Central Metal Ion Research Articles

Metal-Organic Framework (MOF)-Based Sensors for Mercury (Hg) Detection: Design Strategies and Recent Progress.

Monitoring mercury (Hg) is critical for environmental and public health. Metal-organic framework (MOF)-based sensors demonstrate the advantage of high sensitivity and rapid response. We summarize the advances of MOF sensors for Hg2+ detection from the perspective of MOF type and role in the sensors. First, we introduce three MOFs used in Hg sensors-UIO, ZIF, and MIL-that have demonstrated superior performance. Then, we discuss the specifics of MOF-based sensors for Hg2+ detection in terms of the recognition and signal elements. Currently, the recognition elements include T-rich aptamers, noble metal nanoparticles, central metal ions, and organic functional groups inherent to MOFs. Sensors with fluorescence and colorimetric signals are the two main types of optical MOF sensors used for Hg detection. Electrochemical sensors have also been fabricated, but these are less frequently reported, potentially due to the limited conductivity and cycling stability of MOFs. Notably, dual-signal sensors mitigate background signals interference and enhance the accuracy of Hg2+ detection. Furthermore, to facilitate portability and user-friendliness, portable devices such as microfluidics, paper-based devices, and smartphones have been developed for Hg2+ detection, showcasing potential applications. We also address the challenges related to MOF-based sensors for Hg2+ and future outlook.

Synthesis, Structural, DFT, In Vitro Biological Exploration, and DNA Interaction of New Ni(II) and Cu(II) Mixed‐Ligand Complexes Featuring 2,2′‐Pyridine‐2,6‐diylbis(1H‐benzimidazole) and 2‐Hydroxy‐naphthaldehyde‐Based Schiff‐Base

ABSTRACTThis research article provides a comprehensive analysis of the preparation, structural characterization, 3D modeling, and biological screening of two novel formulated metal complexes, NiPDBZNPH and CuPDBZNPH. These complexes were obtained by combining 2,2′‐pyridine‐2,6‐diylbis(1H‐benzimidazole) (PDBZ) and 2‐hydroxy‐naphthaldehyde Schiff‐base (NPH) ligands with Ni(II) and Cu(II) ions, resulting in the compounds [Ni (NPH)(PDBZ)(Cl)] and [Cu (NPH)(PDBZ)(Cl)], respectively. Spectroscopic and analytical techniques confirmed that both complexes exhibit octahedral geometry around the central metal ion. Computational studies using density functional theory (DFT) corroborated the molecular structures and investigated the quantum chemical properties of the ligands and complexes. A series of in vitro assays were conducted to assess their anti‐inflammatory, antifungal, antibacterial, and antioxidant properties, revealing enhanced bioactivity compared to the uncoordinated ligands. The potential of NiPDBZNPH and CuPDBZNPH as therapeutic candidates was also explored through interactions with calf thymus DNA (CT‐DNA). Molecular docking simulations targeting specific protein receptors were performed to evaluate binding affinities and ligand–protein interactions, with results highlighting significant interactions within enzyme active sites. These findings emphasize the pivotal role of metal–ligand coordination in enhancing pharmacological properties and contribute valuable insights toward the design of novel therapeutic compounds for use in medicinal chemistry and pharmaceutical research.

Polarized Bimetallic Site Synergy in Ionic Structures of Cu(II), Fe(III), and Mn(III) Porphyrins: Electrochemistry and Catalytic Hydrogenation of Nitroaromatics.

