Development of Functional Materials Based on Ene-Yne Oligomers

我们成功地合成了1，2-环戊烯-乙炔和3，4-亚硫烯-乙炔齐聚物。已有文献记载的末端炔烃与烯基或芳基卤化物的钯催化偶联反应被反复应用于这些低聚物的合成，并通过光谱分析和元素分析进行了充分的表征。1，2-环戊烯-乙炔齐聚物的电子吸收光谱随着链长的增加而发生红移，表明pi-电子的共轭作用增强。另一方面，3，4-亚硫烯-乙炔齐聚物的电子光谱显示出特征的pi-pi^&lt；**&gt；，吸收峰几乎相同，表明亚硫烯-乙炔基团具有良好的扭曲构象，这降低了pi-电子的共轭。3，4-亚硫烯-乙炔齐聚物的固态构象经X-射线单晶分析确证，它们具有完全的海尔构象。通过对低聚物~1H核磁共振谱的详细比较，发现了噻吩基质子的高场位移，支持了噻吩环的螺旋构象和分子内堆积结构在溶液中也占主导地位。在高于2 0 0ﾟC的溶液中，1，2-环戊烯-乙炔体系发生串联环化反应。尽管3，4-亚硫烯-乙炔体系是热稳定的，但它们在四氯化碲的影响下被环化，得到了新型的噻吩基-稠合戊烯体系。这些低聚物在可见光区显示出强烈的荧光，这表明这些低聚物有可能成为光电子器件。

We have successfully synthesized 1,2-cyclopentenylene-ethynylene and 3,4-thienylene-ethynylene oligomers. The well-documented palladium-caralyzed coupling reaction of terminal alkynes and alkenyl or aryl halides was repeatedly applied to the synthesis of these oligomers, which were fully characterized by spectroscopic and elemental analyzes. Electronic absorption spectra of 1,2-cyclopentenylene-ethynylene oligomers showed bathochromic shifts with increasing chain length, indicating increasing conjugation of the pi-electrons. On the other hand, electronic spectra of 3,4-thienylene-ethynylene oligomers showed a characteristic pi-pi^<**> transition with almost identical absorption maximum, suggesting a favorable twist conformation of the thienyl-ethynyl moieties, which decreases conjugation of the pi-electrons. The solid-state conformations of 3,4-thienylene-ethynylene oligomers were elucidated by an X-ray crystallographic analysis, and they take a totally heilcal conformation. A detailed comparison of the ^1H NMR spectra of the oligomers revealed high-field shifts of the thienyl protons, supporting that the helical conformation with intramolecular stacking of the thiophene moieties also dominates in solution. A tandem cyclization reaction of the 1,2-cyclopentenylene-ethynylene system was induced at above 200ﾟC in a solution. Although the 3,4-thienylene-ethynylene systems were thermally stable, they were cyclized under the influence of tellurium tetrachloride to afford novel thiophene-fused pentalene system. These oligomers showed intense fluorescence in a visible region, suggesting potential materials as optoelectronic devices.