A Simple and Rational Approach for Binodal Metal-Organic Frameworks with Tetrahedral Nodes and Unexpected Multimodal Porosities from Nonstoichiometric Defects

Abstract

The fact that asymmetrically substituted dicarboxylate is capable of forming two different coordination modes is exploited to synthesize a binodal metal-organic framework containing tetrahedral nodes, and thus [H2N(CH3)(2)](2)[Zn-5(hbdc)(6)(dabco)(2)] (1) (hbdc = 2-hydroxyterephthalate, dabco = 1,4-diazabicyclo[2.2.2]octane) possesses the (8,4)-coordinated fluorite topology. This simple approach is verified by using symmetrically substituted ligand, 2,5-dihydroxyterephthalate to synthesize a uninodal, 4-coordinated net whose tetrahedral nodes lead to the rare lonsdaleite topology. It has been found that 1 readily loses some of the neutral ligand and cations during the activation processes without collapsing the whole framework, and multimodal porosities are observed due to the nonstoichiometric defects.