Kirkwood–Buff integrals for ideal solutions

Ploetz, Elizabeth A.; Bentenitis, Nikolaos; Smith, Paul E.

doi:10.1063/1.3398466

Cited by 25 publications

(19 citation statements)

References 44 publications

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“…The Ben + Tol com rdfs and N ij were not included in Figures 4 and 5 because we have discussed the excellent simulation of this ideality previously. 77 The Tol + Ben com rdfs displayed a first solvation shell at ~0.6 nm, however the g Ben-Ben and g Tol-Tol distributions had slightly different magnitudes with a small increase in the probability for finding a Ben ~0.6 nm away from a central Ben than a Tol ~0.6 nm away from a central Tol. This was likely due to the tighter packing that is possible between Ben molecules due to the absence of a methyl group when compared to Tol.…”

Section: Resultsmentioning

confidence: 93%

A Kirkwood–Buff force field for the aromatic amino acids

Ploetz

Smith

2011

Phys. Chem. Chem. Phys.

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In a continuation of our efforts to develop a united atom non-polarizable protein force field based upon the solution theory of Kirkwood and Buff i.e., the Kirkwood-Buff Force Field (KBFF) approach, we present KBFF models for the side chains of phenylalanine, tyrosine, tryptophan, and histidine, including both tautomers of neutral histidine and doubly-protonated histidine. The force fields were specifically designed to reproduce the thermodynamic properties of mixtures over the full composition range in an attempt to provide an improved description of intermolecular interactions. The models were developed by careful parameterization of the solution phase partial charges to reproduce the experimental Kirkwood-Buff integrals for mixtures of solutes representative of the amino acid sidechains in solution. The KBFF parameters and simulated thermodynamic and structural properties are presented for the following eleven binary mixtures: benzene + methanol, benzene + toluene, toluene + methanol, toluene + phenol, toluene + p-cresol, pyrrole + methanol, indole + methanol, pyridine + methanol, pyridine + water, histidine + water, and histidine hydrochloride + water. It is argued that the present approach and models provide a reasonable description of intermolecular interactions which ensures that the required balance between solute-solute, solute-solvent, and solvent-solvent distributions is obtained.

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Section: Resultsmentioning

confidence: 93%

A Kirkwood–Buff force field for the aromatic amino acids

Ploetz

Smith

2011

Phys. Chem. Chem. Phys.

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“…A study carried out by Ploetz et al provided a different viewpoint on azeotrope formation in this system. 39 Using Kirkwood-Buff integrals 40 they found a large positive value for the integral describing methanol-methanol pairs in benzene-rich mixtures. This indicates the aggregation of methanol molecules and that the mixture approaches heterogeneous phase separation.…”

Section: Figurementioning

confidence: 99%

Microstructures of negative and positive azeotropes

Shephard

Callear

Imberti

et al. 2016

Phys. Chem. Chem. Phys.

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Azeotropes famously impose fundamental restrictions on distillation processes, yet their special thermodynamic properties make them highly desirable for a diverse range of industrial and technological applications. Using neutron diffraction, we investigate the structures of two prototypical azeotropes, the negative acetone-chloroform and the positive benzenemethanol azeotrope. C-H···O hydrogen bonding is the dominating interaction in the negative azeotrope but C-Cl···O halogen bonding contributes as well. Hydrogen-bonded chains of methanol molecules, which are on average longer than in pure methanol, are the defining structural feature of the positive azeotrope illustrating the fundamentally different local mixing in the two kinds of azeotropes. The emerging trend for both azeotropes is that the more volatile components experience the more pronounced structural changes in their local environments as the azeotropes form. The mixing of the acetonechloroform azeotrope is essentially random above 20 Å where the running Kirkwood-Buff integrals of our structural model converge closely to the ones expected from thermodynamic data. The benzene-methanol azeotrope on the other hand displays extended methanol-rich regions and consequently, the running Kirkwood-Buff integrals oscillate up to at least 60 Å. Our study provides first insights into the microstructures of azeotropes and a direct link with their thermodynamic properties. Ultimately, this will provide a route for creating tailored molecular environments in azeotropes to improve and fine-tune their performances.

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“…47,65,66 Hence, we have also included the corresponding SI results for the two liquid mixtures studied here. SI solutions are characterized by G E m = V E m = 0 and give rise to the following general expression for the pair distribution integrals:…”

Section: B Symmetric Ideal Solutionsmentioning

confidence: 99%

Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for liquid mixtures

Ploetz

Smith

2015

The Journal of Chemical Physics

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Kirkwood-Buff or Fluctuation Solution Theory can be used to provide experimental pair fluctuations, and/or integrals over the pair distribution functions, from experimental thermodynamic data on liquid mixtures. Here, this type of approach is used to provide triplet and quadruplet fluctuations, and the corresponding integrals over the triplet and quadruplet distribution functions, in a purely thermodynamic manner that avoids the use of structure factors. The approach is then applied to binary mixtures of water + methanol and benzene + methanol over the full composition range under ambient conditions. The observed correlations between the different species vary significantly with composition. The magnitude of the fluctuations and integrals appears to increase as the number of the most polar molecule involved in the fluctuation or integral also increases. A simple physical picture of the fluctuations is provided to help rationalize some of these variations. C 2015 AIP Publishing LLC. [http://dx

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Kirkwood–Buff integrals for ideal solutions

Cited by 25 publications

References 44 publications

A Kirkwood–Buff force field for the aromatic amino acids

A Kirkwood–Buff force field for the aromatic amino acids

Microstructures of negative and positive azeotropes

Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for liquid mixtures

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