Lan-Lan Wu

Encapsulation of Ln(III) Ions/Dyes within a Microporous Anionic MOF by Post-synthetic Ionic Exchange Serving as a Ln(III) Ion Probe and Two-Color Luminescent Sensors

A new anionic framework {[Me2NH2]0.125[In0.125(H2L)0.25]⋅xDMF}n (1) with one-dimensional (1D) channels along the c axis of about 13.06×13.06 Å(2), was solvothermally synthesized and well characterized. Post-synthetic cation exchange of 1 with Eu(3+), Tb(3+), Dy(3+), Sm(3+) afforded lanthanide(III)-loaded materials, Ln(3+)@1, with different luminescent behavior, indicating that compound 1 could be used as a potential luminescent probe toward different lanthanide(III) ions. Additionally, compound 1 exhibits selective adsorption ability toward cationic dyes. Moreover, the RhB@1 realized the probing of different organic solvent molecules by tuning the energy transfer efficiency between two different emissions, especially for sensing DMF. This work highlights the practical application of luminescent guest@MOFs as sensors, and it paves the way toward other one/multi-color luminescent host-guest systems by rational selection of MOF hosts and guest chromophores with suitable emissive colors and energy levels.

A Metal–Organic Framework/DNA Hybrid System as a Novel Fluorescent Biosensor for Mercury(II) Ion Detection

Mercury(II) ions have emerged as a widespread environmental hazard in recent decades. Despite different kinds of detection methods reported to sense Hg(2+) , it still remains a challenging task to develop new sensing molecules to replenish the fluorescence-based apparatus for Hg(2+) detection. This communication demonstrates a novel fluorescent sensor using UiO-66-NH2 and a T-rich FAM-labeled ssDNA as a hybrid system to detect Hg(2+) sensitively and selectively. To the best of our knowledge, it has rarely been reported that a MOF is utilized as the biosensing platform for Hg(2+) assay.

A Temperature‐Responsive Smart Europium Metal‐Organic Framework Switch for Reversible Capture and Release of Intrinsic Eu3+ Ions

Stimuli‐responsive structural transformations are emerging as a scaffold to develop a charming class of smart materials. A EuL metal‐organic framework (MOF) undergoes a reversible temperature‐stimulated single‐crystal to single‐crystal transformation, showing a specific behavior of fast capture/release of free Eu3+ in the channels at low and room temperatures. At room temperature, compound 1a is obtained with one free carboxylate group severing as further hook, featuring one‐dimensional square channels filled with intrinsic free europium ions. Trigged by lowering the ambient temperature, 1b is gained. In 1b, the intrinsic free europium ions can be fast captured by the carboxylate‐hooks anchored in the framework, resulting in the structural change and its channel distortion. To the best of our knowledge, this is the first report of such a rapid and reversible switch stemming from dynamic control between noncovalent and covalent Eu–ligand interactions. Utilizing EuL MOF to detect highly explosive 2,4,6‐trinitrophenol at room temperature and low temperature provides a glimpse into the potential of this material in fluorescence sensors.

Highly thermostable lanthanide metal–organic frameworks exhibiting unique selectivity for nitro explosives

Three isostructural 3D metal–organic frameworks [Ln(L)1.5(DEF)]n (Ln = Gd (1), Eu (2), Tb (3), H2L = 9,9-diethylfluorene-2,7-dicarboxylic acid) have been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The main framework of compounds 1–3 show high thermal stability to 400 °C but with a distortion or shrinking of the crystal lattice between 200 °C and 250 °C. The high red emission intensity and the microporous instinct of the solvent-free [Eu(L)1.5]n (2a) indicate that it can be potentially used as luminescent sensor. It was then applied in the detection of organic solvent molecules. Notably, it exhibits high sensitivity for 2,4,6-trinitrophenol (TNP) with Ksv constant 6.24 × 104 M−1 through luminescence quenching experiments.

