RESUMO
A luminescent Tb-MOF with excellent stability and dual-emitting properties was constructed with an amide-functionalized tetracarboxylate ligand. Tb-MOFs were initially assembled on one-dimensional Tb3+ chains, then formed a two-dimensional double-decker layer through the synergistic linking of organic ligands and bridging formic acid anions, and further fabricated the final three-dimensional structure through the connection of the organic ligands. Powder X-ray diffraction experiments revealed that Tb-MOFs not only exhibited excellent stability in water but also maintained structural integrity in the pH range of 2-12. Importantly, this Tb-MOF provided the first example of a metal-organic framework (MOF)-based luminescence sensor that can simultaneously detect two acid amino acids (aspartic and glutamic acids) through a turn-off sensing mechanism and two basic amino acids (lysine and arginine acids) through unusual turn-on and turn-off-on sensing mechanisms. Moreover, high sensitivity, low detection limit, and excellent recyclability of this sensor endow Tb-MOFs with great potential as a highly efficient amino acid fluorescence sensor in chemical detection and biological environments.
RESUMO
Combining Zn(II) with two dicarboxylic acids of different length and functional groups results in the 2D metal-carboxylate layer of different size and shape, which are further connected by the same bis-pyridyl-bis-amide pillar to afford two 4-fold and 3-fold interpenetrating pillared-layer networks (1 and 2). Luminescent properties of 1 and 2 have been systematically investigated and demonstrated multi-responsive luminescent sensitivities. 1 can be used for highly sensitive detection of nitroaromatics. In particular, 2 can be used turn-off sensing towards Cr2O72- and MnO4- anions as well as turn-on sensing towards PO43- anion in aqueous solution with high sensitivity and remarkable recyclability. The sensing mechanism is also discussed.
