvette, itself immersed in liquid nitrogen within a dual-chambered cryostat (Janis).…”

Section: Methodsmentioning

confidence: 99%

Flavin Charge Redistribution upon Optical Excitation Is Independent of Solvent Polarity

et al. 2023

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Flavin absorption spectra encode molecular details of the flavin’s local environment through coupling of local electric fields with the chromophore’s charge redistribution upon optical excitation. Translating experimentally measured field-tuned transition energies to local electric field magnitudes and directions across a wide range of field magnitudes requires that the charge redistribution be independent of the local field. We have measured the charge redistribution upon optical excitation of the derivatized flavin TPARF in the non-hydrogen-bonding, nonpolar solvent toluene, with and without a tridentate hydrogen-bonding ligand, DBAP, using electronic Stark spectroscopy. These measurements were interpreted using TD-DFT finite field and difference density calculations. In comparing our present results to previous Stark spectroscopic analyses of flavin in more polar solvents, we conclude that flavin charge redistribution upon optical excitation is independent of solvent polarity, indicating that dependence of flavin transition energies on local field magnitude is linear with local field magnitude.

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Section: Methodsmentioning

confidence: 99%

Flavin Charge Redistribution upon Optical Excitation Is Independent of Solvent Polarity

et al. 2023

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“…The Stark spectrometer has been described in detail previously. , Briefly, the output of a 300 W Xe arc lamp is focused onto a 1/8 m monochromator with a 2 nm bandpass. The monochromatic probe beam is then passed through a depolarizer followed by a Glan–Taylor polarizer to control the polarization.…”

Section: Methodsmentioning

confidence: 99%

Stark Spectroscopy of Lumichrome: A Possible Candidate for Stand-Off Detection of Bacterial Quorum Sensing

2020

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Lumichrome (7,8-dimethylalloxazine, LC) is a natural photodegradation product and catabolite of flavin coenzymes. Although not a coenzyme itself, LC is used for biosignaling in plants and single-celled organisms, including quorum sensing in the formation of biofilms. The noninvasive detection of in vivo lumichrome would be useful for monitoring this signaling event. For molecules that undergo significant charge redistribution upon light excitation (e.g., intramolecular charge transfer), there are optical detection methods (e.g., secondharmonic generation) that would be well suited to this task. Here, we have used Stark spectroscopy to measure the extent and direction of charge redistribution in photoexcited LC. Stark and low-temperature absorption spectra were obtained at 77 K on LC in ethanol glasses and analyzed using the Liptay analysis to obtain the difference dipole moments and polarizabilities. These data were complemented by a computational analysis of the excited states using density functional theory (DFT) at the TD-B3LYP/6-311+G(2d,p) level of theory.

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“…In part, this could be because it is more difficult to characterize. Specifically, Δ d can be measured via electroabsorption (Stark) spectroscopy wherein a field strength approaching 1 MV/cm is applied to the system at cryogenic temperatures to modify its optical properties; − however, such measurements require specialized instrumentation. Another approach to obtain Δ d is to measure the Stokes shift, i.e., the energy difference between the longest-wavelength absorption and shortest-wavelength fluorescence features, in a series of solvents of varying polarity.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure and Excited-State Dynamics of DNA-Templated Monomers and Aggregates of Asymmetric Polymethine Dyes

Duncan,

Byers,

Houdek

et al. 2023

J. Phys. Chem. A

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Aggregates of conjugated organic molecules (i.e., dyes) may exhibit relatively large one- and two-exciton interaction energies, which has motivated theoretical studies on their potential use in quantum information science (QIS). In practice, one way of realizing large one- and two-exciton interaction energies is by maximizing the transition dipole moment (μ) and difference static dipole moment (Δd) of the constituent dyes. In this work, we characterized the electronic structure and excited-state dynamics of monomers and aggregates of four asymmetric polymethine dyes templated via DNA. Using steady-state and time-resolved absorption and fluorescence spectroscopy along with quantum-chemical calculations, we found the asymmetric polymethine dye monomers exhibited a large μ, an appreciable Δd, and a long excited-state lifetime (τ p ). We formed dimers of all four dyes and observed that one dye, Dy 754, displayed the strongest propensity for aggregation and exciton delocalization. Motivated by these results, we undertook a more comprehensive survey of Dy 754 dimer and tetramer aggregates using steady-state absorption and circular dichroism spectroscopy. Modeling these spectra revealed an appreciable excitonic hopping parameter (J). Lastly, we used femtosecond transient absorption spectroscopy to characterize τ p of the dimer and tetramer, which we observed to be exceedingly short. This work revealed that asymmetric polymethine dyes exhibited μ, Δd, monomer τ p , and J values promising for QIS; however, further work is needed to overcome excited-state quenching and achieve long aggregate τ p .

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Measuring electronic structure properties of flavins and flavoproteins by electronic Stark spectroscopy

Cited by 7 publications

References 34 publications

Flavin Charge Redistribution upon Optical Excitation Is Independent of Solvent Polarity

Flavin Charge Redistribution upon Optical Excitation Is Independent of Solvent Polarity

Stark Spectroscopy of Lumichrome: A Possible Candidate for Stand-Off Detection of Bacterial Quorum Sensing

Electronic Structure and Excited-State Dynamics of DNA-Templated Monomers and Aggregates of Asymmetric Polymethine Dyes

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