Self-assembly of highly luminescent bi-1,3,4-oxadiazole derivatives through electron donor–acceptor interactions in three-dimensional crystals, two-dimensional layers and mesophases
作者:Songnan Qu、Xiaofang Chen、Xiang Shao、Fan Li、Hongyu Zhang、Haitao Wang、Peng Zhang、Zhixin Yu、Kai Wu、Yue Wang、Min Li
DOI:10.1039/b804189j
日期:——
We report on the synthesis and self-assembly of a new series of highly luminescent bi-1,3,4-oxadiazole derivatives [2,2â²-bis(4-alkoyphenyl)-bi-1,3,4-oxadiazole, BOXD-n, n = 1, 3, 4, 5, 6, 7, 10, 16]. Fully conjugated conformations were demonstrated either by computer simulation or in a single-crystal state. Well-defined 3D donorâacceptor (DA) architectures with strong face-to-face and edge-to-edge donorâacceptor interactions were observed in the single-crystal structure of BOXD-1. Highly oriented face-on two-dimensional DA layered structures due to edge-to-edge donorâacceptor interactions were observed on highly oriented pyrolytic graphite (HOPG) in BOXD-7 and BOXD-16. Nematic phase, smectic C phase with large tilted angle (θ â 50°) and relatively large transition enthalpic values and a highly ordered smectic X phase were demonstrated in BOXD-n (n = 5, 6, 7, 8, 10, 16) through tailing the terminal chains and relatively large scale monodomains were prepared in the smectic X phase of BOXD-5 even without any surface treatment. Strong blue fluorescent emissions were observed in BOXD-6 either in cyclohexane (ФF â 92%) or in solid state (ФF â 57%). The donorâacceptor interactions between alkyoxyphenylene rings and 1,3,4-oxadiazole rings were thought to be the driving force for the molecules to self-assemble into a large angle tilted layered structure.
我们报告了一系列新的高发光双-1,3,4-恶二唑衍生物[2,2â²-双(4-烷酰基苯基)-双-1,3,4-恶二唑,BOXD-n,n = 1, 3, 4, 5, 6, 7, 10, 16]的合成和自组装。完全共轭构象通过计算机模拟或单晶状态得到了证实。在 BOXD-1 的单晶结构中观察到了清晰的三维供体-受体(DA)结构,其中存在强烈的面对面和边对边的供体-受体相互作用。在BOXD-7和BOXD-16的高取向热解石墨(HOPG)上观察到了由于边对边的供体-受体相互作用而形成的高取向面对面二维DA层状结构。在BOXD-n(n = 5、6、7、8、10、16)中,通过对末端链进行去尾处理,显示出了具有大倾斜角(δ â 50°)和相对较大过渡焓值的向列相、共晶C相以及高度有序的共晶X相;在BOXD-5的共晶X相中,即使没有进行任何表面处理,也制备出了相对较大的单域。在环己烷(¤F â 92%)或固态(¤F â 57%)条件下,BOXD-6都能发出强烈的蓝色荧光。烷氧基苯环和1,3,4-噁二唑环之间的受体-供体相互作用被认为是分子自组装成大角度倾斜分层结构的驱动力。