Chemical modification of single-walled carbon nanotubes (Metallacycles include carbon nanotubes) is a critical step to exploit their properties. Either by covalent modification or by supra molecular functionalisation of their surface, nanotube products are created with applications in e.g. optical sensing and electronics. Other modifications, such as mechanical interlinking of carbon nanotubes with molecules (MINTs), make it possible to design interesting products with similar strength to covalently modified nanotubes, but preserving the natural structure of the tubes. Some promising applications of MINT can be found in strengthening polymers, metal-free catalysts or qubits.
Today, a group of researchers led by Emilio M. Pérez (Chemistry of Low Dimensional Materials Group of IMDEA Nanociencia) and Eduardo Peris (INAM of Universitat Jaume I) took an important step in the synthesis of MINTs by producing them with supra molecular . coordination complex. A supra molecular coordination complex is a chemical product that contains organic ligands bound to metal atoms through a coordination bond. Compared to MINTs constructed from purely organic assemblies, coordination complexes can introduce a new dimension to the resulting MINT due to the presence of the metal. The metal center can improve the photo electrochemical properties of MINTs and help expand their applications. Metal-ligand interactions are also one of the most efficient ways to create mechanical molecules.
To attempt the preparation of complex coordination MINTs, the researchers selected a collection of molecular (Metallacycles include carbon nanotubes) building blocks that lead to metallo macrocycles. They found that MINT formation with palladium-based metallacycles is very sensitive to the large complementarity between the macrocycle opening and the carbon nanotube diameter. However, if the fit is good, the reactions can be successfully performed by “cutting” and “threading” strategies in the same product. That is, these metallo-MINTs can be created by self-assembling metallacycles around a carbon nanotube (“trimming”) or by encapsulating a carbon nanotube into the cavity of a preformed metallacycle (“threading”).
The results show how direct control of coordination geometries can be used to prepare self-assembled structures beyond the molecular level. “We think that our work opens a new field of opportunities for MINTs” Prof. to know Perez.
