1,1′-Bi(2-naphthol-4,5-dicarboximide)s: blue emissive axially chiral scaffolds with aggregation-enhanced emission properties

Abstract

1,1′-Binaphthol (BINOL) is a versatile chiral reagent with widespread applications in asymmetric catalysis and fluorescent bio-sensing and imaging. However, unsubstituted BINOLs exhibit only weak and short-wavelength emission, limiting their scope for the latter applications. Herein, we report axially chiral 1,1′-bi(2-naphthol-4,5-dicarboximide)s which show two reversible reductions, bright blue light fluorescence with fluorescence quantum yields up to 0.67, and aggregation-enhanced emission characteristics. Single crystal X-ray analysis revealed an intriguing double helical supramolecular polymer motif formed by π–π stacking interactions between 2-naphthol-4,5-dicarboximide units. The enantiomers of racemic 1,1′-bi(2-naphthol-4,5-dicarboximide)s were resolved on chiral columns and studied by CD spectroscopy.