Method Of Bjerrum Research Articles

Metal ion interactions with drugs: Electrochemical study of complexation of various bivalent metal ions with nimesulide and ibuprofen

The present study reports the stability constants of complexes of two NSAIDs: nimesulide and ibuprofen with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Sn2+, Hg2+ and Pb2+ ions in water–ethanol medium 50% v/v at three different temperatures (298K, 308K and 318K), keeping ionic strength constant (0.1M KNO3). Experiments were conducted in 1000mL jacketed glass reaction vessels under nitrogen atmosphere. Hydrogen ion concentrations were measured and the stability constants were calculated from the pH-metric titration curves. The order of the stability constants of the formed complexes decreases in the sequence Cu2+>Co2+>Cd2+>Zn2+>Ni2+>Sn2+>Pb2+≈Hg2+ for nimesulide (D1) and Cu2+>Co2+>Zn2+>Ni2+>Cd2+>Sn2+>Pb2+>Hg2+ for ibuprofen (D2). The effect of temperature was also studied and the corresponding thermodynamic functions ΔG, ΔH and ΔS were derived and discussed. The formation of metal complexes has been found to be spontaneous and entropically favorable. The method of Calvin and Bjerrum as adopted by Irving and Rossotti has been employed to determine log K1 values. This order is in good agreement with the Irving–Williams order of stability.

Usage of Layer-by-Layer Method for Obtaining Polyelectrolyte Multilayer Films Containing Transition Metal Cations

<p>The alternating layer-by-layer deposition of oppositely charged polyelectrolytes at solid substrates is an attractive technique for preparation of nanostructured surface coatings of controlled thickness. This paper reports the results of covalently binding of cobalt (II) and copper (II) ions within polyelectrolyte multilayers (PEMs). We have used polycation as polyethyleneimine (BPEI) and polyanion as poly(acrylic acid) (PAA) and the electrostatic layer-by-layer assembly technique to make uniform thin film coating on solid template with controllable thickness. Thermodynamic characteristics as stability constant, free Gibbs energy, enthalpy and entropy of complex forming processes of these polyelectrolytes with Co(II) and Cu(II) cations in solution were calculated by modified method of Bjerrum. The correlation between log β values and some of the fundamental properties of the metal ions are discussed. It was found that the ratio of Me:L in water solvent is 1:4 in the investigating systems Cu<sup>2+</sup>:BPEI and Co<sup>2+</sup>:BPEI and in the systems Cо<sup>2+</sup>:PAA and Cо<sup>2+</sup>:PAA - 1:2. PEMs were deposited onto silicon wafers, glass slides, or coated on silica oxide particles. Dipping solutions of different pH were used in order to find the optimum conditions for absorbing maximum amount of metal cations. These PEMs films are found to offer high capacity and selectivity for copper over cobalt in both acidic and alkaline media. Preliminary investigation have shown that metal containing PEMs has catalytic activity for oxidation of toluene with molecular in mild condition. The alternating layer-by-layer deposition of oppositely charged polyelectrolytes at solid substrates is an attractive technique for preparation of nanostructured surface coatings of controlled thickness. This paper reports the results of covalently binding of cobalt (II) and copper (II) ions within polyelectrolyte multilayers (PEMs). We have used polycation as polyethyleneimine (BPEI) and polyanion as poly(acrylic acid) (PAA) and the electrostatic layer-by-layer assembly technique to make uniform thin film coating on solid template with controllable thickness. Thermodynamic characteristics as stability constant, free Gibbs energy, enthalpy and entropy of complex forming processes of these polyelectrolytes with Co(II) and Cu(II) cations in solution were calculated by modified method of Bjerrum. The correlation between log β values and some of the fundamental properties of the metal ions are discussed. It was found that the ratio of Me:L in water solvent is 1:4 in the investigating systems Cu<sup>2+</sup>:BPEI and Co<sup>2+</sup>:BPEI and in the systems Cо<sup>2+</sup>:PAA and Cо<sup>2+</sup> :PAA - 1:2. PEMs were deposited onto silicon wafers, glass slides, or coated on silica oxide particles. Dipping solutions of different pH were used in order to find the optimum conditions for absorbing maximum amount of metal cations. These PEMs films are found to offer high capacity and selectivity for copper over cobalt in both acidic and alkaline media. Preliminary investigation have shown that metal containing PEMs has catalytic activity for oxidation of toluene with molecular in mild condition.</p>

