title: Synthesis, spectroscopy, nonlinear optics, and theoretical investigations of thienylethynyl octopoles with a tunable core.
abstract: We have synthesized three new molecules that have three thienylethynyl arms substituting a central benzene core and different electron donor/acceptor groups in the three remaining phenyl positions. The absorption, fluorescence, phosphorescence, and transient triplet-triplet spectra are analyzed in the light of the electronic structure of the ground and excited states obtained from quantum-chemical calculations. From the above, the relevant photophysical data (including quantum yields, lifetimes, and rate constants) could be derived. It was found that the major deactivation pathway is internal conversion, which competes with the fluorescence and intersystem crossing processes. For the three investigated compounds, we provide convincing theoretical support corroborating these findings and further conclusions based on the theoretical information obtained. These molecules are one of the very few cases in which the depolarization ratios, obtained from the NLO optical measurements, clearly reflect the octopolar configuration. Molecular hyperpolarizabilities have been measured and display a typical dependence on the donor-acceptor substitution pattern.
authors.affiliation: Department of Physical Chemistry, University of Málaga, Campus de Teatinos s/n, Málaga 29071, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Moreno Oliva
authors.forename: Juan
authors.initials: J
authors.lastname: Casado
authors.forename: Juan T
authors.initials: JT
authors.lastname: López Navarrete
authors.forename: Gunther
authors.initials: G
authors.lastname: Hennrich
authors.forename: Stijn
authors.initials: S
authors.lastname: van Cleuvenbergen
authors.forename: Inge
authors.initials: I
authors.lastname: Asselberghs
authors.forename: Koen
authors.initials: K
authors.lastname: Clays
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Ruiz Delgado
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brédas
authors.forename: J Sérgio
authors.initials: JS
authors.lastname: Seixas de Melo
authors.forename: Luisa
authors.initials: L
authors.lastname: De Cola