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Synthesis and Characterization of Liquid‐Crystalline Tetraoxapentacene Derivatives Exhibiting Aggregation‐Induced Emission
Author(s) -
Hiscock Lana K.,
Raycraft Brooke M.,
WałęsaChorab Monika,
Cambe Coralie,
Malinge Alexandre,
Skene W. G.,
Taing Hi,
Eichhorn S. Holger,
Dawe Louise N.,
Maly Kenneth E.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201804215
Subject(s) - differential scanning calorimetry , liquid crystal , excited state , materials science , molecule , crystallography , diffraction , powder diffraction , aggregation induced emission , characterization (materials science) , terphenyl , discotic liquid crystal , photochemistry , fluorescence , chemistry , organic chemistry , optics , nanotechnology , optoelectronics , physics , nuclear physics , thermodynamics
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.