Abstract
A strategy is presented that enables the quantitative assembly of a heterobimetallic [PdPtL4](4+) cage. The presence of two different metal ions (Pd-II and Pt-II) with differing labilities enables the cage to be opened and closed selectively at one end upon treatment with suitable stimuli. Combining an inert Pt-II tetrapyridylaldehyde complex with a suitably substituted pyridylamine and Pd-II ions led to the assembly of the cage. H-1 and DOSY NMR spectroscopy and ESI mass spectrometry data were consistent with the quantitative formation of the cage, and the heterobimetallic structure was confirmed using single-crystal X-ray crystallography. The structure of the host-guest adduct with a 2,6-diaminoanthraquinone guest molecule was determined. Addition of N,N '-dimethylaminopyridine (DMAP) resulted in the formation of the open-cage [PtL4](2+) compound and [Pd(DMAP)(4)](2+) complex. This process could then be reversed, with the reformation of the cage, upon addition of p-toluenesulfonic acid (TsOH).