Elementary processes triggered in curcumin molecule by gas-phase resonance electron attachment and by photoexcitation in solution

Stanislav A Pshenichnyuk; Nail L Asfandiarov; Angelina V Markova; Alexei S Komolov; Viktor A Timoshnikov; Nikolay E Polyakov

doi:10.1063/5.0180053

Elementary processes triggered in curcumin molecule by gas-phase resonance electron attachment and by photoexcitation in solution

J Chem Phys. 2023 Dec 7;159(21):214305. doi: 10.1063/5.0180053.

Authors

Stanislav A Pshenichnyuk¹, Nail L Asfandiarov¹, Angelina V Markova¹, Alexei S Komolov², Viktor A Timoshnikov³, Nikolay E Polyakov^{3

4}

Affiliations

¹ Institute of Molecule and Crystal Physics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya 151, 450075 Ufa, Russia.
² St. Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia.
³ Voevodsky Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Institutskaya str. 3, 630090 Novosibirsk, Russia.
⁴ Institute of Solid State Chemistry and Mechanochemistry, Russian Academy of Sciences, Kutateladze 18, 630128 Novosibirsk, Russia.

PMID: 38051100
DOI: 10.1063/5.0180053

Abstract

Electron-driven processes in isolated curcumin (CUR) molecules are studied by means of dissociative electron attachment (DEA) spectroscopy under gas-phase conditions. Elementary photostimulated reactions initiated in CUR molecules under UV irradiation are studied using the chemically induced dynamic nuclear polarization method in an acetonitrile solvent. Density functional theory is applied to elucidate the energetics of fragmentation of CUR by low-energy (0-15 eV) resonance electron attachment and to characterize various CUR radical forms. The adiabatic electron affinity of CUR molecule is experimentally estimated to be about 1 eV. An extra electron attachment to the π1* LUMO and π2* molecular orbitals is responsible for the most intense DEA signals observed at thermal electron energy. The most abundant long-lived (hundreds of micro- to milliseconds) molecular negative ions CUR- are detected not only at the thermal energy of incident electrons but also at 0.6 eV, which is due to the formation of the π3* and π4* temporary negative ion states predicted to lie around 1 eV. Proton-assisted electron transfer between CUR molecules is registered under UV irradiation. The formation of both radical-anions and radical-cations of CUR is found to be more favorable in its enol form. The present findings shed some light on the elementary processes triggered in CUR by electrons and photons and, therefore, can be useful to understand the molecular mechanisms responsible for a variety of biological effects produced by CUR.