Size dependence of nanoscale confinement on chiral transformation.

Molecular dynamic simulations of the chiral transition of a difluorobenzo[c]phenanthrene molecule (C(18)H(12)F(2), D molecule) in single-walled boron-nitride nanotubes (SWBNNTs) revealed remarkable effects of the nanoscale confinement. The critical temperature, above which the chiral transition occurs, increases considerably with the nanotube diameter, and the chiral transition frequency decreases almost exponentially with respect to the reciprocal of temperature. The chiral transitions correlate closely with the orientational transformations of the D molecule. Furthermore, the interaction energy barriers between the D molecule and the nanotube for different orientational states can characterize the chiral transition. This implies that the temperature threshold of a chiral transition can be controlled by a suitable nanotube. These findings provide new insights to the effect of nanoscale confinement on molecular chirality.