Unraveling the effects of linker substitution on structural, electronic and optical properties of amorphous zeolitic imidazolate frameworks-62 (a-ZIF-62) glasses: a DFT study

The relaxed atomic models of amorphous ZIF-62 and ZIF-62 crystal.

Assorted functionality-appended UiO-66-NH2 for highly efficient uranium(vi) sorption at acidic/neutral/basic pH

Eight assorted functionalities were anchored on UiO-66-NH₂via PSM strategy displaying MOFs with similar framework but variable uranyl binding affinities. The excellent sorption capacity of UiO-66-PO-Ph makes it efficient uranium sorbent material.

The introduction of functional side groups and the application of the mixed-linker concept in divalent MIL-53(Ni) materials

Divalent MIL-53(Ni) metal–organic frameworks with 2-bromoterephthalate and terephthalate linkers feature interesting material properties as proven by various characterization techniques.

Recent advances in the shaping of metal–organic frameworks

In this review, the recent advances in the shaping of MOFs are overviewed, and some promising strategies recently developed are highlighted, including templated shaping, self-shaping, shaping on substrates, and shaping with sacrificial materials.

Solvent-assisted linker exchange enabled preparation of cerium-based metal–organic frameworks constructed from redox active linkers

Preparation of Ce(iv)-based MOFs with redox active linkers, unattainable de novo, using SALE for the detoxification of chemical warfare agents.

High CO2 Adsorption Enthalpy Enabled by Uncoordinated N-Heteroatom Sites of a 3D Metal-Organic Framework

A 3D metal-organic framework (MOF), Mn2L2(H2O)2 · (DMF) {H2L = 5- (Pyridin-2-yl)-3, 3′-bi (1H-1,2,4-triazole)} (1) with uncoordinated N-heteroatom sites, has been obtained through hydrothermal method and structurally characterized by X-ray structural analysis, powder X-ray diffraction (PXRD), and thermal analysis (TGA). The framework of compound 1 exhibits fascinating adsorption properties and shows high adsorption enthalpy of CO2. The experimental results prove which uncoordinated nitrogen heteroatom sites can markedly increase the reciprocity between host frame and CO2 at room temperature.

Pore Characteristics for Efficient CO2 Storage in Hydrated Carbons

Development of new approaches for carbon dioxide (CO₂) capture is important in both scientific and technological aspects. One of the emerging methods in CO₂ capture research is based on the use of gas-hydrate crystallization in confined porous media. Pore dimensions and surface functionality of the pores play important roles in the efficiency of CO₂ capture. In this report, we summarize work on several porous carbons (PCs) that differ in pore dimensions that range from supermicropores to mesopores, as well as surfaces ranging from hydrophilic to hydrophobic. Water was imbibed into the PCs, and the CO₂ uptake performance, in dry and hydrated forms, was determined at pressures of up to 54 bar to reveal the influence of pore characteristics on the efficiency of CO₂ capture and storage. The final hydrated carbon materials had H₂O-to-carbon weight ratios of 1.5:1. Upon CO₂ capture, the H₂O/CO₂ molar ratio was found to be as low as 1.8, which indicates a far greater CO₂ capture capacity in hydrated PCs than ordinarily seen in CO₂-hydrate formations, wherein the H₂O/CO₂ ratio is 5.72. Our mechanistic proposal for attainment of such a low H₂O/CO₂ ratio within the PCs is based on the finding that most of the CO₂ is captured in gaseous form within micropores of diameter <2 nm, wherein it is blocked by external CO₂-hydrate formations generated in the larger mesopores. Therefore, to have efficient high-pressure CO₂ capture by this mechanism, it is necessary to have PCs with a wide pore size distribution consisting of both micropores and mesopores. Furthermore, we found that hydrated microporous or supermicroporous PCs do not show any hysteretic CO₂ uptake behavior, which indicates that CO₂ hydrates cannot be formed within micropores of diameter 1-2 nm. Alternatively, mesoporous and macroporous carbons can accommodate higher yields of CO₂ hydrates, which potentially limits the CO₂ uptake capacity in those larger pores to a H₂O/CO₂ ratio of 5.72. We found that high nitrogen content prevents the formation of CO₂ hydrates presumably due to their destabilization and associated increase in system entropy via stronger noncovalent interactions between the nitrogen functional groups and H₂O or CO₂.

