Intermolecular dynamics and paramagnetic properties of ethylenediaminetetraacetate complexes with the yttrium subgroup rare earth elements using nuclear magnetic resonance

Abstract

(1)H nuclear magnetic resonance (NMR) measurements are reported for the D(2)O 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 (1)H 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.

NMR Study of Paramagnetic Properties and the Kinetics of Hydrolysis of the Dy-tris-tBu-DOTA-ester Complex

“…It should be noted that other complex compounds, which were earlier investigated by 1 H NMR in both organic and aqueous media are characterized by the paramagnetic CS temperature sensitivity in the range from 0 to 1.5 ppm/K. [8,[10][11][12][13][29][30][31] The obtained result indicate that the coordination compounds I, II and III may be considered as the middle sensitive 1 H NMR lanthanide paramagnetic probes for in situ temperature control in solutions. Therefore, complexes I, II and III can be considered as potential reagents for determining the temperature in liquid samples installed in an NMR spectrometer, either directly in reaction media, or for in situ studies of exothermic or endothermic processes.…”

“…[6,7] Note that in the literature there are many examples of studying the kinetics of chemical exchange processes including in paramagnetic lanthanide (Ln) complexes. [8][9][10][11] However, there are few examples of publications devoted to NMR studies of irreversible processes in lanthanide complexes (and in particular complexes with PAPC ligands). The study of the structure, reactivity, structuraldynamic processes, and various non-covalent interactions (especially with biological substrates) of such compounds in solutions is important for their further use in biochemical studies and in medical diagnostics.…”

“…A review of modern NMR methods for studying the kinetics of reversible and irreversible processes is given in. [8,9,[19][20][21] In particular, the technique (named the homonuclear doubleresonance transfer of local nuclear spin population inversion) was proposed for a qualitative and quantitative study of the kinetics of reversible and irreversible processes. [22] Although these studies have been published in specialized literature.…”

“…[22] Although these studies have been published in specialized literature. [8,9,22] Recently, a similar technique (for the qualitative determination of reversible and irreversible chemical processes) was published in a general chemical journal. [23] A detailed discussion of this issue is published in Ref.…”

Holmium Сomplex with DOTA as NMR Super-Sensitive Temperature Sensor Reagent for Spectroscopic and Tomography Monitoring of Aqueous Systems

“…[6,14,[24][25][26] В настоящее время ведется поиск органических веществ, способных выполнять роль лигандов для получения раз-личных координационных соединений, перспективных в качестве ЯМР-сенсоров для биологических систем.…”