Furan/phenylene co‐oligomer single crystals are considered as future materials for organic optoelectronics. Here, the effects of trifluoromethyl substituents on the crystallization, structure and optical properties of furan/phenylene co‐oligomer 1,4‐bis{5‐[4‐(trifluoromethyl)phenyl]furan‐2‐yl}benzene are studied systematically. The solution growth methods and physical vapor transport result in the formation of three polymorphs depending on the growth method and the solvent. Single‐crystal X‐ray analysis reveals the crystal structures to correspond to H‐, J‐ or mixed aggregates. All obtained crystals exhibit high photoluminescence efficiency and have optical properties which strongly depend on the crystal packing. Variable‐temperature X‐ray powder diffraction analysis shows the thermal transition of two forms (H‐ and J‐aggregates) into a third one (mixed aggregate). Terminal trifluoromethyl groups induce weak intermolecular interactions which control the crystal packing and optical properties of co‐oligomer single crystals.

中文翻译：

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三氟甲基取代的呋喃/亚苯基共聚低聚物的晶体堆积控制。

呋喃/亚苯基共聚低聚物单晶被认为是有机光电的未来材料。在此，系统地研究了三氟甲基取代基对呋喃/亚苯基共聚低聚物1,4-双{5- [4- [三（三氟甲基）苯基]呋喃-2-基}苯的结晶，结构和光学性质的影响。溶液生长方法和物理气相传输导致取决于生长方法和溶剂的三种多晶型物的形成。X射线单晶分析显示晶体结构对应于H，J或混合聚集体。所有获得的晶体均表现出高的光致发光效率，并且具有强烈依赖于晶体堆积的光学性质。可变温度X射线粉末衍射分析显示了两种形式（H和J骨料）到第三种形式（混合骨料）的热转变。末端三氟甲基基团诱导弱的分子间相互作用，从而控制了共聚低聚物单晶的晶体堆积和光学性质。