Synthesis of layered platelets by self-assembly of rhenium-based clusters directed by long-chain amines

Self-assembly of nanomaterials by wet chemistry methods is a suitable approach for the preparation of engineered structures with novel functionalities. In this work, we study the ability of long-chain amines to direct the growth of a layered nanomaterial, using [Re x Se y Cl z ] clusters as building blocks. The amines link to the clusters as ligands during the synthesis, directing the self-assembly due to their amphiphilic properties, which produces a platelet-shaped 2D material with sizes up to several μm in diameter and thicknesses in the range of 60–80 nm. This is, to the best of our knowledge, the first report on a one-step mild chemistry method for the preparation of 2D structures composed of alternate layers of self-assembled amines and sub-nm clusters of a rhenium chalcogenide. Furthermore, these materials can be used as a suitable source of clusters which then, conveniently released by a simple acid/base reaction, have been successfully incorporated to the surface of graphene. The simple clusters deposition method developed here offers a promising route towards the preparation of hybrid clusters/2D materials with outstanding properties arising from quantum confinement effects combined with high surface areas and the enormous compositional variety of 2D materials and clusters. These hybrids are expected to play a key role in the development of active materials for applications ranging from highly efficient energy storage systems, more active catalysts and upper-sensitivity gas sensors. Scaffolds made of chain-shaped molecules can be erected and dismantled to control the assembly of small atomic clusters. Andres Seral-Ascaso, Valeria Nicolosi and colleagues from Trinity College Dublin, Ireland, developed a method to let grains of few Rhenium and Selenium atoms assemble into flat, circular platelets in a liquid solution. Key to the process are the organic molecules composing the solution, having a head that attaches to the clusters and a chain-like tail that makes the molecules align like poles of a scaffold. The clusters are held together in stable platelets, until the addition of another liquid breaks the alignment and disperses the clusters again. Breaking the organic scaffold in a solution that contains graphene sheets makes the re-dispersed clusters deposit on such sheets, forming composite materials that may find use in batteries or sensors.