A MOF nanoparticle@carbon aerogel integrated photothermal catalytic microreactor for CO2 utilization

A practical carbon dioxide (CO2) conversion and utilization system shows great potential for ameliorating the greenhouse effect. Herein, an integrated carbon aerogel-based photothermal catalysis microreactor with photothermal conversion, enhanced mass transfer adsorption and a thermal catalytic reactor is designed. As a solar-powered CO2 utilization module, this microreactor can conveniently convert CO2 into economically valuable products without elaborate equipment and operation processes.

A series of isostructural metal-organic frameworks for an enhanced electro-catalytic oxygen evolution reaction

Three new isostructural MOFs (ZnTIA, CoTIA and CdTIA) were synthesized by the solvothermal synthesis of the organic linker 5-triazole isophthalic acid (5-TIA) with the transition metals Zn(II), Co(II) and Cd(II) in the presence of the structure directing agent tetramethyl ammonium chloride (TMA). These three MOFs were characterized thoroughly by ScXRD, PXRD, FT-IR, TGA, BET and SEM. They have excellent thermal and water stabilities. Among all these MOFs mentioned, pristine CoTIA exhibited excellent electrocatalytic activity toward the oxygen evolution reaction (OER). It exhibits a Tafel slope of 68.9 mV dec-1 with an overpotential of 337 mV at 10 mA cm-2 current density. The OER activity of the CoTIA MOF is relatively equivalent to that of the state-of-the-art catalyst (RuO2). Furthermore, the mechanical stability of crystalline ZnTIA, CoTIA and CdTIA MOFs was tested under ball mill pressure. The result showed that all the MOFs exhibit low tolerance to mechanical force because their structure was highly distorted or collapsed under such pressure, which is reflected by their poor electrocatalytic OER activity.

Fixed-bed adsorption studies of endocrine-disrupting compounds from water by using novel calcium-based metal-organic frameworks

The presence of emerging water pollutants such as endocrine-disrupting compounds (EDCs), including 17-ethynylestradiol (EE2), bisphenol A (BPA), and perfluorooctanoic acid (PFOA), in contaminated water sources poses significant environmental and health challenges. This study aims to address this issue by investigating the efficiency of novel calcium-based metal-organic frameworks, known as mixed-linker calcium-based metal-organic frameworks (Ca-MIX), in adsorbing these endocrine-disrupting compounds. This study analyzed the influence of influent concentration, bed height, and flow rate on pollutant removal, with bed height emerging as a crucial factor. From the breakthrough curves, it was determined that the column maximum adsorption capacities followed the order of 17-ethynylestradiol (101.52 μg/g; 40%) > bisphenol A (99.07 μg/g; 39%) > perfluorooctanoic acid (81.28 μg/g; 32%). Three models were used to predict the adsorption process, with the Yan model outperforming the other models. This suggests the potential of mixed-linker calcium-based metal-organic frameworks for removing endocrine-disrupting compounds from water, using the Yan model as an effective predictor. Overall, this study provides valuable insights for the development of effective water treatment methods using mixed-linker calcium-based metal-organic frameworks to remove endocrine-disrupting compounds from contaminated water sources.

Sequential Sol-Gel Self-Assembly and Nonclassical Gel-Crystal Transformation of the Metal-Organic Framework Gel

Metal-organic framework (MOF) gel, an emerging subtype of MOF structure, is unique in formation and function; however, its evolutionary process remains elusive. Here, the evolution of a model gel-based MOF, UiO-66(Zr) gel, is explored by demonstrating its sequential sol-gel self-assembly and nonclassical gel-crystal transformation. The control of the sol-gel process enables the observation and characterization of structures in each assembly stage (phase-separation, polycondensation, and hindered-crystallization) and facilitates the preparation of hierarchical materials with giant mesopores. The gelation mechanism is tentatively attributed to the formation of zirconium oligomers. By further utilizing the pre-synthesized gel, the nonclassical gel-crystal transformation is achieved by the modulation in an unconventional manner, which sheds light on crystal intermediates and distinct crystallization motions ("growth and splitting" and "aggregation and fusion"). The overall sol-gel and gel-crystal evolutions of UiO-66(Zr) enrich self-assembly and crystallization domains, inspire the design of functional structures, and demand more in-depth research on the intermediates in the future.

