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Synthesis and Characterization of Liquid-Crystalline Tetraoxapentacene Derivatives Exhibiting Aggregation-Induced Emission |
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| Authors: | Lana K. Hiscock Brooke M. Raycraft Monika Wałęsa-Chorab Coralie Cambe Alexandre Malinge Prof. Dr. W. G. Skene Hi Taing Prof. Dr. S. Holger Eichhorn Prof. Dr. Louise N. Dawe Prof. Dr. Kenneth E. Maly |
| Affiliation: | 1. Department of Chemistry and Biochemistry, Wilfrid Laurier University, 75 University Ave. W., Waterloo, ON, N2L 3C5 Canada;2. Département de Chimie, Université de Montréal, CP 6128, Centre-ville Montreal, QC, H3C 3J7 Canada Current address: Faculty of Chemistry, Adam Mickiewicz University in Poznań, Umultowska 89b, 61614 Poznań, Poland These authors contributed equally to this work.;3. Département de Chimie, Université de Montréal, CP 6128, Centre-ville Montreal, QC, H3C 3J7 Canada These authors contributed equally to this work.;4. Département de Chimie, Université de Montréal, CP 6128, Centre-ville Montreal, QC, H3C 3J7 Canada;5. Department of Chemistry and Biochemistry, University of Windsor, Essex Hall, 401 Sunset Ave., Windsor, ON, N9B 3P4 Canada |
| Abstract: | A series of new tetrakis(dialkoxyphenyl) dicyanotetraoxapentacene derivatives ( 1 a – c ) were prepared by reaction of the appropriate terphenyl diols with tetrafluoroterephthalonitrile in good yields. Compounds 1 b and 1 c , which bear hexyloxy and decyloxy side chains, exhibited columnar hexagonal mesophases, as shown by polarized optical microscopy, variable-temperature powder X-ray diffraction, and differential scanning calorimetry. Single-crystal X-ray diffraction of methoxy-substituted 1 a revealed that the dicyanotetraoxapentacene core is highly planar, consistent with the notion that these molecules are able to stack in columnar mesophases. A detailed photophysical characterization showed that these compounds exhibit aggregation-induced emission in solution, emission in nonpolar solvents, weak emission in polar solvents, and strong emission in the solid state both as powder and in thin films. These observations are consistent with a weakly emissive charge-transfer state in polar solvents and a more highly emissive locally excited state in nonpolar solvents. |
| Keywords: | aggregation-induced emission columnar liquid crystals heteroacenes luminescence nucleophilic substitution |