Assembly and tunable luminescence of lanthanide-organic frameworks constructed from 4-(3,5-dicarboxyphenyl)pyridine-2,6-dicarboxylate ligand

A novel N-heterocycle multicarboxylate ligand 4-(3,5-dicarboxyphenyl)pyridine-2,6-dicarboxylic acid (H(4)dpda) was synthesized, and then reacted with lanthanide salts to yield a series of lanthanide metal-organic frameworks, [Ln(Hdpda)(H2O)(4)]center dot 0.5(H2O) (Ln = Eu(1), Gd(2), Tb(3), Dy(4)) and [Tb-1 Eu-x(x) (Hdpda)(H2O)(4)]center dot 0.5(H2O) (x = 0.1-10 mol%). Single crystal X-ray diffraction and powder XRD patterns confirm these MOFs are isostructural. Luminescent measurements suggest that the ligand can provide efficient sensitization for the lanthanide ion Tb(III) and Eu(III) in the mixed lanthanide MOFs. Additionally, the luminescence color of the mixed MOFs can be easily tuned from green to green-yellow, yellow, orange, red-orange and red by varying the molar ratio of Eu(III)/Tb(III). (C) 2012 Elsevier B.V. All rights reserved.