In situ conversion of a MOG to a crystalline MOF: a case study on solvent-dependent gelation and crystallization

Herein, we report in situ transformation of a metal-organic gel (MOG) to a crystalline metal-organic framework (MOF) and solvent-dependent gelation/crystallization via solvothermal reactions of a tetracarboxylic acid, namely 4,4'-dinitro-2,2',6,6'-tetracarboxybiphenyl, and ZnSO₄. The results provide structural insights into MOGs at the molecular level and also help in the synthesis of crystalline MOFs that are otherwise difficult to obtain.

Self-Assembly of Alkylamido Isophthalic Acids toward the Design of a Supergelator: Phase-Selective Gelation and Dye Adsorption

A new series of 5-alkylamido isophthalic acid (ISA) derivatives with varying single and twin alkyl chain lengths were designed and synthesized as potential supramolecular organogelators. 5-alkylamido ISAs with linear or branched alkyl tail-groups of different lengths were effective gelators for low polarity solvents. In particular, among the presented series, a derivative with a branched, 24 carbon atom tail-group behaves as a “supergelator” with up to twenty organic solvents forming gels that are highly stable over time. The gelation behavior was analyzed using Hansen solubility parameters, and the thermal stability and viscoelastic properties of select gels were characterized. Microscopy, spectroscopy, powder X-ray diffraction, and computer modeling studies were consistent with a hierarchical self-assembly process involving the formation of cyclic H-bonded hexamers via the ISA carboxylic acid groups, which stack into elementary fibers stabilized by H-bonding of the amide linker groups and π–π stacking of the aromatic groups. These new nanomaterials exhibited potential for the phase-selective gelation of oil from oil–water mixtures and dye uptake from contaminated water. The work expands upon the design and synthesis of supramolecular self-assembled nanomaterials and their application in water purification/remediation.

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

This review summarizes recent progress in the development and applications of metal–organic gels (MOGs) and their hybrids and derivatives dividing them into subclasses and discussing their synthesis, design and structure–property relationship.

Calcium-Based Metal-Organic Frameworks and Their Potential Applications

Metal-organic frameworks (MOFs) built on calcium metal (Ca-MOFs) represent a unique subclass of MOFs featuring high stability, low toxicity, and relatively low density. Ca-MOFs show considerable potential for molecular separations, electronic, magnetic, and biomedical applications, although they are not investigated as extensively as transition metal-based MOFs. Compared to MOFs made of other groups of metals, Ca-MOFs may be particularly advantageous for certain applications such as adsorption and storage of light molecules because of their gravimetric benefit, and drug delivery due to their high biocompatibility. This review intends to provide an overview on the recent development of Ca-MOFs, including their synthesis, crystal structures, important properties, and related applications. Various synthetic methods and techniques, types of building blocks, structure and porosity features, selected physical properties, and potential uses will be discussed and summarized. Representative examples will be illustrated for each type of important applications with a focus on their structure-property relations.

Fluorescent aminal linked porous organic polymer for reversible iodine capture and sensing

A novel triazene-anthracene-based fluorescent aminal linked porous organic polymer (TALPOP) was prepared via metal free-Schiff base polycondensation reaction of 9,10-bis-(4,6-diamino-S-triazin-2-yl)anthracene and 2-furaldehyde. The polymer has exceptional chemical and thermal stabilities and exhibit good porosity with Brunauer–Emmett–Teller surface area of 401 m²g⁻¹. The combination of such porosity along with the highly conjugated heteroatom-rich framework enabled the polymer to exhibit exceptional iodine vapor uptake of up to 314 wt % and reversible iodine adsorption in solution. Because of the inclusion of the anthracene moieties, the TALPOP exhibited excellent detection sensitivity towards iodine via florescence quenching with K_sv value of 2.9 × 10³ L mol⁻¹. The cost effective TALPOP along with its high uptake and sensing of iodine, make it an ideal material for environmental remediation.

