Gas Sorption Properties Research Articles

Engineering of the High‐Power Laser‐Induced Synthesis of Ni‐Based Metal‐Organic Framework: Investigation of its Optical Properties, Computational Methodology, Electrocatalytic Performances, and Glucose‐Sensing Ability

AbstractMetal‐organic frameworks (MOFs) are porous materials with numerous chemical and structural possibilities. Due to their ease of modification, well‐organized structure, and diverse guest molecule chemistry, MOFs are ideal platforms for uncovering improved functional material design characteristics. Quantitative analysis of glucose is crucial, especially in some food products, for quality control as well as evaluation of the glucose levels helps diagnose and treat diabetes. Recent glucose sensing devices have relied heavily on MOFs and other nanomaterials to enable user‐friendly and safe non‐invasive sensing methods. Nevertheless, the conventional synthesis methods involve multi‐day reactions, cooling, and depressurization processes. This study demonstrates the unprecedented high‐power laser‐induced rapid synthesis (LIRS) of Ni‐based MOF nanospheres with interconnected nano‐rods and noncentrosymmetric primitive triclinic crystalline structure, highlighting their multifunctional usage in sensing and gas sorption applications. Ab initio simulations show excellent agreement with the experimental physical and gas sorption properties. Furthermore, the Ni‐MOF‐based biosensor accurately measures glucose real‐life beverage samples, yielding promising glucose detection biosensor results with a low limit of the detection (LOD) of 13.96 µM and high sensitivity of 120.606 µA mM−1 cm−2.

Polymers of Intrinsic Microporosity Containing [2.2]Paracyclophane Moieties: Synthesis and Gas Sorption Properties

AbstractThe unique structure of [2.2]paracyclophane (PCP) with its rigidity, stability, and planar chirality has gained significant attention in polymer and material research. In this work, the incorporation of amino‐functionalized PCPs within polymers of intrinsic microporosity (PIMs) is reported for the first time. Three different PCP‐PIMs were prepared via a Tröger's base formation mechanism, and their structures characterized via solid‐state NMR, MALDI‐TOF, and SEM. Their porosity was evaluated using gas adsorption (N2 and CO2) based on theoretical calculations such as Brunauer–Emmett–Teller (BET), NLDFT pore size distribution (PSD) and ideal IAST CO2/N2 selectivity (15/85), a crucial separation when considering the capture of CO2 from flue gas. The surface areas were found to be between 200–230 m2 g−1 while the selectivity for CO2/N2 ranged from 46 to 70.

Effect of Polymorphism on the Sorption Properties of a Flexible Square-Lattice Topology Coordination Network.

The stimulus-responsive behavior of coordination networks (CNs), which switch between closed (nonporous) and open (porous) phases, is of interest because of its potential utility in gas storage and separation. Herein, we report two polymorphs of a new square-lattice (sql) topology CN, X-sql-1-Cu, of formula [Cu(Imibz)2]n (HImibz = {[4-(1H-imidazol-1-yl)phenylimino]methyl}benzoic acid), isolated from the as-synthesized CN X-sql-1-Cu-(MeOH)2·2MeOH, which subsequently transformed to a narrow pore solvate, X-sql-1-Cu-A·MeOH, upon mild activation (drying in air or heating at 333 K under nitrogen). X-sql-1-Cu-A·MeOH contains MeOH in cavities, which was removed through exposure to vacuum for 2 h, yielding the nonporous (closed) phase X-sql-1-Cu-A. In contrast, a more dense polymorph, X-sql-1-Cu-B, was obtained by exposing X-sql-1-Cu-(MeOH)2·2MeOH directly to vacuum for 2 h. Gas sorption studies conducted on X-sql-1-Cu-A and X-sql-1-Cu-B revealed different switching behaviors to two open phases (X-sql-1-Cu·CO2 and X-sql-1-Cu·C2H2), with different gate-opening threshold pressures for CO2 at 195 K and C2H2 at 278 K. Coincident CO2 sorption and in situ powder X-ray diffraction studies at 195 K revealed that X-sql-1-Cu-A transformed to X-sql-1-Cu-B after the first sorption cycle and that the CO2-induced switching transformation was thereafter reversible. The results presented herein provide insights into the relationship between two polymorphs of a CN and the effect of polymorphism upon gas sorption properties. To the best of our knowledge, whereas sql networks such as X-sql-1-Cu are widely studied in terms of their structural and sorption properties, this study represents only the second example of an in-depth study of the sorption properties of polymorphic sql networks.

