基于芴和2，4-二氟苯的寡聚物的合成与表征

为了对比不同分子结构的芴类寡聚物在光物理性质上的差异，将9，9-二（十二烷基）-芴（F1）和2，4-二氟苯硼酸通过Suzuki偶联反应合成并表征了一系列寡聚物：2．（2，4-二氟苯）-9，9-二（十二烷基）-芴（FF1）、2，7-二（2，4-二氟苯）-9，9-二（十二烷基）-芴（FF2）、二-（2-（2，4-二氟苯基）．9，9-二（十二烷基）-芴）-7-（2，4-二氟苯）-9，9-二（十二烷基）-芴（FF3）以及1-溴-3，5-二（2-（2，4-二氟苯）9，9-二（十二烷基）．芴）-苯（FF4）。依照F1，FF1，FF2和FF3的次序，由π-π跃迁导致的最大紫外吸收依次红移，而寡聚物FF4的最大紫外吸收相对于寡聚物FF3要蓝移，其薄膜的最大荧光发射相比于寡聚物FF3要红移。这说明分子的线形、支化结构和由此引起的聚集态结构的变化对其光物理性能都有重要影响。密度泛函理论计算和实验结果基本-致。通过光降解实验还发现含氟寡聚物具备较好的光稳定性。

Synthesis and Characterization of Oligomers Based on Fluorene and 2,4-Difluorobenzene

In order to correlate the electro-optical properties of fluorene-based oligomers with different molecular architecture, 9,9-didodecyl-fluorene （ F1 ） segments were coupled with 2,4-difluorophenyl boronic acid by Suzuki reaction to give a series of target oligomers, 2-（2,4-difluorophenyl） -9,9-didodecyl-fluorene （FF1）, 2,7-bis （ 2,4-difluorophenyl ） -9,9-didodecyl-fluorene （ FF2 ）, 2- （ 2- （ 2,4- difluorophenyl ） -9,9-didodecyl-fluoren ） -7- （ 2,4- difluorophenyl） -9,9-didodecyl-fluorene （ FF3 ）, and 1 -bromo-3,5-bis （.,2-（ 2,4-difluorophenyl ） 9,9-didodecyl-fluoren）-benzene（FF4）. The molecular structures of FF3 and FF4 are fully characterized by ^1H-NMR, MALDI-TOF mass spectrometry and elemental analysis, respectively. Absorption and emission spectra show that the absorption maximum attributed to π-π nature of the excitation is red-shifted in the turn of F1, FF1, FF2, and FF3, and the maximum absorption peak of FF4 occurs to be blue-shifted, while the maximum photoluminescence emission of FF4 film is red-shifted relative to that of FF3. Density functional theory （DFT） calculations provide further evidence that the energy band gaps of oligomers are decreased with increasing the conjugated length. At last, the interesting photostability attributed to the molecular architecture and fluorine element are also observed and discussed.