Push–pull amino-nitro helicenes: synthesis, (chir)optical properties and self-assembly into thin films†
Abstract
A series of regioisomeric push–pull amino-nitro [6]helicenes and a related [7]helicene derivative were prepared and their racemates resolved into enantiomers. Compared to the parent helicenes, they exhibit red-shifted UV-Vis spectra, pronounced dipole moments, altered chiroptical properties such as remarkable optical rotatory power, and can form nanocrystalline Langmuir–Blodgett films.