Combined Experimental and Computational Study of Polycyclic Aromatic Compound Aggregation: The Impact of Solvent Composition

Abstract

The aggregation of polycyclic aromatic compound (PAC) molecules is sensitive to the solvent they are dissolved or suspended in. By using both dynamic light scattering and diffusion-ordered nuclear magnetic resonance spectroscopy, in combination with molecular dynamics simulations, the effect of chemical structure on the aggregation of PACs in both aromatic and alkane solvents were systematically investigated. A suite of triphenylene-based PACs offers a robust platform to understand the driving forces of aggregation mechanism across both nanometer and micrometer scales. Both the configuration, either parallel or otherwise, and the arrangement, whether compact or loose, of molecules in their aggregates are determined by a fine balance of different interactions such as those between the polar groups, π–π interactions between the aromatic cores, steric hindrance induced by the side chains, and the degree of solvation. These results suggest that molecular architecture is the major factor in determining how the model compounds aggregate. The shift from aromatic to aliphatic solvent only slightly increases the likelihood of aggregation for the model compounds studied while subtle differences in molecular architecture can have a significant impact on the aggregation characteristics.

Keywords:

• Aggregation
• diffusion NMR
• DLS
• molecular dynamics

Author contributions

The manuscript was written through contributions of all authors and all authors have given approval to the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded by the Engineering and Physical Science Research Council under Grant EP/P007864/1. The diffusion NMR experiments were funded by the RSC Research Fund under Grant RF17-3528.