Molecular dynamics and network analysis reveal the contrasting roles of polar solutes within organic phase amphiphile aggregation

Sadhu, Biswajit; Clark, Aurora E.

doi:10.1016/j.molliq.2022.119226

Cited by 10 publications

(29 citation statements)

References 55 publications

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“…For a more detailed analysis of the molecular organization within these clusters, we refer elsewhere. 64 These clusters are mobile, as witnessed by the very different molecular arrangements shown in the two snapshots in Figure 2 . This variation indicates that the interactions between the polar groups are somewhat unspecific.…”

Section: Resultsmentioning

confidence: 97%

“…This is in qualitative agreement with the results of SANS/SAXS experiments. We also note the distinct roles of nitric acid and water in driving aggregation, and we refer to Sadhu and Clark 64 for a comprehensive discussion. We studied the bonding that took place within these clusters and found that the carbonyl oxygen was the main site for hydrogen bonding in a TODGA molecule.…”

Section: Discussionmentioning

confidence: 99%

“…A detailed account of the molecular organization within these clusters is given by Sadhu and Clark. 64 …”

Section: Discussionmentioning

confidence: 99%

“… 19 , 21 , 58 − 63 A very recent article reports the results of large-scale simulations of the TODGA/ n -dodecane/water/nitric acid system as well as providing a detailed description of the molecular structure of the aggregates. 64 …”

Section: Introductionmentioning

confidence: 99%

“… 19 focused on an organic phase with the same TODGA concentration as above but a nitric acid concentration of 0.01 M. In both cases, these organic phases were in equilibrium with corresponding aqueous phases. These systems have been previously simulated 63 , 64 and the clustering discussed. Bell et al 61 studied nitric acid extraction into TODGA at a higher nitric acid concentration.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Study of the Aggregation Behavior of N,N,N′,N′-Tetraoctyl Diglycolamide

et al. 2022

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Liquid–liquid extraction is a commonly used technique to separate metals and is a process that has particular relevance to the nuclear industry. There has been a drive to use environmentally friendly ligands composed only of carbon, hydrogen, nitrogen, and oxygen. One example is the i-SANEX process that has been developed to separate minor actinides from spent nuclear fuel. The underlying science of such processes, is, however, both complex and intriguing. Recent research indicates that the liquid phases involved are frequently structured fluids with a hierarchical organization of aggregates. Effective flow-sheet modeling of such processes is likely to benefit from the knowledge of the fundamental properties of these phases. As a stepping stone toward this, we have performed molecular dynamics simulations on a metal free i-SANEX system composed of the ligand N , N , N ′, N ′-tetraoctyl diglycolamide (TODGA), diluent hydrogenated tetrapropylene (TPH), and polar species water and nitric acid. We have also studied the effects of adding n -octanol and swapping TPH for n -dodecane. It would seem sensible to understand this simpler system before introducing metal complexes. Such an understanding would ideally arise from studying the system’s properties over a wide range of compositions. The large number of components, however, precludes a comprehensive scan of compositions, so we have chosen to study a fixed concentration of TODGA while varying the concentrations of water and nitric acid over a substantial range. Reverse aggregates are observed, with polar species in the interior in contact with the polar portions of the TODGA molecules and the organic diluent on the exterior in contact with the TODGA alkyl chains. These aggregates are irregular in shape and grow in size as the amount of water and nitric acid increases. At a sufficiently high polar content, a single extended cluster forms corresponding to the third phase formation. No well-defined bonding motifs were observed between the polar species and TODGA. The cluster size distribution fits an isodesmic model, where the Gibbs energy change of adding a TODGA molecule to a cluster ranges between 4.5 and 7.0 kJ mol –1 , depending on the system composition. The addition of n -octanol was found to reduce the degree of aggregation, with n -octanol acting as a co-surfactant. Exchanging the diluent TPH for n -dodecane also decreased the aggregation. We present evidence that this is due to the greater penetration of n -dodecane into the reverse aggregates. It is known, however, that the propensity for the third phase formation is greater with n -dodecane as the diluent than is the case with TPH, but we argue that these two results are not contradictory. This research casts light on the drivin...

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Section: Resultsmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

“…A detailed account of the molecular organization within these clusters is given by Sadhu and Clark. 64 …”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Study of the Aggregation Behavior of N,N,N′,N′-Tetraoctyl Diglycolamide

et al. 2022

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Modern chemical graph theory

Leite,

Banerjee,

Wei

et al. 2024

WIREs Comput Mol Sci

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Graph theory has a long history in chemistry. Yet as the breadth and variety of chemical data is rapidly changing, so too do graph encoding methods and analyses that yield qualitative and quantitative insights. Using illustrative cases within a basic mathematical framework, we showcase modern chemical graph theory's utility in Chemists' analysis and model development toolkit. The encoding of both experimental and simulation data is discussed at various levels of granularity of information. This is followed by a discussion of the two major classes of graph theoretical analyses: identifying connectivity patterns and partitioning methods. Measures, metrics, descriptors, and topological indices are then introduced with an emphasis upon enhancing interpretability and incorporation into physical models. Challenging data cases are described that include strategies for studying time dependence. Throughout, we incorporate recent advancements in computer science and applied mathematics that are propelling chemical graph theory into new domains of chemical study.This article is categorized under: Molecular and Statistical Mechanics > Molecular Dynamics and Monte‐Carlo Methods Structure and Mechanism > Computational Materials Science Structure and Mechanism > Molecular Structures

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