Crystal structure, Hirshfeld surface analysis and physicochemical characterization of bis-[4-(di-methyl-amino)-pyridinium] di-μ-chlorido-bis[di-chlorido-mercurate(II)]

The title mol-ecular salt, (C7H11N2)2[Hg2Cl6], crystallizes with two 4-(di-methyl-amino)-pyridinium cations (A and B) and two half hexa-chlorido-dimercurate(II) anions in the asymmetric unit. The organic cations exhibit essentially the same features with an almost planar pyridyl ring (r.m.s. deviations of 0.0028 and 0.0109 Å), which forms an inclined dihedral angle with the dimethyamino group [3.06 (1) and 1.61 (1)°, respectively]. The di-methyl-amino groups in the two cations are planar, and the C-N bond lengths are shorter than that in 4-(di-methyl-amino)-pyridine. In the crystal, mixed cation-anion layers lying parallel to the (010) plane are formed through N-H⋯Cl hydrogen bonds and adjacent layers are linked by C-H⋯Cl hydrogen bonds, forming a three-dimensional network. The analyses of the calculated Hirshfeld surfaces confirm the relevance of the above inter-molecular inter-actions, but also serve to further differentiate the weaker inter-molecular inter-actions formed by the organic cations and inorganic anions, such as π-π and Cl⋯Cl inter-actions. The powder XRD data confirms the phase purity of the crystalline sample. Furthermore, the vibrational absorption bands were identified by IR spectroscopy and the optical properties were studied by using optical UV-visible absorption spectroscopy.

A cyanide-bridged FeIII-MnII heterobimetallic one-dimensional coordination polymer: synthesis, crystal structure, experimental and theoretical magnetism investigation

A new cyanide-bridged Fe^III-Mn^II heterobimetallic coordination polymer (CP), namely catena-poly[[[N,N'-(1,2-phenylene)bis(pyridine-2-carboxamidato)-κ⁴N,N',N'',N''']iron(III)]-μ-cyanido-κ²C:N-[bis(4,4'-bipyridine-κN)bis(methanol-κO)manganese(II)]-μ-cyanido-κ²N:C], {[FeMn(C₁₈H₁₂N₄O₂)(CN)₂(C₁₀H₈N₂)₂(CH₃OH)₂]ClO₄}_n, (1), was prepared by the self-assembly of the trans-dicyanidoiron(III)-containing building block [Fe(bpb)(CN)₂]^- [bpb^2- = N,N'-(1,2-phenylene)bis(pyridine-2-carboxamidate)], [Mn(ClO₄)₂]·6H₂O and 4,4'-bipyridine, and was structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction analysis shows that CP 1 possesses a cationic linear chain structure consisting of alternating cyanide-bridged Fe-Mn units, with free perchlorate as the charge-balancing anion, which can be further extended into a two-dimensional supramolecular sheet structure via inter-chain π-π interactions between the 4,4'-bipyridine ligands. Within the chain, each Mn^II ion is six-coordinated by an N₆ unit and is involved in a slightly distorted octahedral coordination geometry. Investigation of the magnetic properties of 1 reveals an antiferromagnetic coupling between the cyanide-bridged Fe^III and Mn^II ions. A best fit of the magnetic susceptibility based on the one-dimensional alternating chain model leads to the magnetic coupling constants J₁ = -1.35 and J₂ = -1.05 cm^-1, and the antiferromagnetic coupling was further confirmed by spin Hamiltonian-based density functional theoretical (DFT) calculations.

