Novel ladder π-conjugated materials--sila-pentathienoacenes: synthesis, structure, and electronic properties.
A novel series of ladder π-conjugated materials--sila-pentathienoacenes (Si-PTA) are synthesized and characterized. Crystal structures of the compounds show that the length of alkyl chains substituting on the thiophene ring has a significant influence on molecular packing. A densely packed structure with an interfacial distance of about 3.66 Å between the adjacent molecules is observed for the compound with shorter alkyl chains. However, a large interfacial distance (7.99 Å) is obtained for another compound because of the insertion of long alkyl chains between two planes. The investigation of the optical and electrochemical properties shows that the silylene bridge incorporated into the pentathienoacene framework exerts a clear effect on the electronic properties by the σ*-π* conjugation. Although only a slight enhancement is observed for the HOMO levels, with respect to that of pentathienoacene, the LUMO levels are significantly lowered. The observed electronic properties are consistent with the theoretical calculations.
Wan
Jun-Hua
JH
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, 222 Wenyi Road, Hangzhou, 310012 P.R. China.
Fang
Wei-Fen
WF
Li
Zhi-Fang
ZF
Xiao
Xu-Qiong
XQ
Xu
Zheng
Z
Deng
Yuan
Y
Zhang
Li-Hong
LH
Jiang
Jian-Xiong
JX
Qiu
Hua-Yu
HY
Wu
Lian-Bin
LB
Lai
Guo-Qiao
GQ