Entropy Term Research Articles

Effect of the alkyl chain and composition on the thermodynamics of mixing of small alcohols and water

The thermodynamic changes occurring upon mixing small monovalent alcohols and water are systematically analyzed as a function of both the size and shape of the apolar group of the alcohols and of the mixture composition. For this purpose, the Helmholtz free energy, energy and entropy of mixing of the eight smallest alcohols, i.e., methanol, ethanol, propanol, isopropanol, butanol, isobutanol, s-butanol, and t-butanol with water are calculated in the entire composition range by means of Monte Carlo simulations and thermodynamic integration with three different model combinations. The obtained results are in a satisfactory agreement with existing experimental data. In particular, they are able to well reproduce the qualitative trends, being in the focus of this study. Our results indicate that the thermodynamics of mixing of these systems is primarily governed by the entropic term. In particular, the addition of alcohol to water-rich systems induces an ordering of the water molecules through hydrophobic hydration, while the addition of water to alcohol-rich mixtures induces ordering of the alcohol molecules by providing them additional H-bonds. According to the obtained free energy of mixing data, the former of these two effects clearly becomes more pronounced with increasing size and decreasing branching (i.e., increasing surface area) of the apolar groups, while the latter one is much less sensitive to the apolar tail. As a consequence, the increase of the apolar tail (and the decrease of its branching) leads to partial miscibility of the alcohols with water, with a miscibility gap occurring in water-rich compositions.

The enthalpic and entropic terms of the reduction potential of metalloproteins: Determinants and interplay

Splitting the reduction potential of electron transport (ET) proteins and redox metalloenzymes into the enthalpic and entropic contributions is an insightful practice to gaining insight into the molecular determinants of the thermodynamic propensity of the metal center to accept or release electrons. The strict control of such propensity is essential for the functioning of the electron transport chains in bioenergetics and the organized network of the countless reactions of the redox metabolism in all organisms. Here, the first comprehensive overview is offered on the thermodynamic data obtained in the last three decades for the main classes of ET species, namely c-type cytochromes and proteins containing T1 copper and iron-sulfur centers, along with some heme metalloenzymes. These families show many common features in the balance of the enthalpic and entropic terms, which will be brought to light. The enthalpic terms related to ligation features in the first coordination sphere of the metal and weak binding and electrostatics in the surrounding matrix do count a lot in this balance. Reduction entropy is much less important that it would appear from the raw thermodynamic data, particularly for electron transport (ET) metalloproteins. This is due to reduction-induced solvent-related molecular events which dominate the measured entropy changes but affect much less the reduction free energy due to the compensatory effects of the associated enthalpic terms (a phenomenology known as enthalpy-entropy compensation, EEC). Thus the entropy changes seldom exert a real influence on the E°′ of metalloredox proteins; this is restricted to metal sites subjected to reduction-induced protein-based changes in the accessible configurational microstates. It follows that in most cases, especially for ET species, the E° changes due to point mutations, ligand binding and charge changes have an ultimate enthalpic origin. Hence, they should be accounted for with coordination chemistry and electrostatics notions. Only if they don’t, protein-based entropic effects could play a role. In this review, we go through the data gathered for the main classes of ET species and heme enzymes that brought us to this conclusion.

The investigation of the infinite dilution activity coefficients for molecular compounds in 1-(3-hydroxypropyl)-3-methyl-imidazolium thiocyanate

Measurements of infinite dilution activity coefficients of 46 organic solutes including alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, ethers, ketones, pyridine, thiophene, acetonitrile, and 1-nitropropane in ionic liquids (IL), 1-(3-hydroxypropyl)-3-methyl-imidazolium thiocyanate (abbreviated as [C1C3OHIM][SCN]) are reported in the temperature range from T = (318.15 to 358.15) K. Based on the experimental data, the infinite dilution capacity and selectivity of the studied IL are presented to evaluate the effectiveness of using it as an extractant in the separation of aliphatic from aromatic hydrocarbons and sulfur compounds from alkanes. Obtained selectivity and capacity values for different separation processes are compared with the literature data for other ionic liquids. From the temperature – dependence of the infinite dilution activity coefficient, the partial molar excess Gibbs energy, ΔG1E,∞, enthalpyΔH1E,∞ and entropy term TrefΔS1E,∞ at infinite dilution were calculated and discussed.

