Metal-organic Framework MOF-5 Research Articles

Electrochemical Sensing of Cadmium and Lead Ions in Water by MOF-5/PANI Composites.

For the first time, composites of metal-organic framework MOF-5 and conjugated polymer polyaniline (PANI), (MOF-5/PANI), prepared using PANI in its conducting (emeraldine salt, ES) or nonconducting form (emeraldine base, EB) at various MOF-5 and PANI mass ratios, were evaluated as electrode materials for the electrochemical detection of cadmium (Cd2+) and lead (Pb2+) ions in aqueous solutions. Testing of individual components of composites, PANI-ES, PANI-EB, and MOF-5, was also performed for comparison. Materials are characterized by Raman spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS), and their electrochemical behavior was discussed in terms of their zeta potential, structural, morphology, and textural properties. All examined composites showed high electrocatalytic activity for the oxidation of Cd and Pb to Cd2+ and Pb2+, respectively. The MOF/EB-1 composite (71.0 wt.% MOF-5) gave the highest oxidation currents during both individual and simultaneous detection of two heavy metal ions. Current densities recorded with MOF/EB-1 were also higher than those of its individual components, reflecting the synergistic effect where MOF-5 offers high surface area for two heavy metals adsorption and PANI offers a network for electron transfer during metals' subsequent oxidation. Limits of detection using MOF/EB-1 electrode for Cd2+ and Pb2+ sensing were found to be as low as 0.077 ppm and 0.033 ppm, respectively. Moreover, the well-defined and intense peaks of Cd oxidation to Cd2+ and somewhat lower peaks of Pb oxidation to Pb2+ were observed at voltammograms obtained for the Danube River as a real sample with no pretreatment, which implies that herein tested MOF-5/PANI electrodes could be used as electrochemical sensors for the detection of heavy metal ions in the real water samples.

Environmental Potential of Carbonized MOF-5/PANI Composites for Pesticide, Dye, and Metal Cations-Can They Actually Retain Them All?

The environmental application of the carbonized composites of the Zn-containing metal-organic framework MOF-5 and polyaniline (PANI) in its emeraldine salt and base forms (C-(MOF-5/PANI)) was investigated for the first time. Textural properties and particle size distributions revealed that composites are dominantly mesoporous and nanoscale in nature, while Raman spectroscopy revealed the ZnO phase beneath the carbon matrix. Adsorption of pesticide, dye, and metal cation on C-(MOF-5/PANI) composites in aqueous solutions was evaluated and compared with the behavior of the precursor components, carbonized MOF-5 (cMOF), and carbonized PANIs. A lower MOF-5 content in the precursor, a higher specific surface area, and the pore volume of the composites led to improved adsorption performance for acetamiprid (124 mg/g) and Methylene Blue (135 mg/g). The presence of O/N functional groups in composites is essential for the adsorption of nitrogen-rich pollutants through hydrogen bonding with an estimated monolayer capacity twice as high as that of cMOF. The proton exchange accompanying Cd2+ retention was associated with the Zn/Cd ion exchange, and the highest capacity (9.8 mg/g) was observed for the composite synthesized from the precursor with a high MOF-5 content. The multifunctionality of composites was evidenced in mixtures of pollutants where noticeably better performance for Cd2+ removal was found for the composite compared to cMOF. Competitive binding between three pollutants favored the adsorption of pesticide and dye, thereby hindering to some extent the ion exchange necessary for the removal of metal cations. The results emphasize the importance of the PANI form and MOF-5/PANI weight ratio in precursors for the development of surface, porosity, and active sites in C-(MOF-5/PANI) composites, thus guiding their environmental efficiency. The study also demonstrated that C-(MOF-5/PANI) composites retained studied pollutants much better than carbonized precursor PANIs and showed comparable or better adsorption ability than cMOF.

