Electrochemical Perspective on Hematite–Malonate Interactions

Organic matter (OM) interactions with minerals are essential in OM preservation against decomposition in the environment. Here, by combining potentiometric and electrophoretic measurements, we probed the mode of coordination and the role of pH-dependent electrostatic interactions between organic acids and an iron oxide surface. Specifically, we show that malonate ions adsorbed to a hematite surface in a wide pH window between 3 and 8.7 (point of zero charge). The mode of interactions varied with this pH range and depended on the acid and surface acidity constants. In the acidic environment, hematite surface potential was highly positive (+47 mV, pH 3). At pH < 4 malonate adsorption reduced the surface potential (+30 mV at pH 3) but had a negligible effect on the diffuse layer potential, consistent with the inner-sphere malonate complexation. Here, the specific and electrostatic interactions were responsible for the malonate partial dehydration and surface accumulation. These interactions weakened with an increasing pH and near PZC, the hematite surface charge was neutral on average. Adsorbed malonates started to desorb from the surface with less pronounced accumulation in the diffuse layer, which was reflected in zeta potential values. The transition between specific and non-specific sorption regimes was smooth, suggesting the coexistence of the inner- and outer-sphere complexes with a relative ratio that varied with pH.

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The Role of Outer-Sphere Surface Acidity in Alkene Epoxidation Catalyzed by Calixarene−Ti(IV) Complexes

Journal of the American Chemical Society ◽

10.1021/ja074614g ◽

2007 ◽

Vol 129 (50) ◽

pp. 15585-15595 ◽

Cited By ~ 43

Author(s):

Justin M. Notestein ◽

Leandro R. Andrini ◽

Felix G. Requejo ◽

Alexander Katz ◽

Enrique Iglesia

Keyword(s):

Surface Acidity ◽

Outer Sphere ◽

Sphere Surface

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Electrostatic interactions in cytochrome c. The role of interactions between residues 13 and 90 and residues 79 and 47 in stabilizing the heme crevice structure.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)86087-8 ◽

1980 ◽

Vol 255 (4) ◽

pp. 1689-1697

Author(s):

N. Osheroff ◽

D. Borden ◽

W.H. Koppenol ◽

E. Margoliash

Keyword(s):

Cytochrome C ◽

Electrostatic Interactions

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The Role of the Disulfide Bridge in the Copper (II) Binding by the Cyclic His4-Peptide

International Journal of Molecular Sciences ◽

10.3390/ijms22126458 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6458

Author(s):

Aleksandra Pieniężna ◽

Weronika Witak ◽

Aneta Szymańska ◽

Justyna Brasuń

Keyword(s):

Metal Ions ◽

Coordination Mode ◽

Transition Metal Ions ◽

Disulfide Bridge ◽

Chain Flexibility ◽

Vis Spectroscopy ◽

Ph Range ◽

Cd Studies ◽

Metal Ratios

In this paper, we present studies on the influence of the disulfide bridge on the copper (II) ions’ binding abilities by the cyclic His4-peptide. The studied ligand HKHPHRHC-S-S-C consists of nine amino acids. The cyclic structure was obtained through a disulfide bridge between two cysteinyl groups. Moreover, this peptide is characterized by the presence of four His residues in the sequence, which makes it an interesting ligand for transition metal ions. The potentiometric and spectroscopic (UV-Vis spectroscopy and circular dichroism spectroscopy (CD)) studies were carried out in various molar ligand to metal ratios: 2:1, 1:1, and 1:2, in the pH range of 2.5–11 at 25 °C. The results showed that the cyclic His4-peptide promotes dinuclear complexes in each of these systems and forms the final dinuclear species with the {NIm, 3N-amide}{NIm, 3N-amide} coordination mode. The obtained data shows that cyclization by the formation of the disulfide bond has an impact on the peptide chain flexibility and appearance of additional potential donors for metal ions and influences the copper (II) ions’ coordination.

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The Unusual Role of Pro in Cu(II) Binding by His2-Cyclopentapeptide

International Journal of Molecular Sciences ◽

10.3390/ijms22126628 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6628

Author(s):

Aleksandra Pieniężna ◽

Aleksandra Kotynia ◽

Justyna Brasuń

Keyword(s):

Amino Acid ◽

Potentiometric Titration ◽

Amino Acid Residue ◽

Strong Impact ◽

Mononuclear Complexes ◽

Study Results ◽

Metal Ratio ◽

Ph Range ◽

L1 And L2

In this paper, we present findings from studying the interaction of copper(II) ions with the His2-cyclopentapeptide and the role of proline used for the purpose of potentiometric titration and UV-Vis, CD and EPR spectroscopic measurements. Experiments of two homodetic peptides differing by one amino acid residue were conducted for a ligand to metal ratio of 1:1 in the pH range 2.5–11.0. The presented studies reveal that peptides form only mononuclear complexes, and the CuH2L complex appears in the system first (for both L1 and L2). Study results show that the presence of Pro influences the structure of formed complexes and their stabilities and has a strong impact on the efficiency of copper(II) coordination.

