Installing a molecular truss beam stabilizes MOF structures

Abstract

Enhancing the stability and durability of metal-organic frameworks (MOFs) is vital for practical applications because many promising MOF materials suffer from phase transitions and/or structural decompositions with humidity being a particularly damaging condition. In mechanical engineering, the frame of buildings and furniture can be stabilized significantly by installing a truss beam. Employing the same principle, we functionalized the organic component of MOF-5 to contain a carbazole moiety that can act as a molecular truss beam by reaching across the corner and forming a stable pi-pi interaction with a phenyl group on the edge position of the MOF-skeleton. This structural support enhanced the stability of the MOF substantially, allowing the designed MOF to maintain compositional integrity under steam conditions at 90 degrees C for similar to 5 days. The unmodified MOF-5 shows clear signs of structural collapse after similar to 1 h.