Smartphone-Assisted EY@MOF-5-Based Dual-Emission Fluorescent Sensor for Rapid On-Site Detection of Daclatasvir and Nitenpyram

Fluorescent metal-organic frameworks (MOFs) are promising sensing materials with tunable and robust structural properties and remarkable luminescent capabilities. In this study, a novel dual-emission fluorescent metal-organic framework (EY@MOF-5) composite is synthesized by a one-pot bottle-around-ship approach. Eosin Y (EY) is encapsulated in MOF-5 to enhance its fluorescence properties and selectivity, effectively addressing typical MOF-5 limitations. EY@MOF-5 serves as a versatile dual-functional fluorescent sensor for two different analytes, daclatasvir (DCT) and nitenpyram (NTP), showing an impressive linear range of 10-200 nM and 0.1-300 μM, with detection limits of 233 pM and 65 nM, respectively. The established method is ultrafast, highly sensitive, and extremely selective for DCT and NTP detection in complex biological and food samples. Fluorescence results are compared and validated with the recommended UPLC method. Then, a smartphone-integrated sensing system is introduced for on-site, real-time, and quantitative analysis of DCT and NTP. The smartphone-assisted intelligent sensing method manifests promising results for DCT and NTP monitoring in biological and food samples, demonstrating its promising potential for the on-site detection of biologically and environmentally significant analytes.

Enhanced electrocatalytic activity of fluorine doped tin oxide (FTO) by trimetallic spinel ZnMnFeO4/CoMnFeO4 nanoparticles as a hydrazine electrochemical sensor

In the present study, ZnMnFeO₄ and CoMnFeO₄ tri-metallic spinel oxide nanoparticles (NPs) were provided using hydrothermal methods. The nanoparticles have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and electrochemical techniques. A reliable and reproducible electrochemical sensor based on ZnMnFeO₄/CoMnFeO₄/FTO was fabricated for rapid detection and highly sensitive determination of hydrazine by the DPV technique. It is observed that the modified electrode causes a sharp growth in the oxidation peak current and a decrease in the potential for oxidation, contrary to the bare electrode. The cyclic voltammetry technique showed that there is high electrocatalytic activity and excellent sensitivity in the suggested sensor for hydrazine oxidation. Under optimal experimental conditions, the DPV method was used for constructing the calibration curve, and a linear range of 1.23 × 10^-6 M to 1.8 × 10^-4 M with a limit of detection of 0.82 ± 0.09 μM was obtained. The obtained results indicate that ZnMnFeO₄/CoMnFeO₄/FTO nano sensors exhibit pleasant stability, reproducibility, and repeatability in hydrazine measurements. In addition, the suggested sensor was efficiently employed to ascertain the hydrazine in diverse samples of cigarette tobacco.

Thermally constructed stable Zn-doped NiCoOx-z alloy structures on stainless steel mesh for efficient hydrogen production via overall hydrazine splitting in alkaline electrolyte

Hydrogen has a high energy density of approximately 120 to 140 MJ kg^-1, which is very high compared to other natural energy sources. However, hydrogen generation through electrocatalytic water splitting is a high electricity consumption process due to the sluggish oxygen evolution reaction (OER). As a result, hydrogen generation through hydrazine-assisted water electrolysis has recently been intensively investigated. The hydrazine electrolysis process requires a low potential compared to the water electrolysis process. Despite this, the utilization of direct hydrazine fuel cells (DHFCs) as portable or vehicle power sources necessitates the development of inexpensive and effective anodic hydrazine oxidation catalysts. Here, we prepared oxygen-deficient zinc-doped nickel cobalt oxide (Zn-NiCoO_x-z) alloy nanoarrays on stainless steel mesh (SSM) using a hydrothermal synthesis method followed by thermal treatment. Furthermore, the prepared thin films were used as electrocatalysts, and the OER and hydrazine oxidation reaction (HzOR) activities were investigated in three- and two-electrode systems. In a three-electrode system, Zn-NiCoO_x-z/SSM HzOR requires -0.116 V (vs RHE) potential to achieve a 50 mA cm^-2 current density, which is dramatically lower than the OER potential (1.493 V vs RHE). In a two-electrode system (Zn-NiCoO_x-z/SSM(-)∥Zn-NiCoO_x-z/SSM(+)), the overall hydrazine splitting potential (OHzS) required to reach 50 mA cm^-2 is only 0.700 V, which is dramatically less than the required potential for overall water splitting (OWS). These excellent HzOR results are due to the binder-free oxygen-deficient Zn-NiCoO_x-z/SSM alloy nanoarray, which provides a large number of active sites and improves the wettability of catalysts after Zn doping.

