The affinity of aldehydic compounds to complex formation. Nickel(II) and cobalt(II) complexes with 2-pyridinecarboxaldehyde

1977 ◽  
Vol 55 (14) ◽  
pp. 2613-2619 ◽  
Author(s):  
M. S. El-Ezaby ◽  
M. A. El-Dessouky ◽  
N. M. Shuaib
Keyword(s):  
Complex Formation ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Metal Ion ◽  
Experimental Conditions ◽  
Complex Species ◽  
Spectrophotometric Methods ◽  
Complex Equilibria ◽  
The Stability ◽  
Hydroxy Groups

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M (KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

Palladium(II) sequestration by phytate in aqueous solution - speciation analysis and ionic medium effects

2010 ◽  
Vol 7 (3) ◽  
pp. 259 ◽  
Author(s):  
Antonio Gianguzza ◽  
Demetrio Milea ◽  
Alberto Pettignano ◽  
Silvio Sammartano
Keyword(s):  
Stability Constants ◽  
Urban Areas ◽  
Metal Ion ◽  
Empirical Relationship ◽  
Speciation Analysis ◽  
Stable Complex ◽  
Experimental Conditions ◽  
Complex Species ◽  
Ionic Medium ◽  
The Stability

Environmental context.In the last 20 years, the demand for palladium and other platinum-group elements has intensified, causing a significant increase in their concentration in the environment, with particular accumulation in urban areas. Knowledge about Pd2+ speciation in aqueous media is fundamental for the understanding of its biological and environmental activity in contaminated areas. Phytic acid appears to be a good sequestering agent towards Pd2+ under various conditions, indicating its potential use in the remediation of contaminated sites. Abstract. Palladium(II) speciation in the presence of phytate (Phy12–) was studied by H+ ion selective electrode (ISE) potentiometry at 25°C in NaNO3(aq) and in NaCl(aq) at ionic strength I = 0.1 mol L–1, in order to evaluate the effect of the ionic medium on the sequestering ability of phytate towards palladium(II). Owing to the discrepancies found in the literature on both the nature and the stability of hydrolytic species formed by this cation, Pd2+ hydrolysis was studied under the same experimental conditions as phytate/PdII measurements. As palladium(II) forms stable complex species with the chloride ion, the stability constants of various Pd2+–Cl– species were also calculated, as well as those of weak species formed with nitrate. The stability constants of six palladium(II)–phytate species, namely PdPhyOH11–, PdPhy10–, PdPhyH9–, PdPhyH28–, PdPhyH37– and PdPhyH46–, were determined. The sequestering ability of this ligand towards Pd2+ was evaluated by the calculation of various pL50 values (total ligand concentrations, as antilogarithm, necessary to bind the 50% of the metal ion as a trace present in the solution) under different conditions. Phytate sequestering ability towards palladium(II) was then compared with that towards other divalent cations under various conditions. Finally, the dependence of pL50 on pH was modelled by a simple empirical relationship.

A spectrophotometric study of the complex formation between cobalt(III) and trans-1,2-cyclohexanedinitrilotetraacetic acid (CyDTA)

1979 ◽  
Vol 57 (17) ◽  
pp. 2292-2296 ◽  
Author(s):  
Rita K. Hessley ◽  
Shoba Waykole ◽  
Robert L. Sublett
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Spectrophotometric Study ◽  
Higher Order ◽  
Order Complex ◽  
Spectrophotometric Methods ◽  
Investigation Result ◽  
Unique System ◽  
The Stability

An intriguing and unique system has been observed during the otherwise routine study of the cobalt(III) complex of trans-1,2-cyclohexanedinitrilotetraacetic acid (CyDTA). Using classical spectrophotometric methods to determine the stoichiometry and the stability of a complex, significant deviations from the predicted 1:1 complex were observed in a system buffered at pH = 4.6. It is postulated that in addition to the usual 1:1 complex, the propensity of the reactants to form complexes and the strong oxidizing conditions used in this investigation result in the formation of a second, higher order complex between Co(III) and CyDTA. When the concentration of CyDTA exceeds that of Co(III), the metal:ligand ratio for this complex is 1:2. A structure is proposed, and approximate stability constants of both complexes are discussed.

Complexes du germanium(IV) et du bore(III) avec des o-diphénols substitués

1969 ◽  
Vol 47 (14) ◽  
pp. 2569-2571 ◽  
Author(s):  
R. Meilleur ◽  
R. L. Benoit
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Acidity Constants ◽  
Spectrophotometric Methods ◽  
The Stability

Complex formation between germanium(IV) and boron(III) and some substituted o-diphenols H2L has been studied by potentiometric and spectrophotometric methods. Correlations are established between the stability constants of GeL32− and BL(OH)2− complexes and the acidity constants of the diphenols.

