Synthesis and Photochemical Properties of Axially Chiral Bis(dinaphthofuran)

Both enantiomers of axially chiral bis­(dinaphthofuran) were prepared in only two steps from 1′-hydroxy-4′-methoxy-2,2′-binaphthalenyl-1,4-dione, followed by optical resolution via high-performance liquid chromatography (HPLC) using a chiral stationary phase (CSP). The absolute configurations were determined by comparison of experimental and calculated vibrational circular dichroism (VCD) spectra. Synthetic bis­(dinaphthofuran) exhibited a broad and unstructured emission derived from an intramolecular excimer in both solution and solid state. The methylene bridge brings both chromophores close to each other and induces significant changes in the photophysical behavior. Chiral bis­(dinaphthofuran) displayed a bathochromic shift in emission, as compared to the racemic mixture in the solid state. Furthermore, the compounds showed high circularly polarized luminescence (CPL) with a dissymmetry factor (g_lum) of 10^–3 at 405 nm upon excitation at 265 nm in a methanol solution. This compound serves as a model for the design and synthesis of organic materials having CPL activity.