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

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[Zn5(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.