Binding of the cationic fluorophore Auramine-0 to neutral and charged poly(vinylbenzo-18-crown-6) in water

Summary The cationic fluorophore Auramine-0 strongly interacts with poly(vinylbenzo-18-crown-6), a polymer which in water behaves as a typical polysoap. The intrinsic binding constant at 25°C was found to be 2.2 × 10⁴ M^–1. The binding can be modified by adding crown ether-complexable cations such as K⁺ or Cs⁺. Complexation converts the neutral polycrown ether into a polycation causing repulsion of the cationic fluorophore and a decrease in the observed fluorescence. There is some indication that the cation of the dye specifically interacts with a crown ligand.