Spectral study on the formation of a self-assembled mesoscopic supercoil

Molecular recognition directing self-assembly of two complementary molecula r components, 5-(4-dodecyloxybenzylidene)-2,4,6-(1H,3H)- pyrimidinetrione ( B) and 4-amino-2,6-didodecylamino-1,3,5-triazine (M), was found to form a m esoscopic supercoil structure with length of several tens of mu m and diame ter of ca. 300 nm. Fluorescence spectral studies show that it takes more th an 1200 h for the self-assembling process to reach the equilibrium in chlor oform. It was suggested that in this system with positive cooperation, at l east two steps were involved in the self-assembling process. First, supramo lecular tapes, cyclic hexamers, are formed based on the network of triple c omplementary hydrogen bonds between B and M. Second, pi-aromatic stacking a nd van der Waals interactions drive further the assembling of tapes into mo re complex nanometric strand. The coiling of the strands results in the for mation of the supercoil structure. (C) 1998 Elsevier Science Limited. All r ights reserved.