Binding of CsPbBr3 Nanocrystals to MOF-5 for the Detection of Cadmium Ions in Aqueous Media

CsPbBr3 perovskite nanocrystals (CNCs) have emerged as promising candidates for optoelectronics, although instability issues have retarded their progress toward commercialization. As a solution to this core issue, herein CNCs are bound to the metal–organic framework MOF-5 to form a stable composite MOF:CNC for sensing applications in aqueous media. The electrostatic interaction of Pb2+ and Br– ions of CNCs with the terephthalate and Zn2+ ions of MOF-5 do not disturb the structural integrity of the MOFs and the photoluminescence (PL) properties of the CNCs but renders more stability to both the MOFs and CNCs in a water medium. As a proof-of-concept experiment, this water-resistant MOF:CNC probe was successfully validated for the detection of Cd2+ in a water medium. The mechanism of fluorescence enhancement during the sensing of Cd2+ is elucidated using X-ray photoelectron spectroscopy, temperature-dependent, and time-resolved PL studies. The high stability and photoefficiency exhibited by this MOF:CNC composite proves that it is a viable system for applications in aqueous media.

MOF-5 derived 3D ZnO/Ag micro-octahedra for ultrahigh response and selective triethylamine detection at low temperature

The leakage of raw material triethylamine in the process of chemical production causes harm and damage to health and environment. Therefore, the development of triethylamine sensors with high response and selectivity is urgently needed. Using metal organic frames (MOF) as templates has become a new strategy to prepare nano structural metal oxides based gas sensing materials, which leads to a high specific surface area and enhanced gas sensing performances. In this work, the metal organic framework MOF-5 decorated with large Ag particles is prepared by a conventional one-step solvothermal method. Then 3D ZnO/Ag micro-octahedra assembled from ZnO nanosheets are derived by subsequent calcination. The 3D ZnO/Ag micro-octahedra based sensor exhibits excellent gas sensing performance toward triethylamine, including an ultrahigh response of 293.8–10 ppm and selectivity, as well as a low operating temperature of 200 °C, and long-time stability. The excellent triethylamine gas sensing performance can be attributed to the synergy effect between oxygen vacancies and the catalytic spillover effect generated by the noble metal silver. This work shows that MOF derived hierarchical 3D ZnO/Ag micro-octahedra provides a great potential for triethylamine monitoring.

Enhanced Solid-State Fluorescence of Flavin Derivatives by Incorporation in the Metal-Organic Frameworks MIL-53(Al) and MOF-5.

