Hydrogenated polycyclic aromatic hydrocarbons: isomerism and aromaticity

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Materials Science

Background:

• Hydrogenated polycyclic aromatic hydrocarbons (HPAHs) are prevalent in various environments.
• Understanding HPAH isomer stability is crucial for predicting their behavior and properties.
• Existing models may not efficiently explore the vast structural diversity of HPAHs.

Purpose of the Study:

• To develop a simplified model for evaluating the relative stability of HPAH isomers.
• To investigate the key factors influencing HPAH isomer stability.
• To explore a wide range of HPAH structures with varying sizes and hydrogenation degrees.

Main Methods:

• Development of a model based on connectivity (adjacency) matrices.
• Systematic enumeration of isomeric structures considering hydrogenation positions.
• Validation against Density Functional Theory (DFT) calculations for selected cases.

Main Results:

• Aromaticity emerges as the primary determinant of HPAH isomer stability.
• The most stable HPAH structures generally possess the maximum number of intact aromatic rings.
• The model successfully predicts relative stability trends for various HPAH configurations.

Conclusions:

• The connectivity matrix model provides an efficient approach to study HPAH stability.
• Maximizing non-hydrogenated rings is a key strategy for achieving stability in HPAH isomers.
• This work offers insights into the structure-stability relationships of HPAHs.