STRUCTURAL CONDITIONS FOR SPONTANEOUS GENERATION OF OPTICAL-ACTIVITY IN J-AGGREGATES

Achiral molecules of 5,5',6,6'-tetrachlorobenzimidacarbocyanine dyes h aving 1,1'-di-n-alkyl substituents longer than hexyl combined with 3,3 '-bis(2-acidoethyl) or 3,3'-bis(3-acido-n-propyl) substituents form J- aggregates whose absorption spectrum exhibits Davydov-split subbands t hat display strong circular dichroism, indicating the enantioselective formation of chiral J-aggregates. In this way, for the first time, in the liquid phase self-organization of achiral dye molecules to chiral supramolecular aggregates has been realized which can be controlled b y the molecular structure of the monomeric precursors, A helix-like, c ylindric structure of the chiral J-aggregates is suggested, The result s expose an interesting model for studying and understanding enantiose lective processes in the biosphere.