Study of disorder in pulsed laser deposited double perovskite oxides by first-principle structure prediction

Double perovskite oxides, with generalized formula A2BB^{prime}O6, attract wide interest due to their multiferroic and charge transfer properties. They offer a wide range of potential applications such as spintronics and electrically tunable devices. However, great practical limitations are encountered, since a spontaneous order of the B-site cations is notoriously hard to achieve. In this joint experimental-theoretical work, we focused on the characterization of double perovskites La2TiFeO6 and La2VCuO6 films grown by pulsed laser deposition and interpretation of the observed B-site disorder and partial charge transfer between the B-site ions. A random structure sampling method was used to show that several phases compete due to their corresponding configurational entropy. In order to capture a representative picture of the most relevant competing microstates in realistic experimental conditions, this search included the potential formation of non-stoichiometric phases as well, which could also be directly related to the observed partial charge transfer. We optimized the information encapsulated in the potential energy landscape, captured via structure sampling, by evaluating both enthalpic and entropic terms. These terms were employed as a metric for the competition of different phases. This approach, applied herein specifically to La2TiFeO6, highlights the presence of highly entropic phases above the ground state which can explain the disorder observed frequently in the broader class of double perovskite oxides.

DESN: An unsupervised MR image denoising network with deep image prior

Magnetic Resonance Imaging (MRI) is a widely used medical diagnosis technique. However, the quality of MR image is affected by the noise which is caused by mechanical and environmental reasons during the MR image acquisition process. For decades, various kinds of methods including filtering approaches, transform domain approaches and statistical approaches have been applied to the MR image denoising problem, while there are also some drawbacks exiting in these methods such as arising undesirable change of texture and long computation time needed. In this paper, we proposed a novel MR image denoising method called DESN which is a neural network method and has a novel network architecture with well-designed loss function. In DESN, the convolutional neural networks itself is considered as a regularizer or image prior information for the inverse problems such as denoising. The network architecture of DESN is designed from the auto-encoder architecture, it has three main parts: encoder network for extracting low-resolution image features, decoder network for restoring high-resolution features and skip connections for transmitting abstract information from encoder network to decoder network. Besides, we also design a novel loss function which contains two main parts: data fidelity loss (Lfidelity), image quality penalty (Lq) and three loss terms: mean squared error term (LMSE), image structure similarity term (LS), image information entropy term (LIE). We compare the performance of DESN with DIP and some state of the art denoising methods, and the performance of our network with different loss terms are also compared in three MR modalities. The comparative results show that DESN have the superior performance in generating high-quality MR image with enough edge and texture information.

Thermodynamic Analysis for Binding of 4-O-β-tri-N-acetylchitotriosyl Moranoline, a Transition State Analogue Inhibitor for Hen Egg White Lysozyme.

4-O-β-tri-N-acetylchitotriosyl moranoline (GN3M) is a transition-state analogue for hen egg white lysozyme (HEWL) and identified as the most potent inhibitor till date. Isothermal titration calorimetry experiments provided the thermodynamic parameters for binding of GN3M to HEWL and revealed that the binding is driven by a favorable enthalpy change (ΔH° = −11.0 kcal/mol) with an entropic penalty (−TΔS° = 2.6 kcal/mol), resulting in a free energy change (ΔG°) of −8.4 kcal/mol [Ogata et al. (2013) 288, 6,072–6,082]. Dissection of the entropic term showed that a favorable solvation entropy change (−TΔS solv° = −9.2 kcal/mol) is its sole contributor. The change in heat capacity (ΔC p°) for the binding of GN3M was determined to be −120.2 cal/K·mol. These results indicate that the bound water molecules play a crucial role in the tight interaction between GN3M and HEWL.

One-Step Chemo-, Regio- and Stereoselective Reduction of Ketosteroids to Hydroxysteroids over Zr-Containing MOF-808 Metal-Organic Frameworks.

