Boronate Ester-Capped Helicates.

Triple-stranded helicates were obtained by metal-templated multicomponent reactions of bispyridyloxime ligands with arylboronic acids. The helicates feature two hexa-coordinated MII ions (M=Fe, Zn, or Mn), which are embedded in a macrobicyclic ligand framework, and two arylboronate ester capping groups. The latter can be used to introduce functional groups such as pyridines, aldehydes, nitriles, and carboxylic acids in apical position. The functionalized helicates have the potential to be used as nanoscale building blocks for more complex assemblies, as evidenced by the synthesis of a 3 nm-sized trianglimine.