Synthesis, spectroscopy, nonlinear optics, and theoretical investigations of thienylethynyl octopoles with a tunable core.
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.
Moreno Oliva
María
M
Department of Physical Chemistry, University of Málaga, Campus de Teatinos s/n, Málaga 29071, Spain.
Casado
Juan
J
López Navarrete
Juan T
JT
Hennrich
Gunther
G
van Cleuvenbergen
Stijn
S
Asselberghs
Inge
I
Clays
Koen
K
Ruiz Delgado
M Carmen
MC
Brédas
Jean-Luc
JL
Seixas de Melo
J Sérgio
JS
De Cola
Luisa
L