Tuning CO2 Uptake and Reversible Iodine Adsorption in Two Isoreticular MOFs through Ligand Functionalization

The synthesis and characterization of two isoreticular metal–organic frameworks (MOFs), {[Cd(bdc)(4‐bpmh)]}_n?2 n(H₂O) ( 1 ) and {[Cd(2‐NH₂bdc)(4‐bpmh)]}_n?2 n(H₂O) ( 2 ) [bdc=benzene dicarboxylic acid; 2‐NH₂bdc=2‐amino benzene dicarboxylic acid; 4‐bpmh=N,N‐bis‐pyridin‐4‐ylmethylene‐hydrazine], are reported. Both compounds possess similar two‐fold interpenetrated 3D frameworks bridged by dicarboxylates and a 4‐bpmh linker. The 2D Cd‐dicarboxylate layers are extended along the a‐axis to form distorted square grids which are further pillared by 4‐bpmh linkers to result in a 3D pillared‐bilayer interpenetrated framework. Gas adsorption studies demonstrate that the amino‐functionalized MOF 2 shows high selectivity for CO₂ (8.4 wt % 273 K and 7.0 wt % 298 K) over CH₄, and the uptake amounts are almost double that of non‐functional MOF 1 . Iodine (I₂) adsorption studies reveal that amino‐functionalized MOF 2 exhibits a faster I₂ adsorption rate and controlled delivery of I₂ over the non‐functionalized homolog 1 .     

Synthesis,Water Adsorption,and Proton Conductivity of Solid‐Solution‐Type Metal–Organic Frameworks Al(OH)(bdc‐OH)x(bdc‐NH2)1−x

Mixed‐ligand metal–organic frameworks Al(bdc‐OH)_x(bdc‐NH₂)_1?x (H₂bdc‐NH₂=aminoterepthalic acid, H₂bdc‐OH=hydroxyterephthalic acid) were synthesized and their water adsorption behavior and proton conductivity were investigated. All obtained compounds were isostructural to MIL‐53 (MIL=Materials of Institut Lavoisier) according to XRD measurements under ambient humidity conditions, and were also found to be single phase across the whole mixing ratio from the XRD measurements under humidified conditions. This result clearly shows that all compounds are a solid‐solution‐type mixture of ligands. MIL‐53‐NH₂ adsorbs one water molecule per formula with humidification whereas MIL‐53‐OH adsorbs five water molecules. The mixing ratio of the ligands in Al(OH)(bdc‐OH)_x(bdc‐NH₂)_1?x affected the gate‐opening pressure for water adsorption and total water uptake. Proton conductivity of these compounds largely depends on the adsorbed amount of water, which indicates that the proton conductivity of these compounds depends strongly on the hydrogen‐bond network of the conducting media.     

Features of Protonation of the Simplest Weakly Basic Molecules,SO2, CO,N2O,CO2, and Others by Solid Carborane Superacids

An experimental study on protonation of simple weakly basic molecules (L) by the strongest solid superacid, H(CHB₁₁F₁₁), showed that basicity of SO₂ is high enough (during attachment to the acidic H atoms at partial pressure of 1 atm) to break the bridged H‐bonds of the polymeric acid and to form a mixture of solid mono‐ LH⁺???An^?, and disolvates, L?H⁺?L. With a decrease in the basicity of L=CO (via C), N₂O, and CO (via O), only proton monosolvates are formed, which approach L?H⁺?An^? species with convergence of the strengths of bridged H‐bonds. The molecules with the weakest basicity, such as CO₂ and weaker, when attached to the proton, cannot break the bridged H‐bond of the polymeric superacid, and the interaction stops at stage of physical adsorption. It is shown here that under the conditions of acid monomerization, it is possible to protonate such weak bases as CO₂, N₂, and Xe.     