Zr‐containing MOF‐808 is a very promising heterogeneous catalyst for the selective reduction of ketosteroids to the corresponding hydroxysteroids through a Meerwein‐Ponndorf‐Verley (MPV) reaction. Interestingly, the process leads to the diastereoselective synthesis of elusive 17α‐hydroxy derivatives in one step, whereas most chemical and biological transformations produce the 17β‐OH compounds, or they require several additional steps to convert 17β‐OH into 17α‐OH by inverting the configuration of the 17 center. Moreover, MOF‐808 is found to be stable and reusable; it is also chemoselective (only keto groups are reduced, even in the presence of other reducible groups such as C=C bonds) and regioselective (in 3,17‐diketosteroids only the keto group in position 17 is reduced, while the 3‐keto group remains almost intact). The kinetic rate constant and thermodynamic parameters of estrone reduction to estradiol have been obtained by a detailed temperature‐dependent kinetic analysis. The results evidence a major contribution of the entropic term, thus suggesting that the diastereoselectivity of the process is controlled by the confinement of the reaction inside the MOF cavities, where the Zr4+ active sites are located.

Epitaxial stabilisation of Ge1 x Sn x alloys

The thermodynamic stability of germanium tin alloys is investigated across the composition range by applying density functional theory together with the cluster expansion formalism (CE). It is known that GeSn alloys are immiscible and that non-equilibrium growth techniques are required to produce metastable films and nanostructures. Insight into the driving forces behind component segregation is gained by investigating the equilibrium thermodynamics of GeSn systems. The alloy free energy of mixing is computed by combining enthalpies from the CE with entropy terms for configurational and vibrational degrees of freedom. Volume deformations due to the large mismatch in ionic radii are readily found to be the key driving force for immiscibility at all temperatures of relevance. This leads to a study of epitaxial stabilisation by employing latticed matched substrates to favour growth of alloys with fractional compositions of x = 0, approximately x = 0.5 and x = 1. The reduction in the free energy of mixing due to epitaxial strain in thin films is quantified for each substrate leading to indicators for growth of kinetically stable films.

Insights into Reactivity of Silicon Negative Electrodes: Analysis Using Isothermal Microcalorimetry

Silicon offers high theoretical capacity as a negative electrode material for lithium-ion batteries; however, high irreversible capacity upon initial cycling and poor cycle life have limited commercial adoption. In this work, an operando isothermal microcalorimetry (IMC) study of a model system containing lithium metal and silicon composite film electrodes was reported on the first two cycles of (de)lithiation. The total heat flow data are analyzed in terms of polarization, entropic, and parasitic heat flow contributions to quantify and determine the onset of parasitic reactions. These parasitic reactions, which include solid−electrolyte interphase formation, contribute to electrochemical irreversibility. To complement the calorimetry, operando X-ray diffraction is used to track the phase evolution of silicon. During cycle 1 lithiation, crystalline Si undergoes transformation to amorphous lithiated silicon and ultimately to crystalline Li15Si4. The solid-state amorphization process is correlated to a decrease in entropic heat flow, suggesting that heat associated with the amorphization contributes significantly to the entropic heat flow term. This study effectively uses IMC to probe the parasitic reactions that occur during lithiation of a silicon electrode, demonstrating an approach that can be broadly applied to quantify parasitic reactions in other complex systems.

Adding Prior Information in FWI through Relative Entropy.

Full waveform inversion is an advantageous technique for obtaining high-resolution subsurface information. In the petroleum industry, mainly in reservoir characterisation, it is common to use information from wells as previous information to decrease the ambiguity of the obtained results. For this, we propose adding a relative entropy term to the formalism of the full waveform inversion. In this context, entropy will be just a nomenclature for regularisation and will have the role of helping the converge to the global minimum. The application of entropy in inverse problems usually involves formulating the problem, so that it is possible to use statistical concepts. To avoid this step, we propose a deterministic application to the full waveform inversion. We will discuss some aspects of relative entropy and show three different ways of using them to add prior information through entropy in the inverse problem. We use a dynamic weighting scheme to add prior information through entropy. The idea is that the prior information can help to find the path of the global minimum at the beginning of the inversion process. In all cases, the prior information can be incorporated very quickly into the full waveform inversion and lead the inversion to the desired solution. When we include the logarithmic weighting that constitutes entropy to the inverse problem, we will suppress the low-intensity ripples and sharpen the point events. Thus, the addition of entropy relative to full waveform inversion can provide a result with better resolution. In regions where salt is present in the BP 2004 model, we obtained a significant improvement by adding prior information through the relative entropy for synthetic data. We will show that the prior information added through entropy in full-waveform inversion formalism will prove to be a way to avoid local minimums.

