Stable Zn -Containing MOFs with Large [Zn ] Nanocages from Assembly of Zn Ions and Aromatic [Zn ] Clusters.

Two unique Zn -containing MOFs {[Zn Zn (H O) (HL) ](OH) ⋅13 H O} (x=6, 1; x=2, 2) (HL=tetrazole monoanion) with high-nuclearity Zn-cages were prepared successfully. These Zn-cages are constructed from [Zn ] clusters with multi-centered Zn -Zn bonds and Zn ions. [Zn ] clusters in 1 and 2 display O and D symmetry, respectively. Importantly, eight [Zn ] clusters and six Zn ions form a large [Zn ] nanocage in 1. To our knowledge, this is the first MOF based on polynuclear Zn-cages consisting of Zn and Zn ions. Compared with reported Zn -species, 1 and 2 display high thermal and solvent stabilities. Theoretical investigations based on DFT calculations uncover that effective 4s-4s orbital overlap and electron delocalization through these a +t molecular orbitals on [Zn ] clusters lead to considerable aromatic stabilization, which can explain well the intrinsic stability of 1 and 2. Interestingly, 1 can behave as a luminescent probe to detect the toxic Cr ions in aqueous.