Metal-organic frameworks (MOFs) are highly tunable, porous crystalline materials formed through the coordination-driven self-assembly of organic linkers and metal nodes.1 Through careful ligand design, a vast number of reactive groups and functionalities can be incorporated into the MOF structure to tailor their properties. By incorporating vacant coordination sites into organic linkers, MOFs can undergo post-synthetic metalation (PSMet) with secondary metal species without disrupting the overall framework.2 These MOFs can act as crystalline sponges, enabling single-crystal X-ray analysis of otherwise unstable or reactive metal species.
Our group has shown site isolation and structural elucidation of Rh(I) and Mn(I) complexes in a pyrazole-carboxylate functionalised manganese MOF (MnMOF-1).3, 4 More recently, we developed a series of chemically and thermally stable pyrazole-carboxylate functionalised zirconium MOFs (UAM-1000 series) capable of PSMet with a broad range of mono- and dinuclear metal complexes.5
Here, we report the expansion of the library of chemically and thermally robust flexible MOFs and the synthesis of an indium-based MOF (InMOF-10) with a honeycomb-like stp-topology. This is synthesised from a flexible 4-connected pyrazole-carboxylate linker. SCXRD analysis revealed that InMOF-10 features hexagonal pores with notably large pore diameters of approximately 30 Å and accessible bispyrazole sites that enable PSMet with 4d transition metal complexes. InMOF-10 displays interesting interpenetration behaviour, further contributing to its structural complexity and potential functionality.