Electrochemical study of the π* probe dye 5-nitro-5′-dimethylamino-2,2′-bisthiophene

✍ Scribed by Ester Norambuena; Marcos Caroli Rezende

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 132 KB
• Volume: 11
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199806)11:6<419::aid-poc14>3.0.co;2-k

✦ Synopsis

Cyclic voltamograms of the solvatochromic dye 5-nitro-5'-dimethylamino-2,2'-bisthiophene (1), introduced recently as a sensitive p* probe, were recorded in different solvents. An EPR spectrum of the anionic radical of 1 in DMSO was obtained and compared with other spectra of analogous substituted bisthiophene radicals. It was found that the presence of a donor-acceptor pair of substituents in 1 À . reduces significantly the rotational barrier of the radical compared with the unsubstituted bithienyl radical anion 2 À .

. This is the result of an electronic repulsion between the donor ring fragment and the added electron in the coplanar radical, which does not exist in 2 À .

.