Dosso Jacopo, Marinelli Davide, Demitri Nicola, Bonifazi Davide
School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K.
Elettra-Sincrotrone Trieste, S. S. 14 km 163.5 in Area Science Park, Basovizza 34149, Trieste, Italy.
ACS Omega. 2019 May 28;4(5):9343-9351. doi: 10.1021/acsomega.9b00830. eCollection 2019 May 31.
Here we describe the synthesis and spectroscopic and structural characterization of various borazine-doped polyphenylenes displaying high doping dosages (16-18%). Capitalizing on the condensation reaction approach, the desired products were formed using a mixture of -phenylendiamine and aniline with BCl, followed by the addition of an aryl lithium derivative. The use of mesityl lithium (MesLi) yields strained multiborazine derivatives, which proved to be unstable in the presence of moisture. However, when xylyl lithium (XylLi) was used, chemically stable multiborazines were obtained, with oligomers showing molecular weight up to 10, corresponding to 16-18 monomer units. While the dimer, trimer, and tetramer could be isolated as pure products and their structure characterized by mass and NMR analysis, higher oligomers could only be isolated as mixtures of -hydroxy-substituted derivatives and characterized by gel permeation chromatography. The structures of the dimer and trimer derivatives were confirmed by X-ray analysis, which nicely showed the presence of the two and three borazine rings spaced by one and two 1,4-aryl bridges, respectively. Notably, the trimer forms a porous crystalline clathrate. The peripheral xylyl and phenyl moieties of each molecule intramolecularly embrace each other through C-H and π-π stacking interactions. Steady-state UV-vis absorption characterization suggested that the molecules are UV absorbers, with the extinction coefficient linearly scaling with the degree of oligomerization. On the other hand, low-emission quantum yields were obtained for all derivatives (<7%), suggesting that high BN-doping dosages dramatically affect the emission properties of the doped polyphenylenes.
在此，我们描述了各种硼嗪掺杂聚苯撑的合成、光谱和结构表征，这些聚苯撑具有高掺杂剂量（16 - 18%）。利用缩合反应方法，使用对苯二胺和苯胺与BCl的混合物，随后加入芳基锂衍生物，形成了所需产物。使用均三甲苯基锂（MesLi）会生成应变多硼嗪衍生物，事实证明其在有水分存在时不稳定。然而，当使用二甲苯基锂（XylLi）时，得到了化学稳定的多硼嗪，其低聚物的分子量高达10，对应于16 - 18个单体单元。虽然二聚体、三聚体和四聚体可以作为纯产物分离出来，并通过质谱和核磁共振分析对其结构进行表征，但更高的低聚物只能作为羟基取代衍生物的混合物分离出来，并通过凝胶渗透色谱法进行表征。二聚体和三聚体衍生物的结构通过X射线分析得到证实，该分析很好地显示了分别由一个和两个1,4 - 芳基桥隔开的两个和三个硼嗪环的存在。值得注意的是，三聚体形成了一种多孔晶体包合物。每个分子的外围二甲苯基和苯基部分通过C - H和π - π堆积相互作用在分子内相互环绕。稳态紫外 - 可见吸收表征表明这些分子是紫外线吸收剂，消光系数与低聚程度呈线性比例关系。另一方面，所有衍生物的发射量子产率都很低（<7%），这表明高BN掺杂剂量会显著影响掺杂聚苯撑的发射特性。
