Structural Transformation and Hysteretic Sorption of Light Hydrocarbons in a Flexible Zn–Pyrazole–Adenine Framework

A three‐dimensional metal–organic framework (MOF) was synthesized by combining 4‐pyrazolecarboxylic acid and adenine. This MOF exhibits reversible flexibility and breathing adsorption behaviors in response to light hydrocarbons, with high capacity. The flexibility of the structural transitions was studied on the molecular scale by obtaining the crystal structures at 303, 353 and 373 K. The bridging nitrogen atoms of the pyrazolate rings act as a “kneecap” around the M???M axis, which causes the rotation of ligands around the M???M axis in response to external stimulus, thus giving rise to the deformation of the framework structure.     

碳化多孔有机骨架制备氮掺杂多孔碳及其气体吸附研究

通过简单的一步碳化方法, 以含氮的多孔有机骨架JUC-Z2为碳前驱物制备出氮掺杂多孔碳材料. 与原始JUC-Z2材料相比, 制备的多孔碳材料显示出明显提高的气体吸附量和增强的吸附焓. 其中JUC-Z2-900的CO₂吸附量高达113 cm³·g^-1, H₂吸附量也达到246 cm³·g^-1, 超过了大部分报道的多孔材料. 尤其是JUC-Z2-900的CH₄吸附量在273 K, 1 bar下高达60 cm³·g^-1, 据我们所知, 这一值为目前报道材料的最高值. 除此之外, 样品还显示出选择性吸附CO₂的能力, 273 K下, JUC-Z2-900的CO₂/N₂的选择性高达10, CO₂/H₂的选择性也高达66. 另外, 样品具有很高的热稳定性, 有望应用在碳捕获和清洁能源储存等领域.     

Site‐Selective Synthesis of Janus‐type Metal‐Organic Framework Composites

Herein, bipolar electrochemistry is applied in a straightforward way to the site‐selective in situ synthesis of metal–organic framework (MOF) structures, which have attracted tremendous interest in recent years because of their significant application potential, ranging from sensing to gas storage and catalysis. The novelty of the presented work is that the deposit can be intentionally confined to a defined area of a substrate without using masks or templates. The intrinsic site‐selectivity of bipolar electrochemistry makes it a method of choice to generate, in a highly controlled way, hybrid particles that may have different functionalities combined on the same particle. The wireless nature of electrodeposition allows the potential for mass production of such Janus‐type objects.     

Electrochemical Exfoliation of Pillared‐Layer Metal–Organic Framework to Boost the Oxygen Evolution Reaction

Two‐dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal–organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared‐layer framework. When the 3D pillared‐layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal–organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm^?2 and a turnover frequency as high as 30 s^?1 at an overpotential of 300 mV.     

Synthesis,Characterization, and Crystal Structure of Three Coordination Polymers from 5‐(Pyridin‐2‐ylmethyl)aminoisophthalic Acid

Three new complexes: [M(L)(H₂O)] [M = Zn ( 1 ), Co ( 2 ), Ni ( 3 ); H₂L = 5‐(pyridin‐2‐ylmethyl)aminoisophthalic acid] were synthesized under hydrothermal conditions at 180 °C and were characterized by elemental analysis, FT‐IR spectroscopy, single‐crystal X‐ray diffraction, and thermogravimetric analysis (TGA). The results of X‐ray diffraction analysis reveal that complexes 1 – 3 are isostructural and crystallize in the monoclinic system with space group P2₁/c. Each of the complexes displays a (3,3′)‐connected two‐dimensional (2D) wave‐like network with (4,8²) topology, within which five‐membered uncoplanar N,N‐chelated metallacycles are shaped. Delicate N–H ··· O and O–H ··· O hydrogen bonding interactions exist in complexes 1 – 3 . Adjacent 2D layers are linked by intermolecular interactions, resulting in the construction of extended metal‐organic frameworks (MOFs) in complexes 1 and 2 .     

Solvent‐free Synthesis,Characterization and Solvent‐Vapor Interaction of Zinc(II) and Copper(II) Coordination Polymers containing Nitrogen‐donor Ligands

Coordination polymers of [Zn(INA)₂] ( 1 ) (INA = isonicotinate), [Cu₂(mal)₂(H₂O)₂(bipy)] ( 2 ) (mal = malonate, bipy = 4,4‐bipyridine), and [Zn₂(OAC)₄(bipy)₂] ( 3 ) (OAC = acetate) were prepared using mechanochemical grinding and heating methods. The materials were characterized with elemental analysis, FT‐IR spectroscopy, TGA, SEM, EI‐MS, BET, and PXRD. Comparison of PXRD patterns of the materials with patterns simulated from single‐crystal X‐ray diffraction data allowed identification of the products. Compared to conventional synthetic techniques such as solvothermal/hydrothermal solvent‐based methods, solvent‐free method was found to be simple, highly efficient, and environmentally friendly especially for the preparation of these coordination polymers on a large scale. Solvent‐vapor interaction properties of 1 , 2 , and 3 were investigated by exposure of the compounds to water and methanol at room temperature.     

