Porphyrin-based electrostatically self-assembled multilayers as fluorescent probes for mercury(ii) ions: a study of the adsorption kinetics of metal ions on ultrathin films for sensing applications

摘要

The electrostatic multilayer self-assembly technique was employed to prepare fluorescent probes forudmercury(II) ions. Films showing an appreciable fluorescence emission were obtained by alternateudadsorption of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) with polyelectrolytes. Fluorescenceudintensity quenching, arising from the coordinative interaction between the porphyrin and mercury ions,udwas monitored as a function of time. The response mechanism was studied on the basis of kinetic andudequilibrium models for adsorption. The adsorption process of mercury ions on porphyrin-based filmsudwas described by the pseudo-second-order equation and the kinetic parameters were correlated withudthe initial concentrations of the metal ions in aqueous solution. The kinetic approach was evaluated asudan alternative to monitoring the sensing responses at equilibrium.