Syntheses, structures and luminescent properties of decorated lanthanide metal-organic frameworks of (E)-4,4′-(ethene-1,2-diyl)dibenzoic acids

Abstract

The functionalized ligand (E)-4,4′-(1,4-bis(methylthio)but-2-ene-2,3-diyl)dibenzoic acid (H₂L_S) and four metal-organic frameworks, [M₂(L_H)₃(DMSO)₄]·xDMSO (6 and 7 for M = Tb³⁺, Eu³⁺ respectively; L_H = (E)-4,4′-(ethene-1,2-diyl)dibenzoate) and [M₂(L_S)₃(DMF)₂(H₂O)₂] (8 and 9 for M = Eu³⁺, Tb³⁺) have been synthesized and characterized. All four MOFs adopt the anticipated connectivity, but the fold of interpenetration in each MOF crystal varies as a result of different solvent inclusion and ligand functionality. Compounds 6 and 7 contain a large amount of solvent molecules and tend to lose solvent in air. Compounds 8 and 9 are stable crystals without lattice solvent molecules in the crystals; the coordinating solvent molecules can be reversibly removed and replenished with the skeletons intact. All four MOFs show mainly the ligand-based luminescence, while 8 also displays metal-based luminescence.