title: Optical properties of gas-phase tryptophan-silver cations: charge transfer from the indole ring to the silver atom.
abstract: We present a joint experimental and theoretical investigation of the electronic excitation spectra of the tryptophan-silver complex. The photodissociation spectrum of gas-phase [Trp-Ag]+ was measured from 215 to 330 nm using a quadrupole ion trap coupled to an optical parametric-oscillator laser. The calculated time-dependent density functional theory (TD-DFT) absorption spectra for different prototypes of structures are presented. Low-energy transitions that are experimentally observed are only calculated for the charge-solvation (CS) structures. These transitions are a signature of the metal-pi interaction in [Trp-Ag]+. The recorded spectrum is compared to a Boltzmann average of the absorption spectrum obtained from direct molecular dynamics (MD) simulations involving simultaneous transitions to excited states based on semiempirical configuration interaction (CI) calculations. The results demonstrate that charge transfer can be photoinduced from the indole ring to the silver atom.
authors.affiliation: Laboratoire de Spectrométrie Ionique et Moléculaire, UMR 5579 (Université Lyon I et CNRS), 43 Bd du 11 Novembre 1918, 69622 Villeurbanne cedex (France).
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Thibault
authors.initials: T
authors.lastname: Tabarin
authors.forename: Michel
authors.initials: M
authors.lastname: Broyer
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
authors.forename: Roland
authors.initials: R
authors.lastname: Mitrić
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bonacić-Koutecký
mesh_terms: D002414:Cations, Monovalent / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D055095:Optics and Photonics; D012834:Silver / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D002414:Cations, Monovalent; D005740:Gases; D007211:Indoles; D012834:Silver; C030374:indole; D014364:Tryptophan