Synthesis and luminescent properties of novel silicon-based electroluminescent copolymers with ruthenium(II)-chelated complexes

A new class of silicon-based alternating copolymers having Ruthenium(II)-chelated complexes was synthesized to use as electroluminescent materials by Heck reaction between organosilicon divinyl monomers and Ru(II)-chelated monomers. The incorporation of organosilicon units with the aromatic or aliphatic groups on the silicon atoms into π-conjugated systems improved their processability and interrupted the π-conjugation length. The maximum absorption wavelength (λ_max) of a non-chelated polymer (SiHMPhen) containing a phenanthroline (Phen) unit exhibited one strong bands at 305 nm for Phen units and a moderate peak around 350 nm for π-conjugated backbones. With an excitation wavelength of 360 nm, the PL spectrum of SiHMPhen exhibits a strong band at 420 nm in the blue region. Ru(II)-chelated copolymers showed strong absorption bands around 386∼392 nm. Upon a photoexcitation with 400 nm, their PL spectra show a strong band at 430 nm in the blue region. The Ru(II)-chelated copolymers were thermally stable up to 300°C in air.