A Highly Symmetric Bimetallic-Tetracarboxylate Framework: Two-Step Crystallization and Gas Separation Properties.

A novel noninterpenetrated MOF (NbU-2, NbU denotes Ningbo University) based on an enneanuclear bimetallic cluster was synthesized by postsynthetic uptake of Ni(II) ions of a sodium-based framework via two-step crystallization. This result demonstrated that the hydrolysis of metal ions in the step-by-step synthesis process is controllable and provided a new method for synthesizing high-nuclear metal cluster-based MOF materials. Note that the activated NbU-2 displays relatively high CO2/N2 selectivity, which was proved by breakthrough experiments of CO2/N2 mixtures.