W-Shaped π-Extended Double Undecabenzo[7]helicene.

A chiral W-shaped fully π-extended double [7]helicene ( ED7H ) has been synthesized and fully characterized. It displays fluorescence emission (λ em = 636 nm) with a quantum yield (Φ f ) of 0.10. In comparison to its X-shaped and monomict π-extended [7]helicene analogues, enantiopure W-shaped ED7H exhibited superior chiral optical characteristics, including distinct circular dichroism signals from 400 to 650 nm, a good dissymmetric emission factor | g lum | of 4 × 10 -3 , and a circularly polarized luminescence brightness value B CPL of 42 M -1 cm -1 .