Synthesis of di( 4-chlorophenyl)carbazone and its acidity with bivalent metal ions in solution

Stability constants of the complexes of Mn I I , Co I I , Cd I I , Zn I I , Cu I I and Ni I I with dl(4-chlorophenyl)carbazone (DPClPC) have been determined pH-metrically in 50% (v/v) aqueous-dioxan at an ionic strength of 0.1 M NaClO 4 at different temperatures. The method of Bjerrum and Calvin, as modified by Irving and Rossotti, has been used to find out the values of n and pL. The order of stability constants is found to be: Mn I I < Co I I < Cd I I < Ni I I = Zn I I < Cu I I . Thermodynamic parameters have also been calculated.

Synthesis, Characterization and Thermodynamic Studies on Lanthanide(III) Complexes of Diphenylcarbazone and di(2,3-Dichlorophenyl)Carbazone

Lanthanide(III) complexes of diphenylcarbazone (DPC) and its substituted derivative di(2. 3-dichlorophenyl)carbazonc (D2,3DC1PC) of the composition Ln[(DPC)2(NO3)2]NO3·2H2O and Ln[(D2,3DC1PC)2(NO3)2]NO3·2H2O have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic measurements, electronic, infrared and 1H NMR spectral techniques. The molar conductance of the complexes in DMF suggests them to be 1:1 electrolytes. The diphenylcarbazones behave as bidentate neutral ligands coordinating through the ketonic oxygen and azo nitrogen. Thermal studies show the presence of water molecules outside the coordination sphere. It has been observed that the ligands and their complexes are toxic towards bacteria and fungi. Potentiometric studies have been carried out by the method of Bjerrum and Calvin, as modified by Irving and Rossotti, in 50% (v/v) dioxane-waler (μ = 0.1 M NaClO4) at 25°. 35° and 45°C. The thermodynamic parameters viz., ΔG°. AH” and δ DS° of the metal chelates have also been evaluated. The validity of Born's relation was examined by studying the plot of log K 1 values vs Z2/r.

Stabilities of mixed metal complexes with biologically active colchiceine in dioxan-water and their relation to quantitative softness values: A new approach

Equilibria between colchiceine and protons or bivalent metal ions and mixed metal ions have been investigated potentiometrically. The method of Bjerrum and Calvin, as modified by Irving and Rossotti [1] has been used to find the values ofn andpL. Stability constants have been calculated using NBAR and weighted least-squares programmes. The values ofS min=χ2 have also been calculated. The order of stability constants for bivalent metal complexes was found to be: Zn Ni > Co > Cd > Mn > Mg and for mixed metal complexes: Cu-Ni > Cu-Zn > Cu-Cd. A linear relationship was observed between logK 1 and the softness values of the complexes.

Chelation behaviour of biologically activeo-hydroxy naphthaldehyde derivatives with bivalent metal ions in different solvents: A potentiometric study

Equilibria between the derivatives ofo-hydroxy naphthaldehyde and protons or bivalent metal ions have been investigated potentiometrically at constant ionic strength while varying the solvents in definite ratios (solvent: water). The method of Bjerrum and Calvin as modified by Irving and Rossotti (1954) has been used to find the values of $$\tilde n$$ and pL. The formation constants of metal chelates have been calculated using a weighted least squares method. The values of $$S_{\min } = \chi ^2 $$ have also been calculated. The order of stability constants is determined as Mg2+<Mn2+<Cd2+<Pb2+<Zn2+<Co2+<Ni2+<Cu2+<UO 2 2+ Solvent effects on stability constants and comparative studies of both the derivatives ofo-hydroxy naphthaldehyde have been reported.

Stabilities of some bivalent transition metal ions with 2-hydroxy naphthaldehyde semicarbazones and thiosemicarbazones in dioxane-water mixtures: A potentiometric study

Equilibria between 2-hydroxy naphthaldehyde derivatives (semicarbazone and thiosemicarbazone) and proton or some bivalent metal ions have been investigated potentiometrically at a constant ionic strength and different compositions of the mixed solvent (dioxane: water). The method of Bjerrum and Calvin [1, 2], as modified by Irving and Rossotti [3], has been used to determine the values ofn andpL. The stability constants have been calculated following Sullivan et al. [4] to give β n values. The values ofS min=χ2 have also been calculated. The order of stability constants was found to be found to be UO 2 2+ > Cu2+ > Ni2+ > Co2+ > Zn2+ > Pb2+ > Cd2+ > Mn2+ > Mg2+. The effect of varying the dielectric constant of the medium on the stability constants of the complexes has also been investigated at an ionic strength of 0.100M NaClO4 and a temperature of 20±0.5°C.

