Synchronous or stepwise Mechanism? a theoretical study on the Excited-State double proton transfer properties of shikonin and acetylshikosin

Min Ma; Ye Wang; Chaofan Sun

doi:10.1016/j.saa.2023.123689

Synchronous or stepwise Mechanism? a theoretical study on the Excited-State double proton transfer properties of shikonin and acetylshikosin

Spectrochim Acta A Mol Biomol Spectrosc. 2024 Mar 5:308:123689. doi: 10.1016/j.saa.2023.123689. Epub 2023 Nov 30.

Authors

Min Ma¹, Ye Wang², Chaofan Sun³

Affiliations

¹ College of Science, Northeast Forestry University, Harbin 150040, China.
² College of Physics and Electronic Information, Baicheng Normal University, Baicheng 137000, China. Electronic address: wangye@bcnu.edu.cn.
³ College of Science, Northeast Forestry University, Harbin 150040, China. Electronic address: cfsun@nefu.edu.cn.

PMID: 38064961
DOI: 10.1016/j.saa.2023.123689

Abstract

The excited state double proton transfer (ESDPT) mechanism of shikonin (Shk) and its derivative acetylshikosin (AcShk) were studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The potential energy curves scanned along the coordinates of proton transfer indicate a preference for the ESDPT reaction to occur step by step. The AcShk molecule possesses an additional reaction pathway in comparison to the Shk molecule. Furthermore, efforts have been made to compute the absorption and fluorescence peak, which exhibits favorable conformity with the experimental findings of the system investigated. The fluorescence spectra in cyclohexane and acetonitrile solvents indicate that the solvent polarity affects the location of the ESDPT fluorescence peak in both Shk and AcShk systems. The fluorescence spectra concentrated in the green light region (504 nm ∼ 550 nm) are obtained, which has the potential to promote human health through disinfection and boosting the immune system.

Keywords: Double proton transfer; Potential energy surfaces; Solvent effect; TD-DFT.