Binding the hydrophobic fluorescent probe, 2‐p‐toluidinylnaphthalene‐6‐sulfonate, by polycations that contain apolar pendant groups: Equilibrium dialysis and fluorescence measurements

Abstract

The thermodynamic parameters for the interaction of the hydrophobic fluorescent probe, 2‐p‐toluidinylnaphthalene‐6‐sulfonate (TNS), and polycations that contain a piperidinium cation and various nonpolar pendant groups were calculated. Binding is exothermic and involves a positive entropy gain. The contribution of the entropy term to the free energy change tends to increase with increasing hydrophobicity of the polymers. The intensity of the fluorescence of TNS is enhanced when the probe binds to the polycations. The nature and phenomena of hydrophobic fluorescent probe binding with the polymers are discussed.