Acid-based Metal-organic Frameworks Research Articles

Biphenyl tetracarboxylic acid-based metal-organic frameworks: a case of topology-dependent thermal expansion.

The large inherent flexibility and highly modular nature of metal-organic frameworks (MOFs) make them ideal candidates for the study of negative thermal expansion (NTE). Among diverse organic ligands, the biphenyl unit, which can unrestrictedly rotate along its C-C single bond, can largely enhance the structural flexibility. Herein, we explored the thermal expansion behaviors of four indium biphenyl tetracarboxylates (BPTCs). Owing to the different dihedral angles of BPTC ligands and coordination mode of In3+, they show distinct topologies: InOF-1 (nti), InOF-2 (unc), InOF-12 (pts) and InOF-13 (nou). Intriguingly, it is found that the thermal expansion is highly dependent on the specific topology. The MOFs featuring mononuclear nodes show normal positive thermal expansion (PTE), and the magnitudes of coefficients follow the trend of InOF-2 < InOF-12 < InOF-13, inversely related to averaged molecular volumes. In contrast, the InOF-1, composed of a 1D chain of corner-shared InO6 octahedrons, shows pronounced NTE. Detailed high-resolution synchrotron powder X-ray diffraction and lattice dynamic analyses shed light on the fact that NTE in the InOF-1 is a synergy effect of the spring-like distortion of the inorganic 1D helical chain and twisting of the BPTC ligands. The present work shows how the topological arrangement of building blocks governs the thermal expansion behaviors.

Controlled growth-dependent electrochemical behavior of cobalt and 1,3,5 benzene-tricarboxylic acid-based MOFs for efficient supercapacitor applications

This study investigates the synthesis and electrochemical performance of cobalt-BTC acid-based metal-organic frameworks (Co-MOFs) under different hydrothermal conditions. The crystal growth was controlled by varying the concentration of NaOH during synthesis, resulting in three Co-BTC MOF varieties (labeled as COMOFDW-0mM, COMOFDW-3mM, and COMOFDW-6mM). Exhaustive structural-microstructural characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherms, elucidate the structural and morphological variation among these Co-BTC MOF varieties. The crystal structures of COMOFDW-0mM and COMOFDW-3mM exhibit similar laminar configurations, while COMOFDW-6mM shows major variations, such as changes in the coordination modes between BTC and cobalt complexes and differences in BTC plane directions in MOF crystal faces. SEM images reveal distinctive needle-like morphologies, and the as-synthesized crystals exhibit varying aspect ratios. Nitrogen adsorption-desorption isotherms indicate variations in the presence of micropores and mesoporosities, revealing microstructural differences. Electrochemical evaluations in a three-electrode system reveal superior performance for COMOFDW-6mM, with a maximum specific capacitance of 261.27 F/g, an energy density of 7.34 Wh/kg, and a maximum power density of 1325.2 W/kg under 2 M KOH electrolyte. Two-electrode coin cell measurements further validate its potential, maintaining competitive capacitance values. This systematic exploration of Co-MOFs not only elucidates the impact of growth conditions on crystal structures but also underscores the potential for tailoring electrochemical properties. Moreover, the findings present opportunities for further enhancements through composite strategies, opening new avenues for advancing MOFs in energy storage applications.

Elucidating the redox activity of cobalt-1,2,3,4-cyclopentane-tetracarboxylic acid and 1,2,4,5-benzene-tetracarboxylic acid-based metal-organic frameworks for a hybrid supercapacitor.

The development of electrode materials with extraordinary energy densities or high power densities has experienced a spectacular upsurge because of significant advances in energy storage technology. In recent years, the family of metal-organic frameworks (MOFs) has become an essential contender for electrode materials. Herein, two cobalt-based MOFs are synthesized with distinct linkers named 1,2,4,5-benzene-tetra-carboxylic acid (BTCA) and 1,2,3,4-cyclopentane-tetracarboxylic acid (CPTC). Investigations have been rigorously conducted to fully understand the effect of linkers on the electrochemical properties of Co-based MOFs. The best sample among the MOFs was used with activated carbon to create a battery-supercapacitor hybrid device. Due to its noteworthy results, specific capacity (100.3 C g-1), energy density (23 W h kg-1), power density (3400 W kg-1) and with the lowest ESR value of 0.4 Ω as well as its 95.4% capacity retention, the fabricated hybrid device was discovered to be very appealing for applications demanding energy storage. An approach for evaluating battery-supercapacitors was employed by quantifying the capacitive and diffusive contributions using Dunn's model to reflect the bulk and surface processes occurring during charge storage. This study fills the gap between supercapacitors and batteries, as well as providing a roadmap for creating a new generation of energy storage technologies with improved features.

