The use of layered … … chalcogenide nanoparticles in composite materials was facilitated by a better binding of the nanoparticles to the chalcogenide/matrix interface. In their Communication on page 7578 ff. W. Tremel et al. present a strategy for the reversible functionalization and formation of MS2/MOx nanoparticle assemblies. This functionalization, in which the Pearson HSAB concept is tested on the nanoscale, allows kinetic and thermodynamic control of the product.