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Electrochemical Switch-On of Nonlinear Optical Response in a Nitro-Functionalized Arylimido-Polyoxometalate
Claire F Jones1, Bethany R Hood2,3, Yovan de Coene4
1School of Chemistry, Pharmacy and Pharmacology, University of East Anglia, Norwich, UK.
Abstract:
Electrochemical switch-on of second-order non-linear optical (NLO) responses (β) has been demonstrated in a polyoxometalate (POM) based chromophore (POMophore) for the first time. Reduction of the POM in a POM-imidoaryl-NO2 derivative invokes an up to 15-fold off/on switchable increase in intensity of scattered frequency-doubled light, and the highest "on" state β yet reported for a redox-cyclable POMophore. Computational and spectroscopic studies show that in the oxidized state, directionally opposed charge transfer (CT) transitions to POM and ─NO2 result in a low net β. Upon reduction, the POM becomes a much weaker CT acceptor, resulting in more dipolar imido-aryl to nitro CT, and thus enhanced NLO response.
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