Simulation of Crystallization of Pentacene and Its Derivatives from Solution

The order-emerging stage of crystallization in solution of pentacene and its derivatives was investigated using molecular dynamics simulations. Spontaneous formation of the layered herringbone motif of the pentacene crystal was successfully demonstrated starting from a random mixed solution state. Moreover, I found that the formation of the layer order and the in-layer herringbone-order occurred simultaneously in my simulation because the formation of the layer was driven by the edge-toface (herringbone shape) interaction between pentacene molecules. This is markedly different from the stepwise order formation from the liquid-crystal-like layer order to the subsequent in-layer herringbone order in the corresponding simulation of the dialkylated pentacene derivative 2,9-dioctyl-pentacene. I also demonstrated the change in the crystal motif from herringbone for pentacene to face-to-face pi-stacking for the dechlorinated pentacene derivative 6,13-dichloropentacene because of the steric effect of substituted chlorines disabling the edge-to-face intermolecular interaction in nonsubstituted pentacene.

Automated summary

Molecular dynamics simulations were used to investigate the order-emerging stage of crystallization in solution of pentacene and its derivatives. It was found that the layered herringbone motif of the pentacene crystal spontaneously formed from a random mixed solution state, with layer order and in-layer herringbone order occurring simultaneously in the simulation. The crystal motif transformed from herringbone for pentacene to face-to-face pi-stacking for the dechlorinated pentacene derivative due to steric effects.