Strings-to-Rings Transition and Antiparallel Dipole Alignment in Two-Dimensional Methanols

Zangi, Ronen; Roccatano, Danilo

doi:10.1021/acs.nanolett.6b00460

Cited by 12 publications

(14 citation statements)

References 41 publications

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“…Comparison of the snapshots shows that our systems and confined methanol display very similar trends in structure depending changes with the temperature. This is further confirmed by similarities in the radial distributions functions as well as temperature dependence of the energy and hydrogen bonding 77 .…”

Section: Discussionsupporting

confidence: 62%

“…Morishige and Kawano 76 argue that in a very small nanotube methanol shows possible vitrification observed in the diffraction pattern throughout a range of temperatures. In a recent article on methanol confined between two graphene sheets, authors Zangi and Roccatano 77 show the formation of long chain phases at the lower temperature and the transition to small chains and rings at the high temperature for a dense methanol system. Comparison of the snapshots shows that our systems and confined methanol display very similar trends in structure depending changes with the temperature.…”

Section: Discussionmentioning

confidence: 99%

“…Finally, the investigation of confined liquids has gained noticeable research interest recently 77,82 , both for the physics of the mechanism behind observed structural, dynamical and thermodynamical changes, as well as potential applications 83,84 . A recent study of water encapsulated by graphene showed a structural order with low entropy and order-to-disorder transition at 480–490 K with the sharp reduction in a number of hydrogen bonds and increase in the entropy 82 .…”

Section: Discussionmentioning

confidence: 99%

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A simple two dimensional model of methanol

Primorać

Požar

Sokolić

et al. 2018

Journal of Molecular Liquids

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Methanol is the simplest alcohol and possible energy carrier because it is easier to store than hydrogen and burns cleaner than fossil fuels. It is a colorless liquid, completely miscible with water and organic solvents and is very hygroscopic. Here, simple two-dimensional models of methanol, based on Mercedes–Benz (MB) model of water, are examined by Monte Carlo simulations. Methanol particles are modeled as dimers formed by an apolar Lennard-Jones disk, mimicking the methyl group, and a sphere with two hydrogen bonding arms for the hydroxyl group. The used models are the one proposed by Hribar-Lee and Dill (Acta Chimica Slovenica, 53:257, 2006.) with the overlapping discs and a new model with tangentially fused dimers. The comparison was done between the models, in connection to the MB water, as well as with experimental results and with new simulations done for 3D models of methanol. Both 2D models show similar trends in structuring and thermodynamics. The difference is the most pronounced at lower temperatures, where the smaller model exhibits spontaneous crystallization, while the larger model shows metastable states. The 2D structural organization represents well the clustering tendency observed in 3D models, as well as in experiments. The models qualitatively agree with the bulk methanol thermodynamic properties like density and isothermal compressibility, however, heat capacity at the constant pressure shows trend more similar to the water behavior. This work on the smallest amphiphilic organic solute provides a simple testing ground to study the competition between polar and non-polar effects within the molecule and physical properties.

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Section: Discussionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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A simple two dimensional model of methanol

Primorać

Požar

Sokolić

et al. 2018

Journal of Molecular Liquids

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“…Recently, we investigated the structure and self-assembly of methanol molecules confined between two, or adsorbed on, graphene sheets. 12 In the process of extending this study for larger molecules, we tested the behavior of the bulk liquid phase (in three dimensions) at ambient conditions of a series of larger alcohols. However in this case, we observed that within few hundred nanoseconds, 1-octanol, 1-nonanol, and 1-decanol, when described by the OPLSAA force-field, spontaneously undergo a sharp first-order transition from liquid to solid.…”

Section: Introductionmentioning

confidence: 99%

Refinement of the OPLSAA Force-Field for Liquid Alcohols

Zangi

2018

ACS Omega

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We employ the popular all-atom optimized potential for liquid simulations, OPLSAA, force-field to model 17 different alcohols in the liquid state. Using the standard simulation protocol for few hundred nanosecond time periods, we find that 1-octanol, 1-nonanol, and 1-decanol undergo spontaneous transition to a crystalline state at temperatures which are 35–55 K higher than the experimental melting temperatures. Nevertheless, the crystal structures obtained from the simulations are very similar to those determined by X-ray powder diffraction data for several n -alcohols. Although some degree of deviations from the experimental freezing points are to be expected, for 1-nonanol and 1-decanol, the elevation of the freezing temperature warrants special attention because at room temperature, these alcohols are liquids; however, if simulated by the OPLSAA force-field, they will crystallize. This behavior is likely a consequence of exaggerated attractive interactions between the alkane chains of the alcohols. To circumvent this problem, we combined the OPLSAA model with the L-OPLS force-field. We adopted the L-OPLS parameters to model the hydrocarbon tail of the alcohols, whereas the hydroxyl head group remained as in the original OPLSAA force-field. The resulting alcohols stayed in the liquid state at temperatures above their experimental melting points, thus, resolving the enhanced freezing observed with the OPLSAA force-field. In fact, the mixed-model alcohols did not exhibit any spontaneous freezing even at temperatures much lower than the experimental values. However, a series of simulations in which these mixed-OPLSAA alcohols started from a coexistence configuration of the liquid and solid phases resulted in freezing transitions at temperatures 14–25 K lower than the experimental values, confirming the validity of the proposed model. For all of the other alcohols, the mixed model yields results very similar to the OPLSAA force-field and is in good agreement with the experimental data. Thus, for simulating alcohols in the liquid phase, the mixed-OPLSAA model is necessary for large (7 carbons and above) hydrocarbon chains.

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“…12,13 Yet, biological self-assembly usually occurs at fast rates and with high precision, making it particularly interesting although still poorly understood. 14,15 To date, the self-assembly of small molecules has primarily been studied in extreme cases where systems are under confinement 16 or at low temperatures 17 so as to force the molecules to remain long enough near the solid's surface for supramolecular structures to form. Examples in ambient conditions are scarce, with limited insights into the process.…”

Section: Introductionmentioning

confidence: 99%