Potentiometric studies on the complexation equilibria between some trivalent lanthanide metal ions and biologically active 2-hydroxy-1-naphthaldehyde thiosemicarbazone (HNATS)

The chelation behaviour of some trivalent lanthanide and yttrium metal ion with biologically active 2-hydroxy-1-naphthaldehyde thiosemicarbazone (HNATS) has been investigated by potentiomotric measurements at 20±0.5°C in 75% (v/v) dioxane-water medium at various ionic strengths of sodium perchlorate. The method of Bjerrum and Calvin, as modified by Irving and Rossotti has been used to find out the values of\(\bar n\) (average number of ligand bound per metal ion) andpL (free ligand exponent). The formation constants of metal chelates have been computed on a PC-XT computer, using a program patterned after that of Sullivan et al. to give βn values using weighted least squares method. TheSminvalues (Smin=χ2) have been calculated. The order of formation constants of chelates was found to be: La3+<Ce3+<Pr3+<Nd3+<Sm3+<Eu3+<Gd3+<Y3+<Tb3+<Dy3+. The formation constants of the chelates formed have been correlated to size and ionization potentials of the metal ions.

Evaluation of thermodynamic functions for complexation reactions involving bivalent metal ions and ethyl-2,3-dioxobutyrate-2p-bromophenylhydrazone

Complexation reactions of bivalent metal ions and ethyl-2,3-dioxobutyrate-2p-bromophenylhydrazone (EDOB-2p-BPH) have been studied potentiometrically in 50% (v/v) ethanol/water medium at different ionic strengths with respect to NaClO4 and at different temperatures and their stability constants determined. The method of Bjerrum and Calvin as modified by Irving and Rossotti has been used to determine then andpL values. Smin values which have the same significance as ‘T2’ have also been calculated. The thermodynamic stability constants and standard free energy change (ΔG) have also been calculated. ΔG values are negative in all cases indicating that the reactions are spontaneous. The ligand field stabilization energy (δH) has also been calculated for the 3d transition metals.

Ligational behaviour of ethyltrifluoroacetoacetate towards some tervalent lanthanons in aqueous-dioxane mixture

Thermodynamic step-wise formation constants (log T K n ) of some tervalent lanthanons, namely La, Pr, Nd, Sm, Eu, Gd, Dy, Er and Lu, with ethyltrifluoroacetoacetate, a fluorinated β-ketoester, have been determined pH-metrically in a 50 vol.% dioxane-water mixture at 25 and 35±0.01°C. The method of Bjerrum and Calvin, as modified by Van Uitert and Haas, was used to calculate the formation functions n̄ and free anion concentrations [L −]. Thermodynamic formation constants, calculated on a high-speed computer following a weighted least-squares method, follow the order La < Pr < Nd < Sm < Eu ⩾ Gd ⩾ Dy < Er < Lu. Standard thermodynamic parameters Δ GXXX, Δ HXXX and Δ SXXX associated with their first stepwise formation constant have also been evaluated. Speciation diagrams are depicted in three dimensions. An analysis of error is shown by plotting the weighted deviations against a tested variable. The choice of equilibrium model is justified by statistical analyses of S min values, goodness-of-fit (GOF) and Abrahams-Keve-type normal probability plots.

Physico-chemical studies on the chelation behaviour of biologically active 2-hydroxy-1-naphthaldehyde semicarbazone (HNAS) with some lanthanons

The chelation behaviour of the complexes of La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Y3+, Tb3+, Dy3+, Ho3+ with biologically active 2-Hydroxy-1-naphthaldehyde semicarbazone (HNAS) has been studied potentiometrically in 75% (v/v) dioxane-water medium at various ionic strengths. The method of Bjerrum and Calvin, as modified by Irving and Rossotti has been used to find out the values of n andpL. The formation constants of metal chelates and the values ofSmin have been calculated. The order of formation constants of chelates was found to be: La3+<Ce3+<Pr3+<Nd3+<Sm3+<Eu3+<Gd3+<Y3+<Tb3+<Dy3+<Ho3+.

