title: High resolution electronic spectroscopy of 9-fluorenemethanol in the gas phase: new insights into the properties of Π-hydrogen bonds.
abstract: Rotationally resolved S(1)←S(0) fluorescence excitation spectra of 9-fluorenemethanol (9FM) and deuterated 9-fluorenemethanol (9FMD) have been observed and assigned. Two conformers were detected; sym-9FM and unsym-9FM. The sym conformer has the -OH group symmetrically placed above the fluorene short axis, with its hydrogen atom pointing towards the top of an aromatic ring, whereas the unsym conformer has the -OH group tilted away from this axis, with its hydrogen atom pointing towards the side of an aromatic ring. Only the sym conformer shows a tunneling splitting associated with the torsional motion of the -OH group; the unsym conformer is "rigid." Additionally, a third subband was observed in the spectrum of sym-9FMD, evidencing secondary minima on the potential energy surfaces of the ground and excited electronic states. Studies of these surfaces along the -OH torsional coordinate provide new insights into the properties of π-hydrogen bonds.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Diane M
authors.initials: DM
authors.lastname: Miller
authors.forename: Justin W
authors.initials: JW
authors.lastname: Young
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Morgan
authors.forename: David W
authors.initials: DW
authors.lastname: Pratt