Chiral [Mo8O26]4- Polyoxoanion-Induced Three-Dimensional Architectures With Homochiral Eight-Fold Interpenetrated Metal-Organic Frameworks.

Abstract

A pair of novel chiral compounds based on homochiral 8-fold interpenetrated metal-organic frameworks (MOFs) and chiral polyoxometalates (POMs), formulated as d-[Cu(4,4'-bipy)1.5]4[Mo8O26] (d-1) and l-[Cu(4,4'-bipy)1.5]4[Mo8O26] (l-1) (4,4'-bipy = 4,4'-bipyridine), have been successfully synthesized and characterized by single crystal X-ray diffraction, infrared, thermogravimetric analysis, elemental analysis, and solid circular dichroism spectra. Structural analysis indicates that two compounds are enantiomers. The connection of copper cations and 4,4'-bipy ligands generates helical infinite chains, while adjacent chains are further linked by Cu-N bonds to form a three-dimensional interpenetrating framework with a (10,3)-a topology. Interestingly, the chiral [Mo8O26]4- polyanions are encapsulated in the chiral MOFs via sharing the oxygen atoms. Both d- and l-[Cu(4,4'-bipy)1.5]4[Mo8O26] crystallize in chiral space group C2221. Additionally, two compounds represent new examples of chiral self-assembly.