Binuclear catalytic sites attained in a controlled way with complementary and cooperative metal ion centers are highly relevant in the development of new or enhanced catalytic processes. Herein, binuclear sites carrying Fe(III), Cu(II), or Mn(III) metal ions with a polarized structure have been prepared using the ionic self-assembly of oppositely charged metalloporphyrins. Binary porphyrin structures (BIPOS) have been prepared based on metalloporphyrin cations carrying pyridinium or methylpyridinium groups in conjugation with metalloporphyrin anions carrying sulfonatophenyl groups. BIPOS carrying [cation/anion] tecton pairs of [Cu/Fe], [Fe/Cu], [Cu/Cu], [Fe/Fe], [Mn/Fe], [Fe/Mn], and [Mn/Mn] have been compared. Electrochemical interaction and enhanced catalytic behavior are noticeable for BIPOS [Fe/Cu], [Fe/Fe], and [Mn/Fe] carrying a Fe center and [less electronegative/more electronegative] metal ion centers in the [cation/anion] porphyrin ionic pairs. For high-performance BIPOS, cyclic voltammograms showed a greater separation of the cathodic and anodic peaks, within ΔEp = 0.095-0.125 V, and the rate constants for the catalytic reduction of 4-nitrophenol were within k = 0.380-0.535 min-1/mg of catalyst, significantly superior to the related individual metalloporphyrins. Inverse heterobimetallic [Cu/Fe] and [Fe/Mn] and the homometallic BIPOS [Cu/Cu] and [Mn/Mn] were significantly less active or inefficient. A [Fe/Cu] material could be reused in at least 5 catalytic cycles, maintaining catalytic activity; the best catalysts were also active in the reduction of nitrobenzene to aniline in mild conditions (visible light, 30 °C, 0.5 mol % catalyst), and an [Fe/Fe] catalyst showed 100% aniline yield after 2 h.

Fluorous and Organic Extraction Systems: A Comparison from the Perspectives of Coordination Structures, Interfaces, and Bulk Extraction Phases.

Microscopic structures in liquid-liquid extraction, such as structuration between extractants or extracted complexes in bulk organic phases and at interfaces, can influence macroscopic phenomena, such as the distribution behavior of solutes, including extraction efficiency and selectivity. In this study, we correlated the macroscopic behavior of the Zr(IV) extraction from nitric acid solutions with microscopic structural information to understand at the molecular level the key factors contributing to the higher metal ion extraction performance in the fluorous extraction system as compared to the analogous organic extraction system. The fluorous and organic extraction systems consist of tris(4,4,5,5,6,6,7,7,7-nonafluoroheptyl) phosphate (TFP) in perfluorohexane and tri-n-heptyl phosphate (THP) in n-hexane, respectively. Extended X-ray absorption fine structure, neutron reflectometry (NR), and small-angle neutron scattering revealed the structural information around the central metal ion of the complex, at the interface, and in the bulk extraction phase, respectively. NR results showed that extractant molecules did not accumulate much at the interface in both extraction system. In the fluorous extraction system, extractant aggregates with a 1.46 nm radius of gyration (Rg) were formed after contact with nitric acid, and remained even after Zr(IV) extraction through the form of a 1:3 (Zr(IV):TFP) complex. In contrast, in the organic extraction system, only extractant dimers with Rg of 0.70 nm were formed and Zr(IV) is extracted through the form of a 1:2 (Zr(IV):THP) complex. We speculate that differences in the local coordination structure around the Zr(IV) ion and the structuration of the extractant molecules in the bulk extraction phase contribute to the high Zr(IV) extraction performance in the fluorous extraction system. In particular, the size of the aggregates hardly changed with increasing Zr(IV) concentration in the fluorous phase, which may be closely related to the absence of phase splitting in the fluorous extraction system.

Luminescent rare earth complexes of Ce3+, Eu2+and Yb2+with spiro-bis(pyrazolyl)borate ligands containing C–H···M interactions

Luminescent rare earth complexes based on interconfigurational 5d-4f transition have characteristics of adjustable emission spectra and short excited state lifetimes, showing potential applications in display, lighting and other fields. In this work, nine Ce3+, Eu2+ and Yb2+ complexes with spiro-bis(pyrazolyl)borate ligands, where pyrazolyl stands for pyrazolyl, 3-methylpyrazolyl, or 3,5-dimethylpyrazolyl, were designed and synthesized. Ce3+ complexes show emission colors of blue, with photoluminescence quantum yields (PLQYs) of 94%–100%; Eu2+ complexes show emission colors of yellow-green, with PLQYs of 60%–78%; Yb2+ complexes show emission colors of orange or red, with PLQYs of 3%–4%. In addition, the crystal structures and theoretical calculation results show C–H···M interactions between bridge-head H atoms of the spirane and central metal ions in these complexes. It is found that the introduction of spirane with large steric hindrance and the existence of C–H···M interactions can improve the stability of the complexes in air atmosphere.

