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Updated: May 30, 2025

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
Determination of the rotational isomerization rate along carbon-carbon single bonds in solution
Seongchul Park1,2, Hojeong Yoon2, Juhyang Shin2
1Korea Institute for Future Earth, Pusan National University, Busan 46241, Korea.
Abstract:
The temperature- and viscosity-dependent rotational isomerization time constant (τrot) along the C-C˙ bond of CF2BrCF2 radical in solution was measured using femtosecond infrared spectroscopy after photodissociating the I atom from CF2BrCF2I. Three density functional theory (DFT) functionals, ωB97XD, APFD, and B3LYP were used with the aug-cc-pVTZ basis set to calculate the required parameters in calculating τrot using Kramers' theory of reaction rates. The measured τrot was consistent with the value calculated using the vibrational frequencies and rotational barriers of the related compounds calculated by DFT method with ωB97XD/aug-cc-pVTZ. Kramers' theory calculation of τrot was further verified by an experimental measurement for CF3CF2CF2˙ in CCl4 at 293 K. The τrot along the C-C(˙) bond of ethyl radical and ethane derivatives in solution can be reliably estimated by Kramers' theory combined with DFT calculations using the ωB97XD functional and aug-cc-pVTZ basis set.
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