Uncommon Pyrazoyl-Carboxyl Bifunctional Ligand-Based Microporous Lanthanide Systems: Sorption and Luminescent Sensing Properties

Abstract

Seven new isostructural lanthanide metal-organic frameworks (Ln-MOFs), [Ln(Hpzbc)2(NO3)]·H2O (1-Ln, Ln = Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Er(3+), and Yb(3+) ions, H2pzbc = 3-(1H-pyrazol-3-yl) benzoic acid), with one-dimensional (1D) channels decorated by nitrate anions and pyrazoyl groups have been constructed. 1-Ln, as revealed by structural analysis, represent uncommon microporous 3D Ln-pyrazoyl-carboxyl systems using pyrazoyl-carboxyl bifunctional ligands as bridges. The luminescent investigations show that 1-Eu is an excellent MOF-based fluorescent probe, with high sensitivity, selectivity, and simple regeneration, for environmentally relevant Fe(3+) and Cr2O7(2-) ions. 1-Eu also presents highly selective capture for CO2 over N2 and CH4 due to the multiple binding sites for CO2 molecules, which were supported by Grand Canonical Monte Carlo (GCMC) simulations.

Four New Stable Lanthanide Organic Frameworks: Highly Selective Luminescent Sensing and Magnetic Properties

“…The luminescence intensities gradually weaken with the increase of Cr 2 O 7 2− concentration, and those of 1‐Eu are almost completely quenched at the concentration of 2.105 mM, the plot of I 0 /I vs [M] ([M]=the concentration of Cr 2 O 7 2− ions) can be well fitted by the Stern‐Volmer equation I 0 /I =0.99 + K sv [M] (Figure b), where I 0 and I are the luminescent intensities of 1‐Eu in the absence and presence of Cr 2 O 7 2− ions, respectively, K sv represents quenching rate constant. The K sv value is calculated to about 7510.4, which is comparable with or better than those previously reported well‐designed compounds for sensing Cr 2 O 7 2− ions . The limit of detection (LOD) determined following the 3δ IUPAC criteria can reach 5.99 × 10 −4 M .…”

“…The luminescence quenching mechanism usually induced by anions can, on the one hand, be explained by the electron‐transfer transitions of Cr 2 O 7 2− decreasing the energy transfer between the π and π* orbitals of the L 2− ligand . On the other hand, attribute to the Cr 2 O 7 2− are absorbed on the surface of the target complexes ,. both of the two factors possibly lead to the change and quenching of the luminescence.…”

Fluorene‐based Lanthanide Coordination Polymer: Structure, Luminescence and Sensing of Picric Acid

“…The Tb 3+ ions are coordinated by seven oxygen atoms from five L 2− ligands and one H 2 O molecule and one DMF molecule for Tb1, and five L 2− ligands and one and a half DMF, and half a H 2 O for Tb2, forming the distorted pentagonal bipyramid coordination geometry. The Tb‐O bond lengths range from 2.258(5) to 2.65(3) Å, which are comparable to those reported for other Tb‐O donor complexes . The L 2− ligands adopt the μ 3 and μ 4 bridging modes, respectively, with a carboxylate oxygen atom coordinating to a metal ion.…”

Water‐Stable Coordination Polymers as Dual Fluorescent Sensors for Highly Oxidizing Anions Cr2O72− and MnO4−

“…Cr 2 O 7 2− is a well‐known strong oxidant which has been widely used in various industrial processes including electroplating, paint, leather tanning and pesticides . However, it is not only harmful to the environment, but also poses great threat to living organism, especially for human health . Cr 2 O 7 2− has been proven to be carcinogenic and it will cause a variety of side effect or diseases such as allergic reactions, skin allergy and ulcers, renal failure, lung cancer and even gene mutation once long‐term exposure to Cr 2 O 7 2− .…”