Thermodynamic study of Eu(III) complexation by pyridine monocarboxylates

Rao, Divakar; Rawat, N.S.; Sawant, R. M.; Manna, Debashree; Ghanty, Tapan K.; Tomar, B. S.

doi:10.1016/j.jct.2012.06.017

Cited by 27 publications

(10 citation statements)

References 51 publications

(48 reference statements)

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“…The enthalpy change was found to be negative with a decreasing trend in exothermicity on successive protonation. A similar trend was often seen in the case of aminocarboxylates such as IDA (ΔH 1 = −35 kJ/mol and ΔH 2 = 4.1 kJ/mol), 28 picolinic acid (ΔH 1 = −10.4 kJ/mol and ΔH 2 = ∼0 kJ/mol), 29 and glycine ((ΔH 1 = −41 kJ/mol and ΔH 2 = 3.8 kJ/mol), and etc. 30 The high exothermicity for the first protonation is due to the protonation of the nitrogen atom of the ligand.…”

Section: Resultssupporting

confidence: 74%

Solution Thermodynamics for the Thorium Complexation with N-(2-Hydroxyethyl) Iminodiacetic Acid

2020

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N-(2-Hydroxyethyl)iminodiacetic acid (HEIDA-H 2 ) is one of the major chelating agents present in the mixed nuclear waste of the Hanford site. The complexation of thorium with HEIDA-H 2 in aqueous medium was investigated to understand the capability of HEIDA-H 2 to affect the migration of actinides from the waste storage sites. The present studies aimed at determining the thermodynamic parameters of Th(IV)−HEIDA complexes to know the speciation, stability (log K) and strength of bond formations (enthalpy and entropy changes) by potentiometric and calorimetric titrations, respectively. Thorium forms ML, ML 2 and ML 3 complexes with HEIDA. The obtained log K values 11.25 ± 0.10, 9.24 ± 0.10, and 8.1 ± 0.10, are higher than the complexes of thorium with monodenatate ligands (simple carboxylates), bidentate ligands (aminomonocarboxylates, dicarboxylates), and heterodicarboxylates. The very high entropy values of the Th(IV)−HEIDA complexes in comparison to the Th(IV) complexes with structurally similar ligands reflects the stronger complexation of Th with HEIDA over others. HEIDA acts as a tridentate ligand forming two five-membered chelates through the two carboxylate oxygens and the nitrogen with thorium, while the hydroxyethl group was found to enhance the stabilization by indirect participation. Density functional theory was used to optimize the geometries and to determine the thermodynamic parameters, bond distances and partial charges on individual atoms for the experimentally predicted complexes. The theoretical predictions are found to be in agreement with the experimental observations.

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Section: Resultssupporting

confidence: 74%

Solution Thermodynamics for the Thorium Complexation with N-(2-Hydroxyethyl) Iminodiacetic Acid

2020

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“…The details on instrumentation, chemical and electrical calibration along with the methodology to determine the enthalpy of formation (DH) for a reaction involving successive complexation steps (ML i , i = 1-4) from the raw measurements (heat release vs. time for each addition of ligand solution to metal solution in a calorimetric cup) are given elsewhere [70]. The details on instrumentation, chemical and electrical calibration along with the methodology to determine the enthalpy of formation (DH) for a reaction involving successive complexation steps (ML i , i = 1-4) from the raw measurements (heat release vs. time for each addition of ligand solution to metal solution in a calorimetric cup) are given elsewhere [70].…”

Section: Isothermal Titration Calorimetrymentioning

confidence: 99%

“…The protonation constants of all the three pyridine monocarboxylates under present experimental conditions were taken from our previous work [90] as inputs to analyze the potentiometric data of Th-PCNO complexation to determine the stability constants of all the complexes formed during the course of reaction. (1) represents the protonation of ligand while the Eq.…”

Section: Potentiometrymentioning

confidence: 99%

“…In general, ligand dehydration plays minor role in determining the enthalpy of formation as in case of simple monocarboxylates and neutral ligands like NANO and IANO for which the enthalpy of protonation are À1.83 and 0.40 kJ/mol respectively [90], typical of carboxylic acids (DH P % 0-5 kJ/mol at 298 K). In general the stepwise enthalpy of formation follows a descending order as the charge neutralization becomes more prominent in the stepwise complexation process.…”

