Photophysical and Electrochemical Properties of Thiophene‐Based 2‐Arylpyridines

Two families of thiophene‐based 2‐arylpyridines, in which aryl is phenyl and 2,4‐difluorophenyl, have been developed. The pyridine ring of the new compounds is substituted at the 4‐position with π‐conjugated electron‐rich and electron‐poor thiophene‐based fragments to tune the optical and energetic properties. The high‐yielding synthetic access, which consists of two sequential Suzuki coupling reactions, the first of which is completely regioselective, is of wide applicability and allows access to a large variety of derivatives. The absorption/emission and redox features, as well as the HOMO and LUMO energy levels, have been investigated; the results show that the optical and electronic properties can be tuned over a broad range. The diversity of the characteristics may be effectively exploited by using the thiophene‐substituted 2‐arylpyridines as ligands in cyclometalated sensitizers for dye‐sensitized solar cells and other optoelectronic applications.