Physchem

9 pages, 3075 KiB

Open AccessArticle

Acid-Catalyzed Esterification of Betaines: Theoretical Exploration of the Impact of the Carbon Chain Length on the Reaction Mechanism

by Richail Dubien Moulandou-Koumba, Frédéric Guégan, Jean-Maurille Ouamba, Samuel N’Sikabaka and Gilles Frapper

Physchem 2021, 1(3), 288-296; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030022 - 07 Dec 2021

Viewed by 2596

Abstract

Betaine derivatives, especially esters, are compounds of interest for the development of a more sustainable fine chemistry, as they are widely available from biomass and currently produced as side-products from various industries (among which, sugar production). In this publication, we studied the impact [...] Read more.

Betaine derivatives, especially esters, are compounds of interest for the development of a more sustainable fine chemistry, as they are widely available from biomass and currently produced as side-products from various industries (among which, sugar production). In this publication, we studied the impact of carbon chain length on three considered reaction mechanisms for the esterification of (CH₃)₃N(CH₂)_nCO₂ betaine (n = 1, 2, 3) with glycerol under acid catalysis. DFT calculations show that the mechanism proposed by Bachmann–Frapper et al. may also be active here, but it can interestingly be seen as an avatar of the former proposition by Watson. Conversely, Ingold’s proposition is in this case too energetically prevented. Overall, lower activation barriers and higher reaction exergonicity are reported, suggesting esterification of longer carbon-chain based betaines is more readily achieved. Full article

(This article belongs to the Special Issue Physical Chemistry Perspectives for the New Decade)

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16 pages, 2904 KiB

Open AccessReview

Surface Coatings and Treatments for Controlled Hydrate Formation: A Mini Review

by Tausif Altamash, José M. S. S. Esperança and Mohammad Tariq

Physchem 2021, 1(3), 272-287; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030021 - 04 Dec 2021

Cited by 7 | Viewed by 3221

Abstract

Gas hydrates (GHs) are known to pose serious flow assurance challenges for the oil and gas industry. Neverthless, over the last few decades, gas hydrates-based technology has been explored for various energy- and environmentally related applications. For both applications, a controlled formation of [...] Read more.

Gas hydrates (GHs) are known to pose serious flow assurance challenges for the oil and gas industry. Neverthless, over the last few decades, gas hydrates-based technology has been explored for various energy- and environmentally related applications. For both applications, a controlled formation of GHs is desired. Management of hydrate formation by allowing them to form within the pipelines in a controlled form over their complete mitigation is preferred. Moreover, environmental, benign, non-chemical methods to accelerate the rate of hydrate formation are in demand. This review focused on the progress made in the last decade on the use of various surface coatings and treatments to control the hydrate formation at atmospheric pressure and in realistic conditions of high pressure. It can be inferred that both surface chemistry (hydrophobicity/hydrophilicity) and surface morphology play a significant role in deciding the hydrate adhesion on a given surface. Full article

(This article belongs to the Section Kinetics and Thermodynamics)

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13 pages, 1475 KiB

Open AccessArticle

Identification of Adsorbed Species and Surface Chemical State on Ag(111) in the Presence of Ethylene and Oxygen Studied with Infrared and X-ray Spectroscopies

by Adva Ben Yaacov, Roey Ben David, David C. Grinter, Georg Held and Baran Eren

Physchem 2021, 1(3), 259-271; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030020 - 12 Nov 2021

Cited by 2 | Viewed by 2954

Abstract

Using a combination of two surface-sensitive spectroscopy techniques, the chemical state of the Ag(111) surface and the nature of the adsorbed species in the presence of ethylene and oxygen gases are identified. In the 10 mbar pressure range and 25–200 °C studied here, [...] Read more.

Using a combination of two surface-sensitive spectroscopy techniques, the chemical state of the Ag(111) surface and the nature of the adsorbed species in the presence of ethylene and oxygen gases are identified. In the 10 mbar pressure range and 25–200 °C studied here, Ag(111) remains largely metallic even in O₂-rich conditions. The only adsorbed molecular species with a low but discernible coverage is surface carbonate, which forms due to further oxidation of produced CO₂, in a similar manner to its formation in ambient air on Ag surfaces. Its formation is also pressure-dependent, for instance, it is not observed when the total pressure is in the 1 mbar pressure range. Production of carbonate, along with carbon dioxide and water vapor as the main gas-phase products, suggests that an unpromoted Ag(111) surface catalyzes mainly the undesired full oxidation reaction. Full article

(This article belongs to the Special Issue Novel Characterization Tools for Catalysis of Energy-Transition Related Reactions)

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9 pages, 2166 KiB

Open AccessArticle

The Local Structure of the BiS₂ Layer in RE(O,F)BiS₂ Determined by In-Plane Polarized X-ray Absorption Measurements

by G. M. Pugliese, L. Tortora, E. Paris, T. Wakita, K. Terashima, A. Puri, M. Nagao, R. Higashinaka, T. D. Matsuda, Y. Aoki, T. Yokoya, T. Mizokawa and N. L. Saini

Physchem 2021, 1(3), 250-258; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030019 - 10 Nov 2021

Cited by 1 | Viewed by 2615

Abstract

We have investigated the local structure of BiS

_{2}

-based layered materials by Bi L

_{3}

-edge extended X-ray absorption fine structure (EXAFS) measurements performed on single crystal samples with polarization of the X-ray beam parallel to the BiS

_{2}

plane. The results [...] Read more.