Section: Isothermal Titration Calorimetrymentioning

confidence: 99%

“…1) have an oxygen atom as donor instead of nitrogen as in corresponding pyridine monocarboxylates. The transition metal ion and lanthanide ion complexes with pyridine https://doi.org/10.1016/j.jct.2018.02.006 0021-9614/Ó 2018 Elsevier Ltd. monocarboxylate-N-oxides (PCNOs) in both solid and solution state are extensively studied to explore their applications in luminescence, catalysis and many other fields [26][27][28][29][30][31][32][33][34][35][36][37][38][39] but only a few studies on actinide complexes with pyridine monocarboxylates are available in literature [40][41][42][43][44][45][46][47][48]. The transition metal ion and lanthanide ion complexes with pyridine https://doi.org/10.1016/j.jct.2018.02.006 0021-9614/Ó 2018 Elsevier Ltd. monocarboxylate-N-oxides (PCNOs) in both solid and solution state are extensively studied to explore their applications in luminescence, catalysis and many other fields [26][27][28][29][30][31][32][33][34][35][36][37][38][39] but only a few studies on actinide complexes with pyridine monocarboxylates are available in literature [40][41][42][43]…”

Section: Introductionmentioning

confidence: 99%

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Complexation of thorium with pyridine monocarboxylate-N-oxides: Thermodynamic and computational studies

Dumpala

Rawat

Boda

et al. 2018

The Journal of Chemical Thermodynamics

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a b s t r a c tThe feed wastes and waste water treatment plants are the major sources for the entry of N-oxides into the soils then to aquatic life. The complexation of actinides with potentially stable anthropogenic ligands facilitate the transportation and migration of the actinides from the source confinement. The present study describes the determination of thermodynamic parameters for the complexation of Th(IV) with the three isomeric pyridine monocarboxylates (PCNO) namely picolinic acid-N-oxide (PANO), nicotinic acid-N-oxide (NANO) and isonicotinic acid-N-oxide (IANO). The potentiometric and isothermal calorimetric titrations were carried out to determine the stability and enthalpy of the formations for all the Th(IV)-PCNO complexes. Th-PANO complexes are more stable than Th-NANO and Th-IANO complexes which can be attributed to chelate formation in the former complexes. Formation of all the Th-PCNO complexes are endothermic and are entropy driven. The geometries for all the predicted complexes are optimized the energies, bond distances and charges on individual atoms are obtained using TURBOMOLE software. The theoretical calculation corroborated the experimental determinations.

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Protonation of Pyridine Monocarboxylate‐N‐Oxides – Determination of Thermodynamic, Absorbance and Ion Interaction Parameters

2017

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The thermodynamic parameters (pKa, ΔH, ΔG, ΔS) for the protonation of three isomeric pyridine monocarboxylate‐N‐oxides (PCNO) namely picolinate‐N‐oxide (PANO) nicotinate‐N‐oxide (NANO) isonicotinate‐N‐oxide (IANO) were determined in the present study. The pKa determined by potentiometry follow the order: PANO > IANO > NANO at all ionic strengths. The calorimetric results revealed that the PANO protonation was endothermic and the other are exothermic, indicating the entropy driven protonation of PANO while the other two has minor contribution of enthalpy as well. The ion interaction parameters for PCNOs are obtained by determining the pKa for the same at various ionic strengths (I=0.1 −3.0 M) and the data is extrapolated to find pKa0 (pKa at I=0) by specific ion interaction theory (SIT). The pKa / pKa0 determined by absorption spectra are also in line with potentiometric results. The energetics and variations in charge densities on individual atoms on protonation were calculated theoretically. PCNOs protonation are compared with its base moieties: pyridine monocarboxylates to interpret the effect of the N‐oxide moiety on the protonation thermodynamics.

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Thermodynamic study of Eu(III) complexation by pyridine monocarboxylates

Cited by 27 publications

References 51 publications

Solution Thermodynamics for the Thorium Complexation with N-(2-Hydroxyethyl) Iminodiacetic Acid

Solution Thermodynamics for the Thorium Complexation with N-(2-Hydroxyethyl) Iminodiacetic Acid

Complexation of thorium with pyridine monocarboxylate-N-oxides: Thermodynamic and computational studies

Protonation of Pyridine Monocarboxylate‐N‐Oxides – Determination of Thermodynamic, Absorbance and Ion Interaction Parameters

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