Symmetry-guided syntheses of mixed-linker Zr-MOFs with precise linker locations

Abstract

The construction of multifunctional mixed-linker metal-organic frameworks (MOFs) with precise linker locations in the framework is a challenging task. A series of new Zr-MOFs with 12-c fcu topology containing the two linkers with different linker symmetries and lengths at well-defined locations are prepared. While one-pot reactions of zirconium metal ion with mixtures of dicarboxylate heterolinkers result in only hybrid Zr-MOFs with fcu topology, symmetry-guided stepwise reactions produce a series of Zr-MOFs with fcu topology containing two different dicarboxylate linkers with precise locations in the framework. The symmetry-guided insertions of linear terephthalic acid (H2BDC) derivatives with mmm symmetry into the mmm symmetry-sites of the flexible 8-c bcu Zr-MOF (termed ZRN-bcu) composed of zigzag 2,6-naphthalenedicarboxylic acid with 2/m symmetry result in a series of new Zr-MOFs with 12-c fcu topology. Even though the length of the BDC2- derivatives is much shorter than the distance between the unlinked closest neighboring Zr-clusters in ZRN-bcu, the symmetry-matching BDC2 derivatives are induced-fit into the framework of ZRN-bcu to form a series of stable 12-c fcu Zr-MOFs containing two different dicarboxylate linkers at well-defined locations.