Five Lanthanide-Based Metal-Organic Frameworks Built from a π-Conjugated Ligand with Isophthalate Units Featuring Sensitive Fluorescent Sensing for DMF and Acetone Molecules

Five novel lanthanide metal-organic frameworks constructed from a pi-conjugated ligand with tetracarboxylate group, 5,5'-(naphthalene-1,5-diyl)diisophthalic acid, have been synthesized solvothermally. Depend on the single-crystal X-ray diffraction data, the series of compounds exhibit 3D microporous framework architectures with two kinds of 1D open channels, giving the free volume about 36.5% calculated through PLATON. Room-temperature luminescent behaviors in the solid state reveal that compounds 2 (Eu-MOF) and 4 (Tb-MOF) exhibit the characteristic emissions of Eu(III) and Tb(III) benefiting from the excellent antenna effect of the ligand. It is noteworthy that the Eu-MOF, compound 2, has been proven to be treated as a fluorescent switch for DMF with more than 2-fold enhancement and acetone, which triggers a superior luminescence quenching giving an almost 100% quenching efficiency, based on sensitively turned on and turned off effects, respectively.

Automated summary

Five novel lanthanide metal-organic frameworks were synthesized solvothermally using a pi-conjugated ligand with tetracarboxylate group. The compounds exhibit 3D microporous framework architectures with two kinds of 1D open channels. Compounds 2 and 4 demonstrate characteristic emissions of Eu(III) and Tb(III) in the solid state, with compound 4 acting as a fluorescent switch for DMF.