Spectroscopic and Theoretical Investigations of Flavin Compounds

Flavins, based on the isoalloxazine core, are ubiquitous chromophores in biochemical systems, mediating redox reactions, light sensing and electron transfer in flavoproteins. Spectroscopic techniques, ranging from infrared (IR) and ultraviolet–visible (UV–Vis) absorption to time-resolved terahertz Stark spectroscopy, have been employed alongside quantum-chemical and hybrid computational models to unravel their electronic structure, vibrational dynamics and photochemical pathways. By probing flavin in varying redox and protonation states, in gas phase or in condensed media, researchers have characterised how solvation, protonation site and intermolecular interactions shape absorption spectra, excited-state lifetimes and reactive intermediates. Theoretical frameworks, including time-dependent density functional theory (TD-DFT), multireference perturbation methods and quantum mechanics/molecular mechanics (QM/MM) approaches, complement experimental observations, enabling detailed assignments of electronic transitions, exploration of potential energy surfaces and predictions of vibronic coupling effects. Together, these studies advance our understanding of flavin photophysics and photochemistry and inform applications in biocatalysis, optogenetics and photocatalytic systems.

Research from Nature Portfolio

Time-resolved terahertz Stark spectroscopy has recently been applied to flavin analogues in solution at ambient temperatures, exploiting intense single-cycle terahertz pulses to generate ultrafast electric fields. This approach suppresses solute dipole reorientation, allowing direct measurement of dynamic Stark shifts on vibrational and electronic transitions without freezing the medium. Comparison with conventional Stark spectra and first-principles calculations has demonstrated improved characterisation of excited-state polarizabilities and transition dipole moments. These insights pave the way for studying flavin behaviour in biologically relevant environments under native conditions.

Spectroscopic and Theoretical Investigations of Flavin Compounds publication trend

The graph below shows the total number of articles in spectroscopic and theoretical investigations of flavin compounds across all publications each year (not limited to Nature Index journals).

Technical terms

Isoalloxazine ring: The tricyclic heteroaromatic core of flavin molecules responsible for electronic absorption and redox activity.

FTIR spectroscopy: A technique measuring infrared absorption to probe vibrational modes and molecular interactions in the condensed phase.

QM/MM: A hybrid computational method combining quantum mechanical treatment of a region of interest with molecular mechanical modelling of its environment.

Polarizable continuum model (PCM): An implicit solvent approach representing the solvent as a dielectric medium to simulate solvation effects.

Time-dependent density functional theory (TD-DFT): A quantum-chemical method for computing excited-state properties and electronic transition energies.

Stark spectroscopy: A method using applied electric fields to induce shifts in spectral lines, providing information on polarizabilities and dipole changes in excited states.

Vibronic coupling: The interaction between electronic states and molecular vibrations, affecting absorption band shapes and intensities.

References

1. Time-resolved THz Stark spectroscopy of molecules in solution. Nature Communications (2024).
2. How Aqueous Solvation Impacts the Frequencies and Intensities of Infrared Absorption Bands in Flavin: The Quest for a Suitable Solvent Model. Molecules (2024).
3. Systematic Theoretical Study on the pH-Dependent Absorption and Fluorescence Spectra of Flavins. Molecules (2023).
4. Electronic Structure Methods for Simulating Flavin’s Spectroscopy and Photophysics: Comparison of Multi-reference, TD-DFT, and Single-Reference Wave Function Methods. The Journal of Physical Chemistry B (2024).