A new crosslinking reaction between two pentagonal rings around the periphery of planar pericondensed aromatic molecules is proposed and its impact on soot nanoparticle formation explored. The reaction mechanism was computed, using density functional theory, between an aryl-type σ-radical on arim-based pentagonal ring attacking another rim-based pentagonal ring. A hydrogen migration allowed for the formation of a double bond forming a planar aromatic penta-linked hydrocarbon (APLH) complex, recently experimentally observed. The clustering of this planar species is compared with a pericondensed polyaromatic hydrocarbon (PCAH) and an aromatic aryl-linked hydrocarbon (AALH) using molecular dynamics and metadynamics. Similar clustering is found for the investigated species compared with a peri-condensed structure of similar mass indicating enhanced physical interactions after forming the crosslink. Finally, a further crosslink is possible between the unsaturated pentagonal ring sites forming an aromatic rim-linked hydrocarbon (ARLH) complex of considerable stability. This was con firmed by
simulating the stable molecular dynamics of such a complex with on-the-fly quantum forces from a quantum semi-empirical method, revealing possible
reactions under
ame conditions that might play a role in soot nucleation.National Research Foundation - Singapor