Five novel Pb/Zn/Co metal-organic frameworks using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and carboxylate ligands: Synthesis, characterization, DFT calculation and catalytic PMS degradation of RhB

Five new metal-organic frameworks (MOFs), namely {Pb(atpt)(3-bpd)0.5}n (1); {Co(cbz)2(3-bpd)(H2O)2·2H2O}n (2); {Co(imdc)(3-bpd)(H2O)·H2O}n (3); {Co(tdca)(3-bpd)(H2O)2·DMF}n (4); {Zn(tdca)(3-bpd)(H2O)2·DMF}n (5), were assembled with metal ions Pb²⁺, Zn²⁺, and Co²⁺ using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpd) as the main ligand, combined with 2-aminoterephthalic acid (H2atpt), 4-cyanobenzoic acid (Hcbz), 4,5-imidazoledicarboxylic acid (H2imdc), and thiophene-2,5-dicarboxylic acid (H2tdca) as auxiliary ligands via hydro/solvothermal methods. Their molecular structures were analyzed by single-crystal X-ray diffraction and characterized by FT-IR and PXRD. Complex 1 has a three-dimensional structure with a hepta-coordinated, semi-directed {PbNO6} metal center. The central metal ions in complexes 2–5 exhibit a six-coordinated {MN2O4} (M = Co or Zn) octahedral geometry. In complex 2, the carboxylate ligand does not function as a bridging ligand, resulting in a 1D chain structure, while complexes 3- 5 extend into 2D layered structures. Thermogravimetric analysis indicates good thermal stability for complexes 1–5. Then, the prepared complexes were used as catalysts to degrade Rhodamine B (RhB) during the monopersulfate (PMS) activation. Complexes 3 and 4 demonstrated significant efficiency, achieving degradation rates of 93.61 % and 98.56 % within 10 min. Radical scavenging experiments and EPR analysis identified that the activation of PMS for dye degradation by the two catalysts occurs through both radical and non-radical pathways, with SO4•− and •OH radicals being the dominant species. Density functional theory (DFT) calculations explained the superior catalytic performance of complex 4 compared to complex 3.

Structural, Antioxidant, and Protein/DNA-Binding Properties of Sulfate-Coordinated Ni(II) Complex with Pyridoxal-Semicarbazone (PLSC) Ligand

The pyridoxal-semicarbazone (PLSC) ligand and its transition metal complexes have shown significant biological activity. In this contribution, a novel nickel(II)-PLSC complex, [Ni(PLSC)(SO4)(H2O)2], was obtained, and its structure was determined by X-ray crystallographic analysis, FTIR, and UV-VIS spectroscopy. The sulfate ion is directly coordinated to the central metal ion. The intermolecular stabilization interactions were examined using Hirshfeld surface analysis. The crystal structure was optimized by a B3LYP functional using two pseudopotentials for nickel(II) (LanL2DZ and def2-TZVP) together with a 6-311++G(d,p) basis set for non-metallic atoms. The experimental and theoretical bond lengths and angles were compared, and the appropriate level of theory was determined. The stabilization interactions within the coordination sphere were investigated by the Quantum Theory of Atoms in Molecules (QTAIM). The antioxidant activity towards hydroxyl and ascorbyl radicals was measured by EPR spectroscopy. The interactions between Human Serum Albumin (HSA) and the complex were examined by spectrofluorimetric titration and a molecular docking study. The mechanism of binding to DNA was analyzed by complex fluorescence quenching, potassium iodide quenching, and ethidium bromide displacement studies in conjunction with molecular docking simulations.

Development of Recoverable Magnetic Bimetallic ZIF-67 (Co/Cu) Adsorbent and Its Enhanced Selective Adsorption of Organic Dyes in Wastewater.

In the critical domain of wastewater treatment, the development of cost-effective, durable, and recyclable adsorbents with high adsorption capacities remains a significant challenge. This study introduces a novel magnetic bimetallic Metal-Organic Framework (MOF) adsorbent, MZIF-67-Co/Cu, doped with copper ions. The MZIF-67-Co/Cu adsorbent was successfully synthesized and structurally characterized, demonstrating remarkable selectivity for removing methyl orange (MO) from water. This high selectivity is attributed to the adsorbent's high porosity and Lewis base properties at the coordinating metal ion center. The incorporation of Cu ions significantly enhances the porous architecture and increases the number of metal adsorption sites, leading to an impressive maximum MO adsorption capacity of 39.02 mg/g under optimized conditions (0.5 g/L adsorbent concentration, pH 3.0, 250 rpm agitation speed, adsorption time > 10 min). The adsorption kinetics closely follow the pseudo-second-order model, and the isotherm data fit well with the Langmuir model. The primary adsorption mechanisms involve electrostatic attraction and mesoporous interaction. This study highlights MZIF-67-Co/Cu as a highly efficient adsorbent with magnetic recovery capabilities, positioning it as a promising candidate for addressing critical issues in wastewater treatment.

