Abstract
1H nuclear magnetic resonance (NMR) measurements are reported for the D 2O solutions of [Ln 3+(EDTA 4-)] - complexes, where EDTA 4- is ethylenediaminetetraacetate anion, Ln 3+ = Tb 3+ (I), Ho 3+ (II), Tm 3+ (III), Yb 3+ (IV) and Lu 3+ (V). Temperature dependencies of the 1H NMR spectra of paramagnetic I-IV have been analyzed using the dynamic NMR methods. It is found that the activation free energies (ΔG ∥ 298) of the intermolecular EDTA ions exchange at [Ln 3+(EDTA 4-)] - complexes are 60±3 (I), 66±3 (II), 69±3 (III) and 74±3 (IV) kJ/mol (at pD = 7). A monotonic increase of the free energy of chemical exchange processes along the series of lanthanide [Ln 3+ (EDTA 4-)] - complexes is probably related to the lanthanide contraction. The obtained results indicate that coordination compounds I-IV may be considered as thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solution.
Original language | English |
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Pages (from-to) | 793-797 |
Number of pages | 5 |
Journal | Magnetic Resonance in Chemistry |
Volume | 50 |
Issue number | 12 |
DOIs | |
Publication status | Published - Dec 2012 |
Externally published | Yes |
Keywords
- aqueous solutions
- dynamic NMR
- EDTA
- ethylenediaminetetraacetic acid
- free energy of activation
- kinetics of chemical exchange
- lanthanide complexes
- lanthanide-induced shifts in NMR spectra
- molecular dynamics
- two-site exchange
ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)