The flavin derivatives 10-methyl-isoalloxazine (MIA) and 6-fluoro-10-methyl-isoalloxazine (6F-MIA) were incorporated in two alternative metal-organic frameworks, (MOFs) MIL-53(Al) and MOF-5. We used a post-synthetic, diffusion-based incorporation into microcrystalline MIL-53 powders with one-dimensional (1D) pores and an in-situ approach during the synthesis of MOF-5 with its 3D channel network. The maximum amount of flavin dye incorporation is 3.9 wt% for MIA@MIL-53(Al) and 1.5 wt% for 6F-MIA@MIL-53(Al), 0.85 wt% for MIA@MOF-5 and 5.2 wt% for 6F-MIA@MOF-5. For the high incorporation yields the probability to have more than one dye molecule in a pore volume is significant. As compared to the flavins in solution, the fluorescence spectrum of these flavin@MOF composites is broadened at the bathocromic side especially for MIA. Time-resolved spectroscopy showed that multi-exponential fluorescence lifetimes were needed to describe the decays. The fluorescence-weighted lifetime of flavin@MOF of 4 ± 1 ns also corresponds to those in solution but is significantly prolonged compared to the solid flavin dyes with less than 1 ns, thereby confirming the concept of "solid solutions" for dye@MOF composites. The fluorescence quantum yield (ΦF) of the flavin@MOF composites is about half of the solution but is significantly higher compared to the solid flavin dyes. Both the fluorescence lifetime and quantum yield of flavin@MOF decrease with the flavin loading in MIL-53 due to the formation of various J-aggregates. Theoretical calculations using plane-wave and QM/MM methods are in good correspondence with the experimental results and explain the electronic structures as well as the photophysical properties of crystalline MIA and the flavin@MOF composites. In the solid flavins, π-stacking interactions of the molecules lead to a charge transfer state with low oscillator strength resulting in aggregation-caused quenching (ACQ) with low lifetimes and quantum yields. In the MOF pores, single flavin molecules represent a major population and the computed MIA@MOF structures do not find π-stacking interactions with the pore walls but only weak van-der-Waals contacts which reasons the enhanced fluorescence lifetime and quantum yield of the flavins in the composites compared to their neat solid state. To analyze the orientation of flavins in MOFs, we measured fluorescence anisotropy images of single flavin@MOF-5 crystals and a static ensemble flavin@MIL53 microcrystals, respectively. Based on image information, anisotropy distributions and overall curve of the time-resolved anisotropy curves combined with theoretical calculations, we can prove that all fluorescent flavins species have a defined and rather homogeneous orientation in the MOF framework. In MIL-53, the transition dipole moments of flavins are orientated along the 1D channel axis, whereas in MOF-5 we resolved an average orientation that is tilted with respect to the cubic crystal lattice. Notably, the more hydrophobic 6F-MIA exhibits a higher degree order than MIA. The flexible MOF MIL-53(Al) was optimized essentially to the experimental large-pore form in the guest-free state with QuantumEspresso (QE) and with MIA molecules in the pores the structure contracted to close to the experimental narrow-pore form which was also confirmed by PXRD. In summary, the incorporation of flavins in MOFs yields solid-state materials with enhanced rigidity, stabilized conformation, defined orientation and reduced aggregations of the flavins, leading to increased fluorescence lifetime and quantum yield as controllable photo-luminescent and photo-physical properties.

Carbonization of MOF-5/Polyaniline Composites to N,O-Doped Carbon/ZnO/ZnS and N,O-Doped Carbon/ZnO Composites with High Specific Capacitance, Specific Surface Area and Electrical Conductivity.

Composites of carbons with metal oxides and metal sulfides have attracted a lot of interest as materials for energy conversion and storage applications. Herein, we report on novel N,O-doped carbon/ZnO/ZnS and N,O-doped carbon/ZnO composites (generally named C-(MOF-5/PANI)), synthesized by the carbonization of metal-organic framework MOF-5/polyaniline (PANI) composites. The produced C-(MOF-5/PANI)s are comprehensively characterized in terms of composition, molecular and crystalline structure, morphology, electrical conductivity, surface area, and electrochemical behavior. The composition and properties of C-(MOF-5/PANI) composites are dictated by the composition of MOF-5/PANI precursors and the form of PANI (conducting emeraldine salt (ES) or nonconducting emeraldine base). The ZnS phase is formed only with the PANI-ES form due to S-containing counter-ions. XRPD revealed that ZnO and ZnS existed as pure wurtzite crystalline phases. PANI and MOF-5 acted synergistically to produce C-(MOF-5/PANI)s with high SBET (up to 609 m2 g-1), electrical conductivity (up to 0.24 S cm-1), and specific capacitance, Cspec, (up to 238.2 F g-1 at 10 mV s-1). Values of Cspec commensurated with N content in C-(MOF-5/PANI) composites (1-10 wt.%) and overcame Cspec of carbonized individual components PANI and MOF-5. By acid etching treatment of C-(MOF-5/PANI), SBET and Cspec increased to 1148 m2 g-1 and 341 F g-1, respectively. The developed composites represent promising electrode materials for supercapacitors.

