Induced Circular Dichroism of Optically Active Polyfluorene Derivatives in Phase-Separating Solution

When a non-solvent methanol was added to dilute THF solutions of an optically active polyfluorene derivative, the liquid-liquid phase separation took place, and circular dichroism (CD) was induced at a low temperature. The polymer concentration of the separating minor phase, estimated by light scattering, was very high (~ 0.4 g/cm3). The CD induction occurring in that concentrated phase was sensitive to the temperature. When the phase-separating solution was quenched from 40 to 150C, CD increased according to the first-order reaction kinetics, and it was a rather slow process (the rate constant: 2.5 × 10-4 s-1). The intermolecular chiral interaction in the concentrated phase may be responsible for the CD induction or non-racemization of this helical polyfluorene derivative in phase-separating solutions.

(by Y. Sanada, K. Terao & T. Sato)

	Scheme 1. Chemical structure of fluorene polymers PCF(x) investigated.
	Fig. 1. CD spectra of PCF(x = 1) homopolymer in a phase separating solution.
	Fig. 2. CD spectra of PCF(x) homopolymer and copolymers in phase separating solutions.