title: IR spectroscopy of monohydrated tryptamine cation: rearrangement of the intermolecular hydrogen bond induced by photoionization.
abstract: Rearrangement of intermolecular hydrogen bond in a monohydrated tryptamine cation, [TRA(H(2)O)(1)](+), has been investigated in the gas phase by IR spectroscopy and quantum chemical calculations. In the S(0) state of TRA(H(2)O)(1), a water molecule is hydrogen-bonded to the N atom of the amino group of a flexible ethylamine side chain [T. S. Zwier, J. Phys. Chem. A 105, 8827 (2001)]. A remarkable change in the hydrogen-bonding motif of [TRA(H(2)O)](+) occurs upon photoionization. In the D(0) state of [TRA(H(2)O)(1)](+), the water molecule is hydrogen-bonded to the NH group of the indole ring of TRA(+), indicating that the water molecule transfers from the amino group to NH group. Quantum chemical calculations are performed to investigate the pathway of the water transfer. Two potential energy barriers emerge in [TRA(H(2)O)(1)](+) along the intrinsic reaction coordinate of the water transfer. The water transfer event observed in [TRA(H(2)O)(1)](+) is not an elementary but a complex process.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Graduate School of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakota
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Kouno
authors.forename: Satoshi
authors.initials: S
authors.lastname: Harada
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Masaaki
authors.initials: M
authors.lastname: Fujii
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sekiya
mesh_terms: D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D055668:Photochemical Processes; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D014363:Tryptamines / Q000737:chemistry*; D014732:Vibration; D014867:Water / Q000737:chemistry*
chemical_list: D014363:Tryptamines; D014867:Water; C030820:tryptamine