Cu-trimesic acid-based metal organic frameworks for improved ß-galactosidase immobilization: Enhanced stability, reusability and lactose hydrolysis

The immobilization of β-galactosidase on Cu-trimesic acid-based metal organic frameworks (Cu-TMAs) was studied. The results showed that the immobilization yield was 79 %, and the activity yield was 86 %, indicating that a significant amount of the enzyme activity was retained after immobilization. The morphological structures of Cu-TMA and β-galactosidase@Cu-TMA were studied with SEM, and the chemical changes in Cu-TMA after immobilization were monitored with FTIR spectroscopy. The immobilized enzyme retained 83 % of its activity after it was used for six consecutive batches and showed good storage stability, retaining 78 % of its initial activity after it was stored at 4 °C for two months. Additionally, the optimum pH for the immobilized β-galactosidase was shifted to pH 7.0, and the optimal temperature was 60 °C, 10 °C higher than that of the free enzyme. The immobilized enzyme demonstrated better lactose hydrolysis activity than the free enzyme; it exhibited 83 % hydrolysis after 4 h at 60 °C and continued to hydrolyse the lactose, and 85 % hydrolysis was achieved after 5 h. Overall, this study demonstrated the potential of Cu-trimesic acid-based metal organic frameworks as supports for immobilizing β-galactosidase. The results of this study suggest that the immobilized enzyme may have practical applications in various industrial processes.

SOLVOTHERMAL SYNTHESIS AND CHARACTERIZATION OF TEREPHTHALIC ACID-BASED METAL-ORGANIC FRAMEWORKS AND THEIR CATALYTIC APPLICATION IN BIODIESEL PRODUCTION

Metal-Organic Frameworks (MOFs) are a class of porous crystalline materials, consisting of metal ions or nodes linked with organic ligands. The study was aimed at solvothermal synthesis and characterization of terephthalic acid-based Metal-Organic Frameworks and their catalytic application in biodiesel production. Three MOFs of Cu-, Fe-, and Cr-based were solvothermally synthesized, characterized and applied as catalysts in biodiesel production using ethanol and oil extracted from Yellow Oleander seeds. The MOFs were synthesized using terephthalic acid as the linker and copper (II), iron (III) and chromium (III) nitrates as metal ion sources. Each of the synthesized MOFs showed high melting point exceeding 360 oC. Microscopic view and powder X- ray diffraction analysis indicated Cu-MOF to be crystalline with numerous sharp peaks while those for Fe- and Cr-MOFs were amorphous. A comparison of the FT-IR spectra of the ligand and those of the MOFs confirmed the presence of the ligand in the synthesized MOFs. In the absence of a catalyst, the transesterification was not achieved. However, in the presence of the more crystalline Cu-MOF as catalyst resulted to high yield (83.33%) and in a shorter time compared to the less crystalline Fe- (33.33%) and Cr- (25.00%) MOFs. Thus, catalytic ability of the MOFs were in the order: Cu-MOF &gt; Fe-MOF &gt; Cr-MOF. Hence MOFs especially Cu-MOFs can be applied as catalyst in biodiesel production. Further studies and characterization (single X-ray diffraction) should be done for proper elucidation of the crystal structure of the MOFs.&#x0D;

Comparative Study on Adsorptive Desulfurization of Thiophenic Compounds over Terephthalic Acid-Based and Trimesic Acid-Based Metal–Organic Frameworks

Comparative Study on Adsorptive Desulfurization of Thiophenic Compounds over Terephthalic Acid-Based and Trimesic Acid-Based Metal–Organic Frameworks

Development and characterization of hydroxyapatite layered lanthanum organic frameworks by template method for defluoridation of water

The template preparation of hydroxyapatit (HAp) layered lanthanum-benzene tricarboxylic acid based metal organic frameworks (La-BTC MOFs) abbreviated as HAp-La-BTC-MOFs has been investigated here for defluoridation of water. The nucleation and growth of La-based MOFs was carried out in the prepared HAp hard template using layer-by-layer (LBL) technique. The coulomb and chelation contacts on HAp surface between Ca2+ ions and COO− organic ligands of La-BTC MOFs play vital roles in the preparation process. The batch experiments were employed to assess the defluoridation capacity (DC) of HAp-La based MOFs. The physicochemical properties of HAp-La based MOFs were investigated by various instrumentation techniques. To identify the nature, order and feasibility of HAp-La based MOFs towards defluoridation was examined by adsorption kinetics, isotherms and thermodynamics studies. The mechanism of defluoridation using HAp-La based MOFs were explained in detail. The field and reusability investigations of HAp-La-BTC MOFs also explored to find the potential applicability.