Surface Engineering of Porous Carbon for Self-Healing Nanocomposite Hydrogels by Mussel-Inspired Chemistry and PET-ATRP

In this work, surface-functionalized microcapsules from porous carbon nanospheres (PCNs) were successfully prepared by mussel-inspired chemistry with polydopamine (PDA) and metal-free photoinduced electron transfer-atom transfer radical polymerization (PET-ATRP). These functional microcapsules are introduced into self-healing hydrogels to enhance their mechanical strength. The PCNs synthesized by a simple soft template method are mixed with linseed oil for loading of the biomass healing agent, and the microcapsules are first prepared by coating PDA. PDA coatings were used to immobilize the ATRP initiator for initiating 4-vinylpyridine on the surface of microcapsules by PET-ATRP. Using these functional microcapsules, the self-healing efficiency was about 92.5% after 4 h at ambient temperature and the healed tensile strength can be held at 2.5 MPa with a fracture strain of 625.2%. All results indicated that the surface-functionalized microcapsules for self-healing hydrogels have remarkable biocompatibility and mechanical properties.

Lithium-Doped Silica-Rich MIL-101(Cr) for Enhanced Hydrogen Uptake

Metal-organic frameworks (MOFs) show promising characteristics for hydrogen storage application. In this direction, modification of under-utilized large pore cavities of MOFs has been extensively explored as a promising strategy to further enhance the hydrogen storage properties of MOFs. Here, we described a simple methodology to enhance the hydrogen uptake properties of RHA incorporated MIL-101 (RHA-MIL-101, where RHA is rice husk ash-a waste material) by controlled doping of Li⁺ ions. The hydrogen gas uptake of Li-doped RHA-MIL-101 is significantly higher (up to 72 %) compared to the undoped RHA-MIL-101, where the content of Li⁺ ions doping greatly influenced the hydrogen uptake properties. We attributed the observed enhancement in the hydrogen gas uptake of Li-doped RHA-MIL-101 to the favorable Li⁺ ion-to-H₂ interactions and the cooperative effect of silanol bonds of silica-rich rice-husk ash incorporated in MIL-101.

Reminiscent capillarity in subnanopores

Fluids in large and small pores display different behaviors with a crossover described through the concept of critical capillarity. Here we report experimental and simulation data for various siliceous zeolites and adsorbates that show unexpected reminiscent capillarity for such nanoporous materials. For pore sizes D exceeding the fluid molecule size, the filling pressures p are found to follow a generic behavior k_BT ln p ∼ γ/ρD where γ and ρ are the fluid surface tension and density. This result is rationalized by showing that the filling chemical potential for such ultra-small pores is the sum of an adsorption energy and a capillary energy that remains meaningful even for severe confinements. A phenomenological model, based on Derjaguin’s formalism to bridge macroscopic and molecular theories for condensation in porous materials, is developed to account for the behavior of fluids confined down to the molecular scale from simple parameters.

Confined fluids in porous media exhibit different behaviors in large and small pores, the crossover between the two regimes being not well understood. Here the authors show, by experiments and simulations, that capillarity is reminiscent even for very small pore diameters, providing a unified picture.

Applicability of Tail Corrections in the Molecular Simulations of Porous Materials

Molecular simulations with periodic boundary conditions require the definition of a certain cutoff radius, rc, beyond which pairwise dispersion interactions are neglected. For the simulation of homogeneous phases the use of tail corrections is well-established, which can remedy this truncation of the potential. These corrections are built under the assumption that beyond rc the radial distribution function, g(r), is equal to one. In this work we shed some light on the discussion of whether tail corrections should be used in the modeling of heterogeneous systems. We show that for the adsorption of gases in a diverse set of nanoporous crystalline materials (zeolites, covalent organic frameworks, and metal-organic frameworks), tail corrections are a convenient choice to make the adsorption results less sensitive to the details of the truncation.

Structure and Density Comparison of Noble Gas Hydrates Encapsulating Xenon, Krypton and Argon

Understanding the effect of guest species on the host framework is important for the development of structure-based properties of inclusion compounds. Herein, the crystal structures of the noble gas hydrates encapsulating Xe, Kr, and Ar were studied by powder X-ray diffraction measurements. The crystal structures and hydration numbers of these noble gas hydrates were solved by Rietveld refinements using optimized models with the direct-space technique. It was revealed that host cage size of these hydrates changed depending on the type of guest species even though their unit-cell parameters were the same. Based on the structure models obtained, the densities of Xe, Kr, and Ar gas hydrates were also determined to be 1.837, 1.445 and 1.097 g/cm³ at 93 K, respectively. Our findings, from a crystallographic point of view, may give insight into further understanding the thermodynamic stability and physical properties of gas hydrates encapsulating small guests.