Determination of thermodynamic parameters and equilibrium constants for complexation reactions involving lanthanon(III) ions with 1,2-naphthoquinone-2-semicarbazone-4-sulphonic acid (sodium salt) (NQS · 4S)

The thermodynamic parameters and equilibrium constants of complexation reactions of 1,2-naphthoquinone-2-semicarbazone-4-sulphonic acid (sodium salt) (NQS · 4S) involving lanthanon ions were evaluated by potentiometric estimation of [H +], in aqueous medium at various ionic strengths (0.02, 0.05, 0.10 and 0.20 M NaClO 4) and at different temperatures (20, 30, 40 and 50±0.5°C). The − n and pL values calculated by the method of Bjerrum and Calvin, as modified by Irving and Rossotti, were used for the calculation of the equilibrium constants on an HCL Busy Bee PC/AT computer using the weighted least-squares method. The values of S min were also evaluated. The order of equilibrium constants was found to be Ho(III) > Dy(III) > Tb(III) > Y(III) > Eu(III) > Sm(III) > Gd(III) > Nd(III) > Pr(III) > Ce(III) > La(III). The thermodynamic parameters Δ G, Δ H and Δ S were also calculated at a fixed temperature (30±0.05°C) and ionic strength (0.10 M NaClO 4).

Smear Effects of Vertical Drains on Soft Bangkok Clay

Smear effects due to the installation of prefabricated vertical drains were studied in the laboratory using special equipment and in the field using a full‐scale test embankment. The prefabricated vertical drains were installed by two different sizes of mandrel. The test results showed that the smear zone can be assumed to be twice the equivalent mandrel diameter and the horizontal permeability coefficient in the smeared zone, kh′, was approximately equal the vertical permeability coefficient in the undisturbed zone, kv. A faster settlement rate and higher amounts of compression were observed in the small mandrel area than in the large mandrel area, suggesting lesser smear effects in the former than in the latter. The total settlement prediction using the method of Skempton and Bjerrum of 1957, with stress distribution using Poulos's 1967 method, yielded reasonable agreement with the observed values. More accurate settlement‐rate predictions can be obtained using Asaoka's 1978 method when the prediction was based on settlement data having at least 60% consolidation.

Investigation of complexation equilibria and evaluation of thermodynamic parameters of complexes of bivalent metal ions with 2,4-pentanedione-1-(3-chlorophenylhydrazone),PD3CPH

Thermodynamic stability constants of the complexes of various dipositively charged metal ions, UO 2(II), Cu(II), Zn(II), Cd(II), Ni(II), Co(II) and Mn(II), with 2,4-pentanedione-1-(3-chlorophenylhydrazone) have been determined potentiometrically, in 50% (v/v) dioxan-water medium, at different temperatures and ionic strengths. The stability constants and S min values have been calculated at different ionic strengths and temperatures. The method of Bjerrum and Calvin, as modified by Irving and Rossotti, has been used to find out the values of n̄ and pL. The thermodynamic parameters Δ G, Δ H and Δ S have also been evaluated from temperature-dependent data

Studies on the complexation behaviour of dehydroacetic acid-4-methyl-2-quinolylhydrazone with bivalent metal ions

The complexation behaviour of bivalent metal complexes of dehydroacetic acid-4-methyl-2-quinolylhydrazone (DAMQH) has been studied potentiometrically in 75% (v/v) aqueous dioxan medium at different ionic strengths with respect to sodium perchlorate and at different temperature in order to determine their stability constants. The method of Bjerrum and Calvin as modified by Irving and Rossotti has been used to determine the {ie497-1} andp L values.S min values which have the same significance as ‘x 2’, have also been calculated. The thermodynamic stability constants and the standard free energy change (ΔG) have also been calculated. ΔG values are negative in all cases. Thus complexation is spontaneous. The order of stability constants of bivalent metal complexes of DAMQH has been determined.