Aspartic acid based metal–organic frameworks with dual function of NADH peroxidase and glycerol dehydrogenase-mimicking activities

CuAsp with a fiber-like structure exhibited both NADH peroxidase- and glycerol dehydrogenase (GlyDH)-mimetic activities.

Deciphering of advantageous electrocatalytic water oxidation behavior of metal-organic framework in alkaline media

Carboxylic acid-based metal-organic frameworks (MOFs) are normally passed for the “pre-catalysts” for oxygen evolution reaction (OER) due to the hydroxides constructed in-situ during its alkaline hydrolysis process (AHP) in lye. Whereas, it remains a mystery that they show advantageous activity over prototypical hydroxides when they are directly acted as OER catalysts. Herein, we propose for the first time that the steric hindrance effect of Nafion can induce enhanced catalytic activity of such MOFs. Different from conventional catalysts without AHP, the Nafion with 3D structure weakens the AHP of Co-MOF nanoribbons, thus forming small size and low crystallinity species (cobalt hydroxide) with more active sites. And the existence of Nafion also optimizes its electronic structure, which is confirmed by transmission electron microscopy (TEM), in-situ UV absorption spectra, in-situ Raman spectroscopy and so on. Compared with Co-MOF-K obtained by directly immersing the Co-MOF nanoribbons in 1.0 M KOH, the Co-MOF-NK obtained by AHP of Co-MOF mixed with Nafion shows better catalytic activity. Based on the above inspiration, we realized the low overpotential of 268 mV at 10 mA·cm−2 by preparing CoFe-MOF-NK. This work provides a new understanding of the structural reconstruction of MOFs in the field of electrocatalysis.

Facile design of metal ion fabricated benzene-1,3,5-tricarboxylic acid based metal organic frameworks for defluoridation of water

The leaching of fluoride in potable water leads to fluorosis. To prevail over this trouble, tunable porous metal organic frameworks (MOFs) were prepared by solvothermal method and utilized for fluoride removal. Herein, polyvalent metal ions namely Zr4+, Fe3+ and Al3+ fabricated benzene-1,3,5-tricarboxylic acid (BTC) based MOFs namely Zr-BTC, Fe-BTC, and Al-BTC MOFs exhibits higher defluoridation capacities (DCs) of 4998, 4940, and 4920 mgF- kg-1 respectively. The developed metal based BTC (M-BTC) MOFs were investigated by XRD, TEM, SEM, FTIR, XPS and EDAX investigation. The influencing factors of adsorption viz., solution pH, M-BTC MOFs dosage, shaking time, preliminary fluoride concentration, temperature, and challenger anions were optimized under batch scale. The fluoride adsorption ability of M-BTC MOFs was slightly affected by adsorbate pH medium and bicarbonate ion in water. In addition, the experimental data was fitted with various adsorption kinetic and isotherm models. The thermodynamic investigation shows the feasible, spontaneous and endothermic nature of fluoride adsorption. The plausible fluoride adsorption mechanism of M-BTC MOFs was majorly ruled by electrostatic attraction and complexation. Furthermore, synthesized M-BTC MOFs can be reused upto eight cycles. The field trial indicates M-BTC MOFs diminish fluoride concentration below the acceptance limit in field water which helps in supply of water with secure fluoride levels.

Design and Preparation of Succinic Acid-Based Metal-Organic Frameworks for CO_2 Adsorption Technology

Design and Preparation of Succinic Acid-Based Metal-Organic Frameworks for CO_2 Adsorption Technology

Effects of electrolytes and fractionated dissolved organic matter on selective adsorption of pharmaceuticals on terephthalic acid-based metal-organic frameworks

