Dynamics of flavin containing radical pairs in SDS micellar media probed by static and pulse magnetic field effect and pulse ADMR

ABSTRACT

The dynamics of the radical pairs generated from the electron transfer reaction from indole derivatives to flavin derivatives are studied by three techniques, time resolved magnetic field effect (TR-MARY) and pulse absorption detected magnetic resonance (ADMR), and absorption detected switching of external magnetic field techniques (AD-SEMF). The three techniques complementarily work for the precise analysis of the radical pair kinetics. The results by all three techniques reflect the difference of the hydrophobic nature of the radicals in the lifetime of RP in a micelle. Overcoming the difficulty of the determination of the short RP lifetime under the nearly quasi steady state due to slow and inhomogeneous decay kinetics of the precursor triplet excited state, AD-SEMF analysis enabled us to determine the kinetic parameters, which is consistent with the qualitatively observed by the other techniques.

GRAPHICAL ABSTRACT

KEYWORDS:

• Spin chemistry
• magnetic field effect
• magnetic resonance
• flavin
• micelle

Acknowledgments

We express the thanks to Prof. Hisao Murai (Shizuoka University) and Prof. Tatsuo Arai (University of Tsukuba) for giving us the opportunity to use set-up in their laboratories. We gratefully thank to Prof. Tomoaki Miura (Niigata University) for assistance to the AD-SEMF setup and stimulating discussion. We also acknowledge to Prof. J. R. Woodward (University of Tokyo) for stimulating discussion.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

K.M. acknowledges the financial support from JSPS KAKENHI [grant number 18H01184] and the ‘Lab-to-Lab program’ in Saitama University for funding his travel to SCM 2017.