Polybinaphthyls incorporating chiral 2,2′-binaphthyl and isoquinoline moieties by Sonogashira reaction

Abstract

Polymers P- 1, P- 2, P- 3, P- 4 and P- 5 were synthesized by the polymerization of 5,8-bis(ethynyl)isoquinoline ( M- 1) with ( R)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl (( R)- M- 2), ( S)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl (( S)- M- 2), ( R)-6,6′-dibromo-2,2′-bisbutoxy-1,1′-binaphthyl (( R)- M- 3), ( S)-6,6′-dibromo-2,2′-bisbutoxy-1,1′-binaphthyl (( S)- M- 3), and rac-6,6′-dibromo-2,2′-bisbutoxy-1,1′-binaphthyl ( M- 4) under Sonogashira reaction, respectively. Both monomers and polymers were analyzed by NMR, MS, FT-IR, UV–vis spectroscopy, DSC–TGA, fluorescence spectroscopy, GPC and circular dichroism (CD) spectroscopy. CD spectra of polymers P- 1 and P- 2, P- 3 and P- 4 are almost identical except that they gave opposite signals at each wavelength. The long wavelength CD effect of P- 1 and P- 2 can be regarded as the more extended conjugated structure in the repeating unit and the helical backbone in the polymer chain. All five polymers have strong blue-green fluorescence due to the efficient energy migration from the extended π-electronic structure of the repeating unit of the polymers to the chiral binaphthyl core and are expected to provide understanding of structure–property relationships of the chiral conjugated polymers.