An exceptionally stable, porphyrinic Zr metal-organic framework exhibiting pH-dependent fluorescence.

A reaction between a Zr(IV) salt and a porphyrinic tetracarboxylic acid leads to a metal-organic framework (MOF) with two types of open channels, representing a MOF featuring a (4,8)-connected sqc net. The MOF remains intact in both boiling water and aqueous solutions with pH ranging from 1 to 11, a remarkably extensive pH range that a MOF can sustain. Given its exceptional stability and pH-dependent fluorescent intensity, the MOF can potentially be applied in fluorescent pH sensing.