In this study, we investigated the synergetic effects of coexisting electrolytes and dissolved organic matter (DOM) on Carbamazepine (CBZ) and Ciprofloxacin (CIP) adsorption on the 1D flexible structure of MIL-53(Al) and 3D rigid structure of UiO-66(Zr). The effects of electrolytes on the adsorption of CBZ and CIP on 1D flexible framework of MIL-53(Al) were more significant than those observed from the 3D framework of UiO-66(Zr). The presence of sulfate, nitrate, and phosphate anions indicates high potential to promote the adsorption of CBZ and CIP onto MIL-53(Al) and UiO-66(Zr) because of the decrease of solubility and strengthening of electrostatic interactions by substitution of oxo-anions at the metal complex node via covalent bonding. The lower hydration energy of the potassium ion enhanced CBZ adsorption on MIL-53(Al), while the higher hydration energy of calcium and magnesium ions reduced the adsorption capacity of CBZ and CIP on MIL-53(Al) and UiO-66(Zr). CBZ interacted with fractionated humic acid better than CIP. High-density carboxylic and aromatic functional groups on humic acid ensured that only humic acid larger than 1KDa was adsorbed by MIL-53(Al). Tryptophan-like and humic acid-like DOM were both detected in real hospital effluent, and their effects on CIP and CBZ adsorption onto MIL-53(Al) were investigated. The presence of tryptophan did not affect CBZ adsorption on MIL-53(Al) (except when coexisting with calcium ions). Conversely, tryptophan interfered with CIP adsorption. The presence of humic acid lower than 1KDa promoted the adsorption of CBZ and CIP by increasing the breathing effect of MIL-53(Al)'s 1D flexible framework. The presence of humic acid with molecular size greater than 1KDa enhanced both CBZ and CIP adsorption via a multilayer adsorption mechanism.

Synthesis of tricarboxylic acid based metal organic frameworks: Structural and gas adsorption studies

Two folded interpenetrating metal organic frameworks (MOFs) viz. {[Zn4(L)2(NO3)(H2O)3]+ [S1]}n(LZn) and {[Cd4(L)2(NO3)(DMF)8(H2O)](NO3)(DMF)2(S2)}n (LCd) where S1 denotes squeezed nitrate anions and solvent molecules and S2 denotes the squeezed solvent molecule, have been synthesized from (4,4′,4′'-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(azanediyl))tribenzoic acid) (H3L) ligand and Zn(NO3)2•6H2O/Cd(NO3)2•4H2O metal salts by solvothermal process. The structural analysis showed that both LZn and LCd are two dimensional (2D) interpenetrating metal organic frameworkscontaining binuclear paddle wheel secondary building units (SBUs), Zn2(COO)3 and Cd2(COO)3, with hexagonal (hcb) net topology having 3-connected uninodal net. In LZn, both interpenetrating frameworks are vertical while in LCd, these are parallel to each other. Thermogravimetric analysis showed that both MOFs are stable up to 350 °C. Gas adsorption study demonstrated that these MOFs are selective towards CO2 over N2 gas due to sieving effect as well as Lewis acid-Lewis base interaction.

An amino acid, l-Glutamic acid-based metal-organic frameworks and their antibacterial, blood compatibility, biocompatibility, and sensor properties

Abstract In this study, metal-organic frameworks (MOFs) based on l -Glutamic acid (L-Glu), a natural amino acid as organic linker and Co (II), Ni (II), and Cu (II) metal ions were used in construction with 37.1 ± 5.3%, 41.4 ± 6.1%, 49.2 ± 4.9% yields, respectively in ethanol under reflux. The prepared L-Glu-M (M: Co(II), Ni(II), and Cu(II)) MOFs were characterized in terms of their porosity, optical, thermal, electrical, and structural properties. Correspondingly, 102.1 m2/g, 83.7 m2/g, and 71.0 m2/g specific surface areas and 2.72 cm3/g, 0.46 cm3/g, and 0.07 cm3/g pore volumes were measured for L-Glu-based Co, Ni, and Cu MOFs. Moreover, the antimicrobial studies of L-Glu-M MOFs on Escherichia coli ATCC 8739, as gram-negative, and Staphylococcus aureus ATCC 6538 as gram-positive bacteria revealed that the highest inhibition zones with 42 ± 2 mm and 44 ± 1 mm were observed for L-Glu-Co MOFs. The hemolysis induction of L-Glu-M MOFs was evaluated, except L-Glu-Cu that induced 8.3 ± 0.4% hemolysis, and the hemolytic characters of other MOF preparations were found to reside in safety margins possessing ≤4% hemolysis ratios. The blood clotting index of L-Glu-M MOFs were measured as 87.4 ± 6.3% (Co(II)), 91.8 ± 10.1% (Ni(II)), and 95.7 ± 4.8% (Cu(II)) with neglectable interference to clotting mechanisms. Cytocompatibility of L-Glu-based MOFs were demonstrated that all MOF preparations with 25 μg/mL concentrations maintained approximately 90% cell viabilities. Furthermore, Glu-based MOFs were demonstrated to possess sensory properties for NH3 vapor and could be employed in at least five cycles of repeated use. Therefore, L-Glu-M based MOFs can provide useful avenues in material science for a variety of biomedical and industrial applications.

