Group 13th metal-organic frameworks and their role in heterogeneous catalysis

Luminescent Bis(amidinate) Indium Complexes

Bis-amidinate indium(III) monochlorides [(tBuN)2C(Ph)]2InCl (1), [(tBuN)2C(2-naphthyl)]2InCl (2), [(tBuN)2C(2-anthryl)]2InCl (3), [(tBuN)2C(9-anthryl)]2InCl (4), [(tBuN)2C(9-phenanthryl)]2InCl (5), and [(tBuN)2C(1-pyrene)]2InCl (6) were prepared by the reaction of the corresponding Li-amidinate ligand with InCl3. Single crystal X-ray analysis of compounds 1, 2, 4, and 5 reveals that the In(III) center is bound with two chelating amidinate ligands. The overall coordination geometry around In(III) is distorted trigonal bipyramidal with the chloride occupying one of the equatorial positions. The photophysical properties of these compounds have been analyzed. Compounds 2-6 are emissive in the solution state. The 9-anthryl substituted compound 4 was found to exhibit a maximum quantum yield of 45.5% in dichloromethane. Compound 3 has a maximum lifetime of 11 ns in solution. Theoretical studies were performed to validate the photophysical properties observed in these compounds.

A Multimetal Approach for the Reticulation of Iridium into Metal-Organic Framework Building Units

Noble metal elements are ubiquitous in our everyday life, from medical applications to electronic devices and synthetic chemistry. Iridium is one of the least abundant elements, and despite its scarcity, it remains essential for efficient and active catalytic processes. Consequently, the development of heterogeneous catalysts with the presence of active iridium sites is of enormous interest as it leads to the improvement of their recyclability and reusability. Here, we demonstrate a strategy to incorporate iridium atoms into metal-organic frameworks (MOFs), as part of their secondary building units (SBUs), resulting in robust and reusable materials with heterogeneous photocatalytic activity.

Mechanism Exploration of the Photoelectrochemical Immunoassay for the Integration of Radical Generation with Self-Quenching

Photoelectrochemical (PEC) sensing mechanisms based on enzyme-catalyzed strategies primarily achieve the quantitative analysis of biomolecules through the enhancement or attenuation of photocurrent signals. However, there are still no reports that delve into the principles of photocurrent signaling conversion in the reaction between photoactive materials and the biomolecules. In this work, we demonstrated that indium oxysulfide InOS-0.5 heterojunction has excellent peroxidase activity to catalyze the reaction of H2O2-generated hydroxyl radicals (•OH) with the self-generated electrons, thereby resulting in synergistic quenching of the photocurrent signal. Based on the above principles, we coupled InOS-0.5 with a sandwich-type immunoassay to introduce H2O2 production catalyzed by glucose oxidase for the development of a PEC immunosensing platform. H2O2 reacted with InOS-0.5 to produce •OH with strong oxidizing properties, thus quenching the photogenerated electrons and realizing the PEC detection of the carcinoembryonic antigen (CEA, as a model analyte). The photocurrent intensity decreases with the logarithmic increase in CEA concentration (0.02-50 ng mL-1), with a remarkable limit of detection of 8.9 pg mL-1 (S/N = 3). This study further investigates the mechanism of hydrogen peroxide-induced photocurrent quenching, providing deeper insights into the mechanisms of electron-hole transport in hollow porous semiconductor materials and paving the way for the development of efficient PEC sensors.

A Highly Stable Multifunctional Bi-Based MOF for Rapid Visual Detection of S2- and H2S Gas with High Proton Conductivity

