Ion pair driven self-assembly of a flexible bis-zwitterion in polar solution: formation of discrete nanometer-sized cyclic dimers.

The self-complementary flexible bis-zwitterion 1 forms discrete nanometer-sized cyclic dimers via ion pair driven self-assembly even in polar solvents. The existence of such dimers was confirmed by DOSY NMR, FAB-MS, and scattering experiments (DLS, SANS) which all indicate the concentration-dependent formation of cyclic dimers with a hydrodynamic radius of rH approximately 2.5 nm in solution.