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Durham University

Department of Chemistry

Publication details for Dr Robert Pal

Neil, E.R., Fox, M.A., Pal, R., Pålsson, L.O., O'Sullivan, B.A. & Parker, D. (2015). Chiral probe development for circularly polarised luminescence: comparative study of structural factors determining the degree of induced CPL with four heptacoordinate europium(III) complexes. Dalton Transactions 44(33): 14937-14951.

Author(s) from Durham

Abstract

A series of bright, europium(III) complexes has been prepared based on an achiral heptadentate triazacyclononane ligand bearing two strongly absorbing, coordinated aralkynyl pyridyl moieties. The binding of chiral carboxylates, including α-hydroxy acids such as lactate and mandelate, has been monitored by emission spectroscopy and is signalled by the switching on of strong circularly polarised emission. In each case, an R-chiral carboxylate gave rise to emission typical of a Δ complex, most clearly shown in the form of the ΔJ = 4 transition manifold around 700 nm. Variations in the sign and magnitude of the CPL allow the enantiomeric purity and absolute configuration of the acid to be assessed in a sample. Analysis of the relative energies of the parent aqua complexes and their stereoisomeric adducts has been aided by lifetime measurements and density functional theory calculations.