Metal organic frameworks (MOFs) constructed with bismuth metal have not been widely reported, especially multifunctional Bi-MOFs. Therefore, developing multifunctional MOFs is of great significance due to the increasing requirements of materials. In this work, a 3D Bi-MOF (Bi-TCPE) with multifunctionality was successfully constructed, demonstrating high thermal stability, water stability, a porous structure, and strong blue fluorescence emission. We evaluated the properties of Bi-TCPE in detecting anions (S2-, Cr2O72-, and CrO42-) in aqueous solution, along with the rapid visual detection of H2S gas and proton conduction. In terms of anion detection, Bi-TCPE achieved the rapid detection of trace S2- in aqueous solutions, while the Ksv value was 1.224 × 104 M-1 with a limit of detection (LOD) value of 1.93 μM through titration experiments. Furthermore, Bi-TCPE could sensitively detect Cr2O72- and CrO42-, with Ksv values of 1.144 × 104 and 1.066 × 104 M-1, respectively, while LOD reached 2.07 and 2.18 μM. Subsequently, we conducted H2S gas detection experiments, and the results indicated that Bi-TCPE could selectively detect H2S gas at extremely low concentrations (2.08 ppm) and with a fast response time (<10 s). We also observed significant color changes under both UV light and sunlight. Therefore, we developed a H2S detection test paper for the rapid visual detection of H2S gas. Finally, we evaluated the proton conductivity of Bi-TCPE, and the experimental results showed that the proton conductivity of Bi-TCPE reached 4.77 × 10-2 S·cm-1 at 98% RH and 90 °C, achieving an excellent value for unmodified and encapsulated MOFs. In addition, Bi-TCPE showed high stability in proton conduction experiments (it remained stable after 21 consecutive days of testing and 12 cycles of testing), demonstrating relatively high application value. These results indicate that Bi-TCPE is a multifunctional MOF material with great application potential.

Defect Induced Structural Transition and Lipase Immobilization in Mesoporous Aluminum Metal-Organic Frameworks

The transition from disorder to order and structural transformation are distinctive metal-organic framework (MOF) features. How to adapt or control both behaviors in MOF has rarely been studied. In this case, we demonstrate that our successful synthesis of [Al(OH)(PDA)]n (AlPDA-53-DEF, AlPDA-53-H, and AlPDA-68) with H2PDA=4,4'-[1,4-phenylenebis(ethyne-2,1-diyl)]-di benzoic acid has shown the intricate world of Aluminum Metal-Organic Frameworks (Al-MOFs). It offers profound insights into defect structures to order and transformations. AlPDA-53-DEF, in particular, revealed a fascinating interplay of various pore sizes within both micro and mesoporous regions, unveiling a unique lattice rearrangement phenomenon upon solvent desorption. Defects and disorders emerged as crucial impacts of transforming AlPDA-53-DEF, with its initially imperfect crystallinity, into the highly crystalline, hierarchically porous AlPDA-53-H.

Structural Diversity in Ga/In-Hydroxamate Metal-Organic Materials

Developing metal-organic materials (MOMs) with chemical robustness is a prerequisite to exploring their intriguing properties and applications. As part of a continuing effort to construct robust MOMs featuring chelated building units, here we introduce a "bent" thiophene-2,5-dihydroxamate ligand with multiple intrinsic conformations when it is used as a chelating linkage. This approach should further diversify the coordination chemistry in hydroxamate-based MOM structures without compromising the stability. In combination with Group 13 metals Ga/In to ensure homoleptic metal vertices, we report the successful crystallization of four MOMs with diverse structures and dimensionalities: SUM-81 as a 0D metal-organic polyhedron (MOP), SUM-82 as a 2D MOF with an fes topology, SUM-83 and SUM-84 as distinct 1D coordination polymers with shapes mimic stairs and mesh tubes, respectively. As these structures indeed contain the aforementioned different ligand conformations and combinations thereof, these results expand our understanding of the coordination chemistry of hydroxamates. To demonstrate the potential applicability of hydroxamate-chelated robust MOMs, the permanently porous SUM-81 MOP was successfully incorporated in a series of mixed matrix membranes for CO2/N2 separation, showing impressive performances.

Tailored Porous Ferrocene-Based Metal-Organic Frameworks as High-Performance Proton Conductors

