Solid-state assemblies and optical properties of conjugated oligomers combining fluorene and thiophene units
作者:Mathieu Surin、Prashant Sonar、Andrew C. Grimsdale、Klaus Müllen、Steven De Feyter、Satoshi Habuchi、Stefano Sarzi、Els Braeken、An Ver Heyen、Mark Van der Auweraer、Frans C. De Schryver、Massimiliano Cavallini、Jean-François Moulin、Fabio Biscarini、Cristina Femoni、Roberto Lazzaroni、Philippe Leclère
DOI:10.1039/b610132a
日期:——
Two conjugated oligomers, representing elementary segments of fluorene–thiophene copolymers, are compared in terms of the microscopic morphology and the optical properties of thin deposits. The atomic force microscopy morphological data and the solid-state absorption and emission spectra are interpreted in terms of the assembly of the conjugated molecules. The compound with a terthiophene central unit and fluorene end-groups shows well-defined monolayer-by-monolayer assembly into micrometer-long stripe-like structures, with a crystalline herringbone-type organization within the monolayers. Polarized confocal microscopy indicates a strong orientation of the crystalline domains within the stripes. In contrast, the compound with a terfluorene central unit and thiophene end groups forms no textured aggregates and the optical spectra in the solid-state are very similar to those recorded in solution, suggesting that the molecules interact only weakly in the solid. The difference in behaviour between the two compounds most probably originates from their different capability to form densely-packed assemblies of interacting π-systems.
从薄层沉积物的微观形态和光学特性的角度,对代表芴-噻吩共聚物基本片段的两种共轭低聚物进行了比较。原子力显微镜形态数据以及固态吸收和发射光谱都是从共轭分子的组装角度进行解释的。以噻吩为中心单元、以芴为末端基团的化合物显示出明确的单层逐层组装成微米长的条纹状结构,单层内呈人字形结晶组织。偏振共聚焦显微镜显示,条纹内的结晶结构域具有很强的定向性。相比之下,具有三芴中心单元和噻吩末端基团的化合物没有形成纹理聚集体,固态的光学光谱与溶液中记录的光谱非常相似,表明分子在固态中的相互作用很微弱。这两种化合物在行为上的差异很可能是由于它们形成相互作用 π 系统密集集合体的能力不同造成的。