Quantitative evaluation of Ln(III) pyridine N-oxide carboxylic acid spectra under chemometric and metrological aspects

Meinrath, G.; Lis, Stefan; Böhme, Uwe

doi:10.1016/j.jallcom.2004.11.082

Cited by 11 publications

(8 citation statements)

References 21 publications

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“…The pyridine N‐oxide group often acts in O‐donor coordination mode . Thus, it is evident that systems bearing N‐oxide groups form more stable complexes with metal ions than the parent ligands . Pyridine carboxylic acid N‐oxides (Figure ) and their substituted derivatives, having oxygen donor atoms, form thermodynamically stable six‐membered ring complexes.…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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

2017

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“…Probably, chemical systems less suitable for factor analysis may advantageously be analyzed by other experimental techniques. Thus, application of the rules of metrology in chemistry carry does not only the hope of Picolinic acid N-oxide [22] Nicotinic acid N-oxide [32] Pyridine 2,4 dicarboxylic acid N-oxide [28] Pyridine 2,6 dicarboxylic acid N-oxide [33] Diethyl(2-oxopropyl)phosphonate [34] Diethyl(2-oxo-2-phenylethyl) phosphonate [34] Arsenazo (III) [35] Sulfate a , hydroxide a [36] a With U(VI) as metal ion traceable and internationally comparable measurement values, but also criteria by which the most suitable experimental method for the analysis of a chemical system can be selected.…”

Section: Discussionmentioning

confidence: 99%

Chemometrics in f-element speciation: a metrological challenge?

Lis

Meinrath

2011

Accred Qual Assur

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The UV-Vis spectra of the f-elements, especially the lanthanides, are known for their rather sharp absorption bands showing systematic and reproducible changes upon coordination with suitable ligands. These absorption bands have been used as indicators allowing interpretation of the processes in solution. Modern absorption spectrometers in combination with digital recording of the spectra allow a precise collection of a large number of absorptions for many samples. The number of absorption thus collected easily amounts to several thousands of individual data. Chemometric techniques, especially factor analysis, are occasionally used to extract information from these data sets on basis of BouguerLambert-Beer law. Recent studies indicate the sensitivity of parameter values obtained from uncritical use of chemometric techniques to various influence and nuisance factors. On the basis of selected examples, the effects of parameter correlations, residual correlations, and measurement uncertainty introduced by volume operations are demonstrated. Using the ISO Guide to the Expression of Uncertainty as a convention for assessing measurement uncertainty, formation constants lg K derived from UV-Vis spectra of f-elements should be associated with a measurement uncertainty u of at least u = 0.15 (k = 1).

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“…The TB CAT returns an estimate of the empirical cumulative distribution function of the measurement uncertainty for the formation quotients and the single component spectra of the species whose estimates form the columns of matrix E. Further details on TB CAT [22] and application examples (e.g. [1,17,[23][24][25]) have been given previously. Readers inexperienced in chemometrics, statistics and metrology in chemistry are advised to consult respective literature because such concepts are an essential element of the following discussion without being explicitly presented.…”

Section: Numerical Treatment By Factor Analysis In Combination With Cmentioning

confidence: 99%

“…Such cause and effect diagrams have been developed and applied for several techniques of thermodynamic data determination, e.g. solubility studies [15], UV-Vis absorption spectroscopy [16,17] or glass-electrode potentiometry [18].…”

Section: Introductionmentioning

confidence: 99%

An application of the total measurement uncertainty budget concept to the thermodynamic data of uranyl (VI) complexation by sulfate

Meinrath¹,

Lis²,

Piskuła³

et al. 2006

The Journal of Chemical Thermodynamics

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Quantitative evaluation of Ln(III) pyridine N-oxide carboxylic acid spectra under chemometric and metrological aspects

Cited by 11 publications

References 21 publications

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

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

Chemometrics in f-element speciation: a metrological challenge?

An application of the total measurement uncertainty budget concept to the thermodynamic data of uranyl (VI) complexation by sulfate

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