Heterofullerene C48B12-impregnated MOF-5 and IRMOF-10 for hydrogen storage: A combined DFT and GCMC simulations study

The H2 storage properties of isoreticular metal-organic framework materials (IRMOFs), MOF-5 and IRMOF-10, impregnated with different numbers and types of heterogeneous C48B12 molecules were investigated using density functional theory and grand canonical Monte Carlo (GCMC) calculations. The excess hydrogen adsorption isotherms of IRMOFs at 77 K within 20 bar indicate that suitable number and type of C48B12 molecules play a crucial role in improving the H2 storage properties of IRMOFs. Among the studied pure and nC48B12 (n = 1, 2, 4, 8) in Ci symmetry impregnating into MOF-5, at 77 K under 6 bar, MOF-5-4C48B12 with a 3.5 wt% and 29.9 g/L hydrogen storage density, and at 77 K under 12 bar, the pure MOF-5 with a 4.9 wt% and 31.0 g/L hydrogen storage density has the best hydrogen storage properties. Whereas, among the studied pure and nC48B12 (n = 1, 2, 4, 8) in S6 symmetry impregnating into IRMOF-10, IRMOF-10-8C48B12 always shows the best hydrogen storage properties among the pure and C48B12-impregnated IRMOF-10 at 77 K within 20 bar. IRMOF-10-8C48B12 has a 6.0 wt% and 34.6 g/L hydrogen storage density at 77 K under 6 bar, and has a 7.1 wt% and 41.4 g/L hydrogen storage density at 77 K under 12 bar. The confinement effect of IRMOFs on C48B12 molecules, and steric hindrance effect of C48B12 molecules on IRMOFs mainly affects the H2 uptake capacity by comparing the absolute H2 molecules in individual IRMOFs units, C48B12 molecules, and IRMOFs-nC48B12 compounds. The absolute hydrogen adsorption profiles show that eight C48B12 molecules impregnating into MOF-5 can exert obvious steric effects for H2 adsorption. The saturated gravimetric and volumetric H2 densities of IRMOF-10-8C48B12 higher than those of MOF-5-8C48B12 due to with larger free volume.

Antibacterial Films of Composite Materials Based on the Biocompatible Metal–Organic Framework MOF-5 and Hydrocolloids

Antibacterial Films of Composite Materials Based on the Biocompatible Metal–Organic Framework MOF-5 and Hydrocolloids

A Hessian-based assessment of atomic forces for training machine learning interatomic potentials.

In recent years, many types of machine learning potentials (MLPs) have been introduced, which are able to represent high-dimensional potential-energy surfaces (PESs) with close to first-principles accuracy. Most current MLPs rely on atomic energy contributions given as a function of the local chemical environments. Frequently, in addition to total energies, atomic forces are also used to construct the potentials, as they provide detailed local information about the PES. Since many systems are too large for electronic structure calculations, obtaining reliable reference forces from smaller subsystems, such as molecular fragments or clusters, can substantially simplify the construction of the training sets. Here, we propose a method to determine structurally converged molecular fragments, providing reliable atomic forces based on an analysis of the Hessian. The method, which serves as a locality test and allows us to estimate the importance of long-range interactions, is illustrated for a series of molecular model systems and the metal-organic framework MOF-5 as an example for a complex organic-inorganic hybrid material.

Fullerene-impregnated IRMOFs for balanced gravimetric and volumetric H2 densities: A combined DFT and GCMC simulations study

This paper aimed to study the effects of fullerene (C60) impregnation on the isoreticular metal-organic framework (IRMOF) materials MOF-650 (ZnO4 nodes were connected to azulenedicarboxylate linkers), MOF-5(ZnO4 nodes were connected to benzenedicarboxylate linkers), and IRMOF-10 (ZnO4 nodes were connected to biphenyldicarboxylate linkers) for H2 storage, these IRMOFs had similar structures but different pore volumes and organic linkers. Density functional theory (DFT) and grand canonical monte Carlo (GCMC) calculations indicated that C60 plays an important role in balancing the gravimetric and volumetric H2 densities of the IRMOFs. The C60@IRMOFs revealed improved volumetric density when H2 was undersaturated but reduced gravimetric density under H2 saturation. The saturated gravimetric H2 density of the IRMOFs was decided by the free volume. At 77 K, C60@MOF-650 had a gravimetric H2 density of 5.3 wt% and volumetric H2 density of 42 g/L under 10 bar, and C60@IRMOF-10 had a gravimetric H2 density of 7.4 wt% and volumetric H2 density of 43 g/L under 18 bar. These values nearly meet the United States Department of Energy (DOE) gravimetric and volumetric H2 density ultimate targets (gravimetric H2 density, 6.5 wt%; volumetric H2 density, 50 g/L) under ambient pressures. Among the studied IRMOFs, C60@MOF-650 and C60@IRMOF-10 demonstrated the best H2 storage properties at 233 and 298 K.