A novel threefold‐interpenetrating primitive cubic network based on a dinuclear Zn2 node

In the mixed‐ligand metal–organic polymeric compound poly[[μ₂‐1,4‐bis(imidazol‐1‐yl)benzene](μ₂‐terephthalato)dizinc(II)], [Zn₂(C₈H₄O₄)₂(C₁₂H₁₀N₄)]_n or [Zn₂(bdc)₂(bib)]_n [H₂bdc is terephthalic acid and bib is 1,4‐bis(imidazol‐1‐yl)benzene], the asymmetric unit contains one Zn^II ion, with two half bdc anions and one half bib molecule lying around inversion centers. The Zn^II ion is in a slightly distorted tetrahedral environment, coordinated by three carboxylate O atoms from three different bdc anions and by one bib N atom. The crystal structure is constructed from the secondary building unit (SBU) [Zn₂(CO₂)₂N₂O₂], in which the two metal centers are held together by two bdc linkers with bis(syn,syn‐bridging bidentate) bonding modes. The SBU is connected by bdc bridges to form a two‐dimensional grid‐like (4,4)‐layer, which is further pillared by the bib ligand. Topologically, the dinuclear SBU can be considered to be a six‐connected node, and the extended structure exhibits an elongated primitive approximately cubic framework. The three‐dimensional framework possesses a large cavity with dimensions of approximately 10 × 13 × 17 Å in cross‐section. The potential porosity is filled with mutual interpenetration of two identical equivalent frameworks, generating a novel threefold interpenetrating network with an α‐polonium topology [Abrahams, Hoskins, Robson & Slizys (2002). CrystEngComm, 4 , 478–482].     

catena‐Poly[[aqua(11‐chloropyrido[2′,3′:2,3]pyrimidino[5,6‐f][1,10]phenanthroline‐κ2N4,N5)cadmium(II)]‐μ‐benzene‐1,4‐dicarboxylato‐κ3O1,O1′:O4]: an inclined interpenetrating (6,3) network

The asymmetric unit of the title compound, [Cd(C₈H₄O₄)(C₁₇H₈ClN₅)(H₂O)]_n, contains one Cd^II atom, two half benzene‐1,4‐dicarboxylate (1,4‐bdc) anions, one 11‐chloropyrido[2′,3′:2,3]pyrimidino[5,6‐f][1,10]phenanthroline (L) ligand and one coordination water molecule. The 1,4‐bdc ligands are on inversion centers at the centroids of the arene rings. The Cd^II atom is six‐coordinated by two N atoms from one L ligand, three carboxylate O atoms from two different 1,4‐bdc ligands and one water O atom in a distorted octahedral coordination sphere. Each Cd^II center is bridged by the 1,4‐bdc dianions to give a one‐dimensional chain. π–π stacking interactions between L ligands of neighboring chains extend adjacent chains into a two‐dimensional supramolecular (6,3) network. Neighboring (6,3) networks are interpenetrated in an unusual inclined mode, resulting in a three‐dimensional framework. Additionally, the water–carboxylate O—H...O hydrogen bonds observed in the network consolidate the interpenetrating nets.     

Evidence of Amine–CO2 Interactions in Two Pillared‐Layer MOFs Probed by X‐ray Crystallography

Two pillared‐layer metal–organic frameworks (MOFs; PMOF‐55 and NH₂‐PMOF‐55) based on 1,2,4‐triazole and terephthalic acid (bdc)/NH₂‐bdc ligands were assembled and display framework stabilities, to a certain degree, in both acid/alkaline solutions and toward water. They exhibit high CO₂ uptakes and selective CO₂/N₂ adsorption capacities, with CO₂/N₂ selectivity in the range of 24–27, as calculated by the ideal adsorbed solution theory method. More remarkably, the site and interactions between the host network and the CO₂ molecules were investigated by single‐crystal X‐ray diffraction, which showed that the main interaction between the CO₂ molecules and PMOF‐55 is due to multipoint supramolecular interactions of C?H???O, C???O, and O???O. Amino functional groups were shown to enhance the CO₂ adsorption and identified as strong adsorption sites for CO₂ by X‐ray crystallography.     

Bis(μ‐benzene‐1,2‐dicarboxylato)bis{aqua[2‐(2‐chloro‐6‐fluorophenyl)‐1H‐imidazo[4,5‐f][1,10]phenanthroline]cadmium(II)} and its zinc(II) analogue

