Circularly Polarized Luminescence From Solvent-Free Chiral Organic Pi-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.