Octupolar Merocyanine Dyes: A New Class of Nonlinear Optical Chromophores

Authors

  • Dr. Yevgen M. Poronik,

    1. Institute of Organic Chemistry of the Polish Academy of Sciences, 44/52 Kasprzaka Str., 01-224 Warsaw (Poland)
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  • Vincent Hugues,

    1. Université de Bordeaux, ISM (UMR5255 CNRS), 33400, Bordeaux (France)
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  • Dr. Mireille Blanchard-Desce,

    Corresponding author
    1. Université de Bordeaux, ISM (UMR5255 CNRS), 33400, Bordeaux (France)
    • Université de Bordeaux, ISM (UMR5255 CNRS), 33400, Bordeaux (France)
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  • Prof. Dr. Daniel T. Gryko

    Corresponding author
    1. Institute of Organic Chemistry of the Polish Academy of Sciences, 44/52 Kasprzaka Str., 01-224 Warsaw (Poland)
    • Institute of Organic Chemistry of the Polish Academy of Sciences, 44/52 Kasprzaka Str., 01-224 Warsaw (Poland)
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Abstract

A set of new octupolar merocyanine chromophores was designed and synthesized. These compounds were prepared from the reaction of 1,3,5-triformyl-2,4,6-trihydroxybenzene with heterocyclic nucleophiles. Octupolar dyes were formed exclusively in their open-dye form. The one- and two-photon-absorption spectra of the dyes consist of two bands: The long-wavelength band in the two-photon absorption spectrum (a few hundreds GM above 1000 nm) matches well with the intense, long-wavelength-absorption band that is located in the visible region in the linear spectrum. Interestingly, an additional, much-more-intense TPA band in the NIR region is observed at higher energy, which corresponds to a weakly allowed one-photon electronic transition. Changing the peripheral heterocyclic moieties allows tuning of the optical properties to approach the cyanine limit (i.e., polymethine state), thus resulting in a red-shift of the low-energy one-photon-absorption band as well as to the rise of an intense two-photon-absorption band in the NIR region. To the best of our knowledge, this is the first synthesis and TPA characterization of octupolar merocyanine chromophores with typical low-bond-length alternation.

Abstract

Otrzymano barwniki funkcjonalne typu merocyjanin o budowie oktupolowej. Synteza oparta jest o reakcję 1,3,5-triformylo-2,4,6-trihydroksybenzenu z nukleofilami heterocyklicznymi. Udowodniono, że barwniki istnieją wyłącznie w formie otwartej. Otrzymane związki absorbują silnie światło czerwone i pomarańczowe, wykazują fluorescencję (λem=590–690 nm) oraz dwa silne pasma w absorpcji dwufotonowej (σ2=500–2300 GM). Zmiana jednostki heterocyklicznej pozwala na modulowanie właściwości optycznych i zbliżenie się do tzw. granicy cyjaninowej, co bezpośrednio skutkuje batochromowym przesunięciem maksimum absorpcji jednofotonowej i zwiększeniem intensywności absorpcji dwufotonowej.

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