Size-Dependent Mechanical Properties of a Metal-Organic Framework: Increase in Flexibility of ZIF-8 by Crystal Downsizing

Size engineering is an emerging strategy to modulate the mechanical properties of crystalline materials. Herein, micro- and nanodimensional single crystals of the prototypical metal-organic framework (MOF) ZIF-8 are generated using solvothermal and solution methods, respectively. Atomic force microscopy-based nanoindentation technique was used to measure the Young's modulus values of micro- and nanodimensional individual ZIF-8 crystals. We demonstrate that crystal downsizing to nanoscale dimensions results in a 40% reduction in crystal stiffness. The change is attributed to a greater contribution of surface effects to the physical properties of nanocrystalline ZIF-8. The observed change in the mechanical properties may be used to explain reported size-dependent changes in gas adsorption of ZIF-8, thought to be a result of differences in framework flexibility at the nanoscale. Our work provides an important example on how downsizing of crystalline metal-organic materials can give rise to specific and tunable physical properties.

The Origin of p-Xylene Selectivity in a DABCO Pillar-Layered Metal-Organic Framework: A Combined Experimental and Computational Investigation

We report high experimental p-xylene (pX) selectivity in a pillar-layered metal-organic framework, DUT-8(Cu). Vapor- and liquid-phase adsorption experiments were carried out to confirm high pX selectivity and large pX uptakes in DUT-8(Cu). Grand canonical Monte Carlo simulation results show that the presence of DABCO ligands allows for the packing of pX molecules and is responsible for the pX selective nature of the material. The simulation also suggests that the presence of isooctane solvents in the liquid-phase experiments plays an essential role by lowering the adsorption of other xylene isomers, and leads to increased pX selectivity in the liquid-phase as compared to the vapor phase. Density functional theory simulations show that the preferential arrangement is due to the preferential adsorption of pX on the DABCO ligand and the preferential adsorption of isooctane over other xylene isomers.

Implementing Metal-Organic Frameworks for Natural Gas Storage

Methane can be stored by metal-organic frameworks (MOFs). However, there remain challenges in the implementation of MOFs for adsorbed natural gas (ANG) systems. These challenges include thermal management, storage capacity losses due to MOF packing and densification, and natural gas impurities. In this review, we discuss discoveries about how MOFs can be designed to address these three challenges. For example, Fe(bdp) (bdp2− = 1,4-benzenedipyrazolate) was discovered to have intrinsic thermal management and released 41% less heat than HKUST-1 (HKUST = Hong Kong University of Science and Technology) during adsorption. Monolithic HKUST-1 was discovered to have a working capacity 259 cm3 (STP) cm−3 (STP = standard temperature and pressure equivalent volume of methane per volume of the adsorbent material: T = 273.15 K, P = 101.325 kPa), which is a 50% improvement over any other previously reported experimental value and virtually matches the 2012 Department of Energy (Department of Energy = DOE) target of 263 cm3 (STP) cm−3 after successful packing and densification. In the case of natural gas impurities, higher hydrocarbons and other molecules may poison or block active sites in MOFs, resulting in up to a 50% reduction of the deliverable energy. This reduction can be mitigated by pore engineering.