Enhancing Dynamic Spectral Diffusion in Metal-Organic Frameworks through Defect Engineering

The crystal packing of organic chromophores has a profound impact on their photophysical properties. Molecular crystal engineering is generally incapable of producing precisely spaced arrays of molecules for use in photovoltaics, light-emitting diodes, and sensors. A promising alternative strategy is the incorporation of chromophores into crystalline metal-organic frameworks (MOFs), leading to matrix coordination-induced emission (MCIE) upon confinement. However, it remains unclear how the precise arrangement of chromophores and defects dictates photophysical properties in these systems, limiting the rational design of well-defined photoluminescent materials. Herein, we report new, robust Zr-based MOFs constructed from the linker tetrakis(4-carboxyphenyl)ethylene (TCPE^4-) that exhibit an unexpected structural transition in combination with a prominent shift from green to blue photoluminescence (PL) as a function of the amount of acid modulator (benzoic, formic, or acetic acid) used during synthesis. Time-resolved PL (TRPL) measurements provide full spectral information and reveal that the observed hypsochromic shift arises due to a higher concentration of linker substitution defects at higher modulator concentrations, leading to broader excitation transfer-induced spectral diffusion. Spectral diffusion of this type has not been reported in a MOF to date, and its observation provides structural information that is otherwise unobtainable using traditional crystallographic techniques. Our findings suggest that defects have a profound impact on the photophysical properties of MOFs and that their presence can be readily tuned to modify energy transfer processes within these materials.

A novel electrochemical sensor for glucose detection based on a Ti3C2Tx/ZIF-67 nanocomposite

A Ti₃C₂T_x/ZIF-67 nanocomposite with outstanding conductivity has been prepared by loading ZIF-67 onto a two-dimensional Ti₃C₂T_x nanosheet. Ti₃C₂T_x sheets were synthesized by etching Ti₃AlC₂, and then ZIF-67 was grown in situ on the Ti₃C₂T_x nanosheet. The Ti₃C₂T_x/ZIF-67 nanocomposite exhibits excellent detection performance for glucose, with a low LOD of 3.81 μM and wide linear detection range of 5–7500 μM. This terrific result is contributed by the synergistic effect of the high electrically conductive ability of Ti₃C₂T_x and active catalytic performance of ZIF-67. Moreover, the electrochemical sensor prepared using the Ti₃C₂T_x/ZIF-67 nanocomposite also shows excellent selectivity, stability and repeatability for glucose detection. The Ti₃C₂T_x/ZIF-67 nanocomposite with outstanding performance has potential applications for electrochemical sensors.

A Ti₃C₂T_x/ZIF-67 nanocomposite with outstanding conductivity has been prepared. The electrochemical sensor based on this nanocomposite exhibits excellent selectivity, stability and repeatability for glucose detection.

One step synthesis of a bimetallic (Ni and Co) metal–organic framework for the efficient electrocatalytic oxidation of water and hydrazine

A series of metal–organic frameworks (MOFs) with varying Ni : Co ratios are synthesized by an easy one-step solvothermal method using trimesic acid as an organic linker.

A novel electrochemical sensor for glyphosate detection based on Ti3C2Tx/Cu-BTC nanocomposite

The copper benzene-1,3,5-tricarboxylate (Cu-BTC) with outstanding chemical and physical properties, is a novel and promising material in the field of electrochemical sensing. However, it has significant limitations for direct application in electrochemical sensing due to the relatively weak conductivity of Cu-BTC. Here, the conductivity of Cu-BTC was improved by loading Cu-BTC onto two-dimensional Ti₃C₂T_x nanosheets with high conductivity. Thanks to the synergistic effect produced by the high conductivity of Ti₃C₂T_x and the unique catalytic activity of Cu-BTC, the Ti₃C₂T_x/Cu-BTC nanocomposite exhibits excellent sensing performance for glyphosate, with a low limit of detection (LOD) of 2.6 × 10⁻¹⁴ M and wider linear sensing range of 1.0 × 10⁻¹³ to 1.0 × 10⁻⁶ M. Moreover, the electrochemical sensor based on Ti₃C₂T_x/Cu-BTC also shows excellent selectivity, good reproducibility and stability.