Ligand effects on gas adsorption in nanoporous phthalocyanine crystals.

X-ray diffraction is used to study the sorption of CO and NO in two phthalocyanine nanoporous crystals (PNCs) with 4,4' bipyridine or 4,4' bipyrimidine trans coordinated to open Co2+ sites, demonstrating how the trans coordinated ligands influence the gas sorption properties and structures of the PNCs.

Reticular Synthesis of Flexible Rare-Earth Metal-Organic Frameworks: Control of Structural Dynamics and Sorption Properties Through Ligand Functionalization.

An exciting direction in metal-organic frameworks involves the design and synthesis of flexible structures which can reversibly adapt their structure when triggered by external stimuli. Controlling the extent and nature of response in such solids is critical in order to develop custom dynamic materials for advanced applications. Towards this, it is highly important to expand the diversity of existing flexible MOFs, generating novel materials and gain an in-depth understanding of the associated dynamic phenomena, eventually unlocking key structure-property relationships. In the present work, we successfully utilized reticular chemistry for the construction of two novel series of highly crystalline, flexible rare-earth MOFs, RE-thc-MOF-2 and RE-teb-MOF-1. Extensive single-crystal to single-crystal structural analyses coupled with detailed gas and vapor sorption studies, shed light onto the unique responsive behavior. The development of these series is related to the reported RE-thc-MOF-1 solids which were found to display a unique continuous breathing and gas-trapping property. The synthesis of RE-thc-MOF-2 and RE-teb-MOF-1 materials represents an important milestone as they provide important insights into the key factors that control the responsive properties of this fascinating family of flexible materials and demonstrates that it is possible to control their dynamic behavior and the associated gas and vapor sorption properties.

Single Crystals of Insoluble Porous Salicylimine Cages.

Porous organic cages (POCs) are meanwhile an established class of porous materials. Most of them are soluble to a certain extend and thus processable in or from solution. However, a few of larger salicylimine cages were reported to be insoluble in any organic solvents and thus characterized as amorphous materials. These cages were now synthesized as single-crystalline materials to get insight into packing motifs and preferred intermolecular interactions. Furthermore, the pairs of crystalline and amorphous materials for each cage allowed to compare their gas-sorption properties in both morphological states.

Zn-based Metal-Organic Frameworks Using Triptycene Hexacarboxylate Ligands: Synthesis, Structure, and Gas-Sorption Properties.

A series of metal-organic frameworks (MOFs) based on zinc ions and two triptycene ligands of different size were synthesized under solvothermal conditions. The structural analyses revealed that these are isostructural three-dimensional-network MOFs. The high porosity and thermal stability of these MOFs can be attributed to the highly rigid triptycene-based ligands. Their BET specific surface areas depend on the size of the triptycene ligands. In contrast to these surface-area data, the H2 and CO2 adsorption of these MOFs is larger for MOFs with small pores. Consequently, we introduced functional groups to the bridge-head position of the triptycene ligands and investigated their effect on the gas-sorption properties. The corresponding results unveiled the role of the functional groups in the specific CO2 binding via an induced interaction between adsorbates and the functional groups. Excellent H2 and CO-2 properties in these MOFs were achieved in the absence of open metal sites.

The Effect of Pendent Groups upon Flexibility in Coordination Networks with Square Lattice Topology.

