title: The conformational landscape of 5-methoxytryptamine studied by rotationally resolved fluorescence spectroscopy and resonant ionization spectroscopy.
abstract: Rotationally resolved electronic spectra of three different conformers of 5-methoxytryptamine were recorded in a molecular beam. 5-Methoxy substitution reduces the number of observed conformers to three compared to seven that have been reported for tryptamine. Quantum chemical calculations indicate that anti-rotamers of the methoxy-group are more stable relative to the syn-forms. Two gauche structures (Gpy(in) and Gph(in)) of the ethylamino group with respect to the indole chromophore were found to be less stable than the other seven. The lowest electronically excited state has been identified as the (1)L(b) one for all observed conformers which was confirmed by quantum-chemical calculations. Based on the comparison of rotational constants obtained from fits using evolutionary algorithms with those from calculations, the three observed conformers were determined to be the Gpy(up), Gph(up), Gpy(out) ethylamino side-chain conformations.
authors.affiliation: Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225, Düsseldorf, Germany. mschmitt@uni-duesseldorf.de.
authors.forename: Thi Bao Chau
authors.initials: TB
authors.lastname: Vu
authors.forename: Ivo
authors.initials: I
authors.lastname: Kalkman
authors.forename: W Leo
authors.initials: WL
authors.lastname: Meerts
authors.forename: Christian
authors.initials: C
authors.lastname: Brand
authors.forename: Yuriy N
authors.initials: YN
authors.lastname: Svartsov
authors.forename: Sascha
authors.initials: S
authors.lastname: Wiedemann
authors.forename: Rainer
authors.initials: R
authors.lastname: Weinkauf
authors.forename: Michael
authors.initials: M
authors.lastname: Schmitt