The Ti₃C₂T_x/Cu-BTC nanocomposite exhibits excellent sensing performance for glyphosate with a low detection limit and wide detection range. Moreover, the electrochemical sensor also shows excellent selectivity, good reproducibility and stability.

A New Molecular Recognition Concept: Multiple Hydrogen Bonds and Their Optically Triggered Proton Transfer in Confined Metal-Organic Frameworks for Superior Sensing Element

We report a new sensing mechanism based on an indium-dihydroxyterephthalic acid metal-organic framework (MOF, SNNU-153), in which the spatially fitted analyte-MOF hydrogen-bond (H-bond) formation provides selective recognition while the analyte-H-bond assisted excited-state intramolecular proton transfer (ESIPT) and the resulting ratiometric emission act as a superior signal transducer with ultrafast response. The synergy of ESIPT signal transduction and confined MOF pore enables the SNNU-153 sensor selectively sensing hydrazine even among nitrogen-containing hydride analogs such as NH₃, NH₂OH, and (Me)₂NNH₂. The key of H-bond and associated ESIPT was further counter evidenced by an indium-2,5-dimethoxyterephthalic acid MOF (SNNU-152), where the hydroxyl protons were removed by methylation, showing near inertness to N₂H₄. The new molecular recognition concept thus makes SNNU-153 a powerful N₂H₄ sensor, which should be far-reaching to other sensing elements.

Synthesis and catalytic activities of a Zn(ii) based metallomacrocycle and a metal-organic framework towards one-pot deacetalization-Knoevenagel tandem reactions under different strategies: a comparative study

Solvothermal reactions between a pyridine based amide functionalized dicarboxylic acid, 4,4'-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L), and zinc(ii) nitrate in the absence and presence of a base produced the binuclear metallomacrocyclic compound [Zn2(L)2(H2O)4]·2(H2O)·6(DMF) (1) and the metallomacrocyclic based two dimensional MOF [Zn5(L)4(OH)2(H2O)4]n·8n(DMF)·4n(H2O) (2), respectively. Compound 1 bears two tetrahedral Zn(ii) centres, whereas the 2D framework 2 includes a penta-nuclear Zn(ii) cluster as a secondary building block unit, with two of the metal cations assuming a tetrahedral type geometry and the remaining three an octahedral type geometry. The topological analyses reveal that compound 1 has a 2-connected uninodal net and framework 2 has a 2, 8-connected binodal net. These compounds heterogeneously catalyse the tandem deacetalization-Knoevenagel condensation reactions carried out under conventional heating, microwave irradiation or ultrasonic irradiation. Comparative studies show that ultrasonic irradiation (final product yield of 99% after 2 h of reaction time) provides the most favourable method (e.g., microwave irradiation leads to a final product yield of 91% after 3 h of reaction time). Moreover, the catalysts can be reused at least for five consecutive cycles without losing activity significantly.

Crystal structure of diaqua-dichlorido-bis(μ3-6,6′-(hydrazine-1,2-diylidenebis(methanylylidene))bis(2-methoxyphenolato)κ6 O,N:N′,O′,O′:O′′)trizinc(II) - ethanol (1/2), C36H44Cl2N4O12Zn3

C36H44Cl2N4O12Zn3, orthorhombic, Pbca (no. 61), a = 8.3378(8) Å, b = 21.188(2) Å, c = 22.802(2) Å, Z = 4, V = 4028.3(7) Å3, R gt(F) = 0.0513, wR ref(F 2) = 0.1193, T = 296(2) K.

A phthalimide-functionalized UiO-66 metal–organic framework for the fluorogenic detection of hydrazine in live cells

A phthalimide-functionalized Zr(iv) UiO-66 MOF was utilized for fluorogenic detection of hydrazine in HEPES buffer and inside living cells.