Enhancing the Circularly Polarized Luminescence of Self-assembled Cyanostilbenes through Extended π-Conjugation

Chiral supramolecular assembly of pi-conjugated luminophores provides a promising avenue for enhancing circularly polarized luminescence. In this study, we shed light on the impact of pi-conjugation length on circularly polarized luminescent performance of the resulting supramolecular assemblies, by designing a tetra-cyanostilbene monomeric compound alongside two dicyanostilbene control compounds. These cyanostilbene-based compounds possess the ability to form chiral supramolecular polymers in toluene, driven by a synergistic combination of intermolecular hydrogen bonding and pi-pi stacking interactions. The extended pi-aromatic skeleton brings bathochromic-shifted fluorescence and enhanced intermolecular stacking capability for the tetra-cyanostilbene compound. Consequently, chiral supramolecular assemblies formed by the tetra-cyanostilbene compound demonstrate a remarkable two-fold increase in g(lum) values relative to the assemblies formed by the dicyanostilbene compounds. Overall, this study provides valuable insights into the relationship between pi-conjugation length and the circularly polarized luminescent performance of pi-conjugated supramolecular assemblies.