Stepwise Synthesis of Diverse Isomer MOFs via Metal-Ion Metathesis in a Controlled Single-Crystal-to-Single-Crystal Transformation

Two new metal–organic frameworks (MOFs) based on TMBDI linker (TMBDI = 2,3,5,6-tetramethyl-1,4-diisophthalate) and [M2(COO)4] paddlewheel, {[Zn2(TMBDI)(H2O)2]•2.5DMF•2(1,4-dioxane)•6H2O}n (UPC-6) and {[Co2(TMBDI) (DMA)2]•2DMA•5EtOH}n (UPC-8), have been obtained under solvothermal conditions. Due to the low stability of Zn/Co paddlewheels upon the removal of axial solvates, UPC-6 and UPC-8 possesses a very low surface area and adsorption capacity. Through metal-ion metathesis in a single-crystal-to-single-crystal fashion, two new Cu(II) MOFs (termed Cu-UPC-6 and Cu-UPC-8) with identical robust frameworks were produced, which could not be prepared by routine solvothermal methods. Meanwhile, the influence of the reaction solvents on the metathesis process were also investigated, and the results show that the form of solvented ions can induce obviously kinetic issues. Through gas adsorption measurements, the stability and porosity of frameworks have been shown improved significantly.