Synthesis and characterization of fluorene-based oligomers and polymers incorporating N-arylphenothiazine-S,S-dioxide units

A series of 3,7-bis(9,9-di-n-hexylfluoren-2-yl)-N-arylphenothiazine-S,S-dioxide trimers and (9,9-di-n-octylfluorene-2,7-diyl-co-N-arylphenothiazine-S,S-dioxide) co-polymers, with varying ratios of phenothiazine-S,S-dioxide units, have been prepared in good yields by palladium-catalyzed cross-coupling reactions. The materials are deep blue emitters and show no solvatochromism or evidence for an intramolecular charge-transfer state. The photoluminescence quantum yields of the trimers are ϕPL 15-30% in solution and 14-25% in films. The polymers demonstrated very high values in solution (ϕPL 74-84%) and ϕPL values in films of 28-47%. The estimated HOMO energy levels are between −5.64 and −5.62 eV for the polymers with 15% incorporation of the phenothiazine-S,S-dioxide units. An analogous N-arylphenothiazine co-polymer shows significantly red shifted absorption and emission. Solution electrochemical data and density functional theory calculations are also presented.