A selective colorimetric chemosensor for lanthanide ions

The synthesis and complexing properties of a calix[4]arene derivate (6) carrying two spirobenzopyran moieties are described. The addition of lanthanide ions resulted in significant UV-vis spectral shifts (68-84 nm) in visible region. It indicates that the synthetic receptor can recognize lanthanide ions by naked eyes over other cations including Na+, K+, Mg2+, Ca2+, Fe3+, CU2+ and Zn2+. The mechanism of recognition was studied with H-1 NMR, UV-vis spectra and emission spectra. The receptor may be applied to sense lanthanide ions. (c) 2006 Elsevier Ltd. All rights reserved.