TWO 3D Cd (II) luminescent coordination polymers as highly selective and sensitive sensing for Fe3+ and CrO42−/Cr2O72− ions in aqueous system

RhB-Embedded Zirconium-Biquinoline-Based MOF Composite for Highly Sensitive Probing Cr(VI) and Photochemical Removal of CrO42-, Cr2O72-, and MO

How to accurately detect and efficiently sweep Cr(VI) from contaminated water has come into focus. Zirconium-based metal-organic frameworks (MOFs) play vital roles in water environmental chemistry due to excellent hydrolysis-resistant stability. However, as photochemical probes and photocatalysts, poor performances in detection sensitivity, selectivity, and photosensitiveness limit sole Zr-MOFs' applications. So, it is urgent to quest valid strategies to break through the dilemmas. Embedding luminous dyes into MOFs has been considered one of the most feasible avenues. Herein, a dual-emissive RhB@Zr-MOF with orange-yellow fluorescence has been assembled by in situ-encapsulating rhodamine B (RhB) into a zirconium-biquinoline-based MOF. Actually, within RhB@Zr-MOF, the aggregation fluorescence quenching (ACQ) effect of RhB molecules was effectively avoided. Notably, RhB@Zr-MOF exhibits a rapid fluorescence quenching response toward Cr(VI) ions with high selectivity, sensitivity, and anti-interference abilities. More interestingly, unlike the most widely reported fluorescence resonance energy transfer (FRET) between MOFs and encapsulated guest modules, photoinduced electron transfer from RhB to Zr-MOF has been confirmed by modeling the ground state and excited states of RhB@Zr-MOF using density functional theory (DFT) and time-dependent DFT (TD-DFT). The effective electron transfer makes RhB@Zr-MOF more sensitive in probing Cr₂O₇^2- and CrO₄^2- ions with ultralow detection limit (DL) values of 6.27 and 5.26 ppb, respectively. Prominently, the detection sensitivity based on DL values has been increased about 6 and 9 times, respectively, compared with pristine Zr-MOF. Moreover, rather negative CB and positive VB potentials make RhB@Zr-MOF have excellent photochemical scavenging ability toward Cr(VI) and MO.

Cd (II) coordination polymer as a strip based fluorescence sensor for sensing Fe3+ ions in aqueous system

The design and construction of a sensor that can sensitively and conveniently recognize metal ions are essential for the treatment of industrial wastewater. In this work, {[Cd₄(HL)₂(pyp)₂(H₂O)₂]·2H₂O·1.5Diox}_n (1) was synthesized under solvothermal condition and presented a 2D 3,5-connected layered network with the point symbol of {3.4.5} {3².4.5.6².7⁴}, which was coated on the surface of polyvinylidene fluoride (PVDF) to construct a novel paper sensor (1@PVDF). Meanwhile, the stability of 1@PVDF was characterized by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). In addition, fluorescence sensing experiments of 1@PVDF sensor for cations in aqueous system indicated that it has high sensitivity for sensing Fe³⁺ ions with the detection limit (DL) of 4.0 × 10^-8 M. By the characterization of PXRD, UV-vis spectra, ICP, XPS, time-resolved excited-state decay measurements, the sensing mechanisms of 1@PVDF for Fe³⁺ ions were attributed to the competitive absorption and interaction between 1 and Fe³⁺. And the sensing process of 1@PVDF for Fe³⁺ ions was static in the Fe³⁺ concentration of 0 to 0.05 mM. In addition, the binding energies of Fe³⁺ and Zn²⁺ with the framework of 1 were calculated by density functional theory (DFT), which further proved that there was an obvious interaction between Fe³⁺ and the uncoordinated O atom in 1. Based on the thin film technology, a portable and convenient paper-based probe has been developed for practical applications.

A Highly Stable Eu−MOF Multifunctional Luminescent Sensor for the Effective Detection of Fe3+, Cr2O72−/CrO42− and Aspartic Acid in Aqueous Systems

Heavy metal ions were common pollutants in water pollution. Amino acids, as important substances in organisms, participate in many life activities. The detection of heavy metal ions and amino acids...

Luminescent MOFs for selective sensing of Ag+ and other ions(Fe(III) and Cr(VI))in aqueous solution

Two new title MOFs, [Zn(BTA)2]n(MOF-1), [Zn3(BTA)2(5-tbuip)2]n(MOF-2) (BTA=1H-Benzotriazole, 5-tbuip=5-tert-Butylisophthalcc Acid) have been synthesized by solvothermal method. The structures of two complexes have been determined by single-crystal X-ray diffraction analysis and further...