Although crystalline metal-organic frameworks (MOFs) have gained a great deal of interest in the field of proton conduction in recent years, the low stability and poor proton conductivity (σ) of some MOFs have hindered their future applications. As a result, resolving the issues listed above must be prioritized. Due to their exceptional structural stability, MOFs with ferrocene groups that exhibit particular physical and chemical properties have drawn a lot of attention. This study describes the effective preparation of a set of three-dimensional ferrocene-based MOFs, MIL-53-FcDC-Al/Ga and CAU-43, containing both main group metals and 1,1'-ferrocene dicarboxylic acid (H2FcDC). Multiple measurements, including powder X-ray diffraction (PXRD), infrared (IR), and scanning electron microscopy (SEM), confirmed that the addition of ferrocene groups enhanced the thermal, water, and acid-base stabilities of the three MOFs. Consequently, their proton-conductive behaviors were meticulously measured utilizing the AC impedance approach, and their best proton conductivities are 5.20 × 10-3, 2.31 × 10-3, and 1.72 × 10-4 S/cm at 100 °C/98% relative humidity (RH), respectively. Excitingly, MIL-53-FcDC-Al/Ga demonstrated an extraordinarily ultrahigh σ of above 10-4 S·cm-1 under 30 °C/98% RH. Using data from structural analysis, PXRD, SEM, thermogravimetry (TG), and activation energy, their proton transport mechanisms were thoroughly examined. The fact that these MOFs are notably easy to assemble, inexpensive, toxin-free, and stable will increase the range of practical uses for them.

Ligand-Functionalized MIL-68-type Indium(III) Metal-Organic Frameworks with Prominent Intrinsic Proton Conductivity

Indium-based metal-organic frameworks (In-MOFs) have now become an attractive class of porous solids in materials science and electrochemistry due to their diverse structures and promising applications. In the field of proton conduction, to find more crystalline MOFs with splendid proton-conductive properties, herein, five three-dimensional isostructural In-MOFs, MIL-68-In or MIL-68-In-X (X = NH2, OH, Br, or NO2) using terephthalic acid (H2BDC) or functionalized terephthalic acids (H2BDC-X) as multifunctional linkages were efficiently fabricated. First, the outstanding structural stability of the five MOFs, including thermal and water stability, was verified by thermal analysis and powder X-ray diffraction. Subsequently, the H2O-mediated proton conductivities (σ) were fully assessed and compared. Notably, their σ evinced a significant positive correlation between the temperature or relative humidity (RH) and varied with the functional groups on the organic ligands. Impressively, their highest σ values are up to 10-3-10-4 S/cm (100 °C/98% RH) and change in this order: MIL-68-In-OH (1.72 × 10-3 S/cm) > MIL-68-In-NH2 (1.70 × 10-3 S/cm) > MIL-68-In-NO2 (4.47 × 10-4 S/cm) > MIL-68-In-Br (4.11 × 10-4 S/cm) > MIL-68-In (2.37 × 10-4 S/cm). Finally, the computed activation energy values under 98 or 68% RHs are assessed, and the related proton conduction mechanisms are speculated. Moreover, after electrochemical testing, these MOFs illustrate remarkable structural rigidity, laying a meritorious material foundation for future applications.

Recent progress in high-performance environmental impacts of the removal of radionuclides from wastewater based on metal-organic frameworks: a review

The nuclear industry is rapidly developing and the effective management of nuclear waste and monitoring the nuclear fuel cycle are crucial. The presence of various radionuclides such as uranium (U), europium (Eu), technetium (Tc), iodine (I), thorium (Th), cesium (Cs), and strontium (Sr) in the environment is a major concern, and the development of materials with high adsorption capacity and selectivity is essential for their effective removal. Metal-organic frameworks (MOFs) have recently emerged as promising materials for removing radioactive elements from water resources due to their unique properties such as tunable pore size, high surface area, and chemical structure. This review provides an extensive analysis of the potential of MOFs as adsorbents for purifying various radionuclides rather than using different techniques such as precipitation, filtration, ion exchange, electrolysis, solvent extraction, and flotation. This review discusses various MOF fabrication methods, focusing on minimizing environmental impacts when using organic solvents and solvent-free methods, and covers the mechanism of MOF adsorption towards radionuclides, including macroscopic and microscopic views. It also examines the effectiveness of MOFs in removing radionuclides from wastewater, their behavior on exposure to high radiation, and their renewability and reusability. We conclude by emphasizing the need for further research to optimize the performance of MOFs and expand their use in real-world applications. Overall, this review provides valuable insights into the potential of MOFs as efficient and durable materials for removing radioactive elements from water resources, addressing a critical issue in the nuclear industry.