Computational study (MM and DFT) on the conformations of some aromatic crown ether rotaxane macrocycles

We examined the preferred conformations of several aromatic crown ether macrocycles containing dibenzo (DB24C8 (1), BMP25C8 (2), BPP34C10 (3)), dinaphtho (2/3DN30C10 (4), 1/5DN38C10 (5)), diphenyl phenanthroline (6) or isophthalamide (7) groups in order to elucidate their preferred conformations and to test the performance of computational methods (molecular mechanics and DFT) in the description of the building blocks of some mechanically interlocked molecules. An exhaustive search for low energy conformations was carried out. The analyses of the geometries of the low-energy conformations of 1–7 revealed that all they have either preformed cavities for adopting substrates, or due to the high flexibility and easy deformability of the macrorings, they have the potential to allow threading of an axle-like molecular component as a slippage step in the formation of a rotaxane structure. Unexpectedly, for one of the macrorings, 4, the geometries of the low-energy conformations differ significantly from the representative conformations of prima facie conformationally similar macrocycles. Contributions from the vibrational entropy term reorder the steric energy lists of conformations in some cases (1, 2, 4, 6), compensating relative steric energies up to 0.9 kcal mol−1. Cluster analysis of the molecular conformations was performed with examining the dependence of the results on the number of torsions for the clustering and the characteristic threshold distances, defining the clustering. All conformations with relative steric energies not exceeding 2.0 kcal mol−1 were examined also with the DFT method (M06-2X functional). In some cases (1 and 2) conformations with relative steric energies ca. 2.0 kcal mol−1 are with the lowest total energies in the corresponding DFT energy lists. These are conformations where the aromatic fragments are facing each other at short distance, ca. 5 Å. We are inclined to conclude that in such cases the DFT models used enhance the dispersion interactions at short distances.

Thermodynamic Decomposition of Solvation Free Energies with Particle Mesh Ewald and Long-Range Lennard-Jones Interactions in Grid Inhomogeneous Solvation Theory.

Grid Inhomogeneous Solvation Theory (GIST) maps out solvation thermodynamic properties on a fine meshed grid and provides a statistical mechanical formalism for thermodynamic end-state calculations. However, differences in how long-range nonbonded interactions are calculated in molecular dynamics engines and in the current implementation of GIST have prevented precise comparisons between free energies estimated using GIST and those from other free energy methods such as thermodynamic integration (TI). Here, we address this by presenting PME-GIST, a formalism by which particle mesh Ewald (PME)-based electrostatic energies and long-range Lennard-Jones (LJ) energies are decomposed and assigned to individual atoms and the corresponding voxels they occupy in a manner consistent with the GIST approach. PME-GIST yields potential energy calculations that are precisely consistent with modern simulation engines and performs these calculations at a dramatically faster speed than prior implementations. Here, we apply PME-GIST end-state analyses to 32 small molecules whose solvation free energies are close to evenly distributed from 2 kcal/mol to -17 kcal/mol and obtain solvation energies consistent with TI calculations (R2 = 0.99, mean unsigned difference 0.8 kcal/mol). We also estimate the entropy contribution from the second and higher order entropy terms that are truncated in GIST by the differences between entropies calculated in TI and GIST. With a simple correction for the high order entropy terms, PME-GIST obtains solvation free energies that are highly consistent with TI calculations (R2 = 0.99, mean unsigned difference = 0.4 kcal/mol) and experimental results (R2 = 0.88, mean unsigned difference = 1.4 kcal/mol). The precision of PME-GIST also enables us to show that the solvation free energy of small hydrophobic and hydrophilic molecules can be largely understood based on perturbations of the solvent in a region extending a few solvation shells from the solute. We have integrated PME-GIST into the open-source molecular dynamics analysis software CPPTRAJ.

Self-assembly of quaternary benzo[c]phenanthridine plant alkaloids into dimer in aqueous solution

Self-association of three biologically active natural quaternary benzo[c]phenanthridine alkaloids, nitidine, sanguinarine, and chelerythrine was studied by spectrophotometry, fluorescence spectroscopy, fluorescence decay measurements and isothermal titration calorimetry in aqueous solution. The increase of alkaloid concentration brought about moderate changes in the absorption spectra, while the fluorescence properties altered only in the case of nitidine. Enthalpy-controlled self-binding occurred and the variation of the association enthalpy was substantially compensated by the unfavorable entropic term. Nitidine dimerization was the most exothermic and the equilibrium constant of this process exceeded by a factor of ~5 the corresponding values of the other two alkaloids. The results of quantum chemical calculations agree well with the experimental data and provide information on the structural features of the dimers.