In the isomorphous title compounds, [Cd₂(C₈H₄O₄)₂(C₁₉H₁₀ClFN₄)₂(H₂O)₂] and [Zn₂(C₈H₄O₄)₂(C₁₉H₁₀ClFN₄)₂(H₂O)₂], the Cd^II centre is seven‐coordinated by two N atoms from one [2‐(2‐chloro‐6‐fluorophenyl)‐1H‐imidazo[4,5‐f][1,10]phenanthroline (L) ligand, one water O atom and four carboxylate O atoms from two different benzene‐1,2‐dicarboxylate (1,2‐bdc) ligands in a distorted pentagonal–bipyramidal coordination, while the Zn^II centre is six‐coordinated by two N atoms from one L ligand, one water O atom and three carboxylate O atoms from two different 1,2‐bdc ligands in a distorted octahedral coordination. Each pair of adjacent metal centres is bridged by two 1,2‐bdc ligands to form a dimeric structure. In the dimer, each L ligand coordinates one metal centre. The dimer is centrosymmetric, with a crystallographic inversion centre midway between the two metal centres. The aromatic interactions lead the dimers to form a two‐dimensional supramolecular architecture. Finally, O—H...O and N—H...O hydrogen bonds reinforce the two‐dimensional structures of the two compounds.     

A Flexible Pro‐porous Coordination Polymer: Non‐conventional Synthesis and Separation Properties Towards CO2/CH4 Mixtures

The novel coordination polymers [Cu(Hoxonic)(H₂O)]_n ( 1 ) and [Cu(Hoxonic)(bpy)_0.5]_n ? 1.5 n H₂O ( 2?H₂O ) (H₃oxonic: 4,6‐dihydroxy‐1,3,5‐triazine‐2‐carboxylic acid; bpy: 4,4′‐bipyridine) have been isolated and structurally characterised by ab initio X‐ray powder diffraction. The dense phase 1 contains 1D zig‐zag chains in which Hoxonic dianions bridge square‐pyramidal copper(II) ions, apically coordinated by water molecules. On the contrary, 2?H₂O , prepared by solution and solventless methods, is based on 2D layers of octahedral copper(II) ions bridged by Hoxonic ligands, further pillared by bpy spacers. The resulting pro‐porous 3D network possesses small hydrated cavities. The reactivity, thermal, magnetic and adsorptive properties of these materials have been investigated. Notably, the adsorption studies on 2 show that this material possesses unusual adsorption behaviour. Indeed, guest uptake is facilitated by increasing the thermal energy of both the guest and the framework. Thus, neither N₂ at 77 K nor CO₂ at 195 K are incorporated, and CH₄ is only minimally adsorbed at 273 K and high pressures (0.5 mmol g^?1 at 2500 kPa). By contrast, CO₂ is readily incorporated at 273 K (up to 2.5 mmol g^?1 at 2500 kPa). The selectivity of 2 towards CO₂ over CH₄ has been investigated by means of variable‐temperature zero coverage adsorption experiments and measurement of breakthrough curves of CO₂/CH₄ mixtures. The results show the highly selective incorporation of CO₂ in 2 , which can be rationalised on the basis of the framework flexibility and polar nature of its voids.     

Rational Design of Microporous MOFs with Anionic Boron Cluster Functionality and Cooperative Dihydrogen Binding Sites for Highly Selective Capture of Acetylene

Separation of acetylene (C₂H₂) from carbon dioxide (CO₂) or ethylene (C₂H₄) is important in industry but limited by the low capacity and selectivity owing to their similar molecular sizes and physical properties. Herein, we report two novel dodecaborate‐hybrid metal–organic frameworks, MB₁₂H₁₂(dpb)₂ (termed as BSF‐3 and BSF‐3‐Co for M=Cu and Co), for highly selective capture of C₂H₂. The high C₂H₂ capacity and remarkable C₂H₂/CO₂ selectivity resulted from the unique anionic boron cluster functionality as well as the suitable pore size with cooperative proton‐hydride dihydrogen bonding sites (B?H^δ????H^δ+?C≡C?H^δ+???H^δ??B). This new type of C₂H₂‐specific functional sites represents a fresh paradigm distinct from those in previous leading materials based on open metal sites, strong electrostatics, or hydrogen bonding.     

Controlling the BET Surface Area of Porous Carbon by Using the Cd/C Ratio of a Cd–MOF Precursor and Enhancing the Capacitance by Activation with KOH