Endowing Porphyrinic Metal-Organic Frameworks with High Stability by a Linker Desymmetrization Strategy

The fabricating of metal-organic frameworks (MOFs) that integrate high stability and functionality remains a long-term pursuit yet a great challenge. Herein, we develop a linker desymmetrization strategy to construct highly stable porphyrinic MOFs, namely, USTC-9 (USTC represents the University of Science and Technology of China), presenting the same topological structure as the well-known PCN-600 that readily loses crystallinity in air or upon conventional activation. For USTC-9, the involved porphyrinic linker (TmCPP-M) with carboxylate groups located in the meta-position presents a chair-shaped conformation with lower C_2h symmetry than that (D_4h) of the common porphyrinic carboxylate (TCPP) linker in PCN-600. As a result, the wrinkled and interlocked linker arrangements collectively contribute to the remarkable stability of USTC-9. Given the high stability and porosity as well as Lewis acidity, USTC-9(Fe) demonstrates its excellent performance toward catalytic CO₂ cycloaddition with diverse epoxides at moderate temperature and atmospheric pressure.

Novel strategies for the formulation and processing of aluminum metal-organic framework-based sensing systems toward environmental monitoring of metal ions

Aluminum is a relatively inexpensive and abundant metal for the mass production of metal-organic frameworks (MOFs). Aluminum-based MOFs (Al-MOFs) have drawn a good deal of research interest due to their unique properties for diverse applications (e.g., excellent chemical and structural stability). This review has been organized to highlight the current progress achieved in the synthesis/functionalization of Al-MOF materials with the special emphasis on their sensing application, especially toward metal ion pollutants in the liquid phase. To learn more about the utility of Al-MOF-based sensing systems, their performances have been evaluated for diverse metallic components in reference to many other types of sensing systems (in terms of the key quality assurance (QA) criteria such as limit of detection (LOD)). Finally, the challenges and outlook for Al-MOF-based sensing systems are discussed to help expand their real-world applications.

Framework Adaptability and Concerted Structural Response in a Bismuth Metal-Organic Framework Catalyst

Bismuth metal-organic frameworks (MOFs) as heterogeneous catalysts are scarce, and there is little knowledge on the influence of the MOF features on their resulting activity and behavior. Here, we present the synthesis, characterization, and catalytic activity in the one-pot multicomponent Strecker reaction with ketones of three new MOFs prepared with the combination of indium or bismuth and 4,4',4'',4'''-methanetetrayltetrabenzoic acid. One of them, denoted BiPF-7, is very robust and chemically stable, and demonstrates a high activity in the formation of the desired α-aminonitriles. The interaction of the catalytic substrates with the metal centers in this MOF has been crystallographically characterized, showcasing a concerted framework adaptability process that involves structural changes in framework components that are not directly involved in the binding of the guests.

Reticular Chemistry for the Construction of Highly Porous Aluminum-Based -Metal-Organic Frameworks

Edge-transitive nets are regarded as appropriate blueprints for the practice of reticular chemistry, and in particular, for the rational design and synthesis of functional metal-organic frameworks (MOFs). Among edge-transitive nets, type I edge-transitive nets have unique coordination figures, offering only one edge-transitive target for their associated expressed net-cBUs. Here, we report the reticulation of the binodal edge-transitive (6, 6)-c nia net in MOF chemistry, namely, the deliberate assembly of trinuclear aluminum clusters and 6-connected hexacarboxylate ligands into highly porous nia-MOFs. Further studies reveal that Al-nia-MOF-1 shows promising attributes as a storage media for oxygen (O₂) at high-pressure adsorption studies.

Building a Green, Robust, and Efficient Bi-MOF Heterogeneous Catalyst for the Strecker Reaction of Ketones

In this work, we present the new [Bi₁₄(μ₃-O)₉(μ₄-O)₂(μ_3–OH)₅(3,5-DSB)₅(H₂O)₃]·7H₂O, BiPF-4 (bismuth polymeric framework—4) MOF, its microwave hydrothermal synthesis, as well as its behavior as a heterogeneous catalyst in the multicomponent organic Strecker reaction. The BiPF-4 material shows a three-dimensional (3D) framework formed by peculiar inorganic oxo-hydroxo-bismutate layers connected among them through the 3,5-dsb (3,5-disulfobenzoic acid) linker. These two-dimensional (2D) layers, built by junctions of Bi7 polyhedra SBU, provide the material of many Lewis acid catalytic sites because of the mixing in the metal coordination number. BiPF-4 is a highly robust, green, and stable material that demonstrates an excellent heterogeneous catalytic activity in the multicomponent Strecker reaction of ketones carried out in one-pot synthesis, bringing a reliable platform of novel green materials based on nontoxic and abundant metal sources such as bismuth.