A series of four novel alkaline earth metal-organic frameworks constructed of Ca(ii), Sr(ii), Ba(ii) ions and tetrahedral MTB linker: structural diversity, stability study and low/high-pressure gas adsorption properties

A series of four novel microporous alkaline earth metal–organic frameworks (AE-MOFs) containing methanetetrabenzoate linker (MTB) with composition {[Ca₄(μ₈-MTB)₂]·2DMF·4H₂O}_n (UPJS-6), {[Ca₄(μ₄-O)(μ₈-MTB)_3/2(H₂O)₄]·4DMF·4H₂O}_n (UPJS-7), {[Sr₃(μ₇-MTB)_3/2]·4DMF·7H₂O}_n (UPJS-8) and {[Ba₃(μ₇-MTB)_3/2(H₂O)₆]·2DMF·4H₂O}_n (UPJS-9) (UPJS = University of Pavol Jozef Safarik) have been successfully prepared and characterized. The framework stability and thermal robustness of prepared materials were investigated using thermogravimetric analysis (TGA) and high-energy powder X-ray diffraction (HE-PXRD). MOFs were tested as adsorbents for different gases at various pressures and temperatures. Nitrogen and argon adsorption showed that the activated samples have moderate BET surface areas: 103 m² g⁻¹ (N₂)/126 m² g⁻¹ (Ar) for UPJS-7′′, 320 m² g⁻¹ (N₂)/358 m² g⁻¹ (Ar) for UPJS-9′′ and UPJS-8′′ adsorbs only a limited amount of N₂ and Ar. It should be noted that all prepared compounds adsorb carbon dioxide with storage capacities ranging from 3.9 to 2.4 wt% at 20 °C and 1 atm, and 16.4–13.5 wt% at 30 °C and 20 bar. Methane adsorption isotherms show no adsorption at low pressures and with increasing pressure the storage capacity increases to 4.0–2.9 wt% of CH₄ at 30 °C and 20 bar. Compounds displayed the highest hydrogen uptake of 3.7–1.8 wt% at −196 °C and 800 Torr among MTB containing MOFs.

Four novel microporous alkaline earth metal–organic frameworks (AE-MOFs) containing methanetetrabenzoate linker (MTB): UPJS-6, UPJS-7, UPJS-8 and UPJS-9 have been successfully prepared, characterized and tested as adsorbents for different gases.

Building a robust 3D Ca-MOF by a new square Ca4O SBU for purification of natural gas

For the first time, a new square Ca4O SBU is introduced into a 3D Ca-MOF, ([MeNH2]2[Ca4O(MTB)2(EtOH)4])·(solvent)n (1), to generate a (4,8)-connected flu-topology structure. Compound 1 exhibits selective adsorption of C3 and C2 hydrocarbons and CO2 over CH4 with especially high IAST selectivities for C3 hydrocarbons over CH4 (at 15/85 and 50/50 ratio) at 298K and 1 bar.

Metal-Organic Gels Derived from Iron(III) and Pyridine Ligands: Morphology, Self-Healing and Catalysis for Ethylene Selective Dimerization

Metal-organic gels showing potential application in catalysis have received much concern. In this work, we designed and synthesized two metal-organic gels based on coordination between Fe^III and pyridine ligands at room temperature. The gels were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to reveal their assembly structures and morphologies, and it was found the metal-organic gel derived from di-topic ligand was composed of three-dimensional network of nanofibers, while the gel derived from tri-topic ligand was constituted of sponge-like structure with amorphous phase. Rheological analysis showed the gel consisting of nanofiber networks displayed self-healing property. The gels were used as catalysts for selective ethylene dimerization, and the optimum catalysis results of the gel with nanofibers reached the maximal catalytic activity of 1.48×10⁵  g/(mol Fe⋅h) with C₄ yield more than 90 %, whereas the sponge-like gel only gave 38 % C₄ products at the same condition. The higher dimerization selectivity of the former Fe^III gel was attributed to its regular assembly structure and lower steric hindrance of the surface metal sites. Due to its catalytic activity, high selectivity and preparation simplicity, the Fe^III gel might be potentially applicable for the preparation of C₄ α-olefins.

