Templated synthesis of a Zr-formate zeolite - like metal organic framework

Abstract

The templated synthesis of a new 3-dimensional Zr-formate MOF with the formula {[Zr₆(µ₃-O)₄(µ₃-OH)₄(HCOO)₁₂]₃(Me₂NH₂)₆(4-MepyH)₆(Cl)₈(CoCl₄)₂}_n – ZrFA-4 displaying a sodalite topology is reported. The assembly of the hexanuclear Zr secondary building unit of ZrFA-4 to form the sodalite cage led to a giant [Zr₆]₂₄ capsule templated by organic and inorganic ions, including [CoCl₄]²⁻, Cl⁻, Me₂NH₂⁺, and 4-MepyH⁺. These [Zr₆]₂₄ capsules are connected through anti–anti bridging formate groups, giving rise to a 3-dimensional network. ZrFA-4 represents the third example of a sod Zr-MOF and of zeolite-like Zr-MOF, in general, and the first example of a 3-dimensional Zr MOF made only with formate organic ligands. Its isolation highlights the structure-directing capability of the template molecules, which enabled the formation of a MOF based on the simplest carboxylate ligand (formate) with a topology that could only be achieved previously by designed synthesis using organic ligands with appropriate geometrical characteristics. ZrFA-4 is stable in common organic solvents and displays a BET surface area of 262 m² g⁻¹.