Development of Functional Materials Based on Ene-Yne Oligomers

我们成功地合成了1，2-环戊烯基-乙炔基和3，4-噻吩基-乙炔基齐聚物。利用钯催化的末端炔与卤代烯基或卤代芳基的偶联反应合成了这些齐聚物，并通过光谱和元素分析对其进行了表征。1，2-环戊烯基-乙炔基低聚物的电子吸收光谱显示出随着链长的增加而红移，表明π电子的共轭增加。另一方面，3，4-噻吩基-乙炔基低聚物的电子光谱显示出具有几乎相同的吸收最大值的特征π-π ^**>跃迁，表明噻吩基-乙炔基部分的有利的扭曲构象，这降低了π电子的共轭。用X-射线晶体学方法研究了3，4-噻吩-乙炔低聚物的固态构象，发现它们呈全对称构象。通过对低聚物的^1H NMR光谱进行详细比较，发现噻吩基质子的高场位移，支持了噻吩部分分子内堆积的螺旋构象在溶液中也占主导地位。在高于200 ℃的温度下，在溶液中诱导1，2-亚环戊烯-亚乙炔体系的串联环化反应。虽然3，4-噻吩亚基-乙炔亚基体系是热稳定的，但它们在四氯化碲的影响下被环化，得到了新的噻吩稠合并环戊二烯体系。这些低聚物在可见光区域显示出强烈的荧光，表明作为光电器件的潜在材料。

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.