Synthesis and Characterization of Optical and Redox Properties of Bithiophene-Functionalized Diketopyrrolopyrrole Chromophores

• Published in: Journal of organic chemistry 2011-04, Vol.76 (8), p.2426-2432
• Main Authors: Bürckstümmer, Hannah, Weissenstein, Annike, Bialas, David, Würthner, Frank
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Energy; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Natural energy; Organic chemistry; Photovoltaic conversion; Preparations and properties; Solar cells. Photoelectrochemical cells; Solar energy
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo2003117

A series of six new 2,2′-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a−f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a−f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes. The diamino-substituted DPP derivative 7e exhibits a strong absorption band reaching in the near-infrared (NIR) region, which is a highly desirable feature for application in organic photovoltaics.