| Abstract
| - The morphology of J-aggregates formed by 3,3‘-bis(3-carboxypropyl)-5,5‘,6,6‘-tetrachloro-1,1‘-dioctylbenzimidacarbocyanine dye (C8O3) in aqueous solution upon addition of alcohols was characterized byspectroscopic methods, optical microscopy, and cryo-transmission electron microscopy (cryo-TEM). Withincreasing concentration of methanol, ethylene glycol, 1-octanol, or 1-decanol, the well-known 3-fold splitexcitonic absorption spectrum of the superhelical J-aggregates obtained in the absence of alcohols is replacedby a 2-fold split spectrum (von Berlepsch et al. J. Phys. Chem. B2000, 104, 5255), while the circulardichroism signal generally increases. The spectral changes indicate alcohol-induced modifications of theaggregates' molecular packing. Cryo-TEM revealed that these novel J-aggregates are composed of individualbilayer-walled tubules having a diameter of 11 ± 1 nm, which are assembled to form ropelike superhelicesof several micrometers in length. The superhelices' diameter is markedly increased if compared with thatin the alcohol-free system.
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