A Postsynthetic Modified MOF Hybrid as Heterogeneous Photocatalyst for α‑Phenethyl Alcohol and Reusable Fluorescence Sensor

The recent discovery of lanthanide-based metal–organic frameworks (Ln-MOFs) offers the potential to extend the chemical sensing and catalysis capabilities of metal–organic frameworks (MOFs). Herein, a new europium functionalized material based on MIL-125­(Ti)-NH₂ is synthesized by covalent postsynthetic modification and shows photocatalytic oxidation properties of α-phenethyl alcohol, and their fluorescence quenching behaviors are investigated. The catalytic efficiency is tested by monitoring the photocatalytic oxidation of α-phenethyl alcohol under ultraviolet light irradiation. Furthermore, MIL-125­(Ti)-AM-Eu is developed as a fluorescence sensor integrated with its photocatalytic and luminescent properties. The MIL-125­(Ti)-AM-Eu is used for detecting α-phenethyl alcohol, which could be successfully oxidized to acetophenone by the catalyst, and the fluorescence of MIL-125­(Ti)-AM-Eu has changed accordingly

Numerical Recognition System and Ultrasensitive Fluorescence Sensing Platform for Al³⁺ and UO₂²⁺ Based on Ln (III)-Functionalized MOF-808 via Thiodiglycolic Acid Intermediates

Continuous accumulation of Al3+ in the human body and unintended leakage of UO22+ have posed a great threat to human health and the global environment; thus searching an efficient probe for the detection of Al3+ and UO22+ is of great importance. Herein, we designed and synthesized two hydrolytically stable Eu3+- and Tb3+-functionalized MOF materials Eu@MOF-808-TDA and Tb@MOF-808-TDA via thiodiglycolic acid (TDA) intermediates by the postsynthetic modification method. Among them, Tb@MOF-808-TDA was applied to construct numerical recognition systems of multiples of three and four by the combination of fluorescent signals, hierarchical cluster analysis, and logical gates. In addition, Tb@MOF-808-TDA exhibits good selectivity and sensitivity for the detection of Al3+ and UO22+. The detection limit is calculated to be 0.085 ppm for Al3+ and 0.082 ppm for UO22+ in aqueous solutions, which is lower than or close to that of latest reported Ln-MOFs. Moreover, the probe shows excellent hydrolytic stability and luminescence stability in the pH range of 4–11, further providing solid evidence for the practical application of Tb@MOF-808-TDA. More importantly, a mixed matrix hydrogel PVA-Tb@MOF-808-TDA was prepared to achieve the visual detection of Al3+, which broadens the potential in real-world sensing applications

“One-Stone–Two-Birds” Modulation for Na₃ScF₆‑Based Novel Nanocrystals: Simultaneous Morphology Evolution and Luminescence Tuning

Control over the morphology, size, and crystallographic phase of nanocrystals (NCs) through impurity doping is central to the realization of their unprecedented or improved properties. Herein we present the “one-stone–two-birds” modulation including simultaneous modification of the morphology and tuning of the luminescence for Na₃ScF₆ based NCs via a simple doping strategy. Ce³⁺/Tb³⁺ codoped Na₃ScF₆ NCs with monoclinic structure and hexagonal nanoplate or nanorod morphology were obtained through a modified solvothermal method. The formation of monodisperse Na₃ScF₆-based NCs with diverse architectures closely correlates with the doping level of Tb³⁺. On the basis of the experimental results, the possible growth mechanism for nanoparticles is proposed. Under UV light excitation, Na₃ScF₆:Ce³⁺/Tb³⁺ samples exhibited characteristic emissions from both Ce³⁺ and Tb³⁺ ions. By proper variation of the amount of Tb³⁺ doping while maintaining Ce³⁺ concentration, the emission color tuned from blue to green accompanied by the shape evolution from hexagonal nanoplate to short nanorod. Furthermore, the higher quantum yield from the current nanostructures compared with those of a LaPO₄-based nanophosphor indicated that this scandium-containing sample is a promising green emission phosphor candidate for lighting and display applications

Imparting Tunable and White-Light Luminescence to a Nanosized Metal–Organic Framework by Controlled Encapsulation of Lanthanide Cations

