A novel L-tyrosine derivative of poly[(fluoren-2,7-diyl)-alt-co-(benzen-1,4-diyl)]:: Strategy of synthesis and chiroptical and electrochemical characterization

A novel optically active conjugated copolymer of fluorene and phenylene units, modified by tyrosine derivative, was synthesized. Two different methods were probed: Suzuki cross-coupling of chiral monomer and post-modification over halogenous precursor polymer. Only the first strategy was successful in affording the chiral derivative copolymer, while the post-modification route by substitution fails, even into large scale reactions. All monomers and polymers were elucidated and characterized by NMR and FTIR spectrocopies. Molecular weights of the polymers were measured by coupled size exclusion chromatography-evaporative light scattering detector with typical polydispersity values. The optical and chiroptical properties of the new conjugated tyrosine derivative of polyfluorene were studied in a mixture of solvents, where exhibit a significant Cotton effect with respect to the precursors. Fluorescence emission of polyfluorenes was analyzed as a function of different polarity surrounding. Electrochemical doping and degradation studies of new chiral polymer were also performed.