Self-assembly of tripodal squaraines: Cation-assisted expression of molecular chirality and change from spherical to helical morphology

(Figure Presented) Let's do the twist: Tripodal squaraines self-assemble from acetonitrile to form hollow spheres, the complexation of which with Ca 2+ or Mg2+ results in extended networks. An analogous chiral dye exhibits a bisignate CD couplet and a helical morphology upon Ca 2+ binding (see figure). Thus, the molecular chirality of a functional dye is expressed through specific cation binding and manifested in the form of supramolecular helicity. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.