Molecular Dynamics Study on the Structure-Property Relationship of Self-Assembled Gear-Shaped Amphiphile Molecules...

Gaining insight into the encapsulation mechanism is important for controlling the encapsulation rate toward the self-assembly of gear-shaped amphiphile molecules (GSAs). To this aim, we conducted molecular dynamics (MD) simulations for three different hexameric nanocubes (1₆¹²⁺, 2₆¹²⁺, and 3₆¹²⁺) of GSAs (1²⁺, 2²⁺, and 3²⁺, respectively) to elucidate the quantitative structure-property relationship between the stability of the nanocubes and the rate of encapsulation of a guest molecule. The 1²⁺, 2²⁺, and 3²⁺ monomers differ from each other in the number of methyl groups, having three, zero, and two methyl groups, respectively. The 3₆¹²⁺ hexamer has methyl groups only on the equatorial region. In the cases of the simulations of 1₆¹²⁺ and 3₆¹²⁺, the cubic structures are maintained due to a tight triple-π stacking around the equator region. Meanwhile, 2₆¹²⁺ deforms easily due to the occurrence of a large fluctuation. These results indicate that the methyl groups on the equator are crucial to stabilize the nanocubes. The encapsulation of an iodide ion as a guest molecule is revealed to occur through the pole region via a gap that is easily formed in the nanocubes without methyl groups on the poles. Our study clearly suggests that self-assembled nanocubes can be designed to attain a specific stability and encapsulation efficiency simultaneously.