Inhibition of SARS-CoV-2 main protease: a repurposing study that targets the dimer interface of the protein

Coronavirus disease-2019 (COVID-19) was firstly reported in Wuhan, China, towards the end of 2019, and emerged as a pandemic. The spread and lethality rates of the COVID-19 have ignited studies that focus on the development of therapeutics for either treatment or prophylaxis purposes. In parallel, drug repurposing studies have also come into prominence. Herein, we aimed at having a holistic understanding of conformational and dynamical changes induced by an experimentally characterized inhibitor on main protease (Mpro) which would enable the discovery of novel inhibitors. To this end, we performed molecular dynamics simulations using crystal structures of apo and α-ketoamide 13b-bound Mpro homodimer. Analysis of trajectories pertaining to apo Mpro revealed a new target site, which is located at the homodimer interface, next to the catalytic dyad. Thereafter, we performed ensemble-based virtual screening by exploiting the ZINC and DrugBank databases and identified three candidate molecules, namely eluxadoline, diosmin, and ZINC02948810 that could invoke local and global conformational rearrangements which were also elicited by α-ketoamide 13b on the catalytic dyad of Mpro. Furthermore, ZINC23881687 stably interacted with catalytically important residues Glu166 and Ser1 and the target site throughout the simulation. However, it gave positive binding energy, presumably, due to displaying higher flexibility that might dominate the entropic term, which is not included in the MM-PBSA method. Finally, ZINC20425029, whose mode of action was different, modulated dynamical properties of catalytically important residue, Ala285. As such, this study presents valuable findings that might be used in the development of novel therapeutics against Mpro. Communicated by Ramaswamy H. Sarma

Computational study of the thermodynamics of urea methanolysis

Enthalpies, entropies, Gibbs free reactions of the interaction of urea and carbamic acid methyl ester with a monomer, dimer and trimer of methanol to form, respectively, carbamic acid methyl ester and dimethyl carbonate were determined using B3LYP and M06 density functional methods with the 6–311++G(df, p) basis set. Both of the quantum chemical methods used lead to comparable results. The enthalpies and entropies of transformations increase with an increase in the degree of association of alcohol. Changes in the free energies of the reactions discussed are controlled by the entropy term, which leads to the thermodynamic preference for reactions involving methanol complexes compared to its monomer.

Statistical mechanics of quantum error correcting codes

We study stabilizer quantum error correcting codes (QECC) generated under hybrid dynamics of local Clifford unitaries and local Pauli measurements in one dimension. Building upon 1) a general formula relating the error-susceptibility of a subregion to its entanglement properties, and 2) a previously established mapping between entanglement entropies and domain wall free energies of an underlying spin model, we propose a statistical mechanical description of the QECC in terms of "entanglement domain walls". Free energies of such domain walls generically feature a leading volume law term coming from its "surface energy", and a sub-volume law correction coming from thermodynamic entropies of its transverse fluctuations. These are most easily accounted for by capillary-wave theory of liquid-gas interfaces, which we use as an illustrative tool. We show that the information-theoretic decoupling criterion corresponds to a geometric decoupling of domain walls, which further leads to the identification of the "contiguous code distance" of the QECC as the crossover length scale at which the energy and entropy of the domain wall are comparable. The contiguous code distance thus diverges with the system size as the subleading entropic term of the free energy, protecting a finite code rate against local undetectable errors. We support these correspondences with numerical evidence, where we find capillary-wave theory describes many qualitative features of the QECC; we also discuss when and why it fails to do so.

