Lanthanides as NMR probes of fast molecular dynamics at high magnetic fields and temperature sensors: Conformational interconversion of erbium ethylenediaminetetraacetate complexes

Sergey P. Babailov, Pavel A. Stabnikov, Eugeny N. Zapolotsky, Vasily V. Kokovkin

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

1H NMR measurements are reported for D2O solutions of paramagnetic complex [Er(H2O)(EDTA4-)]- (I) for temperature interval 273-319 K. Diamagnetic complex [Lu(H 2O)(EDTA4-)]- (II) was used as an NMR reference compound. The spectra obtained have been analyzed using a band-shape analysis technique in the framework of dynamic NMR (DNMR) taking into account the temperature dependence of lanthanide-induced shifts. Intramolecular dynamics in I was assigned to the interconversion of Δ-λE- δδδδ and Δ-δE- δδδδ conformers with estimated activation free energy ΔG(298 K) = 50 ± 4 kJ/mol. The methodology of paramagnetic 4f-element probe applications on the example of Er3+ for the study of free-energy changes in chemical exchange processes, as well as the advantages of this method in comparison with DNMR studies of diamagnetic substances, is discussed. In accordance with the literature reviewed, the fulfilled experimental study is the first example of intramolecular dynamics determination for erbium complexes. An additional advantage of the investigation is in the approach proposed which extends the range of measurement of the NMR rate constants for paramagnetic 4f-element complexes compared to diamagnetic ones. Coordination compounds investigated represent a new type of thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solutions.

Original languageEnglish
Pages (from-to)5564-5569
Number of pages6
JournalInorganic Chemistry
Volume52
Issue number9
DOIs
Publication statusPublished - 6 May 2013
Externally publishedYes

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

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