Solvent effects on the chirality in two-dimensional molecular assemblies

In this work we reported the observations, using scanning tunneling microscopy (STM), on the solvent effects upon the expression of supramolecular chirality on the graphite surface in the two-dimensional assembly of 3,5-di(4-n-tetradecyloxyphenyl) pyrazole (DTPP). It was observed that DTPP dissolved in a 1:3 solvent mixture of toluene and chloroform can form chiral lamellae, while no chiral characteristics can be found when DTPP is dissolved in toluene alone. Rod-shaped molecular cores are observed in the assembly from toluene solution, while bent-shaped molecules are observed in the solvent mixture of toluene and chloroform. The observation suggests that surface-stabilized supramolecular chiral lamellae may be appreciably affected by solvents through tuning of intermolecular hydrogen-bond configuration.