Gas or vapor-induced phase transformations in flexible coordination networks (CNs) offer the potential to exceed the performance of their rigid counterparts for separation and storage applications. However, whereas ligand modification has been used to alter the properties of such stimulus-responsive materials, they remain understudied compared with their rigid counterparts. Here, we report that a family of Zn2+ CNs with square lattice (sql) topology, differing only through the substituents attached to a linker, exhibit variable flexibility. Structural and CO2 sorption studies on the sql networks, [Zn(5-Ria)(bphy)]n, ia = isophthalic acid, bphy = 1,2-bis(pyridin-4-yl)hydrazine, R = -CH3, -OCH3, -C(CH3)3, -N=N-Ph, and -N=N-Ph(CH3)2, 2-6, respectively, revealed that the substituent moieties influenced both structural and gas sorption properties. Whereas 2-3 exhibited rigidity, 4, 5, and 6 exhibited reversible transformation from small pore to large pore phases. Overall, the insight into the profound effect of pendent moieties of linkers upon phase transformations in this family of layered CNs should be transferable to other CN classes.

Anti-cluster behavior and its mechanism during water vapor sorption in chitin and chitosan membranes

Alternating petroleum-based plastics to inexhaustible natural resource-based ones is an important issue worldwide, especially for the plastic packaging application. Polysaccharides are soluble in liquid water or swelled with liquid water; thus, they have been considered unsuitable materials for this application. Hence, reports on water vapor (i.e., gas) sorption properties of polysaccharide membranes are few. Polymers are well-known to demonstrate water vapor clustering during water vapor sorption. Unlike others, anti-cluster behavior for water vapor was discovered for chitin and chitosan membranes in this study. Therefore, chitin and chitosan membranes possess resistance to moisture during storage of a package, particularly for dried food. The anti-cluster mechanism was also revealed in this study. The sorption of water vapor in both membranes was considered a 1:1 interaction between hydrophilic groups and water molecules and the manner by which water molecules act on hydrophilic groups has an order.

Metal‐Organic Frameworks with Rod Yttrium Secondary Building Units

AbstractWe report a new hydroxamate‐based yttrium MOF, named MOF‐419 [Y(HCOO)(BDH)], with rod‐SBUs. The compound was synthesized employing chelating construction of benzene‐1,4‐hydroxamate (BDH2−) linkers, and the use of formic acid as the modulator was found to be crucial for the formation of rod‐shaped SBUs. MOF‐419 shows permanent porosity and has a BET surface area of 1130 m2/g. Its hydrophobic pore environment and gas sorption properties were demonstrated through the combination of single crystal X‐ray diffraction and nitrogen, carbon dioxide, and water sorption experiments. We envision that these results will aid the study and understanding of rod MOFs with chelating linkages.

Nano-Biocomposite Materials Obtained from Laser Ablation of Hemp Stalks for Medical Applications and Potential Component in New Solar Cells

The study in this paper presents a new material that was produced as a thin film by the Pulsed Laser Deposition technique (PLD) using a 532 nm wavelength and 150 mJ/pulse laser beam on the hemp stalk as target. The analyses performed by spectroscopic techniques (Fourier Transform Infrared Spectroscopy-FTIR, Laser-Induced Fluorescence Spectroscopy-LIF, Scanning Electron Microscopy coupled with Energy Dispersive X-ray-SEM-EDX, Atomic Force Microscopy-AFM and optical microscope) evidenced that a biocomposite consisting of lignin, cellulose, hemicellulose, waxes, sugars and phenolyc acids p-coumaric and ferulic, similar to the hemp stalk target was obtained. Nanostructures and aggregated nanostructures of 100 nm to 1.5 μm size were evidenced. Good mechanical strength and its adherence to the substrate were also noticed. It was noticed that the content in calcium and magnesium increased compared to that of the target from 1.5% to 2.2% and from 0.2% to 1.2%, respectively. The COMSOL numerical simulation provided information on the thermal conditions that explain phenomena and processes during laser ablation such as C-C pyrolisis and enhanced deposition of calcium in the lignin polymer matrix. The good gas and water sorption properties due to the free OH groups and to the microporous structure of the new biocomposite components recommends it for studies for functional applications in medicine for drug delivery devices, filters in dialysis and for gas and liquid sensors. Functional applications in solar cells windows are also possible due to the conjugated structures of the contained polymers.

