Subscribe to RSS
DOI: 10.1055/s-0028-1087307
Fusing Phosphole and Thiophene
Contributor(s):Timothy M. Swager, Jan M. SchnorrPublication History
Publication Date:
20 November 2008 (online)
Key words
phospholes - fused-ring systems - thiophenes
Significance
The authors synthesized bithiophene-fused benzo[c]phospholes with different orientations of the thiophene moiety. After performing a Ti(II)-mediated cyclization of diynes 1-3 and addition of PhPCl2 a mixture of unreacted starting material and products 7-9 was obtained. Reacting this mixture with AuCl(SMe2) allowed the separation of the respective Au(I)-phosphole complex. The target compounds were then obtained by treatment with excess P(NMe2)3.
Comment
Compounds 7 and 8 both show broad absorptions at around 400-550 nm and emissions at 500-800 nm with quantum yields of 17.6 and 9.7%, respectively. Product 9 on the other hand exhibits only very weak absorption and emission bands with a low quantum yield of 0.6%. This effect can be attributed to the less efficient delocalization of the π-electrons in 9 compared to 7 and 8. Their ortho-quinonoid character renders most benzo[c]phospholes highly reactive and limits their application. It is therefore remarkable that the presented systems are thermally and kinetically stable.