Novel Pentafluorophenyl- And Alkoxyphenyl-Appended 2,2 '-Bipyridine Push-Pull Fluorophores: A Convenient Synthesis And Photophysical Studies

A convenient method for the synthesis of new highly in non-polar solvents soluble photoactive pentafluorophenyl-substituted and extended alkoxyphenyl-substituted 2,2'-bipyridines is reported. The synthetic strategy for the preparation of such ligands involves a sequence of several structural transformations, such as O-alkylation, nucleophilic substitution of hydrogen (SNH) in 1,2,4-triazine precursors via the `addition-elimination' scheme, and the subsequent conversion of the obtained 1,2,4-triazines into 2,2'-bipyridines by means of the aza-Diels-Alder reaction. The photophysical properties of the synthesized novel pentafluoroaryl-substituted 2,2'-bipyridines were comprehensively studied. The obtained photophysical data indicate the competitive advantages of the herein reported pentafluoroarylated push-pull fluorophores, bearing extended aliphatic moieties, over their analogues containing benzoxy or phenolic fragments in terms of improvement in quantum yield and well-pronounced positive solvatochromism confirmed by the mathematical analysis according to the Lippert-Mataga equation.