Coordination polymers of CdII and PbII derived from bipyridine-glycoluril: influence of metal-ion size and counter-ions

Two new one-dimensional (1D) coordination polymers (CPs), namely catena-poly[[[aquacadmium(II)]-bis(μ-4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione)] bis(perchlorate) dihydrate], {[Cd(C₁₄H₁₀N₆O₂)₂(H₂O)](ClO₄)₂·2H₂O}_n or {[Cd(BPG)₂(H₂O)](ClO₄)₂·2H₂O}_n, 1, and catena-poly[[lead(II)-bis(μ-4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione)] bis(perchlorate) dihydrate], {[Pb(C₁₄H₁₀N₆O₂)₂](ClO₄)₂·2H₂O}_n or {[Pb(BPG)₂](ClO₄)₂·2H₂O}_n, 2, have been synthesized using bipyridine-glycoluril (BPG; systematic name: 4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione), a urea-fused tecton, in a mixed-solvent system. The Cd^II ion in 1 is heptacoordinated and the Pb^II ion in 2 is hexacoordinated, with the Cd^II ion adopting a pentagonal bipyramidal geometry and the Pb^II ion adopting a distorted octahedral geometry. Both CPs form infinite linear chain structures which are hydrogen bonded to each other leading to the formation of three-dimensional supramolecular network structures. Topological analysis of CPs 1 and 2 reveals that the structures exhibit 1D chain-like arrangements in an AB-AB sequence and shows platonic uniform 2-connected uninodal topologies. Furthermore, a comparative analysis of a series of structures based on the BPG ligand indicates that the size of the metal ion and the types of counter-ions used have a great influence on the resulting frameworks and properties.

Electrochemically Mediated Syntheses of Titanium(III)-Based Metal-Organic Frameworks

Although metal-organic frameworks featuring coordinatively unsaturated transition metal sites are relatively common, examples with redox-active cations are rare. In this report, we describe the electrochemically mediated synthesis of Ti^III-MIL-101 from the inexpensive Ti⁴⁺ precursor TiCl₄. The framework obtained via electrosynthesis is identical to that prepared from the significantly more expensive and air-sensitive starting material TiCl₃. The above electrosynthetic strategy was also extended to prepare Ti^III-MIL-100 and two high-quality extended Ti^III-MIL structures, for the first time. These materials represent examples of titanium-based MOFs with extended pore structures. Several physical methods demonstrate that these materials are superior in quality to samples of the analogous MOFs prepared via conventional routes from starting exogenous TiCl₃. Given the ease with which the electrosyntheses may be carried out and their compatibility with a broad range of bridging ligands, we expect that this new methodology will find utility for the synthesis of a number of novel materials containing coordinatively unsaturated, redox-active metal cations.

Enhancement of organic pollutants bio-decontamination from aqueous solution using newly-designed Pseudomonas putida-GA/MIL-100(Fe) bio-nanocomposites

As a natural adsorption material, graphene has become a hot research topic in water treatment due to its unique framework, large surface area, low cost, and simple preparation. Here, a series of composite material aerogels (GA/MIL-100(Fe)) consisting of Fe metal-organic frameworks (MIL-100 (Fe)) and graphene-based aerogel (GA) were prepared through a hydrothermal and step-by-step strategy and used for the adsorption of an azo dye in wastewater, scilicet acid orange 10 (AO10). The adsorption equilibrium of AO10 solutions with concentrations of 50 and 100 mg/L was reached within 45 min but the dye could not be fully removed. Besides, the synthesized composite material (GA/MIL-100(Fe)) was a good carrier for immobilized Pseudomonas putida cells due to its good biocompatibility and non-toxicity. A new, environmentally friendly adsorption and biodegradation process has been exploited here, which was to immobilize bacterial cells to the surface of GA/MIL-100(Fe) by a covalent bonding method to form a novel biocomposite material. The material could be used to completely remove AO10 dyes in 14 and 26 h from solutions with initial AO10 concentrations of 50 and 100 mg/L, respectively. This way of combining biological and physical adsorption has a higher processing efficiency and shows huge potential for the treatment of industrial wastewater.

A Zn(ii) metal-organic framework with dinuclear [Zn2(N-oxide)2] secondary building units

We report the synthesis, structural characterisation, and adsorption properties of a three-dimensional metal-organic framework [Zn(pydcao)(DMF)] (H2-pydcao = 3,5-pyridinedicarboxylic acid N-oxide) that has an unprecedented [Zn2(N-oxide)2] secondary building unit.