Synthesis and characterization of Mn(II),Co(II), Ni(II),Cu(II) ,Ca(II) complexes with the ligand derived from indomethacin

The 2-(1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indol-3-yl)-N'-(4-methylbenzylidene)acetohydrazide ( (IB) was synthesized through the condensation of hydrazide derived from indomethacin with 4-methyl benzaldehyde. Additionally, the complexes obtained from the ligand were characterized by infrared, UV-visible, 1H, 13C NMR spectroscopy, elemental analysis, atomic absorption, molar conductance, and magnetic susceptibility. Measurements have shown that the ligand behaves as a bidentated ligand and is coordinated to the central metal ion through the oxygen atom for the carbonyl group and the nitrogen atom for the azomethine group. The structure of the ligand and complexes was confirmed. With the exception of the copper complex, which has an octahedral geometry, all of the complexes have adopted a tetrahedral geometry.

Microwave-Assisted, Preparation, Characterization, and Biological Activities of Schiff Bases Derived from 4-Aminoantipyrine with Acetonyl Acetone for Some New Rare-Earth Metals

Five new lanthanide complexes based on azomethine (Schiff bases) ligands have been synthesized, including La, Nd, Er, Gd, and Dy. Complexes were synthesized using the azomethine Schiff bases resulting from condensation reactions between 4-aminoantipyrine and acetonylacetone. The structural characteristics of azomethine obtained are characterized quantitatively and qualitatively through various techniques, including elemental analyses, magnetic susceptibility measurement, molar conductivity, infrared, ultraviolet absorption, GC-mass, and 1H- and 13C-NMR spectroscopy studies. The structural characteristics of Ln+3 complexes indicate that the complexes possess a composition of a specific type. Based on the elemental analyses, magnetic susceptibility measurement, molar conductivity, and ultraviolet absorption spectroscopy data, it can be inferred that the central metal ion is surrounded by a coordination number of 10, the general formula of [Ln(L)2(NO3)]·nNO3nH2O. The physical measurements confirmed that the synthesized complexes exhibit non-electrolyte behavior and paramagnetic properties. The antibacterial activity of the compounds was assessed in vitro against 4 pathogenic strains: E. coli, S. aureus, K. pneumoniae, and S. mutans. The evaluation was conducted using the agar disc spreading method. The results demonstrated that certain complexes exhibited significant antibacterial efficacy in comparison to the biological activity of the ligand.

Synthesis, characterization, and crystal structure of hexa-kis-(1-methyl-1H-imidazole-κN 3)zinc(II) dinitrate.

The synthesis of the title compound, [Zn(C4H6N2)6](NO3)2, is described. This complex consists of a central zinc metal ion surrounded by six 1-methyl-imidazole ligands, charge balanced by two nitrate anions. The complex crystallizes in the space group P. In the crystal, the nitrate ions are situated within the cavities created by the [Zn(N-Melm)6]2+ cations, serving as counter-ions. The three oxygen atoms of the nitrate ion engage in weak C-H⋯O inter-actions. In addition to single-crystal X-ray diffraction analysis, the complex was characterized using elemental analysis, 1H NMR, 13C NMR, and FTIR spectroscopy.

A Minireview on Porphyrin and Phthalocyanine Based Catalysts for Electrocatalytic Synthesis of Ammonia

AbstractAmmonia (NH3) is an important raw material in the chemical industry, but the synthesis of NH3 by the traditional Haber‐Bosch process will increase the carbon footprint. Therefore, it is necessary to develop sustainable routes for NH3 production. New NH3 production schemes, including nitrogen reduction (N2RR), nitrite reduction (NO2RR), and nitrate reduction (NO3RR), have been proposed. Porphyrins and phthalocyanines are macrocyclic compounds with a central metal ion coordinated with nitrogen. The metal centers in these catalysts play a crucial role in binding and activating nitrogen, nitrite, and nitrate. Their unique structure allows for effective electron transfer and catalytic activation in NH3 synthesis. Recently, metal porphyrin and phthalocyanine based catalysts have been demonstrated to be efficient in catalyzing N2RR, NO2RR, and NO3RR. Unfortunately, there is no review focusing on such macrocyclic catalysts for the electrocatalytic synthesis of NH3. In this review, we discuss the electrocatalytic reduction performances and summarize the key factors and reaction mechanisms that affect the catalytic performance of metal porphyrin and phthalocyanine based catalyst systems. This review helps to design more effective new electrocatalysts for NH3 synthesis.