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Rotational Diffusion of Organic Solutes in Surfactant−Block Copolymer Micelles: Role of Electrostatic Interactions and Micellar Hydration

The Journal of Physical Chemistry B ◽

10.1021/jp068490q ◽

2007 ◽

Vol 111 (21) ◽

pp. 5878-5884 ◽

Cited By ~ 21

Author(s):

K. S. Mali ◽

G. B. Dutt ◽

T. Mukherjee

Keyword(s):

Block Copolymer ◽

Electrostatic Interactions ◽

Rotational Diffusion ◽

Organic Solutes ◽

Block Copolymer Micelles ◽

Copolymer Micelles

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The Role of Electrostatic Interactions in Protease Surface Diffusion and the Consequence for Interfacial Biocatalysis

Langmuir ◽

10.1021/la103080a ◽

2010 ◽

Vol 26 (24) ◽

pp. 18916-18925 ◽

Cited By ~ 9

Author(s):

Bob E. Feller ◽

James T. Kellis ◽

Luis G. Cascão-Pereira ◽

Channing R. Robertson ◽

Curtis W. Frank

Keyword(s):

Surface Diffusion ◽

Electrostatic Interactions

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Phase diagram, structure and rheology of boehmite dispersions: role of electrostatic interactions

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/j.colsurfa.2021.127564 ◽

2021 ◽

Vol 631 ◽

pp. 127564

Author(s):

Maria Dronova ◽

Eric Lécolier ◽

Loïc Barré ◽

Laurent J. Michot

Keyword(s):

Phase Diagram ◽

Electrostatic Interactions

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Role of Dispersion Attraction in Differential Geometry Based Nonpolar Solvation Models

Computational and Mathematical Biophysics ◽

10.1515/mlbmb-2015-0012 ◽

2015 ◽

Vol 3 (1) ◽

Author(s):

Zhan Chen

Keyword(s):

Differential Geometry ◽

Electrostatic Interactions ◽

Polar Component ◽

Great Success ◽

Free Energies ◽

Dispersion Interactions ◽

Solvation Models ◽

Nonpolar Solvation ◽

Solvation Analysis

AbstractDifferential geometry (DG) based solvation models have shown their great success in solvation analysis by avoiding the use of ad hoc surface definitions, coupling the polar and nonpolar free energies, and generating solvent-solute boundary in a physically self-consistent fashion. Parameter optimization is a key factor for their accuracy, predictive ability of solvation free energies, and other applications. Recently, a series of efforts have been made to improve the parameterization of these new implicit solvent models. In thiswork, we aim at studying the role of dispersion attraction in the parameterization of our DG based solvation models. To this end, we first investigate the necessity of van derWaals (vdW) dispersion interactions in the model and then carry out systematic parameterization for the model in the absence of electrostatic interactions. In particular, we explore how the changes in Lennard-Jones (L-J) potential expression, its decomposition scheme, and choices of some fixed parameter values affect the optimal values of other parameters as well as the overall modeling error. Our study on nonpolar solvation analysis offers insights into the parameterization of nonpolar components for the full DG based models by eliminating uncertainties from the electrostatic polar component. Therefore, it can be regarded as a step towards better parameterization for the full DG based model.

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Solvent effect on the conformational behavior of substituted spiro[4.5]decanes and spiro[5.5]undecanes

Canadian Journal of Chemistry ◽

10.1139/v95-089 ◽

1995 ◽

Vol 73 (5) ◽

pp. 703-709 ◽

Cited By ~ 6

Author(s):

S. Sağ Erdem ◽

T. Varnali ◽

V. Aviyente ◽

M.F. Ruiz-Lopez

Keyword(s):

Solvent Effect ◽

Electrostatic Interactions ◽

Multipole Moment ◽

Semiempirical Methods ◽

Main Role ◽

Solvent Interactions ◽

Reaction Field ◽

Solvent Models ◽

Conformational Equilibria

We studied the relatively complex polar systems 6-substituted-1,4-dioxospiro[4.5]decanes and 7-substituted-1,5-dioxospiro[5.5]undecanes with substituents X = CH3, F, Cl, CN, OH, OCH3, and NO2. Solvent effects on the equilibrium have been analysed by means of a Self-Consistent-Reaction-Field model and the PM3 method. Complete geometry optimizations have been carried out for all the structures in the gas phase and in solution. For some substituents, a set of rotamers have been separately optimized. The discussion of the results is focussed on the effects arising from structural aspects and from steric and electrostatic interactions on the axial/equatorial relative stability. The role played by multipole moment is considered. In general, good agreement with available experimental data and with previous theoretical studies has been obtained. Though the use of semiempirical methods and simple solvent models prevents us from reaching definitive conclusions, this approach seems to be very useful in predicting the main role of solute–solvent interactions in conformational equilibria of complex systems for which ab initio calculations cannot be performed. Keywords: conformational equilibria, spiro decanes and undecanes, cavity model, SCRF, solvent effect, PM3 calculations.

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