Jump to main content
Jump to site search


Eu(III) and Tb(III) complexes of 6-fold coordinating ligands showing high affinity for the hydrogen carbonate ion: a spectroscopic and thermodynamic study

Author affiliations

Abstract

In the present contribution, four classes of Ln(III) complexes (Ln = Eu and Tb) have been synthesized and characterized in aqueous solution. They differ by charge, Ln(bpcd)+ [bpcd2− = N,N′-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane N,N′-diacetate] and Ln(bQcd)+ (bQcd2− = N,N′-bis(2-quinolinmethyl)-trans-1,2-diaminocyclohexane N,N′-diacetate) being positively charged and Ln(PyC3A) (PyC3A3− = N-picolyl-N,N′,N′-trans-l,2-cyclohexylenediaminetriacetate) and Ln(QC3A) (QC3A3− = N-quinolyl-N,N′,N′-trans-l,2-cyclohexylenediaminetriacetate) being neutral. Combined DFT, spectrophotometric and potentiometric studies reveal the presence, under physiological conditions (pH 7.4), of a couple of equally and highly stable isomers differing by the stereochemistry of the ligands (trans-N,N and trans-O,O for bpcd2− and bQcd2−; trans-O,O and trans-N,O for PyC3A3− and QC3A3−). Their high log β values (9.97 < log β < 15.68), the presence of an efficient antenna effect and the strong increase of the Ln(III) luminescence intensity as a function of the hydrogen carbonate concentration in physiological solution, render these complexes as very promising optical probes for a selective detection of HCO3in cellulo or in extracellular fluid. This particularly applies to the cationic Eu(bpcd)+, Tb(bpcd)+ and Eu(bQcd)+ complexes, which are capable of guesting up to two hydrogen carbonate anions in the inner coordination sphere of the metal ion, so that they show an unprecedented affinity towards HCO3 (log K for the formation of the adduct in the 4.6–5.9 range).

Graphical abstract: Eu(iii) and Tb(iii) complexes of 6-fold coordinating ligands showing high affinity for the hydrogen carbonate ion: a spectroscopic and thermodynamic study

Back to tab navigation

Supplementary files

Publication details

The article was received on 07 Sep 2018, accepted on 07 Nov 2018 and first published on 08 Nov 2018


Article type: Paper
DOI: 10.1039/C8DT03621G
Citation: Dalton Trans., 2019, Advance Article
  •   Request permissions

    Eu(III) and Tb(III) complexes of 6-fold coordinating ligands showing high affinity for the hydrogen carbonate ion: a spectroscopic and thermodynamic study

    F. Piccinelli, C. De Rosa, A. Melchior, G. Faura, M. Tolazzi and M. Bettinelli, Dalton Trans., 2019, Advance Article , DOI: 10.1039/C8DT03621G

Search articles by author

Spotlight

Advertisements