Effect of central metal ion on some pharmacological properties of new Schiff base complexes. Anticancer, antioxidant, kinetic/thermodynamic and computational studies

The biological capacities of Schiff Base complexes such as anti-cancer, anti-microbial and anti-oxidant properties have been widely studied in the scientific community. However, the effect of central metal ion in the occurrence of their biological properties should be paid more attention. With this aim, novel 2-(hydroxyimino)-1-phenylpropylidene)benzohydrazide (HIPB) Schiff base ligand, and C1/palladium(II), C2/platinum(II), and C3/zinc(II) complexes derived from it were synthesized and characterized. Theoretical studies showed that C2 is more reactive and also has a higher pharmacological affinity than C1 and C3. Experimental investigations were done to compare some biological properties of the complexes. The anticancer assay showed that C1-C3 have the ability to inhibit the growth of HCT116 colon cancer cell lines, but C2 shows a relatively better effect than other. Antioxidant studies using •DPPH (2,2-diphenyl-1-picrylhydrazyl) assay presented the following trend: C2 > C1 > C3 > HIPB. Considering the importance of the antioxidant enzyme catalase in removing reactive oxygen species (ROS), the interaction of C1-C3 with Bovine Liver Catalase (BLC) was evaluated. Kinetic studies showed that C1-C3 can inhibit the catalytic performance of BLC by a similar mechanism, i.e. mixed-type inhibition. Among them, C1 was the strongest inhibitor (Activity inhibition% = 82.2). The C1-C3 quenched the BLC fluorescence emission with dynamic quenching mechanism. The binding affinity to BLC was higher for C1 and C2 than C3. The most important forces in the interaction of C1-C3 with BLC were hydrophobic interactions, which was strongly confirmed by molecular docking data. Tracking the structural changes of catalase showed that BLC undergoes structural changes in the presence of C1 more than C2 and C3.

Synthesis, crystal Structure, theoretical calculation and luminescence properties of Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Zn(Ⅱ) quinolinyl benzimidazole complexes with multiple coordination number induced by proton

The innovative ligand H2L, featuring a benzimidazole structure substituted with 8-hydroxyquinoline and equipped with N,O donor sites, underwent successful synthesis and meticulous characterization. Notably, this ligand was exclusively synthesized through catalysis under protonated conditions, accompanied by an in-depth exploration of the catalytic mechanism. Employing single-crystal X-ray diffraction, we acquired and authenticated four distinct asymmetric double-decker sandwich mononuclear transition metal complexes: [Cu(HL)2]·2H2O, [Co(HL)2]·CH3OH, [Ni(HL)2] and [Zn(HL)2]·CH2Cl2. Among these, complex 1 revealed an intriguing five-coordinate Cu(II) center adopting a distorted square pyramidal geometry, whereas the central metal ions in complexes 2–4 exhibited a six-coordinate configuration, characterized by a distorted octahedral geometry. Noteworthy is the observation that the dihedral angles within the crystal structures of complexes 2–4 approached approximately 90° to a significant extent. To delve deeper into the electronic properties and transitions, meticulous DFT and TD-DFT calculations were performed on both the ligand H2L and complexes 1–4. Furthermore, a comprehensive investigation into the luminescence properties of both H2L and its complexes was conducted, revealing a pronounced luminescence quenching effect in the complexes compared to the ligand. Through thorough analysis utilizing Hirshfeld surface examination and IRI analysis, various weak intermolecular interactions within the system were elucidated.

