Stable Zn I ‐Containing MOFs with Large [Zn 70 ] Nanocages from Assembly of Zn II Ions and Aromatic [Zn I 8 ] Clusters

Two unique Zn I ‐containing MOFs {[Zn I 8 Zn II 3 (H 2 O) x (HL) 12 ](OH) 2 ⋅ 13 H 2 O} n ( x= 6, 1 ; x= 2, 2 ) (HL=tetrazole monoanion) with high‐nuclearity Zn‐cages were prepared successfully. These Zn‐cages are constructed from [Zn I 8 ] clusters with multi‐centered Zn I −Zn I bonds and Zn II ions. [Zn I 8 ] clusters in 1 and 2 display O h and D 4 h symmetry, respectively. Importantly, eight [Zn I 8 ] clusters and six Zn II ions form a large [Zn 70 ] nanocage in 1 . To our knowledge, this is the first MOF based on polynuclear Zn‐cages consisting of Zn I and Zn II ions. Compared with reported Zn I ‐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 1g +t 1u molecular orbitals on [Zn I 8 ] 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 VI ions in aqueous.