Herein, four new cadmium metal–organic frameworks (Cd–MOFs), [Cd(bib)(bdc)]_∞ ( 1 ), [Cd(bbib)(bdc)(H₂O)]_∞ ( 2 ), [Cd(bibp)(bdc)]_∞ ( 3 ), and [Cd₂(bbibp)₂(bdc)₂(H₂O)]_∞ ( 4 ), have been constructed from the reaction of Cd(NO₃)₂ ? 4 H₂O with 1,4‐benzenedicarboxylate (H₂bdc) and structure‐related bis(imidazole) ligands (1,4‐bis(imidazol‐1‐yl)benzene (bib), 1,4‐bis(benzoimidazol‐1‐yl)benzene (bbib), 4,4′‐bis(imidazol‐1‐yl)biphenyl (bibp), and 4,4′‐bis(benzoimidazol‐1‐yl)biphenyl (bbibp)) under solvothermal conditions. Cd–MOF 1 shows a 2D (4,4) lattice with parallel interpenetration, whereas 2 displays an interesting 3D interpenetrating dia network, 3 exhibits an unusual 3D interpenetrating dmp network, and 4 presents a 3D self‐catenated pillar‐layered framework with a Schäfli symbol of [4³ ? 6³]₂ ? [4⁶ ? 6¹⁶ ? 8⁶]. The structural diversity indicates that the backbone of the bis(imidazole) ligand (including the terminal group and spacer) plays a crucial role in the assembly of mixed‐ligand frameworks. By using the pore‐forming effect of cadmium vapor, for the first time we have utilized these Cd–MOFs as precursors to further prepare porous carbon materials (PCs) in a calcination–thermolysis procedure. These PCs show different porous features that correspond to the topological structures of Cd–MOFs. Significantly, it was found that the specific surface area and capacitance of PCs are tuned by the Cd/C ratio of the MOF. Furthermore, the as‐synthesized PCs were processed with KOH to obtain activated porous carbon materials (APCs) with higher specific surface area and porosity, which greatly promoted the energy‐storage capacity. After full characterization, we found that APC‐bib displays the largest specific surface area (1290 m² g^?1) and total pore volume (1.37 cm³ g^?1) of this series of carbon materials. Consequently, APC‐bib demonstrates the highest specific capacitance of 164 F g^?1 at a current density of 0.5 A g^?1, and also excellent retention of capacitance (≈89.4 % after 5000 cycles at 1 A g^?1). Therefore, APC‐bib has great potential as the electrode material in a supercapacitor.     

Borromean‐Entanglement‐Driven Assembly of Porous Molecular Architectures with Anion‐Modified Pore Space

A series of metal–organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1? Mn?OH^?, 2? Mn?SO₄^2?, 3? Mn?bdc^2?, 4? Eu?SO₄^2? (H₂BpybcCl₂=1,1′‐bis(4‐carboxybenzyl)‐4,4′‐bipyridinium dichloride, H₂bdc=1,4‐benzenedicarboxylic acid) have been obtained by a self‐assembly process. Single‐crystal X‐ray‐diffraction analysis revealed that all of these compounds contained the same n‐fold 2D→3D Borromean‐entangled topology with irregular butterfly‐like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non‐interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1? Mn?OH^? further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π‐conjugated structures.     

Poly[aqua(μ2‐benzene‐1,4‐dicarboxylato)(μ2‐4,4′‐bipyridine N,N′‐dioxide)cadmium(II)], a threefold interpenetrating diamond net

In the title compound, [Cd(C₈H₄O₄)(C₁₀H₈N₂O₂)(H₂O)]_n, (I), each Cd^II atom is seven‐coordinated in a distorted monocapped trigonal prismatic coordination geometry, surrounded by four carboxylate O atoms from two different benzene‐1,4‐dicarboxylate (1,4‐bdc) anions, two O atoms from two distinct 4,4′‐bipyridine N,N′‐dioxide (bpdo) ligands and one water O atom. The Cd^II atom and the water O atom are on a twofold rotation axis. The bpdo and 1,4‐bdc ligands are on centers of inversion. Each crystallographically unique Cd^II center is bridged by the 1,4‐bdc dianions and bpdo ligands to give a three‐dimensional diamond framework containing large adamantanoid cages. Three identical such nets are interlocked with each other, thus directly leading to the formation of a threefold interpenetrated three‐dimensional diamond architecture. To the best of our knowledge, (I) is the first example of a threefold interpenetrating diamond net based on both bpdo and carboxylate ligands. There are strong linear O—H...O hydrogen bonds between the water molecules and carboxylate O atoms within different diamond nets. Each diamond net is hydrogen bonded to its two neighbors through these hydrogen bonds, which further consolidates the threefold interpenetrating diamond framework.     

