Interruption of the inner rotation initiated in isolated electron-driven molecular rotors

Pshenichnyuk, S. A.; Asfandiarov, N. L.; Кухто, А. В.

doi:10.1103/physreva.86.052710

Cited by 10 publications

(3 citation statements)

References 29 publications

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“…(where M stands for a target parent molecule) closed-shell anions at incident electron energies around 1 eV [25][26][27][28][29][30]. Elimination of two hydrogen atoms from the molecular anion was observed in the DEA spectra of indole and related molecules [27], polyphenolic compounds [31], and other molecules able to form new more stable structures [32]. The present research provides some new insight into this interesting phenomenon.…”

Section: Dea To Many Molecules With Biological Activity Is Dominated mentioning

confidence: 67%

Resonance electron interaction with five-membered heterocyclic compounds: Vibrational Feshbach resonances and hydrogen-atom stripping

et al. 2019

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Low-energy (0-15 eV) resonance electron attachment to a series of 5-membered heterocyclic rings (isoxazole, imidazole, pyrazole, pyrrole, 1-methyl-, and 2-methylimidazole) is studied under gas-phase conditions by means of electron transmission spectroscopy (ETS) and dissociative electron attachment spectroscopy (DEAS). Experimental spectral features are assigned on the basis of Hartree-Fock and density functional theory (DFT) calculations. Sharp features, with a width of less than 0.1 eV, observed in the electron transmission spectra of imidazole, pyrazole and pyrrole close to 0.45 eV, i.e. well below the energy of their lowestlying π* shape resonances detected at 1.90, 1.87, and 2.33 eV, respectively, are associated with formation of negative ion states bound by long-range electron-molecule interactions. Effective range theory (ERT) calculations which include both dipolar and polarization interactions support this interpretation. In addition to the general observation of cleavage of the N-H bond at incident electron energies close to 2 eV, elimination of as many as three hydrogen atoms from the molecular negative ions is detected at higher energies by DEAS with the only exception of methylated imidazoles. This complex process is associated with ring opening and formation of diatomic hydrogen as one of the neutral fragments, as indicated by the calculations to satisfy the energetic requirements. The present results are of importance for understanding the basic mechanisms of damages caused in living tissues by high-energy radiations.

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Section: Dea To Many Molecules With Biological Activity Is Dominated mentioning

confidence: 67%

Resonance electron interaction with five-membered heterocyclic compounds: Vibrational Feshbach resonances and hydrogen-atom stripping

et al. 2019

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“…Насколько известно авторам, выброс двух атомов водорода из ОМИ наблюдается (при низких энергиях электронов) лишь в тех случаях, когда молекула-мишень имеет определённую структуру: либо содержит несколько гидроксильных групп (полифенол) [11,12,33], либо существует возможность внутренних вращений одних частей молекулы по отношению к дру-гим, при которых происходит сближение атомов водо-рода [34]. В обоих случаях необходимо, чтобы в качестве нейтрального фрагмента образовалась молекула водо-рода: только при таком условии удаётся объяснить факт наблюдения анионов [M -2H] -при низких (вплоть до тепловых) энергиях электронов.…”

Section: ние фрагментов [M -2h]unclassified

Resonance electron attachment to natural polyphenolic compounds and their biological activity

Pshenichnyuk¹,

Asfandiarov²,

Воробьев³

et al. 2015

LoM

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Resonance low-energy (0-14 eV) electron attachment to natural polyphenolic stilbenes possessing antioxidant properties, namely resveratrol and piceatannol, was investigated by means of dissociative electron attachment spectroscopy. Experimental findings were assigned on base of density functional theory (DFT) calculations of energies and symmetry of vacant molecular orbitals. It was found that characteristic decay of the molecular negative ions of compounds under investigation under gasphase conditions can be associated with elimination of neutral H 2 molecule and formation of quinone-like structure bearing excess electron. These fragment species can be responsible for ability of polyphenolic compounds to scavenge free radicals in the living cells. The gas-phase data were extrapolated to reactions in cellular environment by means of DFT calculations using polarizable continuum model approach. A molecular mechanism for antioxidant activity of polyphenolic compounds in proximity to the mitochondrial respiratory chain under conditions of excess negative charge was suggested. Namely, it is thought that molecular hydrogen, known for its selective antioxidant properties, can be efficiently generated via attachment of electrons ("leaked" from the respiratory chain into mitochondrial intermembrane space) to polyphenolic compound and may be responsible for its antioxidant activity. The corresponding negative fragment, i.e., quinone bearing an excess negative charge, can serve as electron carrier and can return the captured electron back to the respiration cycle. The number of hydroxyl substituents and their relative positions on aromatic rings of polyphenolic molecule are crucial for the present molecular mechanism, because these properties determine dissociative electron attachment cross-section.

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“…The present Rapid Communication attracts attention to the possibility of using substantially different and less common experimental means to study internal rotations in molecular systems bearing an excess electron, i.e., molecular negative ions. In fact, our previous results [11,12] show that rotational motion in isolated molecules can be initiated by low-energy (0-15-eV) electron attachment via resonance mechanisms [13]. A dissociative electron attachment (DEA) study of dianilindoanthracene (DAA) [11] concluded that an incoming electron initiates rotational motion of (at least) one aniline substituent around a C-N bond of the long-lived (mass-spectrometrically detectable) molecular anion as schematically shown in Fig.…”

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confidence: 96%

Electron attachment spectroscopy as a tool to study internal rotations in isolated negative ions

Pshenichnyuk

Modelli

Asfandiarov

et al. 2020

Phys. Rev. Research

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Electron-driven processes in the triclosan molecule are studied under gas-phase conditions using dissociative electron attachment (DEA) spectroscopy with the support of density functional theory calculations. Several decay channels of the short-lived (less than 17 µs) molecular anion of triclosan are associated with excitation of internal rotations of the phenyl rings around the CO bonds. This leads to production of a dioxin anion by elimination of a neutral HCl molecule or negatively charged hypochlorous acid and dibenzofuran as the neutral counterpart. These decays are accompanied by cleavage and formation of several covalent bonds and appear on the microsecond timescale as confirmed by detection of metastable anions. On the basis of the present and earlier findings, DEA spectroscopy demonstrates to be a suitable technique for studying internal rotations in negative ions, although quite differently from the experimental techniques-microwave and Raman spectroscopies-usually employed to study internal rotations in neutral molecules.

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Interruption of the inner rotation initiated in isolated electron-driven molecular rotors

Cited by 10 publications

References 29 publications

Resonance electron interaction with five-membered heterocyclic compounds: Vibrational Feshbach resonances and hydrogen-atom stripping

Resonance electron interaction with five-membered heterocyclic compounds: Vibrational Feshbach resonances and hydrogen-atom stripping

Resonance electron attachment to natural polyphenolic compounds and their biological activity

Electron attachment spectroscopy as a tool to study internal rotations in isolated negative ions

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