Circularly polarized luminescence and high photoluminescence quantum yields from rigid 5,10-dihydroindeno[2,1-a]indene and 2,2′-dialkoxy-1,1′-binaphthyl conjugates and copolymers

Abstract

5,5,10,10-Tetramethyl-5,10-dihydroindeno[2,1-a]indene (COPV1(Me)) was installed into either the 3,3′- or 6,6′-positions of chiral 2,2′-dioctyloxy-1,1′-binaphthyl to afford 2 : 1 conjugates (monomeric compounds) and 1 : 1 copolymers. These compounds showed high photoluminescence quantum yields of >0.95 whilst also exhibiting circular dichroism (CD) and circularly polarized luminescence (CPL). The dissymmetry factors of CPL (g_CPL) for the 3,3′- and 6,6′-monomeric compounds in THF were 6.6 × 10⁻⁴ and 3.3 × 10⁻⁴, respectively. The 3,3′-isomer has a higher g value than the 6,6′-isomer, which was attributed to the difference in the extent of π-conjugation and the angle between electronic and magnetic transition moments. The g_CPL values of the 3,3′-linked and 6,6′-linked copolymers were 1.1 × 10⁻³ and 6.8 × 10⁻⁴, respectively. The structural rigidity of the COPV units is beneficial to achieve relatively high g values whilst maintaining a photoluminescence quantum yield that is close to unity by using a single type of fluorophore.