Chelating Ligands Tethered to Carbon Nanotubes

Summary: Carbon nanotubes offer an inert platform on which various species may be supported. A range of applications have been addressed using this approach. Anchoring sites on the nanotubes are usually groups introduced via an oxidative procedure. These groups provide convenient reactive functionality that can be accessed in a variety of ways. In this case, carboxyl functionality have been utilized to attach, through a linker, a good coordinating ligands, 1-10-phenanthroline. In the first instance, 1,10-phenanthroline was converted to the 5,6-epoxide by treatment with hypochlorite. The epoxide was opened in sulfuric acid to generate the 5-hydroxy compound. This, in turn, was treated with ethylene oxide in the presence of a base to provide the alkoxylated compound. The alcohol terminus, as the alkoxide, was used to couple the nanotubes by displacement of tosyl anion from the methylol ester. The carboxyl groups at the nanotubes surface were reduced to the corresponding alcohol and treated with p-toluenesulfonyl chloride in the presence of pyridine to generate the tosylate used for coupling. In a second approach the carboxyl groups were converted to the corresponding acid chloride which was treated with alkoxylated phenanthroline to achieve coupling via an ester linkage.