5-(1H-1,2,3-Triazol-5-yl)isophthalic Acid: A Versatile Ligand for the Synthesis of New Supramolecular Metallogels

The gelation ability of 5-(1H-1,2,3-triazol-5-yl)isophthalic acid (click-TIA) in the presence of different metal acetates has been studied in different solvents and ligand/metal ratios. This manuscript is focused on the metallogel obtained from the combination of click-TIA and copper(II) acetate, which has been used as a model system in terms of characterization and gelation studies. Sonication treatment of the initial mixture of compounds and the nature of the counter anion were found to be critical factors for the supramolecular assembly of the metal/click-TIA complexes and, hence, for the formation of stable and homogeneous metallogels. The gel materials have been characterized with a variety of techniques including infrared, rheology, UV-vis spectroscopy, powder X-ray diffraction, and scanning electron microscopy.

Discotic Organic Gelators in Ion Sensing, Metallogel Formation, and Bioinspired Catalysis

Two organogelators G2 and G3 with a carboxamide group have been synthesized and characterized with different spectroscopic tools. Dimethylformamide or dimethyl sulfoxide solutions of both the compounds upon the addition of a minute quantity of water show the tendency to form gels. Supramolecular self-assembly for gel formation paves the way for aggregation-induced emission enhancement (AIEE) phenomena for both the gelator molecules. Introduction of metal ions in organogels strengthens the gel property without much affecting the fluorescence behavior. However, the introduction of Ag⁺, Fe²⁺, and Fe³⁺ ions in the G2 organogel separately results in total quenching of AIEE, making it possible to sense that particular cation in the gel state. The G3 organogel shows a similar behavior with the Fe²⁺ ion. Remarkably, other metallogels such as Ni(II)G2 and Co(II)G2 can sense sulfide ion and Cu(II)G2 can sense iodide ion by switching off the fluorescence even in multianalyte conditions. Furthermore, the copper-based metallogel Cu(II)G2 can be utilized as a catalyst and reaction medium for aerobic oxidation of catechol to quinone. To the best of our knowledge, this is the first attempt known so far to utilize a metallogel material for bioinspired catalysis such as catechol oxidation.

Supramolecular metallogels constructed from carboxylate gelators

Serendipity still plays a role in gel discovery as the prediction of gel formation is difficult. This work explores the role of ligand, metal salt, solvent, and temperature in the formation of a low molecular mass carboxylate iron(iii) system. The influence of each component is discussed. The gels obtained were characterised using thermal analysis, Fourier transform-infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, elemental analysis, microwave plasma-atomic emission spectroscopy, and inductively coupled plasma optical emission spectrometry. The response to external stimuli, including dye and gas sorption was examined.

Nitrogen-Rich Porous Polymers for Carbon Dioxide and Iodine Sequestration for Environmental Remediation

The use of fossil fuels for energy production is accompanied by carbon dioxide release into the environment causing catastrophic climate changes. Meanwhile, replacing fossil fuels with carbon-free nuclear energy has the potential to release radioactive iodine during nuclear waste processing and in case of a nuclear accident. Therefore, developing efficient adsorbents for carbon dioxide and iodine capture is of great importance. Two nitrogen-rich porous polymers (NRPPs) derived from 4-bis-(2,4-diamino-1,3,5-triazine)-benzene building block were prepared and tested for use in CO₂ and I₂ capture. Copolymerization of 1,4-bis-(2,4-diamino-1,3,5-triazine)-benzene with terephthalaldehyde and 1,3,5-tris(4-formylphenyl)benzene in dimethyl sulfoxide at 180 °C afforded highly porous NRPP-1 (SA_BET = 1579 m² g^-1) and NRPP-2 (SA_BET = 1028 m² g^-1), respectively. The combination of high nitrogen content, π-electron conjugated structure, and microporosity makes NRPPs very effective in CO₂ uptake and I₂ capture. NRPPs exhibit high CO₂ uptakes (NRPP-1, 6.1 mmol g^-1 and NRPP-2, 7.06 mmol g^-1) at 273 K and 1.0 bar. The 7.06 mmol g^-1 CO₂ uptake by NRPP-2 is the second highest value reported to date for porous organic polymers. According to vapor iodine uptake studies, the polymers display high capacity and rapid reversible uptake release for I₂ (NRPP-1, 192 wt % and NRPP-2, 222 wt %). Our studies show that the green nature (metal-free) of NRPPs and their effective capture of CO₂ and I₂ make this class of porous materials promising for environmental remediation.