Poly[aqua[μ2‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ2N3:N3′](μ2‐5‐hydroxybenzene‐1,3‐dicarboxylato‐κ4O1,O1′:O3,O3′)cadmium(II)], a twofold interpenetrated CdSO4‐like metal–organic polymer

In the title cadmium(II) complex, [Cd(C₈H₄O₅)(C₁₄H₁₄N₄)(H₂O)]_n, the 5‐hydroxybenzene‐1,3‐dicarboxylate (5‐OH‐1,3‐bdc) and 1,4‐bis(imidazol‐1‐ylmethyl)benzene (1,4,‐bix) ligands bridge water‐coordinated Cd^II atoms to generate a three‐dimensional network. Two carboxylate groups from different ligands function as O,O′‐chelates, while two imidazole N atoms from different ligands coordinate in a monodentate fashion, and one water molecule completes the seven‐coordinate pentagonal bipyramid around the Cd^II atom, in which the N atoms occupy the axial sites and the O atoms occupy the equatorial sites. The overall architecture is a twofold interpenetrated CdSO₄‐type framework. The two crystallographically equivalent frameworks are linked by O—H...O hydrogen bonds between the water, hydroxy and carboxylate groups.     

Weak interactions in imidazole-containing zinc(II)-based metal–organic frameworks

The self-assembly of the two zinc(II) metal–organic frameworks, [Zn₂(L)(bdc)₂]·3MeOH·4H₂O}_n ( 1 , L = 2-(pyridin-4-yl)-3H-imidazo[4,5-c]pyridine, H₂bdc = 1,4-benzenedicarboxylic acid) and [Zn₂(L)(bdc)₂]·2DMF·H₂O}_n ( 2 ), was achieved under mild reaction conditions. Both compounds 1 and 2 were structurally characterized by single-crystal X-ray diffraction analysis. Interestingly, the coordination modes of the ligand L in two structures are entirely different. Compounds 1 and 2 were made up of paddle wheel-shaped {Zn₂(O₂C)₄} secondary building unit (SBU) clusters, which adopted three-dimensional structures with a pcu topology. Rich weak interactions were observed in the structures of both 1 and 2 . The uncoordinated imidazole and pyridine moieties exhibited electron donor–acceptor interactions, π–π stacking, hydrogen bonding, and CH–π interactions. These interactions also facilitated the abilities of the framework to adsorb CO₂ molecules. Gas adsorption studies revealed that compound 1 selectively adsorbed CO₂ (131.1 cm³/g) over N₂ (23.5 cm³/g) and H₂ (36.5 cm³/g) at a pressure of 1 atm.     

Secondary interactions in n‐(chloromethyl)pyridinium chlorides (n = 2, 3, 4)

In the isomeric title compounds, viz. 2‐, 3‐ and 4‐(chloro­methyl)pyridinium chloride, C₆H₇ClN⁺·Cl^?, the secondary interactions have been established as follows. Classical N—H?Cl^? hydrogen bonds are observed in the 2‐ and 3‐isomers, whereas the 4‐isomer forms inversion‐symmetric N—H(?Cl^??)₂H—N dimers involving three‐centre hydrogen bonds. Short Cl?Cl contacts are formed in both the 2‐isomer (C—Cl?Cl^?, approximately linear at the central Cl) and the 4‐isomer (C—Cl?Cl—C, angles at Cl of ca 75°). Additionally, each compound displays contacts of the form C—H?Cl, mainly to the Cl^? anion. The net effect is to create either a layer structure (3‐isomer) or a three‐dimensional packing with easily identifiable layer substructures (2‐ and 4‐isomers).     

A Novel Bismuth‐Based Metal–Organic Framework for High Volumetric Methane and Carbon Dioxide Adsorption

