スピロ炭素戦略を用いた立体規則性共役系高分子の創製

a)在典型的山本偶联反应条件下，通过意想之外的分子内环化，成功建立了一种由9,9 ' -双氟苯基二聚体（BF）合成高度应变的9,9 ' -双氟苯基环二聚体（CBF）的简单方法。顺序的山本偶联反应可能使我们得到定义良好且高度扭曲但共轭的9,9'-BF梯形四聚体（LBF）。b)通过紫外-可见吸收和CV测量系统地研究了BF和CBF的光物理和电化学性能。结果表明，BF和CBF具有接受两个电子的能力，这可能是由于近端芳环释放位阻和14电子系统的发展。c)用热重分析（TGA）和差示扫描量热法（DSC）确定了BF和CBF的热行为和相变过程。DSC表征显示CBF在25°C和200°C之间没有相变，可能是由于存在对映体混合物（P， P）和（M， M），使CBF更非晶态而不是晶体。与之形成鲜明对比的是，在第二次加热过程中，高炉的熔点在153℃左右出现了扩大，这可能是由于高炉的多构象。令人惊讶的是，在冷却过程中，在150°C处观察到一个尖峰，在154°C处观察到一个小峰，因此我们推断，通过改变BF的构象，多个相变顺序发生。

a) I successfully established a straightforward approach to synthesize the highly strained 9,9’-bifluorenylidene cyclic dimer (CBF) from 9,9’-bifluorenylidene (BF) by unexpected intramolecular cyclization via typical Yamamoto coupling reaction conditions. Sequential Yamamoto coupling reactions potentially allowed us to obtain well-defined and highly twisted but conjugated 9,9'-BF ladder tetramer (LBF).b) The photophysical and electrochemical properties of BF and CBF were systematically investigated by using UV-vis absorption and CV measurements. The BF and CBF were demonstrated to have ability to accept two electrons, probably favored by release of steric hindrance from proximal aromatic rings and development of a 14- electron system.c) The thermal behavior and phase transition processes of BF and CBF was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Characterization by DSC reveals no phase transitions between 25°C and 200°C for CBF, presumedly due to the existence of enantiomeric mixture namely (P, P) and (M, M), yielding CBF more amorphous than crystalline. In stark contrast, BF showed the broadening melting point at around 153°C in the second heating process, probably attributable to multi-conformations from BF. Surprisingly, in the cooling process, one sharp peak at 150°C in additional to one small peak at 154°C was observed, thus we infer that multiple phase transitions occur sequentially by alternating the conformation of BF.