A copper(ii) metal-organic hydrogel as a multifunctional precatalyst for CuAAC reactions and chemical fixation of CO2 under solvent free conditions

A copper(ii) metal-organic hydrogel has been synthesised and characterised. This hydrogel is an efficient, reusable precatalyst for CuAAC reactions and chemical fixation of CO₂ under solvent free conditions.

Enantiopure Tertiary Urea and Thiourea Derivatives of Trianglamine Macrocycle: Structural Studies and Metallogeling Properties

Synthesis and detailed experimental and theoretical study on new urea and thiourea derivatives of chiral trianglamine are presented. In solution, the urea derivative of the trianglamine adopts cone conformation, whereas a respective thiourea derivative exists in solution predominantly as a partial cone conformer. In the crystalline phase, the thiourea trianglamine derivative adapts partial cone conformation. In the solid state, the two symmetry independent molecules of thiourea trianglamine create bilayers, containing molecules arranged in a zipper motif. The bilayers are separated by channels filled with disordered solvent molecules. The thiourea derivative of trianglimine appeared to be a simple, low molecular weight supergelator that formed stable chiral metallogels in N,N-dimethylformamide with Ag(I), Cu(I). and Cu(II) salts. The enantiomeric enrichment of the macrocycle is a necessary condition for effective gelling because neither racemic nor enantiomerically enriched samples (up to 50% ee) form metallogels. The metallogels formed from silver cations and thiourea trianglamine show reversible thixotropic property rarely observed in metallogels.

Mechano-switchable, luminescent gels derived from salts of a long-chained, fatty-acid gelator

Stimulus-responsive molecular gel systems, based on metal salts of a luminescent gelator, 9,10-dioxooctadecanoic acid (DODA), are reported. These salts are structurally the simplest metallo-gelators of which we are aware that exhibit controllable mechano-responsive and luminescent properties. Aggregation is more favored by the metal salts than for DODA itself. However, gelation ability differs dramatically depending on the metal ion: whereas the salts with zinc(ii) and calcium(ii) are inefficient gelators, those with nickel(ii) and copper(ii) can gelate various aromatic liquids, alkanes, and long-chained alcohols. Unlike the DODA gels, no aggregation-induced shift in the positions of the emission spectra of the metal salts could be observed as the sols were transformed to their gel phases. Gels of both nickel(ii) and copper(ii) salts in benzonitrile are among the few known examples with crystalline networks and exhibiting thixotropic behavior. However, there are significant differences in their abilities to recover the initial viscoelastic properties. Structural data for the solid and gel states lead us to conclude that differences among the gelating abilities can be attributed principally to the specific nature of interactions of the salts at their head groups. They appear to control the mechanical and emissive properties of the gels as well as whether the initial aggregation of the salts in the sol phases will support the growth of 1D objects that are capable of maintaining strong contacts, leading to 3D networks and gel formation. Overall, the results provide a facile strategy for the design of luminescent materials with controllable mechano-responsiveness by modifying the metal ions within fibrillar assemblies.

Structure modulation from unstable to stable MOFs by regulating secondary N-donor ligands

Four new Cd/Zn(ii) MOFs have been synthesized and structurally modulated from unstable to stable by regulating secondary N-donor ligands. Furthermore, YZ-10 shows excellent CO₂ selective uptake over CH₄ and N₂ and uncommon H₂ selective uptake over N₂ at 77 K.

