Adsorption of сucurbit[6]uril and styryl dye complexes on the surface of silver nanoparticles

Abstract

Fluorescence spectroscopy and electrochemistry methods have been applied to study the adsorption of complexes of styryl dye, trans-4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide (DSMI), with cucurbit[6]uril (CB6) on the surface of silver nanoparticles (AgNPs) (with an average size of 15 nm) prepared by silver nitrate reduction using sodium borohydride. It is established that in the presence of AgNPs the intensity of fluorescence of the DSMI@CB6 complex decreases by approximately 40%; the fluorescence of only free complexes in the bulk solution is observed, and the fluorescence of the complexes, which were adsorbed on the AgNPs surface, is completely quenched. The Frumkin isotherm (adsorption equilibrium constant B = 7.0 × 10⁶ L/mol) is used to describe the adsorption. In addition, the binding constant of the inclusion host–guest DSMI@CB6 complex is adjusted: K = 10⁶ L/mol.