Comparative studies of the geometric and electronic properties of 1,1-disubstituted-2,3,4,5-tetraphenylsiloles and 1,1,2,2-tetramethyl-3,4,5,6-tetraphenyl-1,2-disila-3,5-cyclohexadiene
作者:Xiaowei Zhan、Chad Risko、Alexander Korlyukov、Francis Sena、Tatiana V. Timofeeva、Mikhail Yu. Antipin、Stephen Barlow、Jean-Luc Brédas、Seth R. Marder
DOI:10.1039/b605343b
日期:——
We present an experimental and density functional theory comparison of the geometric structure, electronic characteristics and optical properties of 1,1-dimethyl-2,3,4,5-tetraphenylsilole (I), 1,1-(propane-1,3-diyl)-2,3,4,5-tetraphenylsilole (II), 1,1-dimethoxy-2,3,4,5-tetraphenylsilole (III) and 1,1,2,2-tetramethyl-3,4,5,6-tetraphenyl-1,2-disila-3,5-cyclohexadiene (IV). The molecular structures of II–IV have been determined using X-ray crystallography and are compared to the previously reported structure of I. Many characteristics of IV are significantly different from those of I–III, due to the presence of the additional silicon atom. In contrast to I–III, which have planar central rings, IV has a non-planar ring conformation due to the presence of two approximately tetrahedrally coordinated silicon atoms. Cyclic voltammetry suggests that I–III are reduced at similar potentials to that for tris(8-hydroquinolinato)aluminium and that IV is more readily oxidizable than I–III. Additionally, while IV is non-emissive in both solution and the solid state, the three siloles are fluorescent in the solid state. For the four compounds, we have calculated the intramolecular reorganization energies for electron- and hole-transfer reactions, ionization potentials and electron affinities.
我们采用实验和密度泛函理论对1,1-二甲基-2,3,4,5-四苯基硅氧(I)、1,1-(丙烷-1,3-二基)-2,3,4,5-四苯基硅氧(II)、1,1-二甲氧基-2,3,4,5-四苯基硅氧(III)和1,1,2,2-四甲基-3,4,5,6-四苯基-1,2-二硅-3,5-环己二烯(IV)的几何结构、电子特性和光学性质进行了比较。II-IV的分子结构已通过X射线晶体学测定,并与之前报道的I的结构进行了比较。由于存在额外的硅原子,IV的许多特性与I-III的明显不同。与具有平面中心环的I-III相比,IV具有非平面环构象,这是由于存在两个近似四面体配位的硅原子。循环伏安法表明,I-III的还原电位与三(8-氢喹啉)铝的还原电位相似,而IV比I-III更容易氧化。此外,IV在溶液和固态下均不发光,而三种硅氧在固态下具有荧光性。对于这四种化合物,我们计算了电子和空穴转移反应的分子内重排能、电离电位和电子