title: Supramolecular chirality from an achiral azobenzene derivative through the interfacial assembly: effect of the configuration of azobenzene unit.
abstract: The Langmuir-Schaefer (LS) films of an achiral azobenzene derivative, 4-octyl-4'-(5-carboxypentamethyleneoxy) azobenzene (C8AzoC5), were fabricated and their optical activities were investigated. It was found that the LS film of the trans-C8AzoC5 showed strong Cotton effect, while that of cis-C8AzoC5 did not. The characterization of the LS films by UV-vis, Fourier transform infrared (FT-IR) spectra, and X-ray diffraction (XRD) revealed that this interesting phenomenon was due to the different packing of the azobenzene unit in the LS film. The planar conjugated trans-azobenzene favored ordered cooperative packing in a helical sense and produced the supramolecular chirality, while the cis-isomer did not due to the bulky twisted configuration.
authors.affiliation: Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, China.
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Penglei
authors.initials: P
authors.lastname: Chen
authors.forename: Minghua
authors.initials: M
authors.lastname: Liu