Highly efficient pyrazine-based organo-lanthanide luminescent ionogels for white light emission through energy transfer

A novel pyrazine based bichromophoric system was designed to achieve the efficient white light emission through partial resonance energy transfer in ionic liquid based gel medium i.e., ionogel. The partial resonance energy transfer was taken place between the pyrazine based bichromophoric unit and lanthanide ion {Eu 3+ }. Herein, pyrazine based bichromophoric unit acts as a donor while lanthanide ion as an acceptor. The ionogel was self-assembled from pyrazine based bichromophoric units in a carboxylic acid functionalized imidazole based ionic liquid. The corresponding absolute quantum yield values for pyrazine-phenanthrene-Eu 3+ ( PPE ), pyrazine-naphthol-Eu 3+ ( PNE ), and pyrazine-pyrene-Eu 3+ ( PPyE ) were 10.4%, 8.6%, and 5.3%, respectively in ionogel. The CIE (Commission International d’Eclairage) coordinates values for PPyE , PNE , and PPE are {0.32, 0.36}, {0.37, 0.30}, and {0.28, 0.34}, respectively in ionogel. In solution phase, the CIE coordinates are significantly away from the white light region owing to the inefficient energy transfer between bichromophoric unit and lanthanide ion. Moreover, the electrical conductivity was measured for pyrazine based bichromophoric systems in the presence and absence of lanthanide ion in ionogel. The electrical conductivity was increased up to 2–3 times in the presence of the lanthanide ion for the pyrazine based bichromophoric systems.