ICMUB - News

Vendredi 20 avril 2007 : Conf de James Canary, New York (USA)

Stereodynamic coordination complexes

The unique structure-activity relationships associated with exciton-coupled circular dichroism (ECCD) have provided an avenue for the study of stereodynamic organic ligands and coordination complexes in
solution.  Conformationally biased tripodal ligands fold into propeller shapes upon protonation or complexation with certain divalent metal ions, affording unique fluorescence and chiroptical signatures. Careful design of ligands results in differentiation of analytes depending on metal ion, oxidation state, and the nature of solvent or coordinating anion. Several interesting strategies for metal ion and pH determination have become apparent that offer advantages over isotropic methods, although further evolution of instrumentation may be required for broad application. For example, the use of chiral ligands with appropriate chromophores allowed the development of a new technique to reduce background fluorescence.   

The method, Circularly Polarized Fluorescence Excitation (CPE), is closely related to the known fluorescence-detected circular dichroism technique.  CPE allows selective observation of chelation-enhanced circular dichroism when concurrent with chelation-enhanced fluorescence. The requirement for changed in both CD and fluorescence upon binding allows to eliminate background fluorescence.

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Contact : Jean-Claude Chambron

ICMUB (UMR 5260) - University of Burgundy - Dijon (France)