Circularly Polarized Luminescence of Chiral Perylene Diimide Based Enantiomers Triggered by Supramolecular Self-Assembly.

Two perylene diimide (PDI) enantiomers ( d/l-PDI) incorporating the d/ l-alanine moiety have been designed and synthesized. d/l-PDI in chloroform displays bright-yellow fluorescence that is redshifted to orange-red when the solvent contains a methanol fraction of 99 vol %. No circular dichroism (CD) or circularly polarized luminescence (CPL) signals were observed for d/l-PDI enantiomers in CHCl₃. Interestingly, the d/l-PDI enantiomers exhibit clear mirror-image Cotton effects and CPL emission in the aggregate state. The optical anisotropy factor ( g_lum) is as high as 0.02 at f_m=99 %, which can be attributed to self-assembly through intermolecular π-π interactions in the aggregate state. [ABSTRACT FROM AUTHOR]