Jozeliūnaitė Augustina, Rahmanudin Aiman, Gražulis Saulius, Baudat Emilie, Sivula Kevin, Fazzi Daniele, Orentas Edvinas, Sforazzini Giuseppe
Laboratory of Macromolecular and Organic Materials, Institute of Material Science and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
Department of Organic Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, LT-0325, Vilnius, Lithuania.
Chemistry. 2022 Nov 21;28(65):e202202698. doi: 10.1002/chem.202202698. Epub 2022 Oct 31.
We present a quaterthiophene and sexithiophene that can reversibly change their effective π-conjugation length through photoexcitation. The reported compounds make use of light-responsive molecular actuators consisting of an azobenzene attached to a bithiophene unit by both direct and linker-assisted bonding. Upon exposure to 350 nm light, the azobenzene undergoes trans-to-cis isomerization, thus mechanically inducing the oligothiophene to assume a planar conformation (extended π-conjugation). Exposure to 254 nm wavelength promotes azobenzene cis-to-trans isomerization, forcing the thiophenic backbones to twist out of planarity (confined π-conjugation). Twisted conformations are also reached by cis-to-trans thermal relaxation at a rate that increases proportionally with the conjugation length of the oligothiophene moiety. The molecular conformations of quaterthiophene and sexithiophene were characterized by using steady-state UV-vis spectroscopy, X-ray crystallography and quantum-chemical modeling. Finally, we tested the proposed light-responsive oligothiophenes in field-effect transistors to probe the photo-induced tuning of their electronic properties.
我们展示了一种四噻吩和六噻吩，它们可以通过光激发可逆地改变其有效π共轭长度。所报道的化合物利用了光响应分子致动器，该致动器由通过直接键合和连接基辅助键合连接到联噻吩单元的偶氮苯组成。暴露于350 nm光下，偶氮苯发生反式到顺式异构化，从而机械诱导寡噻吩呈现平面构象（扩展π共轭）。暴露于254 nm波长会促进偶氮苯顺式到反式异构化，迫使噻吩主链扭曲出平面（受限π共轭）。通过顺式到反式热弛豫也能达到扭曲构象，其速率与寡噻吩部分的共轭长度成比例增加。通过稳态紫外可见光谱、X射线晶体学和量子化学建模对四噻吩和六噻吩的分子构象进行了表征。最后，我们在场效应晶体管中测试了所提出的光响应性寡噻吩，以探测其电子性质的光诱导调谐。