Dynamic structural and microstructural responses of a metal–organic framework type material to carbon dioxide under dual gas flow and supercritical conditions

The structural and microstructural responses of a model metal–organic framework material, Ni(3-methyl-4,4′-bipyridine)[Ni(CN)4] (Ni-BpyMe or PICNIC-21), to CO2 adsorption and desorption are reported for in situ small-angle X-ray scattering and X-ray diffraction measurements under different gas pressure conditions for two technologically important cases. These conditions are single or dual gas flow (CO2 with N2, CH4 or H2 at sub-critical CO2 partial pressures and ambient temperatures) and supercritical CO2 (with static pressures and temperatures adjusted to explore the gas, liquid and supercritical fluid regimes on the CO2 phase diagram). The experimental results are compared with density functional theory calculations that seek to predict where CO2 and other gas molecules are accommodated within the sorbent structure as a function of gas pressure conditions, and hence the degree of swelling and contraction in the associated structure spacings and void spaces. These predictions illustrate the insights that can be gained concerning how such sorbents can be designed or modified to optimize the desired gas sorption properties relevant to enhanced gas recovery or to addressing carbon dioxide reduction through carbon mitigation, or even direct air capture of CO2.

Mixed matrix membranes comprising 6FDA-based polyimide blends and UiO-66 with co-continuous structures for gas separations

Membrane gas separation is considered a highly promising alternative to conventional gas separation. Recently, mixed matrix membranes containing UiO-66 metal–organic frameworks (MOFs) have been demonstrated to achieve high gas separation performance, especially in CO2-related separation. To date, few studies have used morphological control strategies to enhance the gas transport properties of mixed matrix membranes. In this study, we fabricated mixed matrix membranes comprising porous UiO-66 nanoparticles and immiscible 6FDA-based polyimide blends with co-continuous structures. The selective location of UiO-66 nanoparticles within one polymer phase of the co-continuous polymer blend was observed. However, this co-continuous structure cannot be referred to as a double-percolative morphology since the percolative UiO-66 networks did not successfully form. The gas permeability and gas sorption properties of pure gases (H2, CO2, N2, O2, and CH4) in the dense membranes and mixed matrix membranes were measured using the constant-volume variable-pressure method and the dual-volume pressure decay method, respectively. On the basis of the solution–diffusion mechanism, the contributions of gas sorption and gas transport to the overall gas permeation properties were determined and examined. When the UiO-66 content reached 35 wt%, the CO2 permeability of the mixed matrix membranes was significantly increased from 16.5 Barrer to 104.7 Barrer (by 635 %) without scarifying the permeability selectivities of CO2/N2 (16.5 ± 1.5) and CO2/CH4 (31.7 ± 5.8). The results suggest that both the addition of porous UiO-66 nanoparticles and the co-continuous structures contributed to the strongly enhanced gas separation performance of the mixed matrix membranes.

Molecular Insight into 6FD Polyimide-Branched Poly(phenylene) Copolymers: Synthesis, Block Compatibility, and Gas Transport Study

