Comparative study on the structural, optical, and electrochemical properties of bithiophene-fused benzo[c]phospholes.
Comparative study on the structural, optical, and electrochemical properties of bithiophene-fused benzo[c]phospholes.
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联噻吩稠合苯并[c]磷的结构、光学和电化学性质的比较研究。
DOI：
10.1002/chem.200801017
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
H. Imahori
中科院分区：
文献类型：
--
作者：
Y. Matano;T. Miyajima;Tatsuya Fukushima;H. Kaji;Y. Kimura;H. Imahori
通过Ti（II）催化的环化反应，成功地合成了三种不同结构的苯并[c]磷杂环戊二烯衍生物。通过Au配位或氧化作用，苯并[c]磷杂环亚基中的每个σ（3）-磷中心很容易转化为σ（4）-磷中心。此外，通过与杂芳基金属的Pd催化的交叉偶联反应和通过与六氟苯的S（N）Ar反应，在α，α ′-碳原子处官能化联噻吩亚基。实验观察到的结果（NMR光谱，X-射线分析，UV/维斯吸收/荧光光谱，和循环/差分脉冲伏安法）已经显示，结构，光学和电化学性质的bithiophene稠合的苯并[c]磷杂环戊二烯组分的π共轭模式依赖于在bithiophene亚基和取代基的变化相当大。发现适当环化的sigma（3）-P衍生物和sigma（4）-P-AuCl络合物在橙红色区域发射荧光，并且sigma（4）-P-oxo衍生物被证明在-1.4到-1.8 V（vs ferrocene/ferrocenium）处进行可逆的单电子还原。这些结果表明，双噻吩稠合苯并[c]磷杂环戊二烯具有窄的HOMO-LUMO能隙和低的LUMO，这一点通过其模型化合物的密度泛函理论计算得到了证实. ITO/苯并[c]磷杂环戊二烯/Al器件的飞行时间测量表明，在低电场下，P-氧代衍生物中的电子迁移率比Alq（3）中的电子迁移率高一个数量级.本研究表明，芳烃稠合的苯并[c]磷杂环戊烯骨架可能是一个非常有前途的平台，用于构建一类新的基于磷杂环戊烯的光电化学材料。
Three types of bithiophene-fused benzo[c]phospholes were successfully prepared by Ti(II)-mediated cyclization of the corresponding dialkynylated bithiophene derivatives as a key step. Each sigma(3)-phosphorus center of the benzo[c]phosphole subunits was readily transformed into sigma(4)-phosphorus center by Au coordination or oxygenation. In addition, the bithiophene subunit was functionalized at the alpha,alpha'-carbon atoms by Pd-catalyzed cross-coupling reactions with heteroarylmetals and by an S(N)Ar reaction with hexafluorobenzene. The experimentally observed results (NMR spectroscopy, X-ray analysis, UV/Vis absorption/fluorescence spectroscopy, and cyclic/differential-pulse voltammetry) have revealed that the structural, optical, and electrochemical properties of the bithiophene-fused benzo[c]phospholes vary considerably depending on the pi-conjugation modes at the bithiophene subunits and the substituents of the heterocyclopentadiene components. The appropriately ring-annulated sigma(3)-P derivatives and sigma(4)-P-AuCl complexes were found to emit fluorescence in the orange-red region, and the sigma(4)-P-oxo derivatives proved to undergo reversible one-electron reduction at -1.4 to -1.8 V (vs ferrocene/ferrocenium). These results indicate that the bithiophene-fused benzo[c]phospholes possess narrow HOMO-LUMO gaps and low-lying LUMOs, which was confirmed by density functional theory calculations of their model compounds. The time-of-flight measurement of an ITO/benzo[c]phosphole/Al device showed that the electron mobility in the P-oxo derivative is one-order higher than that in Alq(3) at low electric fields. The present study demonstrates that the arene-fused benzo[c]phosphole skeleton could be a highly promising platform for the construction of a new class of phosphole-based optoelectrochemical materials.