An alternative way was demonstrated to fabricate highly luminescent MOFs and white-light emitter by encapsulating lanthanide­(III) (Ln³⁺) cations into the channels of Al-MIL-53-COOH (<b>1</b>) nanocrystals. The framework can serve as both a host and an antenna for protecting and sensitizing the luminescence of the Ln³⁺ cations. PXRD, TEM, FTIR, TGA, and N₂ adsorption measurements were performed to determine the structure, thermal stability, and BET surface area of the obtained products. The Ln³⁺-incorporated nanocrystals show strong emission under UV-light irradiation, and their luminescent properties were systematically studied. In contrast to the essentially unchangeable luminescence of lanthanide-based MOF, the luminescence of Ln³⁺ @<b>1</b> allows design and tuning. The versatile luminescence, good thermal stability, nanometer size, and compatibility with aqueous condition reveal these materials may have potential applications in LED lamps, barcoded materials, and biological sensors. In addition, the thin films of Ln³⁺@<b>1</b> were prepared by chemical solution deposition (CSD) from their metastabilized colloidal solutions, which open the way to practical applications such as pellets and sensors for vapors

Phosphonate MOFs Composite as Off–On Fluorescent Sensor for Detecting Purine Metabolite Uric Acid and Diagnosing Hyperuricuria

The recent discovery of lanthanide organic frameworks (Ln-MOFs) offers the potential for biomarkers or metabolites sensing. This is another field that is closely connected with life science and medicine. In this work, a stable and luminescent phosphonate Ln-MOFs MIL-91­(Al:Eu) and its derivatives composite Cu²⁺@MIL-91­(Al:Eu) were synthesized. The rebound of luminescence of Cu²⁺@MIL-91­(Al:Eu) that origin of Eu³⁺ is observed in the presence of uric acid. This On–Off–On pattern is utilized for detecting uric acid, which is the final metabolite of purine. The composite reveals excellent selectivity and sensitivity for sensing uric acid. The detection of uric acid in real urine is also investigated. The effective detection of uric acid and tentative diagnosis of hyperuricuria on the basis of test paper is demonstrated

Trace Detection of Organophosphorus Chemical Warfare Agents in Wastewater and Plants by Luminescent UIO-67(Hf) and Evaluating the Bioaccumulation of Organophosphorus Chemical Warfare Agents

Organophosphorus chemical warfare agents (OPCWAs) are a group of organic pollutants characterized by high toxicity and chemical stability, and they are very difficult to be degraded. The trace quality of OPCWAs in water and food will cause great harm to the human body. Therefore, the detection of OPCWAs is a difficult challenge, which has become the research hotspot over the world. In this work, a Hf-based luminescent metal–organic framework (Eu@<b>1</b>) is prepared, and the reactivity of Hf₁₂ results in a methanephosphonic acid (MPA)-induced luminescence quenching and the charge transfer from MPA to Hf­(IV) and generated exciplexes which are responsible for this quenching effect. The excellent performance of Eu@<b>1</b> in the detection of MPA, with its finer selectivity, high sensitivity (LOD = 0.4 ppm), and large linear range (10^–7 to 10^–3 M), is encouraging for application in wastewater detection. Importantly, MPA is a pollutant that can be absorbed by plants and causes the bioaccumulation effect, and thus, the detection of MPA in real plant samples is a purposeful topic. Eu@<b>1</b> also achieved satisfactory results in actual plant sample testing, and the bioaccumulation of MPA in onions, turnips, and cabbages is determined via our sensor. This fabricated detector provides a feasible path for the detection of ppm-level OPCWAs in a complex environment, which will help humans to avoid OPCWA-contaminated foods

Suppressing Ion Transfer Enables Versatile Measurements of Electrochemical Surface Area for Intrinsic Activity Comparisons