Set of Multifunctional Azo Functionalized Semiconducting Cd(II)-MOFs Showing Photoswitching Property and Selective CO2 Adsorption

Syntheses, structural characterizations, photoluminescence, and adsorption properties of three new azo-functionalized Cd(II)-MOFs, namely, {[Cd(azbpy)(msuc)]·2.5(H₂O)}_n (2), {[Cd(azbpy)(mglu)]·5(H₂O)}_n (3), and {[Cd_1.5(azbpy)₂(glu)]·(NO₃)·MeOH}_n (4) [where msuc^2- = methylsuccinate; mglut^2- = methylglutarate; glut^2- = glutarate; azbpy = 4,4'-azobispyridine] have been reported. The compounds show different structures only with the variation of aliphatic dicarboxylates. The photoswitching behavior for the above-mentioned newly synthesized Cd(II)-MOFs along with one of our previously reported other azo-functionalized Cd(II)-MOF, namely, {[Cd(azbpy)(suc)]·2(H₂O)}_n (1), has been studied extensively. At photoilluminated condition, the conductivity values can draw a clear structure-property relationship among the structures of compounds 1-4. Single crystal structural analysis reveals that all the compounds exhibit a three-dimensional (3D) framework connected by azbpy linker and respective aliphatic dicarboxylate through their bis-chelating mono/bis oxo-bridging fashion. Compounds 1-3 exhibit an iso-structural honeycomb like 3D framework showing the same coordination environments, where the metal-carboxylate 2D sheets of compounds 1-3 are pillared by N,N'-donor azbpy linkers. On the other hand, compound 4 exhibits a 2-fold interpenetrated 3D framework with a little difference in its coordination environment and the pillaring of 1D metal-carboxylate ladder by azbpy linkers. All the compounds significantly demonstrate their enhanced sensitivity under light rather than the dark condition. The gas and solvent vapor sorption studies have been performed for the synthesized compounds 2-4. Moreover, compound 2 exhibits an enhanced type IV selective CO₂ adsorption isotherm over N₂ along with the appearance of gate opening phenomena in that.

An Amino-Coordinated Metal-Organic Framework for Selective Gas Adsorption

A novel 3D porous metal organic framework, JUC-141, constructed by 5-aminoisophthalic acid and Cu(NO₃)₂, has been synthesized successfully. The carboxyl groups in the ligand coordinate to Cu²⁺ to form the classic Cu₂(COO)₄ paddle wheel SBU, and the assembly of the SBUs with the isophthalic acid moieties leads to a kagome lattice. Interestingly, the amino groups in the ligand also take part in the coordination and link to the dipole of the paddle wheel as pillars, thus forming a 3D porous framework with eea topology. The sizes of the channels are 5.2 Å in the direction of [111] and 10.9 Å in the direction of [001]. Gas sorption tests show that the CO₂ adsorption capacities of JUC-141 are 79.94 and 51.39 cm³ g^-1 at 273 and 298 K under 1 atm pressure, respectively. However, the N₂ adsorption capacities of JUC-141 are 13.90 and 6.76 cm³ g^-1 at 273 and 298 K under 1 atm pressure, respectively. IAST calculations indicate that the selectivity values of CO₂/N₂ are 21.62 at 273 K and 27.60 at 298 K under 101 kPa, respectively. Good selective adsorption of CO₂ over N₂ makes JUC-141 possible for CO₂ storage and separation.

Metal–organic gels of silver salts with an α,β-unsaturated ketone: the influence of anions and solvents on gelation

A bis-pyridyl substituted α,β-unsaturated ketone was shown to form MOGs with silver salts having anions BF₄, ClO₄, CF₃SO₃ and SF₆ in various organic solvents. They have shown selectivity towards adsorbing an anionic dye from a mixture of cationic and anionic dyes.

A Highly Water-Tolerant Magnesium(II) Coordination Polymer Derived from a Flexible Layered Structure

A two-dimensional (2D) layered Mg(II) coordination polymer (CP) with a high tolerance for H2 O was designed, synthesised, and crystallographically characterised. The synthesis was achieved by the introduction of a flexible 2D layered structure composed of Mg(II) ions and isonicotinate N-oxide ligands. Owing to its high H2 O tolerance, the obtained 2D layered structure has the flexibility to repeatedly adsorb a large amount of H2 O associated with interlayer expansion and enable the removal of H2 O from a H2 O/2-propanol mixed vapour. These results indicate that the CP could be an excellent dehydrating agent.