A study of the chelation behaviour of bivalent metal complexes of biologically active 2-hydroxy-1,4-naphthoquinone monoxime (HNQM) in dioxan-water mixtures

Equilibria between 2-hydroxy-1,4-naphthoquinone monoxime and proton or bivalent metal ions have been investigated potentiometrically at various ionic strengths and solvent compositions (dioxan : water). The method of Bjerrum and Calvin, as modified by Irving and Rossotti, was used to determine the values of n and p L. The stability constants were calculated using an IBM 360 computer, by the weighted least-squares method. The values of S min = X 2 were also calculated. The stability constants were found to decrease in the order. Cu > Ni > Co > Zn > Pb > Cd > Mn > Mg Other thermodynamic parameters and ligand field stabilization energies were calculated from the stability constants.

Thermodynamic stabilities of lanthanide complexes with 3-hydroxy-2-methyl-1,4-naphthoquinone (HMNQ)

The thermal behaviour of complexes of La(III), Pr(III), Nd(III), Y(III), Sm(III) and Tb(III) with 3-hydroxy-2-methyl-1,4-naphthoquinone has been studied potentiometrically in 75% ( v v ) aqueous dioxan medium at various temperatures. The method of Bjerrum and Calvin, as modified by Irving and Rossotti, has been used to find values of n̄ and p L. The stability constants have been calculated on an IBM 360 computer using the weighted least-squares method. The values of S min have also been calculated. The order of stability constants was found to be La < Pr < Nd < Sm < Tb. Thermodynamic parameters (Δ G, Δ H and Δ S) of the complexation reactions have also been calculated.

Determination of stability constants and thermodynamic parameters of complexes of diacetylmono(LEPIDYL)hydrazone (DALH) with lanthanons

The consecutive stability constants of the 1:1 and 2:1 chelate species formed by the interaction of diacetylmono(lepidyl)hydrazone (DALH) with lanthanon ions have been determined potentiometrically at various ionic strengths (0.02, 0.05, 0.1 and 0.2 M NaCl) and temperatures (25, 30, 40 and 50°C±0.5°C) in 75% ethanol/water medium. The method of Bjerrum and Rossotti was used to calculate the values of - n and p L. Stability constants, and the values of S min and the thermodynamic parameters Δ G, Δ H and Δ S are reported.

Thermodynamic stabilities of metal complexes of the biologically active complexing agent, 2-acetylpyridine semicarbazone (2-APS)

The stability constants of the chelates formed by 2-acetylpyridine semicarbazone with UO 2(II), Cu(II), Ni(II), Pb(II), Co(II), Zn(II) and Cd(II) have been determined pH-metrically in 75% (v/v) aqueous dioxan at various temperatures. The method of Bjerrum and Calvin [M. Calvin and K.W. Wilson, J. Am. Chem. Soc., 67 (1945) 2003; J. Bjerrum, Metal Ammine Formation in Aqueous Solution, Haase, Copenhagen, 1941] as modified by Irving and Rossotti [H.M. Irving and H.S. Rossotti, J. Chem. Soc., (1954) 2904] has been used to determine the t̄ n and pL values. The stability constants β have been computed on a VAX-11/750 computer using the weighted least-squares method patterned after that of Sullivan et al. [J.C. Sullivan, J. Rydberg and W.F. Miller, Acta Chem. Scand. 13 (1959) 2023]. The thermodynamic functions Δ G, Δ H and Δ S have also been calculated.

Thermal studies on the chelation behaviour of bivalent metal complexes of biologically active 2-hydroxy-l-naphthaldehyde monosemicarbazone (HNAS)

Thermal behaviour of bivalent metal complexes with 2-hydroxy-1-naphthaldehyde monosemicarbazone (HNAS) has been studied potentiometrically in 75% (v/v) aqueous dioxan medium at various temperatures. The method of Bjerrum and Calvin [J. Bjerrum, Metal Amino Formation of Aqueous Solution, Hasse, Copenhagen, 1941, p. 298; M. Calvin and K.W. Wilson, J. Am. Chem. Soc., 67 (1945) 2003] as modified by Irving and Rossotti [H.M. Irving and H.S. Rossotti, J. Chem. Soc. (1954) 2904] has been used to calculate the values of n̄ and pL. The stability constants have been calculated on an IBM 360 FORTRAN IV computer using the weighted least-squares method. The values of S min have also been calculated. The order of stability constants was found to be UO 2 > Cu > Ni > Co > Zn > Pb > Cd > Mn > Mg. The other thermodynamic parameters (Δ G, Δ H and Δ S) have been calculated from the stability constants obtained for different temperatures at constant ionic strength.