Curated dataset of asphaltene structures

Asphaltenes, a distinct class of molecules found in crude oil, exhibit insolubility in nonpolar solvents like n-heptane but are soluble in aromatic solvents such as toluene and benzene. Understanding asphaltenes is crucial in the petroleum industry due to their detrimental effects on oil processing, resulting in significant economic losses and production disruptions. While no singular structure defines asphaltenes, two major molecular architectures, namely archipelago and continental models, have gained wide acceptance for their consistency with various experimental investigations and subsequent use in computational studies. The archipelago model comprises two or more polyaromatic hydrocarbon entities interconnected via aliphatic side chains. In contrast, the island or continental model features a unified polyaromatic hydrocarbon moiety with 4 to 10 fused aromatic rings, averaging around 7 rings. To establish a comprehensive collection, we meticulously curated over 250 asphaltene structures derived from previous experimental and computational studies in this field. Our curation process involved an extensive literature survey, conversion of figures from publications into molecular structure files, careful verification of conversion accuracy, and structure editing to ensure alignment with molecular formulas. Our database provides digital structure files and optimized geometries for both predominant structural motifs. The optimization procedure commenced with the PM6 semi-empirical method, followed by further optimization utilizing density functional theory employing the B3LYP functional and the 6-31+G(d,p) basis set. Furthermore, we compiled a range of structural and electronic features for these molecules, serving as a valuable foundation for employing machine learning algorithms to investigate asphaltenes. This work provides a ready to use structural database of asphaltenes and sets the stage for future research endeavours in this domain

Computational Analysis of Water Dynamics in AOT Reverse Micelles

Aerosols can be modeled for detailed investigations using reverse micelles in the laboratory as well as in computational simulations. A long-standing question in the description of confined water under these conditions is that of a two-state model of core – interface or a three-state model of core – intermediate – interface. In this work, we present results of analysis of water dynamics inside reverse micelles from fully atomistic molecular dynamics simulations. The size and composition of reverse micelles is expressed through w0, the ratio of the number of water molecules to the number of surfactant molecules. Reverse micelles of diverse sizes, with w0 ranging from 5 to 20, were constructed with Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) surfactant and simulated within isooctane solvent. Residence time and diffusion coefficients, in the simulations, both behaved increasingly like bulk water with the increase in size of reverse micelles. Rotational anisotropy autocorrelation was modeled using exponential functions in the short time range of 10–20 ps and longer time data were modeled as a power law fit. Similarly, the diffusion of water in the reverse micelles was also modeled on a power law fit. All these metrics demonstrate a clear progression towards bulk water behavior as the reverse micelle size increases. Additionally, our results also support a 3-layer model of water in a reverse micelle of core – intermediate – interface. These results extend the understanding of water dynamics in reverse micelles and provide further evidence for the 3-layer model

Curated dataset of asphaltene structures

Asphaltenes, a distinct class of molecules found in crude oil, exhibit insolubility in nonpolar solvents like n-heptane but are soluble in aromatic solvents such as toluene and benzene. Understanding asphaltenes is crucial in the petroleum industry due to their detrimental effects on oil processing, resulting in significant economic losses and production disruptions. While no singular structure defines asphaltenes, two major molecular architectures, namely archipelago and continental models, have gained wide acceptance for their consistency with various experimental investigations and subsequent use in computational studies.The archipelago model comprises two or more polyaromatic hydrocarbon entities interconnected via aliphatic side chains. In contrast, the island or continental model features a unified polyaromatic hydrocarbon moiety with 4 to 10 fused aromatic rings, averaging around 7 rings. To establish a comprehensive collection, we meticulously curated over 250 asphaltene structures derived from previous experimental and computational studies in this field. Our curation process involved an extensive literature survey, conversion of figures from publications into molecular structure files, careful verification of conversion accuracy, and structure editing to ensure alignment with molecular formulas. Our database provides digital structure files and optimized geometries for both predominant structural motifs. The optimization procedure commenced with the PM6 semi-empirical method, followed by further optimization utilizing density functional theory employing the B3LYP functional and the 6-31+G(d,p) basis set. Furthermore, we compiled a range of structural and electronic features for these molecules, serving as a valuable foundation for employing machine learning algorithms to investigate asphaltenes. This work provides a ready to use structural database of asphaltenes and sets the stage for future research endeavours in this domain