Modelling fragmentations of aminoacids after resonant electron attachment: quantum evidence of possible direct -OH detachment

Low-energy electron collisions with the alanine molecule

“…It is well-known that molecules containing -COOH group often show π * resonance features in low-energies electron collisions [73]. Our calculations give a sharp, low-energy resonance peak at 2.7 eV and 3.4 eV for conformers I and M respectively, which are in good agreement with the resonance energy around 3 eV calculated for various amino acids, such as, glycine, alanine, proline and valine, by Panosetti et al [10]. For comparison, our alanine conformer M resonance position is the same as that obtained by Tashiro [71] for glycine using a similar model of polarization to the one we use here.…”

“…These observations have stimulated significant interest in electron-molecule collisions with small biomolecules and the constituents of larger one, with particular emphasis on characterizing the resonance states of these systems. There are many studies of electron collisions with DNA building blocks [3][4][5][6][7][8][9] such as amino acids [10][11][12][13][14][15], nucleobase [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], sugar and phosphate moieties [34][35][36][37][38][39][40][41][42][43].…”

“…For glycine and alanine, the results recorded in these clusters showed that the major product is parent anions which contrasts with the results for the monomer, where dehydrogenated anions (A-H) − are the major product. Panosetti et al [10] calculated total elastic cross sections and resonance features for gas phase glycine, alanine, proline and valine at their equilibrium geometries. They studied the one-dimensional dissociation path of transient negative ions following resonant state formation and concluded that it is not possible to explain the detachment of -OH using a simple one-dimensional model in these complex molecules.…”

Electron scattering from gas phase cis-diamminedichloroplatinum(II): Quantum analysis of resonance dynamics

“…To determine the possible spatial evolution of the 2 B 2 resonance, we have carried out a systematic investigation of the resonance behavior resulting from the symmetric stretch of the rPtCl bond coordinates. Our calculations show that the resonance is lowered in energy as the bond length is increased, in accord with results from a similar research conducted on the C-OH stretch of several amino acid species, 69 and it also exhibits an increased stability by having narrower width values as the bond length is stretched towards dissociation, a clear sign of the formation of a stable anionic fragment from the initial CDDP complex. More research, however, is needed to determine the extent to which the 2 B 2 resonance parameters depend on other geometry variations about the equilibrium structure.…”

Shape and core-excited resonances in electron scattering from alanine

“…Several theoretical methods have been applied to the study of shape resonances in alanine. Panosetti et al 4 performed calculations that investigated resonance formation and fragmentation for the four smallest aminoacids. A resonance centred at approximately 3 eV was detected for all of them, corresponding again to the π * resonance.…”