Thermal properties of PEG/MOF-5 regularized nanoporous composite phase change materials: A molecular dynamics simulation

In this paper, a metal-organic framework MOF-5 loaded polyethylene glycol (PEG) nanowire was used to form composite phase change material PEG/MOF-5. The molecular dynamics method was used to simulate the thermal conductivity, melting point and latent heat by G-K function and pseudo-supercritical path method, respectively. The results show that the pores of MOF-5 promote the increase of the angle of the PEG main chain and the extension of the helical segment. Therefore, the thermal conductivity of the composite (0.60 W/m·K) is 17.6% and 100% higher than that of the PEG nanowire (0.51 W/m∙K) and the skeleton (about 0.3 W/m∙K), respectively. At the same time, MOF-5 can improve the crystallinity of the PEG to a certain extent. The predicted latent heat of PEG/MOF-5 composite material is as high as 78.4 kJ/kg with a mass filling rate of 50%. This paper explores the mechanism from a microscopic perspective in order to provide models and data for the thermal design of such materials.

Polyethylene glycol phase change material embedded in a hierarchical porous carbon with superior thermal storage capacity and excellent stability

Hierarchical porous materials are recommended to trade off the mismatch between high loading and efficient crystallization in pore-based composite phase change materials (PCMs), coupling the functions of expanded pores (mesopores and macropores) along with maintained micropores. Hierarchical porous carbon (HPC) was successfully synthesized from metal organic framework MOF-5 with a large specific surface area (1345 m2/g) and high pore volume (2.69 cm3/g). The adsorption capacity of HPC for low temperature PCMs, polyethylene glycol (PEG) and stearic acid (SA) reaches over 90 wt%. The introduction of HPC has very little impact on the crystallinity of the PCMs, as a result, the composites possess similar high thermal storage capacity to pure PCM. The as-prepared composites efficiently perform heat store and release with reasonable reliability. Moreover, the supercooling of PCM was strongly suppressed due to the large surface area of HPC. Molecular dynamics (MD) simulation confirms that the smaller pores enable a stronger force of the carbon skeleton on the PCM, which ensures effective anchoring of the PCM. Simultaneously, those larger pores provide enough space for storage of PCM, with a reduced negative effect on its crystallization. After the compounding, the phonon vibration matching between guest and host is strengthened, which is beneficial to the transfer of energy thus receives an enhanced thermal conductivity. Our research demonstrates the great potential of using hierarchical porous skeleton to immobilize phase change materials for practical thermal storage.

Simultaneous esterification/transesterification of waste cooking oil and Jatropha curcas oil with MOF-5 as a heterogeneous acid catalyst

Metal–organic framework MOF-5 was used for the first time as a heterogeneous acid catalyst for the simultaneous esterification/transesterification of two nonedible oils, waste cooking oil and Jatropha curcas oil. Fatty acid methyl ester (biodiesel) production was evaluated using an experimental central composite design. A surface response methodology allowed the determination of optimal reaction conditions in terms of methanol/oil molar ratio (3:1–45:1), reaction time (1–15 h), temperature (118–152 °C) and catalyst amount (0.1–0.9 wt%) with a variation lower than 10% with respect to the experimental yield value. The best oil to biodiesel yield conversions were 90.8% (36:1 M/O molar ratio, 12 h, 145 °C, and 0.75 wt% catalyst amount) for waste cooking oil and 88.3% (36:1 M/O molar ratio, 9.59 h, 145 °C, and 0.75 wt% catalyst amount) for Jatropha curcas oil together with respective 93.3% and 94.8% decreases in the free fatty acid content, respectively. It was also verified that the produced biodiesel meets the ASTM D6751 quality standard for some properties of the biofuel and the cost analysis of biodiesel production has also been provided.

