An interlocked coordination cage based on aromatic amide ligands

An interlocked M4L8 coordination cage was synthesized by coordination-driven self-assembly of palladium(II) ions with aromatic amide bidentate ligands. The reaction of the ligand and the metal at 2:1 ratio led to the monomeric M2L4 cage as the kinetic product, while the thermodynamic product M4L8 cage was obtained by prolongating the reaction. This conversion and the interlocked structure was clearly revealed by using H-1 NMR, mass spectrometry and X-ray crystallography. The driving force of interlocking was mainly attributed to the interactions (hydrogen bonding, aromatic stacking and electrostatic interaction) arising from the aptitude of flexibility of the amide ligand. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

An interlocked M4L8 coordination cage was synthesized by coordination-driven self-assembly, with the structure and formation mechanism clearly revealed through various spectroscopic techniques.