Spectroscopic Determination of the Vibrational Potential Energy Surface and Conformation of 1,3-Benzodioxole in Its S1(π,π*) Excited State. The Effect of the Electronic Excitation on the Anomeric Effect Academic Article uri icon

abstract

  • The electronic absorption spectra and the laser-induced fluorescence spectra of supersonic-jet-cooled 1,3-benzodioxole molecules have been investigated to map out the vibronic energy levels in the S1(π,π+*) electronic excited state. These were used to determine a two-dimensional potential energy surface in terms of the ring-puckering and ring-flapping vibrational coordinates, and the molecule was found to be puckered with a dihedral angle of 22°. The barrier to planarity in the excited state is 264 cm-1 (3.16 kJ/mol) as compared to 164 cm-1 (1.96 kJ/mol) in the ground state. This increase is attributed to reduced suppression of the anomeric effect by the benzene ring resulting from decreased π bonding character in the S1(π,:π*) state. As expected, the motion along the flipping coordinate is governed by a more shallow potential energy well. Ab initio calculations carried out for both the ground and excited states support the experimental conclusions.

author list (cited authors)

  • Laane, J., Bondoc, E., Sakurai, S., Morris, K., Meinander, N., & Choo, J

complete list of authors

  • Laane, Jaan||Bondoc, Eugene||Sakurai, Sachie||Morris, Kevin||Meinander, Niklas||Choo, Jaebum

publication date

  • January 1, 2000 11:11 AM