Multifunctional mesoporous curcumin encapsulated iron-phenanthroline nanocluster: A new Anti-HIV agent

A new strategy to encapsulating the drug curcumin into the hydrophobic core of the iron-phenanthroline nanocomplex (NIP) and eventually its release is signified. NIP was prepared via coordinate interaction between Fe²⁺ and the lone pairs present on the N atoms of the bidentate phenanthroline ligand (spherical morphology, diameter 18.8 nm, mesoporous with pore size 2.443 nm, amorphous). Thereafter, curcumin was successfully encapsulated (NCIP) in NIP, resulting in its enhanced stability (spherical morphology, diameter 46.8 nm). The nanocomplex NIP was used for drug delivery applications. We evaluated the anti-HIV effects of NCIP in vitro on cultures of HIV infected human microglia. The treatment of HIV-1 infected microglia with NCIP significantly decreased the expression of HIV-p24 by 41% and pro-inflammatory mediators TNF-α, IL-8 and NO by 61.2%, 41% and 50.2%, respectively, compared to NIP. Flow cytometry data also support the decrease in TNF-α and IL-8 expression in case of NCIP. NCIP induced antioxidative effects by increasing the gene expression of catalase (CAT) and simulatenously decreasing hemeoxygenase-1 (HMOX-1) gene expression, thereby maintaining homeostasis which reduces neuroinflammation. These results support our premise that NCIP may be a significant adjuvant when used with traditional anti-retroviral regimens and may ameliorate HIV-1 associated neurotoxicity.

Metal-Organic Framework Co-MOF-74-Based Host-Guest Composites for Resistive Gas Sensing

Increasing demands in the field of sensing, especially for gas detection applications, require new approaches to chemical sensors. Metal-organic frameworks (MOFs) can play a decisive role owing to their outstanding performances regarding gas selectivity and sensitivity. The tetrathiafulvalene (TTF)-infiltrated MOF, Co-MOF-74, has been prepared following the host-guest concept and evaluated in resistive gas sensing. The Co-MOF-74-TTF crystal morphology has been characterized via X-ray diffraction and scanning electron microscopy, while the successful incorporation of TTF into the MOF has been validated via X-ray photoemission spectroscopy, thermogravimetric analysis, UV/vis, infrared (IR), and Raman investigations. We demonstrate a reduced yet ample uptake of CO₂ in the pores of the new material by IR imaging and adsorption isotherms. The nanocomposite Co-MOF-74-TTF exhibits an increased electrical conductivity in comparison to Co-MOF-74 which can be influenced by gas adsorption from a surrounding atmosphere. This effect could be used for gas sensing.

An Organic Zeolite With 10 Å Diameter Pores Assembles From a Soluble and Flexible Building Block by Non-Covalent Interactions

Two similar molecular building blocks, which both contain a hydrogen-bonded nitro group, have been prepared and crystallised. One structure has more flexibility with a butyl side chain which allows an open framework organic zeolite to form with large 10 Å diameter pores, whereas the other structure has less flexibility with an aryl side chain and is close packed. The pore size is comparable with those of the aluminophosphate VPI-5 (12 Å). It is concluded that some flexibility in the design of the building block for porous organic molecular materials was beneficial.

Selective Ion Exchange in Supramolecular Channels in the Crystalline State

Artificial ion channels are of increasing interest because of potential applications in biomimetics, for example, for realizing selective ion permeability through the transport and/or exchange of selected ions. However, selective ion transport and/or exchange in the crystalline state is rare, and to the best of our knowledge, such a process has not been successfully combined with changes in the physical properties of a material. Herein, by soaking single crystals of Li₂ ([18]crown-6)₃ [Ni(dmit)₂ ]₂ (H₂ O)₄ (1) in an aqueous solution containing K⁺ , we succeeded in complete ion exchange of the Li⁺ ions in 1 with K⁺ ions in the solution, while maintaining the crystalline state of the material. This ion exchange with K⁺ was selectively conducted even in mixed solutions containing K⁺ as well as Na⁺ /Li⁺ . Furthermore, remarkable changes in the physical properties of 1 resulted from the ion exchange. Our finding enables not only the realization of selective ion permeability but also the development of highly sensitive biosensors and futuristic ion exchange agents, for example.