Synthesis of MOF-5 nanostructures by laser ablation method in liquid and evaluation of its properties

Capability of pulsed laser ablation (PLA) in liquid environment as a physical bottom-up method to synthesis metal–organic framework MOF-5 has been investigated experimentally for the first time. In this experiment, a high-purity zinc (Zn) target was irradiated by the fundamental wavelength of a pulsed Nd:YAG laser in a solution of dimethylformamide (DMF) containing terephthalic acid. A variety of diagnostics were employed to investigate the properties of MOF-5 nanostructures and to study the effects of laser fluence and concentration of acid on their characteristics. The porous and rod structure of synthesized MOF-5s observed in SEM images and their cubic shape observed in TEM microimages in good agreement with XRD and FTIR spectra confirm the production of MOF-5 nanostructures by PLA method. Results show that size of synthesized MOF-5 nanostructures was decreased with increasing the laser fluence. Furthermore, an amount of produced nanostructures was increased with increasing the ligand concentration in the liquid environment of ablation and laser fluence.

Theoretical understanding for anchoring effect of MOFs for lithium-sulfur batteries

Metal organic framework materials (MOFs) ZIF-8, ZIF-67 and MOF-5 have been widely used to solve the shuttle effect of lithium-sulfur batteries based on the great anchoring effect. Elucidating the anchoring effect has important implications for the MOFs design. The first-principles calculation shows that the adsorption of polysulfides intermediates occurs through the Li-heteroatom (N/O) bonding with the capacity order of MOF-5 > ZIF-8 > ZIF-67. The electronegativity of Zn in ZIF-8 is lower than that of Co in ZIF-67, leading to a higher charge density of N atoms in the ligand, which results in greater adsorption. The electronegativity of O in the ligand of MOF-5 is higher than that of N in ZIF-8, which contributes to closer Li-O interaction. Besides, MOF-5 provides enough space for both Li atoms to bond with O atoms of the ligand. Accordingly, MOFs with low electronegativity metal center, high electronegativity ligand heteroatom, and sufficient ligand framework space would have great anchoring effect.

Do Internal and External Surfaces of Metal-Organic Frameworks Have the Same Hydrophobicity? Insights from Molecular Simulations.

Reliable information on the hydrophobicity of porous materials is important in the design of many catalytic and separation processes. In general, hydrophobicity is assessed by measuring the contact angle of water (external surface) or the adsorption isotherm of water (internal surface). However, it is not clear how these different assessments are related. In this paper, molecular dynamics simulations of microscopic water droplets on the external surfaces of metal-organic frameworks are used to investigate the influence of the surface nature and hydrophobicity on the contact angle. The metal-organic frameworks MOF-5 and CAU-10 were modeled with external surfaces of different hydrophobicities, while the internal surface was maintained. It was observed that microscopic droplets orientate their spreading to the nature of the external surfaces. Comparing the simulated contact angles and adsorption isotherms confirms the necessity to distinguish between internal and external hydrophobicity.

Molecularly imprinted polymer based on metal-organic frameworks: synthesis and application on determination of dibutyl phthalate

ABSTRACT The molecular surface imprinted graft copolymer of metal-organic framework MOF-5 with methacrylic acid were prepared by free radical polymerization with dibutyl phthalate as the template molecule using initiator of azobisisobutyronitrile as adsorption system. The prepared MIPs@MOF-5 were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, Brunner−Emmet−Teller measurements, adsorption isotherms, kinetics and selectivity experiments, which showed higher specificity, sensitivity, stability, and better adsorption performance. The results suggested that MIPs@MOF-5 had two sites of adsorption behavior and can recognize sensitively and selectively the template molecules. Moreover, the MIPs@MOF-5 was successfully applied to the analysis of tap water sample.

