title: Chiral J-aggregates of atropo-enantiomeric perylene bisimides and their self-sorting behavior.
abstract: Herein we report on structural, morphological, and optical properties of homochiral and heterochiral J-aggregates that were created by nucleation-elongation assembly of atropo-enantiomerically pure and racemic perylene bisimides (PBIs), respectively. Our detailed studies with conformationally stable biphenoxy-bridged chiral PBIs by UV/Vis absorption, circular dichroism (CD) spectroscopy, and atomic force microscopy (AFM) revealed structurally as well as spectroscopically quite different kinds of J-aggregates for enantiomerically pure and racemic PBIs. AFM investigations showed that enantiopure PBIs form helical nanowires of unique diameter and large length-to-width ratio by self-recognition, while racemic PBIs provide irregular-sized particles by self-discrimination of the enantiomers at the stage of nucleation. Steady-state fluorescence spectroscopy studies revealed that the photoluminescence efficiency of homochiral J-aggregated nanowires (47±3%) is significantly higher than that of heterochiral J-aggregated particle-like aggregates (12±3%), which is explained in terms of highly ordered molecular stacking in one-dimensional nanowires of homochiral J-aggregates. Our present results demonstrate the high impact of homochirality on the construction of well-defined nanostructures with unique optical properties.
authors.affiliation: Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Zengqi
authors.initials: Z
authors.lastname: Xie
authors.forename: Vladimir
authors.initials: V
authors.lastname: Stepanenko
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Radacki
authors.forename: Frank
authors.initials: F
authors.lastname: Würthner