Metal organic frameworks enhanced dispersive solid phase microextraction of malathion before detection by UHPLC-MS/MS.

Metal organic frameworks are considered as an efficient and promised adsorbent for separation of several ions and compounds from solutions due to its unique geometric structure. Herein, copper-benzyl tricarboxylic acid based metal organic frameworks have showed a high efficiency in enrichment and microextraction of malathion from food and water samples. The microextraction procedures were followed by determination of malathion by ultra high performance liquid chromatography with tandem mass spectrometry. The optimum recoveries for malathion were obtained at pH 6, and with using 2 mL of ethyl acetate as the eluent. The microextraction procedures showed a detection limits and the quantification limits of 4.0 and 10.0 µg/L, respectively. The intra- and interday precision showed a relative standard deviation% less than 10. The feasibility of the proposed procedure was determined by evaluating the addition/recovery studies of malathion from the real samples. The absolute recovery% was ≥92%. Furthermore, some ions were tested as cointerfering ions, and the recovery% was 93-100%. These results confirm that the developed microextraction procedure based on copper-benzyl tricarboxylic acid based metal organic frameworks as extractor for dispersive solid phase microextraction is matrix-independent, and can be applied for various real samples including different matrix or various malathion content.

Development of Multivalent Metal-Ion-Fabricated Fumaric Acid-Based Metal–Organic Frameworks for Defluoridation of Water

Defluoridation plays a vital role in providing drinking water with safe fluoride levels. The present work concentrated on the development of fumaric acid-based metal–organic frameworks (MOFs) using...

Porous carbon-coated ZnO nanoparticles derived from low carbon content formic acid-based Zn(II) metal-organic frameworks towards long cycle lithium-ion anode material

Single-C formic acid-based metal-organic frameworks (MOFs) are used to construct novel ZnO@porous carbon matrix nanocomposites by controlled pyrolysis. In the constructed nanocomposites, the porous carbon matrices act as a confined support to prevent agglomeration of the ZnO nanoparticles and create a rapid electron conductive network. Meanwhile, the well-defined, continuous porous structured MOFs provide a large specific surface area, which increases the contact of electrolyte-electrode and improves the penetration of electrolyte. Especially, the reasonable choice of formic acid-based MOFs construct the low carbon content composite, which contribute to the high energy density and long cycle life. The constructed nanocomposites show stable, ultrahigh rate lithium ion storage properties of 650mAhg−1 at charge/discharge rate of 1C even after 200 cycles.

Efficient synthesis of aluminum- and zinc-containing metal-organic frameworks

A convenient method has been proposed for the synthesis of aluminum- and zinc-containing terephthalic acid-based metal-organic frameworks. The method offers high productivity and high product yield. Materials produced by this method have been characterized by physicochemical techniques, and their sorption capacity has been assessed.

The ionothermal synthesis, structure, and magnetism-structure relationship of two biphenyl tetracarboxylic acid-based metal-organic frameworks.

Two new metal-organic frameworks (1-2) were ionothermally obtained by the reaction of a biphenyltetracarboxylic sodium (Na4BPTC) ligand and M(OOCCH3)2 (M = Co(1) and Mn(2)). Crystal structure analysis reveals that 1 is a Co3Na6 unit-based three dimensional heterometallic MOF, while 2 exhibits a {Mn(COO)n} chain-based three-dimensional framework. Furthermore, the magnetic measurement shows that both of them have anti-ferromagnetic properties. A combination of Density Functional Theory (DFT) and Quantum Monte Carlo (QMC) simulation uncovers that in 2 the coupling parameters between two adjacent Mn(II) ions are J1 = -2.0 cm(-1) and J2 = -1.6 cm(-1), and the magnetism mainly originates from the propagation of Mn(II) ions by the super-exchange of carboxylates. Interestingly, the superexchange modes of J1 and J2 are different. Two spin nets of -/+/- dominate in the coupling for J1, while for J2 there are two spin nets of -/+/- and one spin net of +/-/+.

The influence of the enantiomeric ratio of an organic ligand on the structure and chirality of metal-organic frameworks.

We have prepared three distinct polyamino acid-based metal-organic frameworks (MOFs) with different chiralities and porosities using the same chemistry, by simply modifying the enantiomeric ratio of the chiral organic ligand used.