Low Symmetry Cage Complexes Formed by Metalation of Symmetric Hexa-Cationic Organic Cages

Abstract

Most metal organic cages are assembled through metal–ligand coordination, resulting in cages where the metal ions are part of the cage architecture, and thus have limited reactivity. There are only a handful of metal organic cages produced by metalation of a pre-synthesised organic cage. In this work, we show that hexa-cationic hydrazone cages coordinate a range of transition metal ions upon deprotonation to give cage complexes with metal ions oriented towards the cage cavity. Remarkably, a cage with ethyl solubilising groups gives the expected three-fold symmetric metallocage, cages with alkoxy solubilising groups give low-symmetry zinc metallocages, and a cage without a solubilising group switches between high and low symmetry conformations depending on solvent. These low symmetry arrangements persist on the NMR timescale at temperatures as high as 360 K and in the presence of a wide range of anions. Show more