Linearly extended hybrid tetrathiafulvalene analogues with bridged dithienylethyleneπ-conjugating spacers
作者:Hugues Brisset、Soazig Le Moustarder、Philippe Blanchard、Bertrand Illien、Amédée Riou、Jesus Orduna、Javier Garin、Jean Roncali
DOI:10.1039/a701463e
日期:——
New linearly extended Ï-electron donors based on bridged dithienylethylene (DTE) end-capped with diversely substituted 1,3-dithiol-2-ylidene electron-releasing groups have been synthesized by WittigâHorner olefination of appropriate aldehydes. Cyclic voltammetry shows that whereas the unbridged analogues are directly oxidized to the dication state through a two-electron transfer, rigidification of the DTE spacer leads to the splitting of the two-electron wave into two successive one-electron steps due to the decrease of the potential corresponding to the formation of the cation radical. This unusual electrochemical behaviour is interpreted with the help of theoretical calculations which suggest that these effects are related to the enhanced electron delocalization resulting from the rigidification of the DTE spacer. This conclusion is supported by an X-ray diffraction structural analysis which reveals that in addition to a fully planar conformation stabilized by intramolecular Sâ¥S interactions, the bridging of the DTE spacer leads to a significant reduction of bond length alternation.
通过对适当的醛进行 WittigâHorner 烯化反应,合成了以桥接的二噻吩乙烯(DTE)为基础、以多种取代的 1,3-二硫醇-2-亚基电子释放基团为端盖的新型线性延伸 Ï 电子供体。循环伏安法显示,未桥接的类似物通过双电子转移直接氧化成二阳离子状态,而 DTE 间隔的刚性化会导致双电子波分裂成两个连续的单电子步骤,这是因为阳离子自由基的形成导致电位下降。理论计算表明,这些效应与 DTE 隔层刚性化导致的电子析出增强有关,从而解释了这种不寻常的电化学行为。这一结论得到了 X 射线衍射结构分析的支持,该分析表明,除了分子内 Sâ¥S 相互作用稳定的完全平面构象外,DTE 间隔物的桥接还导致键长交替的显著减少。