One-dimensional self-assembly of polyaromatic compounds revealed by molecular dynamics simulations.

A series of molecular dynamics simulations were performed on the self-assembly of polyaromatic (PA) compounds in n-heptane. These compounds possess the same PA core but systematically varied side-chain lengths. Regardless of the side-chain lengths, the simulations revealed the formation of one-dimensional (1D) self-assemblies resulting mainly from parallel stacked PA cores. The length over which the parallel stacking persists was found to be 3-5.6 nm. The 1D self-assembly was not observed for the same PA compounds in water or toluene, suggesting the importance of solvent properties in its formation. In particular, n-heptane can prevent the side chains from interfering with PA core stacking while having limited attraction with the cores, which facilitates the 1D self-assembling. These findings, revealed at the molecular level, provide insights into controlling the self-assembling process in the design of optical and electronic nanodevices.