Circularly Polarized Luminescence from Solvent-Free Chiral Organic π-Liquids

The solvent-free organic pi-liquids have been attracting increasing attentions owing to the inherent optoelectronic properties accompanied by the advantages of non-volatility and high processability. Herein, we reported a series of naphthalene derivatives substituted with chiral branched alkyl chains, which are present as liquids (Nap1-3) or solid (Nap4) at room temperature, depending on the substitution positions. Circular dichroism (CD) and circularly polarized luminescence (CPL) were only observed for enantiomeric Nap2 (2,3-substituted) liquid. It is suggested that the chiral aggregation in the pi-liquid leads to the CD signal and the chiral excimer resulting in the CPL performance. When achiral anthracene or pyrene was dissolved in Nap2, the pi-liquid could serve as chirality and energy transfer media in which both CD and CPL emerged from the achiral anthracene. A CPL dissymmetry factor (|g(lum)|) of anthracene reached to 5.2x10(-2) when dissolved in chiral Nap2 liquid, which is nearly two orders of magnitude higher than that of the pure Nap2 pi-liquid.

Automated summary

The study reported naphthalene derivatives substituted with chiral branched alkyl chains, with circular dichroism (CD) and circularly polarized luminescence (CPL) only observed for enantiomeric Nap2 when in liquid form at room temperature.