Stacking structure in liquid polyaromatic hydrocarbons

Area of Science:

• Materials Science
• Chemical Physics
• Condensed Matter Physics

Background:

• Polyaromatic hydrocarbons (PAHs) are crucial in various scientific and industrial applications.
• Understanding the liquid-phase structure of PAHs is essential for accurate modeling and application development.

Purpose of the Study:

• To investigate the liquid structure of phenanthrene and pyrene using neutron total scattering.
• To compare the stacking behavior of these PAHs with smaller molecules like benzene and naphthalene.
• To determine the degree and relative orientation of π-stacked pairs in liquid PAHs.

Main Methods:

• Neutron total scattering experiments were conducted on phenanthrene and pyrene.
• Simulation-based data refinement was employed for structural analysis.
• The degree and relative position of π-stacked pairs were quantified.

Main Results:

• Pyrene exhibited the highest degree of parallel stacking, with 46% of molecules forming stacked pairs.
• A trend of decreasing displacement in stacking was observed with increasing aromatic core size.
• For pyrene, no offset in π-stacking was detected, indicating perfect parallel alignment.

Conclusions:

• The study provides fundamental insights into the liquid-phase structure of PAHs.
• Findings are crucial for modeling PAH behavior in fields like optoelectronics, astrochemistry, and crude oil science.
• The observed stacking trends offer a basis for predicting and controlling PAH molecular arrangements.