A series of 6FDA-DABA (6FD) polyimide and branched poly(phenylene) (PP) block copolymers and homopolymers were successfully synthesized using Diels–Alder and polycondensation reactions. PP and 6FD homopolymer blends in tetrahydrofuran were immiscible. The result coincides with their large chemical dissimilarity and theoretical solubility parameter differences of 25.47 and 33.17 (MJ/m3)1/2. However, 6FD-PP block copolymer solutions were clear, and thin films were robust and creasable. Densities and fractional free volumes (FFV) (0.162–0.346) largely obeyed the rule of mixing, suggesting a “blend-like” morphology. At moderate PP block lengths, two distinct glass transition temperatures (340 and 420 °C) were evident, while large PP block lengths suppressed first-order polyimide transitions entirely. A small-angle X-ray scattering and atomic force microscopy morphological analysis revealed two distinct domains, with separation lengths increasing with the PP block length. Their gas permeation, diffusion, sorption, and separation properties were thoroughly investigated and exhibited a strong correlation with polymer chemistry, block length, and FFV. A block copolymer had an O2 permeability roughly between 6FD and PP, resulting in a 30% increase in O2/N2 selectivity. The N2/CH4 selectivities ranged from 4.2 to 0.58, suggesting that this 6FD-PP system could be efficiently tuned from highly N2-selective to CH4-selective performance. Five structural models, rule-of-mixture, Maxwell, equivalent box model, laminate, and blend, were used to predict gas transport properties. Compared with experimental data, the miscible blend model provided the best results for the 6FD-PP block copolymer system. Block copolymerization by combining highly selective polyimide and highly permeable branched poly(phenylene) provides an opportunity for gas separation tunability and improvement in selected gas pairs.

Unravelling gas sorption in the aluminum metal‐organic framework CAU‐23: CO2, H2, CH4, SO2 sorption isotherms, enthalpy of adsorption and mixed‐adsorptive calculations

AbstractThe report is the first broader evaluation of the gas sorption properties of CAU‐23 for the adsorptives CO2, H2, CH4, and SO2. CAU‐23 is of intermediate porosity among Al‐MOFs with specific BET surface areas of the order of MIL‐100>MIL‐53>CAU‐23>MIL‐160>MIL‐53‐TDC>Alfum>CAU‐10‐H and total pore volumes of the order of MIL‐100>MIL‐53>CAU‐23>Alfum=MIL‐160>MIL‐53‐TDC>CAU‐10‐H. CO2 uptake (3.97 mmol g−1, 293 K) and H2 uptake (10.25 mmol g−1, 77 K) of CAU‐23 are second in the series and only slightly smaller than for MIL‐160. The CH4 uptake of CAU‐23 (0.89 mmol g−1, 293 K) is unremarkable in comparison with the other Al‐MOFs. The SO2 uptake (8.4 mmol g−1, 293 K) follows the porosity and higher SO2 uptakes were only observed for MIL‐53 and MIL‐100. CAU‐23 is one of the best Al‐MOFs for high‐pressure sorption of CO2, with an uptake of 33 wt.‐% at 20 bar, 293 K. Gas sorption measurements at two different temperatures gave near zero‐coverage enthalpy of adsorptions, ▵Hads0 for CO2 of −22 kJ mol−1 and of SO2 for −38 kJ mol−1 which is at the low end of the other Al‐MOFs (−22 to −39 kJ mol−1 for CO2; −41 to −51 kJ mol−1 for SO2), yet ▵Hads increases for CAU‐23 with CO2 and SO2 to −25 and −57 kJ mol−1, respectively. For CO2/CH4 and SO2/CO2 separation, ideal adsorbed solution theory (IAST) predicted gas selectivities of 5 and 27–50 (depending on molar ratio and model), respectively, in line with 4.5–6.3 and 17–50, respectively, with most of the other Al‐MOFs, where only MIL‐53‐TDC with 83 and MIL‐160 with 126 gave a higher SO2/CO2 selectivity at a molar ratio of 0.5.

Highly Selective Adsorption of Perfluorinated Greenhouse Gases by Porous Organic Cages.

Anthropogenic greenhouse gases contribute to global warming. Among those gases, perfluorocarbons (PFCs) are thousands to tens of thousands of times more harmful to the environment than comparable amounts of carbon dioxide. To date, materials that selectively adsorb perfluorocarbons in favor of other less harmful gases have not been reported. Here, a series of porous organic cage compounds with alkyl-, fluoroalkyl-, and partially fluorinated alkyl groups is presented. Their isomorphic crystalline states allow the study of the structure-property relationship between the degree of fluorination of the alkyl chains and the gas sorption properties for PFCs and their selective uptakes in comparison to other, nonfluorinated gases. By this approach, one compound having superior selectivities of PFCs versus N2 or CO2 under ambient conditions is identified.