Solvothermal reaction of H₄L (L=biphenyl‐3,3′,5,5′‐tetracarboxylate) and Bi(NO₃)₃ ? (H₂O)₅ in a mixture of DMF/MeCN/H₂O in the presence of piperazine and nitric acid at 100 °C for 10 h affords the solvated metal–organic polymer [Bi₂(L)_1.5(H₂O)₂] ? (DMF)_3.5 ? (H₂O)₃ (NOTT‐220‐solv). A single crystal X‐ray structure determination confirms that it crystallises in space group P2/c and has a neutral and non‐interpenetrated structure comprising binuclear {Bi₂} centres bridged by tetracarboxylate ligands. NOTT‐220‐solv shows a 3,6‐connected network having a framework topology with a {4 ? 6²}₂{4² ? 6⁵ ? 8⁸}{6² ? 8} point symbol. The desolvated material NOTT‐220a shows exceptionally high adsorption uptakes for CH₄ and CO₂ on a volumetric basis at moderate pressures and temperatures with a CO₂ uptake of 553 g L^?1 (20 bar, 293 K) with a saturation uptake of 688 g L^?1 (1 bar, 195 K). The corresponding CH₄ uptake was measured as 165 V(STP)/V (20 bar, 293 K) and 189 V(STP/V) (35 bar, 293 K) with a maximum CH₄ uptake for NOTT‐220a recorded at 20 bar and 195 K to be 287 V(STP)/V, while H₂ uptake of NOTT‐220a at 20 bar, 77 K is 42 g L^?1. These gas uptakes have been modelled by grand canonical Monte Carlo (GCMC) and density functional theory (DFT) calculations, which confirm the experimental data and give insights into the nature of the binding sites of CH₄ and CO₂ in this porous hybrid material.     

One‐ and Two‐Dimensional PbII Complexes Constructed from N‐Donor Chelating Ligands with Extended π‐System and Organic Dicarboxylates

Two new coordination polymers [Pb(TIP)(1,3‐bdc)]_n ( 1 ) and [Pb(Dpq)(fum)]_n ( 2 ) (TIP = 2‐(2‐thienyl)imidazo[4,5‐f]1,10‐phenanthroline, Dpq = dipyrido[3,2‐d:2′,3′‐f]quinoxaline, 1,3‐H₂bdc = benzene‐1,3‐dicarboxylic acid, fum = fumaric acid) were synthesized by hydrothermal reactions and were characterized by elemental analyses, IR spectroscopy and single‐crystal X‐ray diffraction. Complex 1 is a one‐dimensional (1D) chain, which is bridged by 1,3‐bdc ligands. This is further extended into a three‐dimensional (3D) supramolecular structure by hydrogen bonding interactions. Compound 2 exhibits a two‐dimensional (2D) network structure, which is further stacked by π–π interactions to form a 3D supramolecular framework. The most important feature of these two complexes is that the N‐donor ligands with an extended π‐system play a crucial role in the formation and stabilization of the final supramolecular frameworks. Moreover, the fluorescence property of complex 1 was also investigated in the solid state at room temperature.     

Comparison of Gas Sorption Properties of Neutral and Anionic Metal–Organic Frameworks Prepared from the Same Building Blocks but in Different Solvent Systems

Two different 3D porous metal–organic frameworks, [Zn₄O(NTN)₂]?10 DMA?7 H₂O ( SNU‐150 ) and [Zn₅(NTN)₄(DEF)₂][NH₂(C₂H₅)₂]₂?8 DEF?6 H₂O ( SNU‐151 ), are synthesized from the same metal and organic building blocks but in different solvent systems, specifically, in the absence and the presence of a small amount of acid. SNU‐150 is a doubly interpenetrated neutral framework, whereas SNU‐151 is a non‐interpenetrated anionic framework containing diethylammonium cations in the pores. Comparisons of the N₂, H₂, CO₂, and CH₄ gas adsorption capacities as well as the CO₂ adsorption selectivity over N₂ and CH₄ in desolvated SNU‐150′ (BET: 1852 m² g^?1) and SNU‐151′ (BET: 1563 m² g^?1) samples demonstrate that the charged framework is superior to the neutral framework for gas storage and gas separation, despite its smaller surface area and different framework structure.     

Synthesis of 2‐Aryl‐5‐oxo‐4‐[2‐(phenylmethylidene)hydrazino]‐2,5‐dihydro‐1H‐pyrrole‐3‐carboxylates by the Reaction between Hydrazones,Acetylenedicarboxylates, and 1‐Aryl‐N,N′‐bis(arylmethylidene)methanediamines

An efficient approach for the preparation of functionalized 2‐aryl‐2,5‐dihydro‐5‐oxo‐4‐[2‐(phenylmethylidene)hydrazino]‐1H‐pyrroles is described. The four‐component reaction between aldehydes, NH₂NH₂?H₂O, dialkyl acetylenedicarboxylates, and 1‐aryl‐N,N′‐bis(arylmethylidene)methanediamines proceeds in EtOH under reflux in good‐to‐excellent yields (Scheme 1). The structures of 4 were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS, and, in the case of 4f , by X‐ray crystallography). A plausible mechanism for this type of reaction is proposed (Scheme 2).