Anion triggered metallogels: demetalation and crystal growth inside the gel matrix and improvement in viscoelastic properties using Au-NPs

Progelator complex Zn-TRPA-2 undergoes Cl(-) triggered gelation to afford ZTP2G, while Zn-TRPA-2 capped Au-NPs under similar conditions gave another gel GNZTP2G which also represents a rare nano-composite metallogel. When Zn-TRPA-2 was triggered by Cl(-) and NO3(-) simultaneously, crystals of demetalated species NA-TRPA-2 grew inside the ZTP2G matrix. Interestingly, GNZTP2G exhibits superior viscoelastic properties over ZTP2G.

Coordination polymers of Fe(iii) and Al(iii) ions with TCA ligand: distinctive fluorescence, CO2uptake, redox-activity and oxygen evolution reaction

Remarkable differences in the physicochemical properties of metal–organic gels of Fe(iii) and Al(iii) ions with the TCA ligand is reported.

Porous coordination polymers with ubiquitous and biocompatible metals and a neutral bridging ligand

The design of inexpensive and less toxic porous coordination polymers (PCPs) that show selective adsorption or high adsorption capacity is a critical issue in research on applicable porous materials. Although use of Group II magnesium(II) and calcium(II) ions as building blocks could provide cheaper materials and lead to enhanced biocompatibility, examples of magnesium(II) and calcium(II) PCPs are extremely limited compared with commonly used transition metal ones, because neutral bridging ligands have not been available for magnesium(II) and calcium(II) ions. Here we report a rationally designed neutral and charge-polarized bridging ligand as a new partner for magnesium(II) and calcium(II) ions. The three-dimensional magnesium(II) and calcium(II) PCPs synthesized using such a neutral ligand are stable and show selective adsorption and separation of carbon dioxide over methane at ambient temperature. This synthetic approach allows the structural diversification of Group II magnesium(II) and calcium(II) PCPs.

Inexpensive porous materials synthesized from Group II metals may be useful for industrial applications. Here, the authors demonstrate that neutral bridging ligands can be used for the synthesis of magnesium(II) and calcium(II) porous coordination polymers.

A new small molecule gelator and 3D framework ligator of lead(ii)

A new allene dicarboxylate ligand reacts with hydrated lead(ii) acetate in DMF to yield either a crystalline 3D framework or a metallogel dependent on the reaction temperature.

Nitrogen-doped porous carbon derived from metal-organic gel for electrochemical analysis of heavy-metal ion

A nitrogen-doped porous carbon material (N@MOG-C) was prepared by simple pyrolysis of polypyrrole-doped Al-based metal-organic gel (PPy@MOG) at 800 °C. The N@MOG-C possessed a uniform three-dimensional (3-D) interconnected mesoporous structure with a high surface area of 1542.6 m(2) g(-1) and a large pore volume of 0.76 cm(3) g(-1). By using an ionic liquid (IL) to immobilize N@MOG-C on electrode surface, the N@MOG-C was further used for sensitive detection of heavy metal ion. The doping of nitrogen-endowed N@MOG-C with faster electron transfer kinetics than other carbon materials such as MOG-C, multiwalled carbon nanotubes, and graphene. The N@MOG-C-modified electrode showed a high effective area, because of the porous structure. Under optimized conditions, the N@MOG-C-based sensor could detect Cd ions present in concentrations of 0.025-5 μM, with a detection limit of 2.2 nM. The mesoporous structure, fast electron transfer ability, and simple and green synthesis of N@MOG-C made it a promising electrode material for practical applications in heavy-metal-ion sensing.

A rare example of a porous Ca-MOF for the controlled release of biologically active NO

A 1D-microporous 3D calcium tetracarboxylate MOF has been solvothermally prepared and its structure solved from single crystal data. It exhibits coordinatively unsaturated Ca(2+) Lewis acid sites able to trap and deliver nitric oxide at a biological level.

Multi-stimuli responsive self-healing metallo-hydrogels: tuning of the gel recovery property

A series of amphiphilic tyrosine based self-healable, multi-stimuli responsive metallo-hydrogels have been discovered. Formation of these hydrogels is highly selective to Ni(2+) ions. The self-healing property and the stiffness of these metallo-hydrogels can be tuned by varying the chain length of the corresponding gelator amphiphile.