Impact of point defects on the electrical properties of selenium: A density functional theory investigation with discussion of the entropic term

Selenium in ambient conditions exhibits two crystalline allotropic forms. The thermodynamically stable phase is the pseudo-1D trigonal form with ${}^{1}{/}_{\ensuremath{\infty}}$[Se] chains. A metastable phase composed of $[{\mathrm{Se}}_{8}]$ rings also coexists. Both are studied herein by means of density functional theory. The recent SCAN functional offers a fair description of both phases. The Birch-Murnaghan equation of states is fitted onto ab initio results to obtain the energy-volume and pressure-energy relationships. Phonon properties (bands and DOS) are computed and a pressure-temperature phase diagram is derived. Intrinsic and extrinsic defect formation enthalpies are also computed using SCAN functional and HSE06-GD3 for the band shifts. The low $p$-type conductivity of the trigonal phase can be attributed to Se self-interstitials while the very low conductivity of the metastable phase is related to very deep native defects. Antimony, and bromine extrinsic defects are tested as potential dopants. Of those three, only antimony in the trigonal phase seems to possibly have a positive impact on the conductivity. Finally, the configurational entropy linked to defect creation is computed. Our calculations clearly show that the usual assumption that defect entropy is negligible compared to the enthalpy seems relevant.

Thermodynamic and structural aspects of molecular recognition in mannose-binding protein complexes: a theoretical study over HRP-ArtinM association.

The biomolecular recognition of D-mannose-binding lectin from Artocarpus heterophyllus (ArtinM) by Horseradish Peroxidase (HRP) mediated by glycosylation allows their application in a multitude of biological systems. The present work describes the use of molecular dynamics (MD) to assess the Gibbs free energy associated with the formation of a ArtinM-HRP conjugate mediated by a glycosylation molecule. For the enthalpy term, we applied the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method and for the vibrational entropy term, we use the quasi-harmonic approximation. Our results show that, even without glycosylation, the binding free energy between ArtinM and HRP is - 196.154 kJmol- 1, an extremely high affinity with low selectivity, originated mainly through the van der Waals energy terms. The binding free energy between ArtinM and the glycosylated HRP (gHRP) was calculated at - 66.156 kJmol- 1, an absolute and considerably lower value, however, originated from electrostatic energy terms, which increases the selectivity of molecular recognition. Our work has shown that the HRP active site region has a high affinity and low selectivity for other biomolecules. The presence of glycosylation plays a role in increasing this selectivity for this region. Thus, we conclude that performing mutagenesis of amino acid residues near the entrance of the catalytic site, can improve the activity of non-glycosylated HRPs. This illustrates new insights that can be applied to carbohydrate-based immunochemistry.

Computational Screening of a Functional Cyclodextrin Derivative for Suppressing a Side Effect of Doxorubicin.

The binding affinity of the beta-cyclodextrin (β-CyD) derivatives with Doxorubicin (Dox) is evaluated by means of the 3D-RISM/KH theory combined with the molecular dynamics simulation in order to screen the compounds for suppressing a side-effect of the cancer drug. A protocol revised for the external and conformational entropies of the host-guest system is employed to calculate the binding free energy. It is found that the direct interactions of CyD with Dox and the desolvation free-energies of the both compounds largely cancel out to leave moderate contributions to the affinity, which are comparable to those from the entropies. The results shed light on the entropy terms for determining the binding affinity, although the external-entropy terms are essentially constant over all the compounds examined and do not affect the screening. The theoretical result is compared with the experimental data of the association constant for a CyD derivative which was predicted to be the best compound by the preliminary calculation without the entropy terms.

Insight into the complex formation of β-alanyl-L-histidine with nicotinic acid in water and buffer aqueous solution

Interactions between the peptide, L-carnosine (Car), and heterocyclic ligand, nicotinic acid (NA), in pure water and in aqueous buffer solution (pH 7.4) were studied by calorimetry, UV–vis spectroscopy and densimetry. Under the experimental conditions chosen, stability constants (lgKc) and thermodynamic parameters of complex formation (ΔcG, ΔcH, ΔcS) were determined for the reaction of Car with NA at 298.15 K. The complexation of L-carnosine with nicotinic acid is influenced by the pH of medium and ionic state of the reagents investigated. The results indicate the formation of a more stable complex between Car and NA with 1:2 stoichiometry in water than in buffer. Different negative enthalpic contributions to the free Gibbs energy accompanied by close positive values of entropic terms were obtained for Car/NA complexes in water and buffer. Using the measured density values of NA solutions in Car – water and Car – buffer systems, the apparent molar volumes, partial molar volumes at infinite dilution and their derivatives with respect to temperature have been obtained. The effects of solute concentration, pH and temperature (from 293.15 to 318.15 K) on the volume properties derived were discussed in terms of predominant types of molecular interactions (hydrophilic, hydrophobic, ionic and zwitterionic) on the basis of co-spheres overlap model.