TY  - JOUR
A1  - Hayer, Anna
A1  - de Halleux, Veronique
A1  - Köhler, Anna
A1  - El-Garoughy, Abdel
A1  - Meijer, E. W.
A1  - Barbera, Joaquin
A1  - Tant, Julien
A1  - Levin, Jeremy
A1  - Lehmann, Matthias
A1  - Gierschner, Johannes
A1  - Cornil, Jerome
A1  - Geerts, Yves Henri
T1  - Highly fluorescent crystalline and liquid crystalline columnar phases of pyrene-based structures
N2  - A concept for highly ordered solid-state structures with bright fluorescence is proposed: liquid crystals based on tetraethynylpyrene chromophores, where the rigid core is functionalized with flexible, promesogenic alkoxy chains. The synthesis of this novel material is presented. The therniotropic properties are studied by means of differential scanning calorimetry (DSC), cross-polarized optical microscopy (POM), and X-ray diffraction. The mesogen possesses an enantiotropic Col(h) phase over a large temperature range before clearing. The material is highly fluorescent in solution and, most remarkably, in the condensed state, with a broad, strongly red shifted emission. Fluorescence quantum yields (Phi(F)) have been determined to be 70% in dichloromethane solution and 62% in the solid state. Concentration- and temperature-dependent absorption and emission studies as well as quantum-chemical calculations on isolated molecules and dimers are used to clarify the type of intermolecular interactions present as well as their influence on the fluorescence quantum yield and spectral properties of the material. The high luminescence efficiency in the solid state is ascribed to rotated chromophores, leading to an optically allowed lowest optical transition
Y1  - 2006
UR  - http://pubs.acs.org/journal/jpcbfk
U6  - https://doi.org/10.1021/Jp0573689
SN  - 1520-6106
ER  -