Computational Study of Some Aspects of Chemical Optimization of a Functional Magnetically Triggered Nanocontainer

This work concerns the properties of a nanodevice composed of a carbon nanotube and core-shell magnetic nanopartides bound to the nanotube tips via alkane chains of various lengths. A model nanocontainer is analyzed using Monte Carlo simulations involving an extended potential function that includes magnetic, dispersion, and screened-electrostatic interactions between the nanoparticles, appropriate nanoparticle-alkane chain interactions, and bond bending, stretching, and torsional interactions within the alkane chains. The energy of the system is determined along coordinate linking double-capped, semiuncapped, and double uncapped states. The transitions between these states in the absence of an external magnetic field depend sensitively on the activation barriers, which in turn can be controlled by adjusting the nanoparticle-shell material, its thickness, and the length of the alkane linkers. It is shown that the molecular parameters must be chosen carefully in order that the complete nanodevice possesses the desired properties, i.e., that the system is in a double-capped state under ambient conditions and that the uncapped states can be accessed by exposure to an external magnetic field. Specifically, the alkane linkers must consist of no more than two carbons, and the nanopartide shell material must have a moderate Hamaker constant (e.g., alumina).