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

Abstract

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 H-1, C-13 NMR, FT-IR, elemental analysis. Complex 6 showed a strong ligand centred (LC) absorption band at 355 nm (epsilon 56490 L mol (1) cm (1)) and weak metal-to-ligand charge transfer (MLCT) bands at 445 (epsilon 4154 L mol (1) cm (1)) and 535 nm (epsilon 2606 L mol (1) cm (1)). Complex 6 loses its acac moiety between 248 and 336 Alpha degrees C (under N-2 atmosphere) and emits a red light at 695 nm with a large Stokes shift (160 nm).