Theoretical Study of the σ–π and π–π Interactions in Heteroaromatic Monocyclic Molecular Complexes of Benzene, Pyridine, and Thiophene Dimers: Implications on the Resin–Asphaltene Stability in Crude Oil

Abstract

Asphaltenes are molecular structures that are composed of polyaromatic and polyheteroaromatic condensed nuclei, where benzene, pyridine, and thiophene rings are the smallest basic structural units. A deep understanding of the electronic features governing the interaction between these primary units is essential for subsequent rationalization of the nature of larger scale interand intramolecular interactions between asphaltenes, which could help to enrich the knowledge of why these compounds tend to aggregate and then to flocculate in oil operation processes. In this work, we study the intermolecular interaction potentials of benzeneÀbenzene, thiopheneÀthiophene, pyridineÀpyridine, benzeneÀpyridine, benzeneÀthiophene, and pyridineÀthiophene molecular complexes by using the self-consistent generalized gradient approximation density functional theory with the PerdewÀWang 91 functional (DFT/GGA PW91) in conjunction with the DNP double numerical basis set. In order to understand the dominant electronic interaction of these complexes in terms of the σÀπ and πÀπ electronic interactions, the three most important structural conformations (parallel, antiparallel, and T-shaped) were chosen. These calculations were performed with the DMol3Materials Studio 4.0 program. It was found that the results of the interaction energies calculated with DFT/GGA PW91 are consistent with those reported in the literature for benzene and thiophene dimers. To gain insight about the stability of the studied complexes, their molecular interaction polarizability was evaluated at the PW91PW91/6-31þG(d,p) level of theory. This property allowed us to explain the attraction and repulsion that occur in these dimer formation processes. These statements were also corroborated at the MP2 and MP4 levels of theory for benzene, pyridine, and thiophene homodimer parallel conformations. Additional CCSD/6-31þG(d,p) calculations were performed for the interaction energies of these dimers. To correlate these findings with the stability of crude oil, a real asphaltene and resin dimer complex structure was fully optimized at the PW91/DNP level. The results of interaction energy, which is in good agreement with the value predicted in the literature, and the large value of the interaction polarizability allowed us to explain the stability of these systems.

Fluorine tracers for the identification of molecular interaction with porous asphaltene aggregates in crude oil

“…Intermediate dimerization of benzene rings is another example of this interaction [12]. To this date, only a few numerical simulations are available that have investigated the interaction of maltenes and asphaltenes by density functional theory [13,14]. Related studies were carried out for modeling the interaction of aromatics with a graphene surface [15][16][17][18], where graphene can be considered as an idealized approximation of asphaltene.…”

Theoretical Study on Interactions between N-Butylpyridinium Nitrate and Thiophenic Compounds

“…Although PW91 functional is unable to provide a good description of dispersion interactions, GGA/PW91/DNP can give good results of interactions between conjugated systems. 27 All the stationary structures have been fully optimized without geometrical constraints. A frequency analysis was performed on all structures to insure the absence of imaginary frequencies.…”

Simultaneous interaction between similar and dissimilar structures of aromatic sulfur and aromatic nitrogen compounds with imidazolium‐based ionic liquid using quantum chemical method

“…On the other hand, the lone pair of electrons on sulfur atom, π-electron cloud density on the aromatic ring, and an aromatic ring structure with highly polarizable π-electron cloud density were the driving force for the structural orientation, molecular attraction, S-H interaction, π-π interaction, and CH-π interaction with the charged ion pairs of ionic liquids at the molecular level. [4,22,23] The nature of five-membered and six-membered rings of nitrogen compounds…”

“…[1,2] These six-membered rings of nitrogen compounds can interact with an extracting solvent through N-H interaction, π-π interaction, and CH-π interaction. [22,28] Moreover, the removal of six-membered rings of A. RAMALINGAM AND J. JEWARATNAM Asia-Pacific Journal of Chemical Engineering 908 nitrogen compounds depends strongly on the structure of the catalyst and extracting solvent.…”