Intramolecular dynamics and molecular structure of europium(III) chelate complexes with crown ethers as studied by NMR spectroscopy

Sergey P. Babailov, Dmitry A. Mainichev, Lubov D. Nikulina, Svetlana S. Petrova

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Earlier the intramolecular inversion of the 18-crown-6 molecules was found in the complex ion pairs [Ln(ptfa)2 (18-crown-6)]+ [Ln(ptfa)4]- (H2O)4 where Ln = La(1), Ce (2), Pr (3), Nd (4), and ptfa is 1,1,1-trifluoro-5,5-dimethyl-2,4- hexanedione. In this work the peculiarities of the molecular structure and dynamics were studied for [Eu(ptfa)2 (18-crown-6)]+ [Eu(ptfa)4]- (H2O)4 (5) by NMR spectroscopy techniques. Through VT-NMR spectra analysis the temperature dependence was obtained for the rate constant. The free energy ΔG (320) of 18-crown-6 ring inversion activation was found to be 65 ± 5 kJ mol-1 for 5 in CDCl3. This result is comparable with the earlier data [S.P. Babailov and D.A. Mainichev: J. Inclusion Phenom. Macrocyclic Chem. 43, 187-193 (2002)] for complexes 2, 3, 4 in deuterated toluene (ΔG(320)=65 ± 9, 64 ± 9, 64 ± 9 kJ mol-1 respectively). It was found by relaxation NMR spectroscopy that the effective distance between Ln and protons of the crown molecule is 4.5 ± 0.2 Å. The analysis of structural parameters testifies that the crown ether and chelated anions are in the first coordination sphere of a Ln cation. Obtained geometrical parameters show that the complex cations of Eu, Ce and Pr have similar spatial structures.

Original languageEnglish
Pages (from-to)73-78
Number of pages6
JournalJournal of Inclusion Phenomena and Macrocyclic Chemistry
Volume51
Issue number1
DOIs
Publication statusPublished - Feb 2005
Externally publishedYes

Fingerprint

europium
Crown Ethers
chelates
Molecular Structure
chemical structure
Molecular structure
Nuclear magnetic resonance spectroscopy
nuclear magnetic resonance spectroscopy
ethers
cations
molecular structure
Magnetic Resonance Spectroscopy
nuclear magnetic resonance
molecular dynamics
toluene
anions
inversions
spectroscopy
protons
Cations

Keywords

  • Complexes
  • Crown ethers
  • Dynamic NMR
  • Free energy of activation
  • Lanthanides
  • Molecular dynamics
  • Ring inversion
  • Structure

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

Cite this

Intramolecular dynamics and molecular structure of europium(III) chelate complexes with crown ethers as studied by NMR spectroscopy. / Babailov, Sergey P.; Mainichev, Dmitry A.; Nikulina, Lubov D.; Petrova, Svetlana S.

In: Journal of Inclusion Phenomena and Macrocyclic Chemistry, Vol. 51, No. 1, 02.2005, p. 73-78.

Research output: Contribution to journalArticle

Babailov, Sergey P. ; Mainichev, Dmitry A. ; Nikulina, Lubov D. ; Petrova, Svetlana S. / Intramolecular dynamics and molecular structure of europium(III) chelate complexes with crown ethers as studied by NMR spectroscopy. In: Journal of Inclusion Phenomena and Macrocyclic Chemistry. 2005 ; Vol. 51, No. 1. pp. 73-78.
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abstract = "Earlier the intramolecular inversion of the 18-crown-6 molecules was found in the complex ion pairs [Ln(ptfa)2 (18-crown-6)]+ [Ln(ptfa)4]- (H2O)4 where Ln = La(1), Ce (2), Pr (3), Nd (4), and ptfa is 1,1,1-trifluoro-5,5-dimethyl-2,4- hexanedione. In this work the peculiarities of the molecular structure and dynamics were studied for [Eu(ptfa)2 (18-crown-6)]+ [Eu(ptfa)4]- (H2O)4 (5) by NMR spectroscopy techniques. Through VT-NMR spectra analysis the temperature dependence was obtained for the rate constant. The free energy ΔG ‡(320) of 18-crown-6 ring inversion activation was found to be 65 ± 5 kJ mol-1 for 5 in CDCl3. This result is comparable with the earlier data [S.P. Babailov and D.A. Mainichev: J. Inclusion Phenom. Macrocyclic Chem. 43, 187-193 (2002)] for complexes 2, 3, 4 in deuterated toluene (ΔG‡(320)=65 ± 9, 64 ± 9, 64 ± 9 kJ mol-1 respectively). It was found by relaxation NMR spectroscopy that the effective distance between Ln and protons of the crown molecule is 4.5 ± 0.2 {\AA}. The analysis of structural parameters testifies that the crown ether and chelated anions are in the first coordination sphere of a Ln cation. Obtained geometrical parameters show that the complex cations of Eu, Ce and Pr have similar spatial structures.",
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T1 - Intramolecular dynamics and molecular structure of europium(III) chelate complexes with crown ethers as studied by NMR spectroscopy

