Synthesis, thermal and optical properties of a novel bis(2-(4-dicyanovinylphenyl)pyridinato-N,C2)iridium(acetylacetonate)

•A novel 2-(4-dicyanovinyl-ppy)2Ir(acac) (6) is reported.•Dicyanovinyl shifts emission to red by 179 nm compared to (ppy)2Iracac (λem = 516 nm).•Large Stoke’s shift (160 nm) is observed.•Complex 6 loses its acac moiety between 248 and 336 °C (under N2 atmosphere).

Bis(2-(4-formylphenyl)pyridinato-N,C2)iridium(acetylacetonate) (5) was subjected to a Knoevenagel reaction with malononitrile in dichloromethane in the presence of catalytic amount of pyrrolidine. This gave successfully a novel bis(2-(4-dicyanovinylphenyl)pyridinato-N,C2)iridium(acetylacetonate) (6) in good yield (83%). Complex 6 was fully chracterised by 1H, 13C NMR, FT-IR, elemental analysis. Complex 6 showed a strong ligand centred (LC) absorption band at 355 nm (ε 56 490 L mol−1 cm−1) and weak metal-to-ligand charge transfer (MLCT) bands at 445 (ε 4154 L mol−1 cm−1) and 535 nm (ε 2606 L mol−1 cm−1). Complex 6 loses its acac moiety between 248 and 336 °C (under N2 atmosphere) and emits a red light at 695 nm with a large Stokes shift (160 nm).

Graphical abstractA novel bis(2-(4-dicyanovinylphenyl)pyridinato-N,C2)iridium(acetylacetonate) (6) is reported. Its synthesis, thermal and optical properties were discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide