Highly Emissive, Optically Active Poly(diphenylacetylene) Having a Bulky Chiral Side Group

Abstract

A highly emissive, optically active poly(diphenylacetylene) derivative, NpSi*-PDPA, was synthesized by introducing a bulky chiral pendant group into the polymer chain. NpSi*-PDPA exists in a glassy state having a highly disordered and amorphous structure. Hence, the fractional free volume is quite high, i.e., 0.29. NpSi*-PDPA emits a green light in solution and a yellow light in film. This polymer is quite emissive, as the photoluminescence (PL) quantum yield is 56.1% in solution and 6.2% in film, and the PL lifetime is relatively long, 1.71 ns in solution and 1.05 ns in film. NpSi*PDPA shows the strongest circular dichroism (CD) signal at 384 nm, with a magnitude of circular polarization (g(CD)) of 0.90 x 10(-3) and an optical rotation of 110 degrees (4.30 X 10(-3) g mL(-1), in CHCl3). The CD intensity is significantly increased by annealing at 80 degrees C, reaching an equilibrium at g(CD) of 7.10 X 10(-3) after 72 h.