Optical properties of polyfluorene–thiophene copolymers having chiral side chains

A series of alternating copolymers consisting of chiral thiophene and fluorene, poly[9,9-dihexylfluorene-alt-(3-{2-[(S)-(+)-1-methyloctyloxy]ethyl}thiophene)] (P1), and poly[9,9-dihexylfluorene-alt-(3-{2-[(S)-(+)-1-methyloctyloxy]ethyl}-2,2′-bithiophene)] (P2), were synthesized by Suzuki coupling method. P1 and P2 were characterized by 1H NMR spectra and elemental analyses. Both of the copolymers showed clear solvatochromism and circular dichroism in methanol/chloroform mixed solutions. These two polymers had different spacer lengths between the chiral side chains along the main chain, and accordingly the circular dichroism spectra were apparently different.