title: Optically active chiral CuO "nanoflowers".
abstract: Helical symmetry can be found in most flowers with a rotation of contort petal aestivation. For micro- and nanoscale analogies, flower mimicking structures have been reproduced; however, the conceptual chirality of "nanoflowers" has not yet been defined. Here, the chirality of the "flower" was defined by its nanosized chiral structure and consequent optical activity (OA), opening new horizons for the physical theory and chiral materials. We report the surfactant-mediated hydrothermal synthesis of chiral CuO nanoflowers using sodium dodecyl sulfate (SDS) as a structure-directing agent, an amino alcohol as a symmetry-breaking agent, and cupric salt as the inorganic source. Two levels of hierarchical chirality exist for a CuO nanoflower including primary helically arranged "nanoflakes" and secondary helical "subnanopetals" that form "nanopetals". The nanoflowers exhibited a prominent optical response to circularly polarized light (CPL) at the absorption bands characteristic of CuO.
authors.affiliation: School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai, 200240, P. R. China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Duan
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
authors.forename: Lu
authors.initials: L
authors.lastname: Han
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Asahina
authors.forename: Dongdong
authors.initials: D
authors.lastname: Xu
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Cao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yao
authors.forename: Shunai
authors.initials: S
authors.lastname: Che