title: Lead and mercury sensing by calixarene-based fluoroionophores bearing two or four dansyl fluorophores.
abstract: A detailed study on the photophysical and complexing properties of calixarenes bearing two and four dansyl derivatives (Calix-DANS2 and Calix-DANS4) in a CH3CN/H2O mixture (60:40 v/v) is reported. Calix-DANS2 shows a high selectivity towards Hg2+ over interfering cations (Na+, K+, Ca2+, Cu2+, Zn2+, Cd2+ and Pb2+) and a sensitivity in the 10(-7) mol L(-1) concentration range. The complexation of mercury ion induces a strong fluorescence quenching due to a well-defined electron transfer process from the fluorophore to the metal center. Calix-DANS4 exhibits an extremely high affinity for Pb2+ with a high selectivity over various competing ions. The unprecedented detection limit (4 microg L(-1)) is fully compatible with the level defined by the World Health Organisation. The affinity of Calix-DANS4 for Pb2+ can be rationalized by the activation of the inert pair of electrons on Pb2+. The number of fluorophores involved in the complexation can be determined from a careful time-resolved fluorescence characterization.
authors.affiliation: CNRS UMR 8531: Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires, Département de Chimie, ENS-Cachan, 61 Avenue du Président Wilson, 94235 Cachan Cedex, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Métivier
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leray
authors.forename: Bernard
authors.initials: B
authors.lastname: Valeur
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D007476:Ionophores / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008628:Mercury / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D002412:Cations; D007476:Ionophores; D009942:Organometallic Compounds; D047250:Calixarenes; D007854:Lead; D008628:Mercury