Free electron interaction with genistein: positive and negative ion formation

TL;DR

This study explores how genistein interacts with electrons, forming ions and revealing its molecular stability and reaction pathways.

Contribution

The study identifies specific ion formation mechanisms and stability of genistein under electron impact.

Findings

Intact negatively charged genistein is the most abundant anionic species formed.

Retro-Diels–Alder rearrangement is a major pathway for cation formation.

Quantum calculations support the observed ion appearance energies.

Abstract

Genistein is a member of the group of isoflavones, which are present in edible plants and possess several health supporting properties. In this work we used a crossed beam experiment coupled to mass spectrometry. We investigated the formation of anions and cations from neutral genistein upon the interaction with electrons having kinetic energies from about 0 eV to 70 eV. In the case of negative ion formation, we find the intact negatively charged genistein as the most abundant anionic species. The dehydrogenated parent anion is observed as the only fragment anion formed by dissociative electron attachment to genistein. The parent and dehydrogenated species also represent prominent cations. However, we also observe abundant signals for ions formed upon cleavage of the centred ring via retro-Diels–Alder rearrangement. Quantum chemical calculations on the threshold energies support the experimentally found appearance energies.

In the present study we show that the isoflavone genistein has a pronounced molecular stability towards low-energy electron attachment while ionizing electrons efficiently induces retro-Diels–Alder rearrangement in the molecule.

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