title: Resonance electron attachment to plant hormones and its likely connection with biochemical processes.
abstract: Gas-phase formation of temporary negative ion states via resonance attachment of low-energy (0-6 eV) electrons into vacant molecular orbitals of salicylic acid (I) and its derivatives 3-hydroxy- (II) and 4-hydroxybenzoic acid (III), 5-cloro salicylic acid (IV) and methyl salicylate (V) was investigated for the first time by electron transmission spectroscopy. The description of their empty-level structures was supported by density functional theory and Hartree-Fock calculations, using empirically calibrated linear equations to scale the calculated virtual orbital energies. Dissociative electron attachment spectroscopy (DEAS) was used to measure the fragment anion yields generated through dissociative decay channels of the parent molecular anions of compounds I-V, detected with a mass filter as a function of the incident electron energy in the 0-14 eV energy range. The most intense negative fragment produced by DEA to isomers I-III is the dehydrogenated molecular anion [M-H](-), mainly formed at incident electron energies around 1 eV. The vertical and adiabatic electron affinities were evaluated at the B3LYP/6-31+G(d) level as the anion/neutral total energy difference. The same theoretical method was also used for evaluation of the thermodynamic energy thresholds for production of the negative fragments observed in the DEA spectra. The gas-phase DEAS data can provide support for biochemical reaction mechanisms in vivo.
authors: Institute of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences, Prospeκt Oktyabrya 151, 450075 Ufa, Russia.
authors: Stanislav A
authors: SA
authors: Pshenichnyuk
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna, via Selmi 2, 40126 Bologna, Italy and Centro Interdipartimentale di Ricerca in Scienze Ambientali, via S. Alberto 163, 48123 Ravenna, Italy.
authors: Alberto
authors: A
authors: Modelli
mesh_terms: D004579:Electron Transport; D004583:Electrons; D054879:Halogenation; D006900:Hydroxylation; D008745:Methylation; D008958:Models, Molecular; D010226:Parabens / Q000737:chemistry; D010937:Plant Growth Regulators / Q000737:chemistry*; D010944:Plants / Q000737:chemistry*; D011789:Quantum Theory; D020156:Salicylic Acid / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D010226:Parabens; D010937:Plant Growth Regulators; C038193:4-hydroxybenzoic acid; D020156:Salicylic Acid