Abstract
Randomly distributed colloidal magnetic nanoparticles in solution are polarized in the presence of an external magnetic field, and the interparticle dipole-dipole attraction drives their assembly into linear chains. In this Communication, we report using a model A(3)-coupling reaction, that the field-directed self assembly of gold-coated magnetite (Fe3O4@Au) nanoparticles can be used to remotely control the rate of reaction by manipulating their colloidal assembly of catalyst in situ.