In this work, we present the new [Bi₁₄(μ₃-O)₉(μ₄-O)₂(μ₃₋OH)₅(3,5-DSB)₅(H₂O)₃]·7H₂O, BiPF-4 (bismuth polymeric framework—4) MOF, its microwave hydrothermal synthesis, as well as its behavior as a heterogeneous catalyst in the multicomponent organic Strecker reaction.

Stable isomeric layered indium coordination polymers for high proton conduction

Stable isomeric layered indium coordination polymers with different coordinated anionic sites for high proton conduction.

Cuboctahedral [In36(μ-OH)24(NO3)8(Imtb)24]MOF with Atypical Pyramidal Nitrate Ion in SBU: Lewis Acid-Base Assisted Catalysis and Nanomolar Sensing of Picric Acid

A robust and multifunctional cuboctahedral [In₃₆(μ-OH)₂₄(NO₃)₈(Imtb)₂₄] MOF (In(Imtb)-MOF) with an atypical pyramidal nitrate ion-containing hitherto unknown SBU core [In₉(μ-OH)₆(NO₃)] is reported. The intra- and interlayer nitrate ions adopt pyramidal and inverted pyramidal shapes, which separates the active indium site [(In₃(μ-OH)₂)NO₃-(In₃(μ-OH)₂)] and linear In₃(μ-OH)₂ by 0.5 and 0.9 nm, respectively. Additionally, the high density of active metal sites shows remarkable catalytic activity with higher TOF even for sterically hindered substrates in Strecker synthesis and CO₂ cycloaddition. Moreover, the luminescence behavior of In(Imtb)-MOF and the presence of uncoordinated nitrogen atoms are exploited for selective sensing of explosive trinitrophenol (TNP) with a detection limit (LOD) of 2.3 ppb.

A rare 4-fold interpenetrated metal-organic framework constructed from an anionic indium-based node and a cationic dicopper linker

A unique 4-fold interpenetrated metal-organic framework, TIF-1, was synthesized by combining an anionic indium node with a cationic linker. This framework shows a rare type of 4-fold interpenetrated dia network, constructed from tessellation of biangular and tetragonal type metal-organic micropores. The porosity of TIF-1 is moderate due to four-fold interpenetration and charge-balancing anions. The cationic feature of this MOF may give good efficiency for selective small anion exchange or separation. In addition, the thermal stability and moderate CO2 adsorption property of the complex were studied.

Synthesis, Crystal Structure, DFT Theoretical Calculationand Physico-Chemical Characterization of a New Complex Material (C6H8Cl2N2)2[Cd3Cl10]·6H2O

The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 2,5-dichloro-p-phenylendiaminium decachlorotricadmate(II) hexahydrate complex, (C6H8Cl2N2)2[Cd3Cl10]·6H2O, has been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge-sharing [CdCl6]2− octahedra in linear polymeric chains spreading along the a-axis, while the organic cations surround these latters. The inspection of the Hirshfeld surface analysis helps to discuss the strength of hydrogen bonds and to quantify the inter-contacts, which reveal that H…Cl/Cl…H (38.9%), H…H (13.9%), and Cd…Cl/Cl…Cd (12.4%) are the main interactions that govern the crystal packing of the studied structure. SEM/EDXwas carried out and the powder XRD confirmed the good crystallinity of the material. FT-IR and the DFT calculation reveal the good correlation between the experimental and the theoretical wavenumbers. The HOMO-LUMO energy gap was used to predict the electric conductivity of the compound. Finally, the thermal TGA/DTA analysis shows stability until 380 K.

Indium metal-organic frameworks based on pyridylcarboxylate ligands and their potential applications

Indium metal-organic frameworks (In-MOFs) based on pyridylcarboxylate ligands represent a subclass of MOFs featuring diverse structures, a high stability, and various properties. This review discusses the different aspects of In-MOFs including their design, synthesis and structures as well as their typical potential applications in adsorption and separation, catalysis, and chemical sensors. Importantly, the effect of pyridine on the properties and stability of frameworks has been carefully studied. The introduction of a pyridine group not only significantly enriches clusters of In3+ ions, but also enables flexible, controllably synthesized ionic or neutral frameworks to be fabricated. Based on this, we suggest that this type of In-metal organic framework (MOF) should receive more attention in the field of MOF design.

