Terpyridine-Based, Flexible Tripods: From a Highly Symmetric Nanosphere to Temperature-Dependent, Irreversible, 3D Isomeric Macromolecular Nanocages

A three-dimensional, highly symmetric
sphere-like nanocage was
synthesized using a terpyridine (tpy)-based, flexible tris-dentate
ligand and characterized by single crystal X-ray analysis. To introduce
more rigidity, one of the tpy units of the tris-dentate ligand was
preblocked by stable 2+-tpy> connectivity
to
form the corresponding Ru2+-dimer. The complexation between
Ru2+-dimer and Fe2+ demonstrates an unexpected
temperature-dependent assembly between two irreversible isomeric 3D
nanocages. Investigation of the coordination process and structural
configurations of the metal–ligand framework, affected by the
introduction of rigidity and in the presence of external stimuli (temperature),
is reported.