Hayer Anna, de Halleux Véronique, Köhler Anna, El-Garoughy Abdel, Meijer E W, Barberá Joaquín, Tant Julien, Levin Jeremy, Lehmann Matthias, Gierschner Johannes, Cornil Jérôme, Geerts Yves Henri
Laboratoire de chimie des polymères, CP 206/1, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Brussels, Belgium.
J Phys Chem B. 2006 Apr 20;110(15):7653-9. doi: 10.1021/jp0573689.
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 thermotropic 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.
基于四乙炔基芘发色团的液晶，其中刚性核用柔性的、有介晶性的烷氧基链进行功能化。介绍了这种新型材料的合成方法。通过差示扫描量热法（DSC）、交叉偏振光学显微镜（POM）和X射线衍射研究了热致性质。该液晶元在清亮点之前的较大温度范围内具有互变的Col(h)相。该材料在溶液中具有高荧光性，最显著的是在凝聚态下具有宽的、强烈红移的发射。已确定荧光量子产率（Phi(F)）在二氯甲烷溶液中为70%，在固态中为62%。通过浓度和温度依赖性吸收和发射研究以及对孤立分子和二聚体的量子化学计算，以阐明存在的分子间相互作用类型及其对材料荧光量子产率和光谱性质的影响。固态中的高发光效率归因于发色团的旋转，导致光学上允许的最低光学跃迁。