We have investigated the local structure of BiS

_{2}

-based layered materials by Bi L

_{3}

-edge extended X-ray absorption fine structure (EXAFS) measurements performed on single crystal samples with polarization of the X-ray beam parallel to the BiS

_{2}

plane. The results confirm highly instable nature of BiS

_{2}

layer, characterized by ferroelectric like distortions. The distortion amplitude, determined by the separation between the two in-plane (Bi-S1) bonds, is found to be highest in LaO

_{0.77}

F

_{0.23}

BiS

_{2}

with

Δ

R∼0.26 Å and lowest in NdO

_{0.71}

F

_{0.29}

BiS

_{2}

with

Δ

R∼0.13 Å. Among the systems with intrinsic doping, CeOBiS

_{2}

shows smaller distortion (

Δ

R∼0.15 Å) than PrOBiS

_{2}

(

Δ

R∼0.18 Å) while the highest distortion appears for EuFBiS

_{2}

revealing

Δ

R∼0.22 Å. It appears that the distortion amplitude is controlled by the nature of the RE(O,F) spacer layer in the RE(O,F)BiS

_{2}

structure. The X-ray absorption near edge structure (XANES) spectra, probing the local geometry, shows a spectral weight transfer that evolves systematically with the distortion amplitude in the BiS

_{2}

-layer. The results provide a quantitative measurements of the local distortions in the instable BiS

_{2}

-layer with direct implication on the physical properties of these materials. Full article

(This article belongs to the Special Issue Physical Chemistry Perspectives for the New Decade)

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7 pages, 787 KiB

Open AccessPerspective

Toward Computational Accuracy in Realistic Systems to Aid Understanding of Field-Level Water Quality Issues

by William A. Alexander

Physchem 2021, 1(3), 243-249; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030018 - 31 Oct 2021

Cited by 1 | Viewed by 2270

Abstract

Contemplating what will unfold in this new decade and those after, it is not difficult to imagine the increasing importance of conservation and protection of clean water supplies. A worrying but predictable offshoot of humanity’s technological advances is the seemingly ever-increasing chemical load [...] Read more.

Contemplating what will unfold in this new decade and those after, it is not difficult to imagine the increasing importance of conservation and protection of clean water supplies. A worrying but predictable offshoot of humanity’s technological advances is the seemingly ever-increasing chemical load burdening our waterways. In this perspective are presented a few modest areas where computational chemistry modelling could provide benefit to these efforts by harnessing the continually improving computational power available to the field. In the acute event of a chemical spill incident, true quantum-chemistry-based predictions of physicochemical properties and surface-binding behaviors can be used to help decision making in remediating the spill threat. The chronic burdens of microplastics and perfluorinated “forever chemicals” can also be addressed with computational modelling to fill the gap between feasible laboratory experiment timescales and the much-longer material lifetimes. For all of these systems, field-level accuracy models will avail themselves as the model computational systems are able to incorporate more realistic features that are relevant to water quality issues. Full article

(This article belongs to the Special Issue Physical Chemistry Perspectives for the New Decade)

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11 pages, 3349 KiB

Open AccessArticle

A Computational Study of Molecular Mechanism of Chloroquine Resistance by Chloroquine Resistance Transporter Protein of Plasmodium falciparum via Molecular Modeling and Molecular Simulations

by Chandan Patel and Dipankar Roy

Physchem 2021, 1(3), 232-242; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030017 - 14 Oct 2021

Cited by 3 | Viewed by 2765

Abstract

The molecular mechanism of chloroquine resistance by the chloroquine resistance transporter protein of Plasmodium sp. is explored using molecular modeling and computational methods. The key mutation, lysine(K)-76 to threonine(T) (LYS76THR) in the transporter protein pertains to increased recognition of the protonated forms of [...] Read more.

The molecular mechanism of chloroquine resistance by the chloroquine resistance transporter protein of Plasmodium sp. is explored using molecular modeling and computational methods. The key mutation, lysine(K)-76 to threonine(T) (LYS76THR) in the transporter protein pertains to increased recognition of the protonated forms of the antimalarial drug. Such enhanced affinity can promote drug efflux from host digestive vacuole, rendering aminoquinoline-based treatment ineffective. Full article

(This article belongs to the Special Issue Physical Chemistry Perspectives for the New Decade)

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7 pages, 571 KiB

Open AccessArticle

Dislocations as a Tool for Nanostructuring Advanced Materials

by Vladyslav Turlo

Physchem 2021, 1(3), 225-231; https://0-doi-org.brum.beds.ac.uk/10.3390/physchem1030016 - 26 Sep 2021

Viewed by 2123

Abstract

Dislocations present unique opportunities for nanostructuring advanced structural and functional materials due to the recent discoveries of linear complexions thermodynamically stable nanoscale features with unique chemistry and structure confined at dislocations. The formation of such features is driven by solute segregation near the [...] Read more.

Dislocations present unique opportunities for nanostructuring advanced structural and functional materials due to the recent discoveries of linear complexions thermodynamically stable nanoscale features with unique chemistry and structure confined at dislocations. The formation of such features is driven by solute segregation near the dislocation core and results in the stabilization of dislocations, altering mechanical, thermodynamic, and transport properties of the final material. This perspective article gives an overview of the recent discoveries and predictions made by high-resolution experimental characterization techniques, as well as large-scale atomistic simulations in the newly emerging field of linear complexions. Full article

(This article belongs to the Special Issue Physical Chemistry Perspectives for the New Decade)

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Physchem, Volume 1, Issue 3 (December 2021) – 7 articles

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