Exploration of Synthesis and Coordination Chemistry of Thiazole-Containing Calix[3]Pyrroles

Calix[n]pyrroles have been used as powerful and specific receptors and as extractants for anions and ion pairs over the past 20 years. In the recent past, calix[4]pyrroles have been used as systems that can move ions and ion pairs over lipophilic membranes [1]. Unfortunately, the coordination chemistry of calix[n]pyrroles hardly explored. The ring-contracted analog of calix[n]pyrrole, calix[3]pyrrole, was synthesized and recently published [2]. The structure of calix[3]pyrrole and its analogues is strained, and they show an appealing strain-induced ring expansion response. On the other hand, the synthesis of calix[3]pyrrole requires multistep reactions including cyclization of hexaketone precursor and Paar–Knorr synthesis with the total yield of 4%. Extended use of calix[3]pyrrole analogues necessitates further refinement of the synthesis process.Here, we demonstrate the synthesis of new calix[3]pyrroles analogue, calix[1]pyrrole[2]thiazole (3). Direct macrocyclization between bis(α-bromoketone) and 2,2-dimethylpropane (bis-thioamide) produced the calix[1]furan[2]thiazole (1), with 60% yield. The furan unit of 1 was converted into pyrrole to give calix[1]pyrrole[2]thiazole 3 (Figure 1).Single-crystal X-ray analysis revealed a cone-shaped conformation of calix[1]pyrrole[2]thiazole 3, with all three heterocycles pointing in the same direction through strong intramolecular hydrogen bonding. However, unlike calix[3]pyrrole, calix[1]pyrrole[2]thiazole was completely stable under acidic conditions, which may be due to the basic nature of the thiazolimine units.Metal coordination of calix[1]pyrrole[2]thiazole was attempted and its Zn(II), Ag(I) and Pd(II) complexes were obtained by appropriate metalation procedures. The central metal ion of the Zn(II) complex is coordinated by a conical 3 and an axial ethyl group to behave as a monoanionic tridentate ligand. In contrast, it acts as a bidentate neutral ligand for Pd(II) or Ag(I) complexation. The synthesis of meso-aza calix[1]pyrrole[2]thiazole is in progress. Figure 1

Schiff base derived from 2-hydroxy napthaldehyde as anti-corrosive for mild steel in acid media: experimental investigation and theoretical modelling

Schiff bases (SBs) have the fundamental characteristics of substances that are mostly eligible for testing as inhibitors of corrosion for various metal/electrolyte systems. Through their electron-rich centres, such as the > C = N– (imine) moiety, SBs adsorb and create a surface coating that mitigates corrosion. Because of its π-acceptor characteristics, the > C = N– (imine) moiety provides a strong bonding with the metallic ions. It's vital to note that SBs with polar substituents at the right locations can form chelates with the central metal ions; as a result, these SBs are anticipated to function better as corrosion inhibitors than SBs without substituents. Two distinct Schiff bases, NL1 and NL2, with naphthalene rings have been synthesised, and their structures have been confirmed by the use of 1H and 13C NMR spectrum methods. The anticorrosion potential of the NL1 and NL2 was further confirmed by quantum chemical calculations such as DFT studies and ESP diagrams. The corrosion inhibition potential of the NL1 and NL2 was investigated using the electrochemical method, demonstrating maximum corrosion inhibition efficiency up to 89.2% and 89.5%, respectively on mild steel in 1 M HCl media. The results are further supported by Scanning Electron microscopic (SEM) images and EDAX studies.

Cu-MOF-derived carbon nanomaterials as efficient catalysts for the reduction of nitro compounds

In this paper, we have synthesized a new light blue crystal Cu-MOF-1 with Cu(II) as the central metal ion by using two mixed ligands, where N,N’-bis(3-pyridyl)adipamide (3-bpaa) and fumaric acid (H2FA). Taking this material as the precursor of the study, it is found that Cu-MOF-1 possesses a single-crystal-to-single-crystal (SCSC) transition phenomenon, using its structure in the free state of water molecules in the heating process will be dehydrated and thus transformed into dark blue crystal Cu-MOF-2. This color distinctive change can be intuitively identify the temperature conversion, and thus be applied to the direction of the temperature sensing. Moreover, using Cu-MOF-1 as a precursor, the carbon-based nanostructured materials (Cu@X) of Cu and CuxO were derived from Cu-MOF-1 as a precursor in a straightforward and effective a single-step pyrolysis under different temperatures (400 °C, 600 °C, 800 °C and 1000 °C). As a result, Cu@1000 shown good activity (100 % conversion within 5 min) in the reduction of 4-nitrophenol (4-NP) by the presence of sodium borohydride (NaBH4) at mild circumstances, yielding a rate constant (Kapp) of 1.699 min−1. This remarkable performance is due to the utilization of both the uniform distribution of Cu-based nanoparticals (CuNPs) in the carbon matrix and the abundance of defect sites in the surface. This paper describes innovative MOF-derived catalysts that can be employed in a range of useful applications.