Deep neural network learning of complex binary sorption equilibria from molecular simulation data

We employed deep neural networks (NNs) as an efficient and intelligent surrogate of molecular simulations for complex sorption equilibria using probabilistic modeling. Canonical (N ₁ N ₂ VT) Gibbs ensemble Monte Carlo simulations were performed to model a single-stage equilibrium desorptive drying process for (1,4-butanediol or 1,5-pentanediol)/water and 1,5-pentanediol/ethanol from all-silica MFI zeolite and 1,5-pentanediol/water from all-silica LTA zeolite. A multi-task deep NN was trained on the simulation data to predict equilibrium loadings as a function of thermodynamic state variables. The NN accurately reproduces simulation results and is able to obtain a continuous isotherm function. Its predictions can be therefore utilized to facilitate optimization of desorption conditions, which requires a laborious iterative search if undertaken by simulation alone. Furthermore, it learns information about the binary sorption equilibria as hidden layer representations. This allows for application of transfer learning with limited data by fine-tuning a pretrained NN for a different alkanediol/solvent/zeolite system.

Effective CO2 and CO Separation Using [M2(DOBDC)] (M = Mg, Co, Ni) with Unsaturated Metal Sites and Excavation of Their Adsorption Sites

Isostructural [M₂(DOBDC)(EG)₂] (M = Mg, Co, Ni) frameworks are first synthesized by controlling the pH* in the reaction medium. Coordinated ethylene glycols form a hexagonal OH cluster, which works as a template to grow single crystals with high crystallinity. After the liberation of solvated molecules, [M₂(DOBDC)] shows notably higher surface areas than the reported values and completely different CO₂ and CO separation properties depending on the kinds of unsaturated metal. Therefore, breakthrough experiments using a CO₂/CO mixed gas show that Mg-MOF has a longer breakthrough time for CO₂ than for CO, whereas Co/Ni-MOFs have longer breakthrough times for CO than for CO₂. Apart from CO₂ and CO, other gases such as CH₄, H₂, and N₂ were almost not adsorbed at all in these materials at 298 K. To reveal the role of unsaturated metal sites, CO₂ and CO adsorption sites are unequivocally determined by single-crystal X-ray diffraction analysis. One of very interesting discoveries is that there are two CO₂ and CO adsorption positions (sites A and B) in the hexagonal channels. Site A is the unsaturated metal center working as Lewis acidic sites, and site B is the secondary adsorption site located between two A sites. A close inspection of crystal structures reveals that unsaturated Co(II) and Ni(II) sites adsorb both CO₂ and CO, whereas the unsaturated Mg(II) sites strongly capture only CO₂, not CO. Density functional theory calculations elucidate the discrepancy in CO affinity: Co(II) and Ni(II) form strong π-back-donating bonds with CO via electron transfer from the d orbitals of the transition metals to the antibonding molecular orbitals of CO, whereas Mg(II) does not participate in electron transfer or orbital overlap with CO. This observation provides new insight into the synthesis of novel functional materials with high CO₂/CO separation performance.

A bio-relevant supramolecular Co(ii)-complex for selective fluorescence sensing of μM range inorganic As(iii) in aqueous medium and its intracellular tracking in bacterial systems

A bio-relevant fluorescent supramolecular Co(ii)-complex selectively detects μM range toxic inorganic As(iii) in water and in bacterial systems.

A series of flexible bis(pyridyl)bis(tetrazole)-modulated coordination polymers: construction, electrochemical properties, dye adsorption and magnetic properties

Four new coordination polymers based on three bis(pyridyl)bis(tetrazole) ligands and 4,4′,4′′-benzene-1,3,5-triyltribenzoic acid were synthesized showing electrocatalytic, dye adsorption and antiferromagnetism properties.

MOF-5 derived carbon as material for CO2 absorption

In our study we prepared MOF-5 derived carbon to reveal the thermodynamics of CO₂ absorption processes in great detail.