Shale’s Pore Structure and Sorption-Diffusion Characteristics: Effect of Analyzing Methods and Particle Size

The delineation of pore size and surface area distribution and methane sorption-diffusion capacity in gas shale reservoirs is crucial for the estimation of storage capacity, anticipating flow characteristics, and field development. A systematic approach and guidelines are needed for the analysis of the pore size and surface area distribution of shale formations. The effect of shale sample size on the gas sorption and diffusion properties is not well understood either. The low-pressure nitrogen adsorption technique is a prevalent method for pore characterization of nanoporous shale formations. Although researchers adopted some corrections to the classical method for the analysis of pore size and surface area distribution, there is a significant mismatch between different approaches in depicting fine mesopore size and surface area (2–10 nm). In this study, the classical methods and density functional theory are employed to comparatively analyze the pore characteristics of some shale and clay samples for their applicability, efficacy, and consistency issues. Furthermore, the effect of shale particle size on the methane sorption capacity and diffusion is being investigated. It seems that confinement stress has less of a considerable effect on methane sorption (6% decrease). However, crushing shale rocks into smaller particles can significantly overestimate the methane adsorption capacity. The methane diffusion coefficient also increases with increasing the shale particle size by more than an order of magnitude.

Gas sorption properties and kinetics of porous bismuth-based metal-organic frameworks and the selective CO2 and SF6 sorption on a new bismuth trimesate-based structure UU-200

Bismuth-based metal-organic frameworks (Bi-MOFs) such as bismuth subgallate are important for applications ranging from medicine to gas separation and catalysis. Due to the porous nature of such Bi-MOFs, it would be valuable to understand their gas sorption and separation properties. Here, we present the gas sorption properties of three microporous Bi-MOFs, namely, CAU-17, CAU-33, and SU-101, along with a new trimesate-based structure, UU-200. We perform a detailed analysis of the sorption properties and kinetics of these Bi-MOFs. UU-200 shows good uptake capacities for CO 2 (45.81 cm 3 g −1 STP) and SF 6 (24.69 cm 3 g −1 STP) with CO 2 /N 2 and SF 6 /N 2 selectivities over 35 and 44, respectively at 293 K, 100 kPa. The structure of UU-200 is investigated using continuous rotation electron diffraction and is found to be a 3D porous framework containing pores with a diameter of 3.4–3.5 Å. Bi-MOFs as a group of relatively under-investigated types of MOFs have interesting sorption properties that render them promising for greenhouse gas adsorbents with good gas uptake capacities and high selectivities. • Synthesis of a new permanently porous trimesate-based bismuth metal-organic framework (MOF). • High uptake capacity and selectivity for CO 2 and SF 6 of UU-200 was comparable to other Bi-MOFs. • Rate-limiting mechanisms for CO 2 adsorption were found to likely be governed by film diffusion and micropore diffusion.

A novel trigonal bipyramidal cage-based Zn(ii)-MOF featuring two types of trinuclear clusters with high gas sorption properties

A unique trigonal bipyramidal cage-based Zn(ii)-MOF built from a linear trinuclear pin-wheel cluster and a triangular trinuclear cluster was prepared and shows a moderate gas adsorption amounts and high selectivities towards C2Hn/CH4and C2H2/CO2.

Formation of new crystalline qtz-[Zn(mIm)2] polymorph from amorphous ZIF-8.

The structure of a new ZIF-8 polymorph with quartz topology (qtz) is reported. This qtz-[Zn(mIm)2] phase was obtained by mechanically amorphising crystalline ZIF-8, before heating the resultant amorphous phase to between 282 and 316 °C. The high-temperature phase structure was obtained from powder X-ray diffraction, and its thermal behaviour, CO2 gas sorption properties and dye adsorption ability were investigated.