Tuning the self-assembly of a ditopic crown ether functionalized oligo(p-phenylenevinylene)

A chiral ditopic crown ether functionalized oligo(p-phenylenevinylene), COPV, has been synthesized and fully characterized. The binding properties and the organization of COPV have been studied in solution and in the solid state. In chloroform, due to the benzo-15-crown-5 moieties, COPV is able to bind cations. In case of K⁺ a strong 2:2 complex is formed in which two COPVs are sandwiched between two potassium ions. Na⁺ is bound following a two-step negative cooperative process to form a 2:1 Na⁺/COPV complex. When COPV in the presence of potassium ions is drop-cast on a silicon substrate, fibers are formed. In water COPV forms stable helical aggregates as can be concluded from the Cotton effect, the UV-vis and fluorescence spectroscopy. AFM and light scattering studies show that ellipsoidal aggregates are present in water.