posted on 2017-06-21, 00:00authored byPaul Kautny, Helene Kriegner, Dorian Bader, Michal Dušek, Georg A. Reider, Johannes Fröhlich, Berthold Stöger
Three
ethyne-linked push–pull materials consisting of a
dimethylaniline donor and acceptors of increasing electron-withdrawing
strength were prepared as nonlinear optical chromophores. Despite
a high similarity of the molecular structures, all three materials
featured unrelated non-centrosymmetric crystallization behavior. One
of the compounds exhibits a remarkable packing with Z′ = 16 molecules in the asymmetric unit forming two interpenetrating
subsystems. Inspection of the nonlinear optical activity of single
crystalline powders revealed an extraordinarily efficient second harmonic
generation of one of the materials with a 1200-fold increased second
harmonic response compared to potassium dihydrogen phosphate. The
second harmonic generation efficiency of the materials under investigation
has been related to both the intrinsic molecular properties as well
as the alignment of the individual chromophores within the crystal
packing, highlighting the importance of a multidisciplinary approach
to understand the properties of nonlinear optical materials.