Self-Assembled M₂L₄ Nanocapsules: Synthesis, Structure and Host-Guest Recognition Toward Square Planar Metal Complexes.

Metallosupramolecular cages of the general formulas [M₂(L)₄][X]₄ can be self-assembled in good yields, where M = Pd, X = NO₃, L = (); M = Pd, X = OTf, L = (); M = Pt, X = OTf, L = (); M = Pd, X = OTf, L = (); = 1,3-bis(pyridin-3-ylethynyl)-5-methoxybenzene; and = 2,6-(pyridin-3-ylethynyl)- 4-methoxyaniline, respectively. These cages have been fully characterized using ¹H, C NMR, elemental analysis, IR spectroscopy, and electrospray mass spectrometry. Additionally the molecular structure of [Pd₂()₄][OTf]₄ () was confirmed using single crystal X-ray diffraction. The capacity of central cavities of M₂L₄ cages to accommodate square planar metal complexes was investigated. In particular, the tetracationic cage [Pd₂()₄][OTf]₄ () was found to encapsulate the anionic metal complex [PtCl₄] through electrostatic interactions and also via hydrogen bonding with the amino groups of the bridging ligand displayed by this nanocage.