AU - Babailov, Sergey P.

AU - Mainichev, Dmitry A.

AU - Nikulina, Lubov D.

AU - Petrova, Svetlana S.

PY - 2005/2

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N2 - Earlier the intramolecular inversion of the 18-crown-6 molecules was found in the complex ion pairs [Ln(ptfa)2 (18-crown-6)]+ [Ln(ptfa)4]- (H2O)4 where Ln = La(1), Ce (2), Pr (3), Nd (4), and ptfa is 1,1,1-trifluoro-5,5-dimethyl-2,4- hexanedione. In this work the peculiarities of the molecular structure and dynamics were studied for [Eu(ptfa)2 (18-crown-6)]+ [Eu(ptfa)4]- (H2O)4 (5) by NMR spectroscopy techniques. Through VT-NMR spectra analysis the temperature dependence was obtained for the rate constant. The free energy ΔG ‡(320) of 18-crown-6 ring inversion activation was found to be 65 ± 5 kJ mol-1 for 5 in CDCl3. This result is comparable with the earlier data [S.P. Babailov and D.A. Mainichev: J. Inclusion Phenom. Macrocyclic Chem. 43, 187-193 (2002)] for complexes 2, 3, 4 in deuterated toluene (ΔG‡(320)=65 ± 9, 64 ± 9, 64 ± 9 kJ mol-1 respectively). It was found by relaxation NMR spectroscopy that the effective distance between Ln and protons of the crown molecule is 4.5 ± 0.2 Å. The analysis of structural parameters testifies that the crown ether and chelated anions are in the first coordination sphere of a Ln cation. Obtained geometrical parameters show that the complex cations of Eu, Ce and Pr have similar spatial structures.

AB - Earlier the intramolecular inversion of the 18-crown-6 molecules was found in the complex ion pairs [Ln(ptfa)2 (18-crown-6)]+ [Ln(ptfa)4]- (H2O)4 where Ln = La(1), Ce (2), Pr (3), Nd (4), and ptfa is 1,1,1-trifluoro-5,5-dimethyl-2,4- hexanedione. In this work the peculiarities of the molecular structure and dynamics were studied for [Eu(ptfa)2 (18-crown-6)]+ [Eu(ptfa)4]- (H2O)4 (5) by NMR spectroscopy techniques. Through VT-NMR spectra analysis the temperature dependence was obtained for the rate constant. The free energy ΔG ‡(320) of 18-crown-6 ring inversion activation was found to be 65 ± 5 kJ mol-1 for 5 in CDCl3. This result is comparable with the earlier data [S.P. Babailov and D.A. Mainichev: J. Inclusion Phenom. Macrocyclic Chem. 43, 187-193 (2002)] for complexes 2, 3, 4 in deuterated toluene (ΔG‡(320)=65 ± 9, 64 ± 9, 64 ± 9 kJ mol-1 respectively). It was found by relaxation NMR spectroscopy that the effective distance between Ln and protons of the crown molecule is 4.5 ± 0.2 Å. The analysis of structural parameters testifies that the crown ether and chelated anions are in the first coordination sphere of a Ln cation. Obtained geometrical parameters show that the complex cations of Eu, Ce and Pr have similar spatial structures.

KW - Complexes

KW - Crown ethers

KW - Dynamic NMR

KW - Free energy of activation

KW - Lanthanides

KW - Molecular dynamics

KW - Ring inversion

KW - Structure

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