TY - JOUR A1 - Dähne, Siegfried A1 - v.Berlepsch, H. A1 - Böttcher, C. A1 - Quart, A. A1 - Burger, C. A1 - Kirstein, S. T1 - Supramolecular Structures of J-Aggregates of Carbocyanine Dyes in Solution N2 - Light- and small-angle neutron scattering as well as cryo-transmission electron microscopy (cryo-TEM) studies were performed to probe the structure of J-aggregates formed by a series of achiral dye molecules of the 5,5',6,6'-tetrachlorobenzimidacarbocyanine chromophore having 1,1'-dialkyl substituents combined with 3,3'-bis(4-sulfobutyl)-3,3'-bis(4-carboxybutyl) or 3,3'-bis(3-carboxypropyl) substituents. Assemblies that display a dependence on the substituents different complex supramolecular structures of nanometer-to-micrometer size have been directly visualized by cryo-TEM. The superstructures span from monomolecular layers formed by the 1,1'-diethyl-3,3'-bis(4-sulfobutyl) derivative and stacks of bilayer ribbons in the case of the 1,1'-dioctyl-3,3'-bis(4-carboxybutyl) derivative to twisted ropelike structures for the chiral aggregate of the 1,1'-dioctyl-3,3'-bis(3-carboxypropyl)-substituted chromophore. PY - 2000 DO - https://doi.org/10.1021/jp000220z SN - 1520-6106 SN - 1520-5207 SN - 1089-5647 VL - 104 IS - 22 SP - 5255 EP - 5262 PB - Soc. CY - Washington, DC AN - OPUS4-862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dähne, Siegfried A1 - v.Berlepsch, H. A1 - Böttcher, C. A1 - Quart, A. A1 - Regenbrecht, M. A1 - Akari, S. A1 - Keiderling, U. A1 - Schnablegger, H. A1 - Kirstein, S. T1 - Surfactant-induced changes of morphology of J-aggregates: Superhelix-to-tubule transformation N2 - The morphology of the J-aggregates formed after the addition of ionic surfactants into solutions of the 3,3'-bis(3-carboxypropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine dye (C8O3) was characterized by absorption and circular dichroism spectroscopy, cryogenic temperature transmission electron microscopy, scanning force microscopy, and small-angle neutron scattering. The optical activity of the C8O3 J-aggregates, existing in aqueous solution as superhelices composed of tubular single strands, disappears upon addition of both cationic and anionic surfactants. This is accompanied by distinct spectral changes in the visible region as well as changes of the aggregates' morphology. The anionic surfactant sodium dodecyl sulfate induces the formation of single-walled tubules of 15 nm diameter and 300-600 nm length, which completely transform after several days into thick multilamellar tubes of micrometer length. The cationic surfactant trimethyltetradecylammonium bromide first produces vesicles that later transform again into tubular aggregates of nanometer thickness and micrometer length. PY - 2000 DO - https://doi.org/10.1021/la000014i SN - 0743-7463 SN - 1520-5827 VL - 16 IS - 14 SP - 5908 EP - 5916 PB - American Chemical Society CY - Washington, DC AN - OPUS4-863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Spitz, Christian A1 - Dähne, Siegfried A1 - Quart, A. A1 - Abraham, H.-W. T1 - Proof of chirality of J-Aggregates spontaneously and enantioselectively generated from achiral dyes N2 - The recently published claim1,2 that the achiral 5,5',6,6'- tetrachlorobenzimidacarbocyanine chromophore spontaneously and enantioselectively generates chiral J-aggregates when it is substituted in the 1,1'-position with n-alkyl groups longer than hexyl and in the 3,3'-position with -acido-ethyl or -acido-n-propyl groups has been proved by embedding the J-aggregates of such a dye (1a) in a polymeric PVA film and measuring the CD signal at defined observation angles. Dye 1b, which is assumed to give achiral J-aggregates, has been investigated for comparison as well. Possible contibutions of linear dichroism and birefringence of ordered molecules to the measured CD signal have been excluded by careful checks using both a plain PVA film and a film containing monomers of a dye (2) of known chirality. PY - 2000 DO - https://doi.org/10.1021/jp001805w SN - 1520-6106 SN - 1520-5207 SN - 1089-5647 VL - 104 IS - 36 SP - 8664 EP - 8669 PB - Soc. CY - Washington, DC AN - OPUS4-864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -