The Effect of Metal Cations on the Aqueous Behavior of Dopamine. Thermodynamic Investigation of the Binary and Ternary Interactions with Cd2+, Cu2+ and UO22+ in NaCl at Different Ionic Strengths and Temperatures

The interactions of dopamine [2-(3,4-Dihydroxyphenyl)ethylamine, (Dop−)] with cadmium(II), copper(II) and uranyl(VI) were studied in NaCl(aq) at different ionic strengths (0 ≤ I/mol dm−3 ≤ 1.0) and temperatures (288.15 ≤ T/K ≤ 318.15). From the elaboration of the experimental data, it was found that the speciation models are featured by species of different stoichiometry and stability. In particular for cadmium, the formation of only MLH, ML and ML2 (M = Cd2+; L = dopamine) species was obtained. For uranyl(VI) (UO22+), the speciation scheme is influenced by the use of UO2(acetate)2 salt as a chemical; in this case, the formation of ML2, MLOH and the ternary MLAc (Ac = acetate) species in a wide pH range was observed. The most complex speciation model was obtained for the interaction of Cu2+ with dopamine; in this case we observed the formation of the following species: ML2, M2L, M2L2, M2L2(OH)2, M2LOH and ML2OH. These speciation models were determined at each ionic strength and temperature investigated. As a further contribution to this kind of investigation, the ternary interactions of dopamine with UO22+/Cd2+ and UO22+/Cu2+ were investigated at I = 0.15 mol dm−3 and T = 298.15K. These systems have different speciation models, with the MM’L and M2M’L2OH [M = UO22+; M’ = Cd2+ or Cu2+, L = dopamine] common species; the species of the mixed Cd2+ containing system have a higher stability with respect the Cu2+ containing one. The dependence on the ionic strength of complex formation constants was modelled by using both an extended Debye–Hückel equation that included the Van’t Hoff term for the calculation of the formation enthalpy change values and the Specific Ion Interaction Theory (SIT). The results highlighted that, in general, the entropy is the driving force of the process. The quantification of the effective sequestering ability of dopamine towards the studied cations was evaluated by using a Boltzmann-type equation and the calculation of pL0.5 parameter. The sequestering ability was quantified at different ionic strengths, temperatures and pHs, and this resulted, in general, that the pL0.5 trend was always: UO22+ > Cu2+ > Cd2+.

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Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

Molecules ◽

10.3390/molecules25030511 ◽

2020 ◽

Vol 25 (3) ◽

pp. 511 ◽

Cited By ~ 1

Author(s):

Francesco Crea ◽

Concetta De Stefano ◽

Anna Irto ◽

Gabriele Lando ◽

Stefano Materazzi ◽

...

Keyword(s):

Ionic Strength ◽

Complex Formation ◽

Formation Constants ◽

Titration Calorimetry ◽

Interaction Theory ◽

Thermodynamic Investigation ◽

Experimental Conditions ◽

Complex Formation Constants ◽

Specific Ion Interaction Theory ◽

Enthalpy Changes

The interactions of epinephrine ((R)-(−)-3,4-dihydroxy-α-(methylaminomethyl)benzyl alcohol; Eph−) with different toxic cations (methylmercury(II): CH3Hg+; dimethyltin(IV): (CH3)2Sn2+; dioxouranium(VI): UO22+) were studied in NaClaq at different ionic strengths and at T = 298.15 K (T = 310.15 K for (CH3)2Sn2+). The enthalpy changes for the protonation of epinephrine and its complex formation with UO22+ were also determined using isoperibolic titration calorimetry: ΔHHL = −39 ± 1 kJ mol−1, ΔHH2L = −67 ± 1 kJ mol−1 (overall reaction), ΔHML = −26 ± 4 kJ mol−1, and ΔHM2L2(OH)2 = 39 ± 2 kJ mol−1. The results were that UO22+ complexation by Eph− was an entropy-driven process. The dependence on the ionic strength of protonation and the complex formation constants was modeled using the extended Debye–Hückel, specific ion interaction theory (SIT), and Pitzer approaches. The sequestering ability of adrenaline toward the investigated cations was evaluated using the calculation of pL0.5 parameters. The sequestering ability trend resulted in the following: UO22+ >> (CH3)2Sn2+ > CH3Hg+. For example, at I = 0.15 mol dm−3 and pH = 7.4 (pH = 9.5 for CH3Hg+), pL0.5 = 7.68, 5.64, and 2.40 for UO22+, (CH3)2Sn2+, and CH3Hg+, respectively. Here, the pH is with respect to ionic strength in terms of sequestration.

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Ionic Strength Dependence of Formation Constants, Protonation and Complexation of Phenylalanine with Dioxovanadium(V) at different temperatures

Journal of Chemical Research ◽

10.3184/030823400103166896 ◽

2000 ◽

Vol 2000 (4) ◽

pp. 186-187 ◽

Cited By ~ 19

Author(s):

Farrokh Gharib ◽

Karim Zare ◽

Kavosh Majlesi

Keyword(s):

Ionic Strength ◽

Stability Constants ◽

Sodium Perchlorate ◽

Type Equation ◽

Formation Constants ◽

Ionic Strength Dependence ◽

Different Temperatures ◽

Strength Dependence ◽

The Stability ◽

Ph Range

The protonation constants of phenylalanine and the stability constants of the complexes between dioxovanadium(V) ion and phenylalanine have been determined spectrophotometrically, in the temperature range 15–35°C and ionic strength ranging from 0.1 to 1.5 mol dm−3 sodium perchlorate as a background salt, in the pH range 1.5–10.5, with high ligand to metal ratios. The values of enthalpy and entropy changes based on these formation constants were calculated. The dependence of protonation and the stability constants on ionic strength are described by a Debye-Huckel type equation.

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Adsorption of hexavalent chromium on dunite

Water Science & Technology ◽

10.2166/wst.2011.118 ◽

2011 ◽

Vol 63 (4) ◽

pp. 818-824 ◽

Cited By ~ 1

Author(s):

Antri Demetriou ◽

Ioannis Pashalidis

Keyword(s):

Experimental Data ◽

Ionic Strength ◽

Metal Ion ◽

Outer Sphere ◽

Atmospheric Conditions ◽

Adsorption Model ◽

Wide Ph Range ◽

Ph Range ◽

Relative Adsorption ◽

Outer Sphere Complexes

The paper presents and discusses the effect of various physicochemical parameters (e.g. pH, ionic strength, Cr(VI) initial concentration, amount of the adsorbent, temperature and contact time between metal ion and adsorbent) on the adsorption efficiency of Cr(VI) on dunite in aqueous solutions under atmospheric conditions. Evaluation of the experimental data shows that dunite presents increased affinity for Cr(VI) over a wide pH range and Cr(VI) concentration, and the experimental data are well fitted by the Kd adsorption model. The relative adsorption is pH dependent and decreases slightly (about 10%) with increasing pH, because of changes in the surface charge of the solid. The effect of the ionic strength is significant (particularly at low pH), indicating the predominance of outer-sphere complexes. Moreover, adsorption experiments at various temperatures, two different pH values (pH 3 and pH 8) and three different ionic strengths (0.0, 0.1 and 1.0 M NaClO4), indicate an endothermic but spontaneous entropy-driven processes.

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The interaction of morin and morin-5’-sulfonic acid with lead(II): Study of the 1:1 complex formation process in aqueous solution

Main Group Metal Chemistry ◽

10.1515/mgmc-2019-0007 ◽

2019 ◽

Vol 42 (1) ◽

pp. 67-72

Author(s):

Maxim A. Lutoshkin ◽

Boris N. Kuznetsov ◽

Vladimir A. Levdanskiy

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Sulfonic Acid ◽

Computational Models ◽

Experimental Parameters ◽

Wide Ph Range ◽

Ph Range ◽

Aqueous Complexation ◽

Complex Formation Process

Abstract This article focuses on the aqueous complexation between two flavonoids (morin and morinsulfonate) and Pb2+ at constant ionic strength I=0.5 M (NaClO4). The determination of stability constants of ML complexes were performed at wide pH range. Two obtained constants are 14.8 ± 0.1 and 15.2 ± 0.1 logarithmic units for morin and morin-5’-sulfonic acid, respectively. For estimating the thermodynamic stability of the complexes studied, the Def2-SV(P)/DFT/PBE0/SMD method has been used. Different computational models were tested to describe the data obtained. The theoretical values of logK reproduce the experimental parameters within reasonable errors.

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Nuclear magnetic resonance and potentiometric studies of the complexation of methylmercury(II) by dithiols

Canadian Journal of Chemistry ◽

10.1139/v85-402 ◽

1985 ◽

Vol 63 (9) ◽

pp. 2430-2436 ◽

Cited By ~ 14

Author(s):

Alan P. Arnold ◽

Allan J. Canty ◽

R. Stephen Reid ◽

Dallas L. Rabenstein

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Equilibrium Constants ◽

Formation Constants ◽

Resonance Spectroscopy ◽

Nmr Study ◽

Wide Ph Range ◽

Anionic Species ◽

Ph Range ◽

Nuclear Magnetic

Complexation of methylmercury, CH3Hg(II), by 2,3-dimercaptosuccinic acid (DMSA), 2,3-dimercaptopropanesulfonate (DMPS, Unithiol), dithioerythritol (DTE), and 2,3-dimercaptopropanol (British AntiLewisite, BAL) has been studied by 1H nuclear magnetic resonance spectroscopy and by potentiometric titration. In the nmr study, the equilibrium constants for displacement of mercaptoacetate from its CH3Hg(II) complex by the dithiols were determined over a wide pH range, from mercaptoacetate chemical shift data. Similar competition reactions between the dithiols and mercaptoethanol were used in the potentiometric study. Using previously determined CH3Hg(II) formation constants for the competing ligands, equilibrium constants for the formation of mono- and bis-CH3Hg(II) complexes with the dithiols have been determined. The formation constants for the mono-CH3Hg(II) complexes with the vicinal dithiols BAL and DMPS are significantly higher than expected by consideration of the basicity of the sulfhydryl donors, in comparison with those for DMSA, non-vicinal DTE, and monothiols. We interpret this to indicate chelation of CH3Hg(II) by BAL and DMPS but not by DMSA. The conditional formation constants at physiological pH are discussed with reference to the effectiveness of BAL, DMPS, and DMSA as antidotes for methylmercury poisoning. In particular, the constants obtained indicate that, for dithiol antidotes at concentrations greater than that of methylmercury (II), methylmercury(II) complexes formed at physiological pH are of 1:1 stoichiometry. For BAL, a substantial proportion of the complex will be in the neutral form, in contrast to DMPS and DMSA which form anionic species only.

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Interaction of Dioxovanadium (V) ion with L-alanine at Different Ionic Strengths

JOURNAL OF ADVANCES IN CHEMISTRY ◽

10.24297/jac.v5i1.935 ◽

2009 ◽

Vol 5 (1) ◽

pp. 570-574

Author(s):

Mohammad Hossein Fekri ◽

F. Gharib ◽

M. Darvishpour

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Stability Constants ◽

Least Squares Method ◽

Type Equation ◽

Formation Constants ◽

Amino Group ◽

Fitting Method ◽

The Stability ◽

Curve Fitting Method

The formation constants of species formed in the system H+ + alanine and VO2+ +alanine have been determined in aqueous solution for 1.0<pH<7.0 and at different ionic strengths ranging from 0.1 to 1.0 mol dm-3 NaClO4, using a combination of potentiometric and spectrophotometric techniques.The compositions of the formd complexes and their stability constants were determined by curve fitting method and it was shown that dioxivanadium(V) forms two mononuclear 1:1 and 1:2 species with alanineof type VO2L and VO2L2-.The porotonation constant of the amino group of alanine has been determined using potentiometric techniques and calculated using a computer program wich employ a least-squares method. The dependence of the porotonation of alanine and the stability constants of the species on ionic strength are described by a deby-huckel type equation.

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Interaction of dimethyltin(IV)dichloride with 5′-AMP and 5′-GMP

Canadian Journal of Chemistry ◽

10.1139/v06-152 ◽

2006 ◽

Vol 84 (11) ◽

pp. 1534-1540 ◽

Cited By ~ 10

Author(s):

Farrokh Gharib ◽

Elnaz Farzad ◽

Mostafa Mohammadpour Amini

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Ftir Spectroscopy ◽

Constant Temperature ◽

Elemental Analysis ◽

Formation Constants ◽

Low Ph ◽

Ph Values ◽

Species Formation ◽

Ph Range

The formation constants of the species formed in the systems H+ + dimethyltin(IV) + 5′-AMP and 5′-GMP, H+ + 5′-AMP, and H+ + 5′-GMP have been determined in aqueous solution in the pH range of 1.5–9 at constant temperature (25 °C) and constant ionic strength (0.1 mol dm–3, NaClO4) using spectrophotometric and potentiometric techniques. 1H and 31P NMR investigations in aqueous solution confirmed the species formation and led us to propose their structures. The precipitated complexes of AMP and GMP by Me2Sn(IV)2+ at low pH values were characterized by elemental analysis and FTIR spectroscopy, which ruled out purine moiety (N-1 and N-7) coordination and a bidentated coordination of the phosphate group is concluded in both cases.Key words: dimethyltin(IV)dichloride, guanosine 5′-monophosphate, adenosine 5′-monophosphate, stability and protonation constants.

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The Solution Behavior of Dopamine in the Presence of Mono and Divalent Cations: A Thermodynamic Investigation in Different Experimental Conditions

Biomolecules ◽

10.3390/biom11091312 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1312

Author(s):

Antonio Gigliuto ◽

Rosalia Maria Cigala ◽

Anna Irto ◽

Maria Rosa Felice ◽

Alberto Pettignano ◽

...

Keyword(s):

Divalent Cations ◽

Formation Constants ◽

Binuclear Complexes ◽

Interaction Theory ◽

Thermodynamic Investigation ◽

Experimental Conditions ◽

Complex Formation Constants ◽

Specific Ion Interaction Theory ◽

Speciation Model ◽

Starting Solutions

The interactions of dopamine [2-(3,4-Dihydroxyphenyl)ethylamine, (Dop-)] with methylmercury(II) (CH3Hg+), magnesium(II), calcium(II), and tin(II) were studied in NaCl(aq) at different ionic strengths and temperatures. Different speciation models were obtained, mainly characterized by mononuclear species. Only for Sn2+ we observed the formation of binuclear complexes (M2L2 and M2LOH (charge omitted for simplicity); M = Sn2+, L = Dop−). For CH3Hg+, the speciation model reported the ternary MLCl (M = CH3Hg+) complex. The dependence on the ionic strength of complex formation constants was modeled by using both an extended Debye–Hückel equation that included the Van’t Hoff term for the calculation of enthalpy change values of the formation and the Specific Ion Interaction Theory (SIT). The results highlighted that, in general, the entropy is the driving force of the process. The sequestering ability of dopamine towards the investigated cations was evaluated using the calculation of pL0.5 parameter. The sequestering ability trend resulted to be: Sn2+ > CH3Hg+ > Ca2+ > Mg2+. For example, at I = 0.15 mol dm−3, T = 298.15 K and pH = 7.4, pL0.5 = 3.46, 2.63, 1.15, and 2.27 for Sn2+, CH3Hg+, Ca2+ and Mg2+ (pH = 9.5 for Mg2+), respectively. For the Ca2+/Dop- system, the precipitates collected at the end of the potentiometric titrations were analyzed by thermogravimetry (TGA). The thermogravimetric calculations highlighted the formation of solid with stoichiometry dependent on the different metal:ligand ratios and concentrations of the starting solutions.

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Formation of CT complexes and electron transfer from excited molecules of anthracene derivatives to methylviologen in aqueous and micellar media

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19871658 ◽

1987 ◽

Vol 52 (7) ◽

pp. 1658-1665

Author(s):

Viktor Řehák ◽

Jana Boledovičová

Keyword(s):

Electron Transfer ◽

Complex Formation ◽

Fluorescence Quenching ◽

Rate Constant ◽

Formation Constants ◽

Dynamic Quenching ◽

Micellar Media ◽

Complex Formation Constants ◽

Anthracene Derivatives ◽

Ct Complexes

Disodium 1,5- and 1,8-anthracenedisulphonate (ADS) and 9-acetylanthracene form coloured CT complexes with methylviologen (MV2+) in aqueous and micellar media. The complex formation constants and molar absorptivities were determined by the Benesi-Hildebrandt method. In the fluorescence quenching, its static component plays the major role. The dynamic quenching component is determined by the rate constant of electron transfer from the S1 state of ADS to MV2+.

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Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19912791 ◽

1991 ◽

Vol 56 (12) ◽

pp. 2791-2799 ◽

Cited By ~ 1

Author(s):

Juan A. Squella ◽

Luis J. Nuñez-Vergara ◽

Hernan Rodríguez ◽

Amelia Márquez ◽

Jose M. Rodríguez-Mellado ◽

...

Keyword(s):

Spectrophotometric Study ◽

Absorption Bands ◽

Electrochemical Parameters ◽

Wide Ph Range ◽

Group A ◽

Substituent Constants ◽

Ph Range ◽

The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

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