Molecular dynamics on the self-assembly of mesogenic graphene precursors

Abstract

We characterize the spontaneous aggregation of Disodium Cromoglycate (DSCG) in the isotropic phase of aqueous solutions, which is an archetypical mesogenic precursor for the supramolecular synthesis of graphenic carbons, using molecular dynamics simulations and thermodynamic scaling. DSCG belongs to a broader family of mesogenic precursors called lyotropic chromonic liquid crystals (LCLC). Previously reported experimental self-assembly features were quantitatively reproduced using a full atomistic representation. We find that the formation of hydrogen bonds between solvent water and mesogenic molecules strongly contributes to the self-assembly, a new discovery in LCLC self-assembly. We propose that aggregation is energetically driven by entropic forces which favor the formation of π-π interactions within mesogens' polyaromatic cores by reorienting DSCG hydrophilic groups towards solvent molecules. We carried out different quantitative characterizations that support this mechanism, such as radial distribution function and hydrogen bond distribution analysis. Furthermore, conformation stability calculations were studied using metadynamics sampling technique. These results provide a significant contribution to the ongoing understanding of the self-assembly of LCLC required for the characterization and synthesis of highly ordered supramolecular graphenic materials.