A Eu/Tb-codoped coordination polymer luminescent thermometer

A mixed-lanthanide coordination polymer Eu0.0618Tb0.9382L as a self-referenced luminescent thermometer based on the intensity ratio of the two emissions (Tb3+ at 544 nm and Eu3+ at 613 nm) is more reliable than EuL/TbL based on one emission.

Multishelled NixCo3–xO4 Hollow Microspheres Derived from Bimetal–Organic Frameworks as Anode Materials for High‐Performance Lithium‐Ion Batteries

Metal-organic frameworks (MOFs) featuring versatile topological architectures are considered to be efficient self-sacrificial templates to achieve mesoporous nanostructured materials. A facile and cost-efficient strategy is developed to scalably fabricate binary metal oxides with complex hollow interior structures and tunable compositions. Bimetal-organic frameworks of Ni-Co-BTC solid microspheres with diverse Ni/Co ratios are readily prepared by solvothermal method to induce the Ni x Co3-x O4 multishelled hollow microspheres through a morphology-inherited annealing treatment. The obtained mixed metal oxides are demonstrated to be composed of nanometer-sized subunits in the shells and large void spaces left between adjacent shells. When evaluated as anode materials for lithium-ion batteries, Ni x Co3-x O4 -0.1 multishelled hollow microspheres deliver a high reversible capacity of 1109.8 mAh g-1 after 100 cycles at a current density of 100 mA g-1 with an excellent high-rate capability. Appropriate capacities of 832 and 673 mAh g-1 could also be retained after 300 cycles at large currents of 1 and 2 A g-1 , respectively. These prominent electrochemical properties raise a concept of synthesizing MOFs-derived mixed metal oxides with multishelled hollow structures for progressive lithium-ion batteries.

An ideal detector composed of a 3D Gd-based coordination polymer for DNA and Hg2+ ion

A Gd-based coordination polymer (CP) was synthesized solvothermally with 5-triazole isopthalic acid (H2L) and Gd3+ ion. The crystal structure of GdL showed high thermal stability up to 400 °C and water stability for a wide pH range (pH 2–10). It can be noted that it showed the ability to highly quench the fluorescence and had a different affinity toward ssDNA and dsDNA. The Gd-based CP was employed as an effective fluorescent sensing platform for DNA and Hg2+ ion detection with sensitivity and selectivity.

Design of Substrate Integrated Waveguide (SIW) Elliptic Filter with Novel Coupling Scheme

Abstract A novel fourth-order substrate integrated waveguide (SIW) quasi-elliptic filter with novel coupling scheme is presented in this paper. A microstrip resonator (MR) with two grounded ends is introduced into the filter design. It not only acts as a resonator, but also brings different direct couplings between MR and SIW resonator. Then, quasi-elliptic response can be obtained easily. The proposed filter has better frequency selectivity than the conventional third-order SIW filter. A filter sample is fabricated on single-layer printed circuit board (PCB) technology. Good agreements are obtained between its measured- and simulated S-parameters.

Investigating the Hybrid-Structure-Effect of CeO2-Encapsulated Au Nanostructures on the Transfer Coupling of Nitrobenzene

Due to the obvious distinctions in structure, core-shell nanostructures (CSNs) and yolk-shell nanostructures (YSNs) exhibit different catalytic behavior for specific organic reactions. In this work, two unique autoredox routes are developed to the fabrication of CeO2 -encapsulated Au nanocatalysts. Route A is the synthesis of well-defined CSNs by a one-step redox reaction. The process involves an interesting phenomenon in which Ce3+ can act as a weak acid to inhibit the hydrolysis of Ce4+ under the condition of OH- shortage. Route B is the fabrication of monodispersed YSNs by a two-step redox reaction with amorphous Co3 O4 as an in situ template. Furthermore, the transfer coupling of nitrobenzene is chosen as a probe reaction to investigate their catalytic difference. The CSNs can gradually achieve the conversion of nitrobenzene into azoxybenzene, while the YSNs can rapidly convert nitrobenzene into azobenzene. The different catalytic results are mainly attributed to their structural distinctions.