Evaluating the impact of pellet densification and graphite addition for design of on-board hydrogen storage in a fixed bed of MOF-5 pellets

On-board storage of hydrogen is a key challenge in the deployment of fuel cell technology for transportation and distributed energy generation. Hydrogen adsorption capacity of up to 6 wt% has been reported for the metal-organic framework MOF-5, at 30 bar and 77 K. However, powders of MOF-5 suffer from low volumetric storage density and poor thermal conductivity for practical use in adsorptive storage systems. Compaction of MOF-5 to form pellets and inclusion of expanded natural graphite (ENG) has been used to address these issues, but their effect on the overall refueling dynamics for a fixed-bed has not been studied. To this end, we use simulations of multiscale pellet-and-bed model (developed in a companion paper) to analyze the impact of pellet modification on the dynamics of hydrogen refueling under cryogenic conditions. We show that a fixed bed with 0.52 g/cc density pellets is recommended, compared to MOF-5 powder or lower-density pellets. In spite of some loss of gravimetric capacity, the former shows good performance in a fixed bed with improved volumetric capacity and reasonable refueling time. Although individual pellet behavior is improved by addition of ENG to the 0.52 g/cc pellets, this has only a minor effect on refueling dynamics of the fixed bed with pellet size of 6 mm or lower. Finally, the effect of pellet size, density and ENG addition is analyzed and recommendations for fixed bed adsorber design are presented.

Novel microporous composites of MOF-5 and polyaniline with high specific surface area

Composites of metal organic framework MOF-5 and conjugated polymer polyaniline (PANI) were synthesized for the first time. Two procedures, which avoid humidity during the synthesis in order to preserve the structure of MOF-5, were applied. In the first one, dissolved part of nonconducting emeraldine base form of PANI (PANI-EB) in N,N΄-dimethylformamide was mixed with MOF-5 in different mass ratios. In the second one, the composites were prepared mechano-chemically, by using powdered conducting emeraldine salt form of PANI (PANI-ES) and solid MOF-5, mixed in chloroform in different mass ratios. The composites were characterized by various techniques: scanning electron microscopy (SEM), FTIR spectroscopy, nitrogen sorption and electrical conductivity measurements, XRD, and flame atomic absorption spectroscopy (FAAS). The procedure which used PANI-EB led to microporous PANI/MOF-5 composites with very high BET specific surface area, SBET (the highest value SBET of c.a. 2700 m2 g−1, even higher than SBET of starting pure MOF-5, showed the composite which contains 89 wt.% of MOF-5) and low conductivity (∼10-7 S cm−1). The second procedure which used PANI-ES gave microporous PANI/MOF-5 composites which showed moderate conductivities (the highest conductivity of 1.0 ⋅ 10−3 S cm-1 exhibited the composite which contains 25 wt.% of MOF-5) and also high SBET values, but lower than those measured for the composites with PANI-EB (the highest SBET of c.a. 850 m2 g-1 showed the composite of PANI doped with HCl which contains c.a. 77 wt.% of MOF-5). XRD measurements confirmed that predominately cubic crystalline structure of MOF-5 was present in almost all composites.

Solvothermal Synthesis of the Metal-Organic Framework MOF-5 in Autoclaves Prepared by 3D Printing

The known metal-organic framework {Zn4O(BDC)3} (MOF-5 (I), where BDC is terephthalate anion) is synthesized by the solvothermal method in autoclaves prepared by 3D printing from polypropylene. The synthesized polymer is isolated in the individual state and characterized by elemental analysis and powder X-ray diffraction analysis. The crystal structures of MOF-5 and another coordination polymer based on zinc(II) terephthalate {Zn4O(BDC)3} · (ZnO)0.125 (SUMOF-2 (II)) obtained as a by-product of the solvothermal synthesis are confirmed by X-ray diffraction analysis (СIF files ССDС nos. 1920366 (I) and 1926136 (II)).