Title: Syntheses and Properties of Two-Dimensional, Dicationic Nonlinear Optical Chromophores Based on Pyrazinyl Cores
Authors: Coe, Benjamin J ×
Fielden, John
Foxon, Simon P
Helliwell, Madeleine
Asselberghs, Inge
Clays, Koen
De Mey, Kurt
Brunschwig, Bruce S #
Issue Date: Dec-2010
Publisher: American Chemical Society
Series Title: Journal of Organic Chemistry vol:75 issue:24 pages:8550-8563
Abstract: Six new dicationic 2D nonlinear optical (NLO) chromophores with pyrazinyl-pyridinium electron acceptors have been synthesized by nucleophilic substitutions of 2,6-dichloropyrazine with pyridyl derivatives. These compounds have been characterized as their PF6- salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Large red shifts in the intense, pi -> pi* intramolecular charge-transfer (ICT) transitions on replacing -oMe with -NMe2 substituents arise from the stronger pi-electron donor ability of the latter. Each compound shows a number of redox processes which are largely irreversible. Single crystal X-ray structures have been determined for five salts, including two nitrates, all of which adopt centrosymmetric packing arrangements. Molecular first hyperpolarizabilities beta have been determined by using femtosecond hyper-Rayleigh scattering at 880 and 800 nm, and depolarization studies show that the NLO responses of the symmetric species are strongly 2D, with dominant "off-diagonal" beta(zyy) components. Stark (electroabsorption) spectroscopic measurements on the ICT bands afford estimated static first hyperpolarizabilities beta(0). The directly and indirectly derived beta values are large, and the Stark-derived beta(0) response for one of the new salts is several times greater than that determined for (E)4'-(dimethylamino)-N-methyl-4-stilbazolium hexafluorophosphate. These Stark spectroscopic studies also permit quantitative comparisons with related 2D, binuclear Ru-II ammine complex salts.
ISSN: 0022-3263
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Imaging and Photonics
× corresponding author
# (joint) last author

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