Double π-Extended Undecabenzo[7]helicene

This work reports the first double pi-extended undecabenzo[7]helicene 1, which is a large chiral nanographene, composed of 65 fused rings and 186 conjugated carbon atoms. The molecular identity of 1 has been confirmed by single crystal X-ray diffraction. A wine coloured solution of 1 in dichloromethane absorbs light from ultraviolet to the near infrared, featuring an extremely large molar absorption coefficient of 844 000 M-1 cm(-1) at 573 nm. Optically pure 1 shows a record high electronic circular dichroism intensity in the visible spectral range (|Delta epsilon|=1375 M-1 cm(-1) at 430 nm) known for any discrete polycyclic aromatic hydrocarbon. These unusual photophysical properties of 1 contrast sharply with those of a mono-undecabenzo[7]helicene derivative 2.

Automated summary

The study presents the first double pi-extended undecabenzo[7]helicene 1, a large chiral nanographene with unique photophysical properties, contrasting sharply with the mono-undecabenzo[7]helicene derivative 2.