Luminescence recognition material as an INHIBIT logic gate in presence of Pb2+ and Cu2+ ions in aqueous solutions

A recognition material consisting of silica xerogel with amino-modified surface selectively recognizes Pb2+ and Cu2+ (but only in presence of Pb2+ ions) in aqueous solutions of other metal ions. The analytical action of the material is based on a significant change in luminescence emission spectra of the material after chemisorption of Pb2+ ions. In the presence of Pb2+ in octahedral coordination environment, a new broad and strong emission band appears which is peaking at 443 nm (λexc = 236 nm) ascribed to electronic transition in Pb2+ complex. On the other hand, the presence of Cu2+ cations causes significant depression of the Pb2+ luminescence. The material plays a role of INHIBIT logic gate for both the mentioned cations.Pb2+ can be analyzed quantitatively but Cu2+ only qualitatively in presence of Pb2+. The material can be regenerated after chemisorption and is photochemically stable during UV illumination. Besides the surface of the modified silica support is analyzed by SEM and XPS techniques and coordination sphere of the chemisorbed Cu2+ ions is determined by electron paramagnetic resonance (EPR).