Solvent-Free and Phase-Selective Synthesis of Aluminum Trimesate Metal-Organic Frameworks

Aluminum-based metal-organic frameworks (Al-MOFs) have shown promise as commercially valuable materials due to the variety of applications, excellent thermal, hydrothermal, and chemical stabilities, and the abundance of aluminum. In this work, for the first time, we report the solvent-free synthesis of the aluminum trimesate (Al-BTC) MOFs (MIL-100(Al), MIL-96(Al), and MIL-110(Al)) with phase selectivity and high yield. These MOFs were traditionally prepared with HF, HNO₃, and bulk solvents, but these methods struggled to produce pure-phase isolations. The solvent-free strategy provides valuable insight into the future industrial scale-up production of the Al-MOFs and promotes the potential commercialization of such materials.

Coordination Polymers in Dicyanamido-Cadmium(II) with Diverse Network Dimensionalities

The synthesis and structural characterization of six dicyanamido-cadmium(II) complexes are reported: catena-[Cd(μ1,3-dca)(μ1,5-dca)(3-ampy)] (1), catena-[Cd3(μ1,3,5-dca)2(μ1,5-dca)4(pyNO)2(H2O)2] (2), catena-{Cd(H2O)2(μ1,5-dca)2](2,6-lut-NO)} (3), catena-[Cd(Me2en)(μ1,5-dca)2] (4), catena-[Cd(Me4en)(μ1,5-dca)2] (5), and [Cd(1,8-damnp)2(dca)2] (6), where dca = dicyanamide anion, 3-ampy = 3-aminopyridine, pyNO = pyridine-N-oxide, 2,6-lut-NO = 2,6-lutidine-N-oxide, Me2en = N,N-dimethyl-ethylenediamine, Me4en = N,N,N′,N′-tetramethyl-ethylenediamine, and 1,8-damnp = 1,8-diaminonaphthaline. The coordination polymers have different dimensionalities: 1 and 5 form 3D networks structures; 3 and 4 form polymeric 1D chains and 1DD double chains, respectively. Ribbons of three fused polymeric chains are observed in 2. In 6, the mononuclear complex units form a hydrogen-bonded supramolecular 3D network. In the coordination polymer compounds, the dca linkers display three bonding modes: the most common μ1,5-dca and the least popular μ1,3- and μ1,3,5-dca bonding. The luminescence emission and thermal properties of the complexes were investigated.

Effective nitenpyram detection in a dual-walled nitrogen-rich In(iii)/Tb(iii)–organic framework

A heterometallic MOF probe with the advantages of strong fluorescence, simple synthesis, high density of Lewis acidic and basic sites, and repeatable use, has been designed and synthesized, which exhibits a rapid and sensitive reaction to nitenpyram.

Hexnuclear Cadmium(II) Cluster Constructed from Tris(2-methylpyridyl)amine (TPA) and Azides

A novel rare hexa nuclear cadmium(II)–azide cluster, [Cd6(TPA)4(μ3-1,1,3-N3)4(μ2-1,1-N3)6](ClO4)2·2H2O (1) was isolated and structurally characterized, in which the azide ligands reveal μ-1,1,3- and μ-1,1-N3 bridging modes.

Structural variety of aluminium and gallium coordination polymers based on bis-pyridylethylene: from molecular complexes to ionic networks

Diverse molecular (0D and 1D) as well as ionic (0D, 1D, 2D, mixed 1D–2D) crystal structures of complexes of aluminium and gallium trihalides with bis(4-pyridylethylene) were obtained by solvent-free melt reactions.

Metal organic frameworks as solid catalysts for liquid-phase continuous flow reactions

This Feature Article describes the recent developments in the use of MOFs as catalysts under continuous flow conditions illustrating that these materials can meet the required stability.

