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

Abstract

Molecular recognition directing self-assembly of two complementary molecular 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 mesoscopic supercoil structure with length of several tens of μm and diameter of ca. 300 nm. Fluorescence spectral studies show that it takes more than 1200 h for the self-assembling process to reach the equilibrium in chloroform. It was suggested that in this system with positive cooperation, at least two steps were involved in the self-assembling process. First, supramolecular tapes, cyclic hexamers, are formed based on the network of triple complementary hydrogen bonds between B and M. Second, π-aromatic stacking and van der Waals interactions drive further the assembling of tapes into more complex nanometric strand. The coiling of the strands results in the formation of the supercoil structure.