Conjugated system

Optics

Physics

Absorption (acoustics)

Circular dichroism

Composite material

Organic chemistry

Chemistry

Materials science

Programming language

Ultraviolet

Helicene

Dichloromethane

Solvent

Crystal (programming language)

Molecule

Computer science

Optoelectronics

Polymer

Photochemistry

Crystallography

Fluorescence

Angewandte Chemie International Edition

This work reports the first double π‐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 (|Δ ϵ |=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 .

Double π‐Extended Undecabenzo[7]helicene