Enhancing the Control of a Magnetically Capped Molecular Nanocontainer: Monte Carlo Studies

In a recent paper [Panczyk, T.; Warzocha, T. P.; Camp, P.J.J. Phys. Chem. C 2010, 114, 21299] we discussed some of the factors controlling the properties of a magnetically controlled molecular nanocontainer composed of a carbon nanotube and magnetic nanoparticles. This paper complements that study by (1) analyzing the role of the configuration of anchoring points on the carbon nanotube tips to which the magnetic nanoparticles are bound; (2) discussing possible effects of the presence of electrostatic stabilizing layers on the surfaces of the magnetic nanoparticles; (3) studying the effects of the carbon nanotube length; and (4) analyzing how the rate of increase of the magnetic field affects the uncapping processes. It is found that in some cases the nanocontainer might be locked in the double uncapped state. This effect can be minimized or eliminated by using either nanotubes longer than the sum of the magnetic nanoparticle radii or by utilizing electrostatic repulsion between charged nanoparticles. The magnetically triggered uncapping is better effected by using an instantaneous increase of the magnetic field strength. A slow increase of the field leads to alignment of nanocontainers with the field direction, and this effect reduces the effectiveness of magnetically triggered uncapping.