Tailoring Structural Diversity in Dimethyltin Carboxylates by the pH-Controlled Hydrothermal Approach

The study presents a rational synthesis of new dimethyltin carboxylates, Me₂Sn(H₂btec) (1), Me₂Sn(btec)_0.5(2), [Me₂Sn(H₂O)₂(btec)_0.5]·H₂O (3), and [{Me₂SnOSn(OH)Me₂}(Me₂SnOH)(btec)_0.5]·H₂O (4), derived from tetratopic 1,2,4,5-benzenetetracarboxylic acid (H₄btec). The method relies upon hydrothermal reaction (130 °C, 72 h) of dimethyltin dichloride and H₄btec under optimized pH (2 < pH < 8) conditions that allow control over dimethyltin speciation in aqueous medium as well as degree of deprotonation of the tetrafuntional carboxylic acid. The formation of a three-dimensional assembly in 1 is assisted by the bridging bidentate (μ₂) mode of the carboxylate and O-H···O hydrogen bonds involving -COOH groups. The structure represents a unique example of the diorganotin framework derived from a partially deprotonated polyfuntional carboxylic acid. The structure of 2 adopts a three-dimensional motif wherein each pair of μ₂-carboxylate groups (designated by C1 and C4) of the tetraanionic ligand form different spatial arrangements. For 3, the formation of one-dimensional motif with eight-coordinated tin atoms is assisted by the anisobidentate character of the carboxylate groups. The structure of 4 includes linear chains comprised of [Me₂Sn(μ₂-OH)]₂ and the carboxylate ligand which extend to a layered motif with symmetrically substituted ladder-like distannoxanes acting as linkers. The underlying nets of 1, 2, and 4 exhibit sqc11, scu(sqc170), and sql topologies, respectively. Notably, these assemblies are extremely robust and show no sign of degradation upon exposure to neutral as well as weakly acidic/basic aqueous medium for 7 days.

A mild and efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst under solvent-free sonication

A highly efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst has been developed under solvent-free sonication. This reaction has a broad substrate scope and high yields were obtained within a short reaction time. Remarkably, no additional additives and volatile organic solvent are required for this method and the MIL-53(Al) could be recovered and reused several times without significant drop-off in catalytic activity.

Preparation of Ag@zeolitic imidazolate framework-67 at room temperature for electrochemical sensing of hydrogen peroxide

In this work, a novel non-enzymatic hydrogen peroxide sensor, Ag@zeolitic imidazolate framework-67 (Ag@ZIF-67)/glassy carbon electrode (GCE), was fabricated by a simple method at room temperature. The morphology and structure of Ag@ZIF-67 were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, atomic absorption spectrophotometry, and N2 absorption isotherms, which indicated that core-shell Ag@ZIF-67 was successfully synthesized with a porous rhombic dodecahedron structure. Electrochemical investigations demonstrated that the Ag@ZIF-67/GCE had strong electrocatalytic activity towards hydrogen peroxide reduction with a low detection limit of 1.5 μM (S/N = 3), a fast response time of 3 s, and three different linear relationships in the ranges of 5.0 μM-275 μM, 775 μM-2775 μM, and 4775 μM-16 775 μM with sensitivities of 27 μA mM-1 cm-2, 13 μA mM-1 cm-2, and 5.3 μA mM-1 cm-2, respectively. Moreover, the fabricated sensor exhibited an excellent recovery rate in real sample analysis of medical hydrogen peroxide disinfectant. These results proved that Ag@ZIF-67/GCE is an effective electrochemical sensor for detecting hydrogen peroxide.

High quantum yield pure blue emission and fast proton conduction from an indium–metal–organic framework

A 3D anionic In³⁺–MOF integrates the multifunctionality of pure blue luminescence with a high quantum yield of 61.4% and water-mediated fast proton conduction with σ = 2.90–9.22 × 10⁻³ S cm⁻¹ at 25–60 °C and 99% RH.

Robust synthesis routes and porosity of the Al-based metal–organic frameworks Al-fumarate, CAU-10-H and MIL-160

We confirm that the investigated Al-MOFs are robust with respect to reproducible synthesis and concomitant porosity as a prerequisite for applications.

Anionic and neutral 2D indium metal–organic frameworks as catalysts for the Ugi one-pot multicomponent reaction

Two metal–organic frameworks (MOFs) made of indium and 1,3,5-tris(4-carboxyphenyl)benzene and having a layered structure have been synthesized, showing catalytic activity in the one-pot Ugi reaction.