Geometric Tuning of Coordinatively Unsaturated Copper(I) Sites in Metal-Organic Frameworks for Ambient-Temperature Hydrogen Storage.

Porous solids can accommodate and release molecular hydrogen readily, making them attractive for minimizing the energy requirements for hydrogen storage relative to physical storage systems. However, H2 adsorption enthalpies in such materials are generally weak (-3 to -7 kJ/mol), lowering capacities at ambient temperature. Metal-organic frameworks with well-defined structures and synthetic modularity could allow for tuning adsorbent-H2 interactions for ambient-temperature storage. Recently, Cu2.2Zn2.8Cl1.8(btdd)3 (H2btdd = bis(1H-1,2,3-triazolo-[4,5-b],[4',5'-i])dibenzo[1,4]dioxin; CuI-MFU-4l) was reported to show a large H2 adsorption enthalpy of -32 kJ/mol owing to π-backbonding from CuI to H2, exceeding the optimal binding strength for ambient-temperature storage (-15 to -25 kJ/mol). Toward realizing optimal H2 binding, we sought to modulate the π-backbonding interactions by tuning the pyramidal geometry of the trigonal CuI sites. A series of isostructural frameworks, Cu2.7M2.3X1.3(btdd)3 (M = Mn, Cd; X = Cl, I; CuIM-MFU-4l), was synthesized through postsynthetic modification of the corresponding materials M5X4(btdd)3 (M = Mn, Cd; X = CH3CO2, I). This strategy adjusts the H2 adsorption enthalpy at the CuI sites according to the ionic radius of the central metal ion of the pentanuclear cluster node, leading to -33 kJ/mol for M = ZnII (0.74 Å), -27 kJ/mol for M = MnII (0.83 Å), and -23 kJ/mol for M = CdII (0.95 Å). Thus, CuICd-MFU-4l provides a second, more stable example of optimal H2 binding energy for ambient-temperature storage among reported metal-organic frameworks. Structural, computational, and spectroscopic studies indicate that a larger central metal planarizes trigonal CuI sites, weakening the π-backbonding to H2.

A novel naphthalene diimide-based compound:synthesis, photochromism, ammonia vapor and triethylamine detection

A novel naphthalene diimide-based compound, designated as [Zn(BINDI)0.25·(C2H5NO)]n (1), has been successfully synthesized under solvothermal conditions, utilizing N, N′-bis(5-isophthalic acid) naphthalenediimide (H4BINDI) and Zn(NO3)2·6H2O as raw materials. Single crystal X-ray diffraction analysis revealed that compound 1 forms a 3D structure, with BINDI4− and C2H5NO− serving as organic ligands and Zn(II) as the center metal ion. Notably, upon exposure to a 300 W xenon lamp, compound 1 rapidly transitions from orange to dark blue within 5 s. Furthermore, as the duration of irradiation increases, 1 exhibits photocontrolled fluorescence properties. Additionally, it possesses the capability to detect ammonia vapor and triethylamine.

Ion-selective supramolecular membrane with pH-regulated smart nanochannels for lithium extraction

Tunable gating ion-conducting membranes with high water permeability and precise ion selectivity remain urgently demanded in smart nanofiltration for efficient lithium extraction. Herein, inspired by the filtration function of protein channels, we report a smart and high-performance supramolecular membrane constructed via coordination between quaternary ammonium ligands (m-phenylenediamine/polyethyleneimine) and metal ion center (Cu2+). The pore architecture of the supramolecular membrane is dynamic and can be switched by applying pH stimulus, where coordinated interchain expands when exposed to acidic operating conditions and induces concomitantly reinforced electrostatic exclusion due to enhanced local charge density. The tunable gating regularity enables operando modulation of precise ionic separation in situ. The resulting membrane exhibits significantly enhanced water permeance (19.8 L m−2 h−1·bar−1) and simultaneously promoted Li+/Mg2+ selectivity (RMg2+ = 96.4 %), surpassing typical trade-off between permeability and selectivity at pH 3 condition. This study demonstrates the amazing capability of environmental-responsive regulation of membrane pore-channel structure, and provides inspiration for engineering advanced supramolecular membranes for lithium extraction and beyond.