NANOTUBE FORMATION BETWEEN CYCLODEXTRINS AND 1,6-DIPHENYL-1,3,5-HEXATRIENE

Adduct formation between alpha-, beta-, gamma-, and (permethyl)gamma-c yclodextrins (CDs) on the one band and 1,6-diphenyl-1,3,5-hexatriene ( DPH) on the other was studied by fluorescence spectroscopy in a DMF/wa ter mixed solvent. The four complexes, CD-DPH, were found to exhibit r emarkable differences in their structures. Thus, while the alpha- and beta-homologues form 1/1 complexes with DPH, gamma-homologue forms nan otubes involving ca. 30 cyclodextrin- units and an unknown number of D PH molecules. If, however, the hydrogens of all the OH groups in the g amma-cyclodextrin are replaced by CH3 groups, nanotubes do not form. A lso, when the alkalinity of an aqueous solution, in which gamma-CD and DPH have formed nanotubes, is increased above pH = 12, the nanotubes break down. Moreover, nanotube formation does not occur also when DPH is replaced by certain of its derivatives, very similar to it in struc ture and rodlike in shape.