Correlating the current/voltage response of an electrode to the intrinsic properties of the active material requires knowledge of the electrochemically active surface area (ECSA), a parameter that is often unknown and overlooked, particularly for highly nanostructured electrodes. Here we demonstrate the power of nonaqueous electrochemical double layer capacitance (DLC) to provide reasonable estimates of the ECSA across 17 diverse materials spanning metals, conductive oxides, and chalcogenides. Whereas data recorded in aqueous electrolytes generate a wide range of areal specific capacitance values (7–63 μF/real cm²), nearly all materials examined display an areal specific capacitance of 11 ± 5 μF/real cm² when measured in weakly coordinating KPF₆/MeCN electrolytes. By minimizing ion transfer reactions that convolute accurate DLC measurements, we establish a robust methodology for quantifying ECSA, enabling more accurate structure-function correlations

<i>Ab initio</i> interaction potentials of alkali metal (M = Na and K)–rare gas (Rg = He, Ne, Ar, Kr, Xe and Rn) complexes

Spectroscopic properties and potential energy curves of alkali metal (M = Na and K) – rare gas (Rg = He, Ne, Ar, Kr, Xe and Rn) van der Waals molecules in their ground states have been studied in detail using spin-restricted open-shell coupled cluster with single and double excitations and perturbative contribution of connected triple excitations (RCCSD(T)) methods. The core-valence correlation (CV) effect was found to be crucial for M-RG molecules containing heavy rare gas atoms. The electronic energies were corrected for the basis set superposition error (BSSE) using the counterpoise method. Energies were extrapolated to the complete basis set (CBS) limit using a two-point scheme. The permanent electric dipole moments, static electric dipole polarizabilities and long-range dispersion coefficients were also calculated. The computed spectroscopic constants, vibrational levels and rotational constants were reported for M-RG and good agreement with the available experimental and theoretical values were found.</p

MRCI Study of the Electronic Structure and Transition Properties of a Tin Dimer

The ground and excited states of Sn2 are calculated using the multireference configuration interaction method combined with Davidson correction (MRCI+Q). The influence of the spin–orbit coupling (SOC) effect on the electronic structure is also considered by the state interaction method of Breit–Pauli Hamiltonian. In the calculations, the potential energy curves and spectroscopic constants of 23 Λ-S states and 31 Ω states of Sn2 are obtained. The prominent spectral features in the visible region, new constants, and potential energy curves are discussed. The intensity of weak magnetic and quadrupole transitions in the near IR spectra is also calculated. From a computational point of view, we predict that the weak v′(0–2)–v″(0–5) bands of the magnetic b1Σg,0++-X3Σg,1(Ms=±1)– transition may be detected experimentally; the sub-bands (0, 0), (1, 0), and (2, 0) of the a1Δg,2-X3Σg,1(Ms=±1)– transition also may be observed in experiments since they are not overlapped by the strong electric dipole transition in the same IR region. According to the SOC matrix elements and contributions of the 15Πu0+, 15Πu1 (|Σ| = 0), and 15Πu1 (|Σ| = 2) states to the predissociation line width of the 13Σu– -X3Σg1– transition, the broading and other predissociation features of the 13Σu– state are analyzed. From our calculations, it follows that the strong coupling between the bound 13Σu– state and the repulsive 15Πu state causes the predissociation of the 13Σu– state at the vibrational levels v′ ≥ 8. In addition, our results suggest that the previously observed bands of Sn2 in the visible range of 19000–20000 cm–1 should be reassigned into the mixing transitions among the X3Σg,1–-23Σu,0–+ and X3Σg,0+–-23Σu,1+ manifold. The results are expected to provide new comprehensive information for better understanding the spectra and dynamics of the electronic excited states of the Sn2 molecule

Heazlewoodite, Ni₃S₂: A Potent Catalyst for Oxygen Reduction to Water under Benign Conditions

Electrodeposited thin films and nanoparticles of Ni₃S₂ are highly active, poison- and corrosion-resistant catalysts for oxygen reduction to water at neutral pH. In pH 7 phosphate buffer, Ni₃S₂ displays catalytic onset at 0.8 V versus the reversible hydrogen electrode, a Tafel slope of 109 mV decade^–1, and high faradaic efficiency for four-electron reduction of O₂ to water. Under these conditions, the activity and stability of Ni₃S₂ exceeds that of polycrystalline platinum and manganese, nickel, and cobalt oxides, illustrating the catalytic potential of pairing labile first-row transition metal active sites with a more covalent sulfide host lattice