The stability constants of ethylenediphosphinetetraacetate complexes

1982 ◽  
Vol 47 (4) ◽  
pp. 1078-1085 ◽  
Author(s):  
Jana Podlahová ◽  
Jaroslav Podlaha
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Stability Constants ◽  
Metal Ion ◽  
Computer Programs ◽  
Data Treatment ◽  
Relative Affinity ◽  
Stability Constants Of Complexes ◽  
Soft Metal ◽  
The Stability

The stability constants of complexes formed by the anions of ethylenediphosphinetetraacetic acid and the metal ions Cu(I), Ag(I), Ca(II), Mn(II), Fe(II), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II) and La(III) were determined by various methods (mainly potentiometry and UV-VIS spectrophotometry), followed by data treatment using standard computer programs. The type and stability of the complexes formed depend mostly on the relative affinity of the particular metal ion for the two donor groups of the ligand. Unlike EDTA, the ligand is highly selective for soft metal ions, whose complexes are very stable even in strongly acidic aqueous solutions.

Study of the properties of pyridine-2-azo-p-phenyltetramethylguanidine as a metal ion complexing agent

1991 ◽  
Vol 69 (8) ◽  
pp. 1238-1244 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Arnold Jarczewski
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Metal Ion ◽  
Nmr Spectra ◽  
Dissociation Constants ◽  
Activation Parameters ◽  
Complexing Agent ◽  
The Stability ◽  
Metal Ligand ◽  
C Nmr

Pyridine-2-azo-p-phenyltetramethylguanidine (PAPT) was synthesized and the properties of this compound examined. The dissociation constants of the conjugate acids in H2O are [Formula: see text] and [Formula: see text] at 25 °C at I = 0.1, and in acetonitrile are [Formula: see text] and [Formula: see text]. The properties of metal–ligand chelates in acetonitrile have been examined and the stability constants for Ni2+, Co2+, and Zn2+ complexes measured. The rates of reaction of PAPT with Ni2+, Co2+, and Zn2+ in acetonitrile have been determined and the activation parameters measured for the complex formation of LNi2+. The stability constants for both complexing centres of PAPT have been calculated. The 13C NMR spectra for PAPT and LNi2+ are quoted. The expected enhancement of the metal ion complexing ability of PAPT due to the strongly electron-releasing nature of the tetramethylguanidinyl group was not found. Key words: metal ion complexes, pyridine-2-azo-p-phenyltetramethylguanidine, stability constants, pKa.

Comparison of spectrophotometric methods of determination of zinc(II) in biological material and study of its complex formation reactions with 4-(2-pyridylazo)resorcinol

1979 ◽  
Vol 44 (3) ◽  
pp. 725-741 ◽  
Author(s):  
Miloš Pollák ◽  
Vlastimil Kubáň
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Biological Material ◽  
Complex Species ◽  
Fundamental Parameters ◽  
Methods Of Determination ◽  
Spectrophotometric Methods

The methods of determination of Zn(II) with dithizone, zincone, PAN, and PAR were compared by considering the fundamental parameters of the photometric methods. The compositions, values of the molar absorptivities, and values of the equilibrium and stability constants of the complex species MLH, ML, ML2H2, ML2H, and ML2 of zinc(II) with PAR were determined graphically by means of the slope-intercept transformations, and numerically from the absorbance-pH curves and from the absorbance dependences on the component concentrations by employing the program PRCEK T200 and from the continual variations curves by using the program JOBCON.

scholarly journals Effective replacement of cetyltrimethylammonium bromide (CTAB) by mercaptoalkanoic acids on gold nanorod (AuNR) surfaces in aqueous solutions

Nanoscale ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 658-668 ◽  
Author(s):  
Rafael del Caño ◽  
Jose M. Gisbert-González ◽  
Jose González-Rodríguez ◽  
Guadalupe Sánchez-Obrero ◽  
Rafael Madueño ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Gold Nanorods ◽  
Ligand Exchange ◽  
Cetyltrimethylammonium Bromide ◽  
Gold Nanorod ◽  
Experimental Conditions ◽  
Seed Mediated ◽  
The Stability

The highly packed cetyltrimethylammonium bromide bilayer on the surface of gold nanorods synthesized by the seed-mediated procedure hampers the complete ligand exchange under experimental conditions that preserves the stability of the dispersions.

scholarly journals Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Dariusz Wyrzykowski ◽  
Joanna Pranczk ◽  
Dagmara Jacewicz ◽  
Aleksandra Tesmar ◽  
Bogusław Pilarski ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Substitution Reactions ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Hydroxo Complexes ◽  
Binary Complexes ◽  
Vis Spectroscopy ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Ph Range

AbstractA potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.

SODIUM CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID

1963 ◽  
Vol 41 (1) ◽  
pp. 18-20 ◽  
Author(s):  
Vladimir Palaty
Keyword(s):  
Stability Constant ◽  
Stability Constants ◽  
Ethylenediaminetetraacetic Acid ◽  
Glass Electrode ◽  
Neutral Solution ◽  
Experimental Conditions ◽  
The Stability ◽  
Sensitive Method

The stability constant of the sodium chelate of EDTA was determined by means of a sodium-sensitive glass electrode. It appears that a hydrogen chelate of the formula NaHY2− is formed in the neutral solution of EDTA, but is very unstable. The stability constants, pKNaY = −2.61 and pKNaHY = 0.03, are comparable to the value obtained by Schwarzenbach and Ackermann under different experimental conditions by a less sensitive method.

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