One-Pot Synthesis and Redox Properties of Conjugation-Extended 4,4′-Bipyridines and Related Compounds. New Ligands Consisting of a Heterocyclic Three-Ring Assembly

Abstract

Abstract Dipyridyl-substituted heterocycles such as 2,5-di(4-pyridyl)thiophene 3, 2,5-di(4-pyridyl)furan 4, 2,5-di(4-pyridyl)thieno[3,2-b]thiophene 7, 1,4-di(4-pyridyl)benzene 6, 2,5-di(2-pyridyl)thiophene 8, and 2,5-di(3-pyridyl)thiophene 9 have been efficiently synthesized by a simple one-pot procedure through the palladium-mediated cross-coupling reaction between (trimethylstannyl)pyridines and dibromo-substituted heteroaromatics. The spectroscopic data (IR, 1H NMR, 13C NMR, UV) as well as their reduction potentials of these compounds have been determined to evaluate the utility potentials to chelating ligands for metal complexes or to synthetic precursors of viologen-type bipyridinium salts. The conjugation interaction throughout the three rings appears to be more significant in 3 and 4 than in 6. The formation of stable redical anions and dianions of 3 and 4 has been proved by cyclic voltammetry.