Synthesis,Crystal Structure,and Properties of the 3D Porous Framework [Zn(INAIP)]·DMA·H2O

A new three‐dimensional (3D) porous framework [Zn(INAIP)] · DMA · H₂O ( 1 ) [INAIP = 5‐(isonicotinamido)isophthalate, DMA = N,N′‐dimethylacetamide] was synthesized by solvothermal methods and characterized by single‐crystal and powder X‐ray diffraction, as well as thermogravimetric analysis. The results of X‐ray diffraction analyses revealed that complex 1 has an unusual 3D architecture with the (3,6)‐connected rutile ( rtl ) topology. The adsorption behavior shows that compound 1 exhibits selective adsorptions of CO₂ over N₂ after the removal of the solvent molecules within the pores.     

Solvent‐Free Synthesis of Heterocyclic Thioureas Using Microwave Technology

A new and rapid solvent‐free synthesis of heterocyclic thioureas in a microwave oven has been reported for the first time. Nine heterocyclic thioureas that possess biological activity have been synthesized. The reaction time is short (2–4.5 min) and gives excellent yields (82.9–95.5%).     

Structural Optimization of Interpenetrated Pillared‐Layer Coordination Polymers for Ethylene/Ethane Separation

With the goal of achieving effective ethylene/ethane separation, we evaluated the gas sorption properties of four pillared‐layer‐type porous coordination polymers with double interpenetration, [Zn₂(tp)₂(bpy)]_n ( 1 ), [Zn₂(fm)₂(bpe)]_n ( 2 ), [Zn₂(fm)₂(bpa)]_n ( 3 ), and [Zn₂(fm)₂(bpy)]_n ( 4 ) (tp=terephthalate, bpy=4,4′‐bipyridyl, fm=fumarate, bpe=1,2‐di(4‐pyridyl)ethylene and bpa=1,2‐di(4‐pyridyl)ethane). It was found that 4 , which contains the narrowest pores of all of these compounds, exhibited ethylene‐selective sorption profiles. The ethylene selectivity of 4 was estimated to be 4.6 at 298 K based on breakthrough experiments using ethylene/ethane gas mixtures. In addition, 4 exhibited a good regeneration ability compared with a conventional porous material.     

A Rod‐Packing Microporous Hydrogen‐Bonded Organic Framework for Highly Selective Separation of C2H2/CO2 at Room Temperature

Self‐assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod‐packing 3D microporous hydrogen‐bonded organic framework (HOF‐3). This material shows permanent porosity and demonstrates highly selective separation of C₂H₂/CO₂ at ambient temperature and pressure.     

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.     

A Facile Synthesis of 2,2,4‐Trisubstituted‐1,2‐Dihydroquinolines Catalyzed by Zinc Triflate under Solvent‐Free Conditions

An efficient process has been developed for the synthesis of 2,2,4‐trisubstituted‐1,2‐dihydroquinolines in good yields through a simple one‐pot condensation between anilines and ketones in the presence of zinc triflate as a catalyst at room temperature under solvent‐free conditions.     

Preparation and Gas Separation Properties of Metal‐Organic Framework Membranes

Continuous and intergrown metal‐organic framework (MOF) membranes, MIL‐100(In) (MIL represents Materials Institute Lavoisier), were prepared directly on porous anodic alumina oxide (AAO) membranes using an in situ crystallization method. The pore surface of MIL‐100(In) is conferred with polarity due to the presence of the 1, 3,5‐benzenetricarboxylic acid. The thickness of MIL‐100(In) membranes was tuned by varying the reactant concentration of indium chloride and 1, 3,5‐benzenetricarboxylic acid. Single gas permeation measurements on this MOF membrane indicate the large permeances of 0.90 × 10^–6 and 0.81 × 10^–6 mol · m^–2·s^–1·Pa^–1 for CO₂ and CH₄, and relatively high ideal selective factors of 3.75 and 3.38 for CO₂/N₂ and CH₄/N₂, respectively.     

Highly Selective Sorption and Luminescent Sensing of Small Molecules Demonstrated in a Multifunctional Lanthanide Microporous Metal–Organic Framework Containing 1D Honeycomb‐Type Channels

A rare, robust microporous lanthanide metal–organic framework with 1D honeycomb‐type channels is presented. Excellent adsorption capabilities for N₂, H₂, and CO₂ and significant selective sorption of CO₂ over N₂ and CH₄ were observed. Moreover, the guest‐dependent luminescent behavior of these lanthanide materials shows a potential use for the sensing of small‐molecule pollutants such as benzene and acetone.     

Influence of Solvent‐Like Sidechains on the Adsorption of Light Hydrocarbons in Metal–Organic Frameworks

A variety of strategies have been developed to adsorb and separate light hydrocarbons in metal–organic frameworks. Here, we present a new approach in which the pores of a framework are lined with four different C3 sidechains that feature various degrees of branching and saturation. These pendant groups, which essentially mimic a low‐density solvent with restricted degrees of freedom, offer tunable control of dispersive host–guest interactions. The performance of a series of frameworks of the type Zn₂(fu‐bdc)₂(dabco) (fu‐bdc^2?=functionalized 1,4‐benzenedicarboxylate; dabco=1,4‐diazabicyclo[2.2.2]octane), which feature a pillared layer structure, were investigated for the adsorption and separation of methane, ethane, ethylene, and acetylene. The four frameworks exhibit low methane uptake, whereas C2 hydrocarbon uptake is substantially higher as a result of the enhanced interaction of these molecules with the ligand sidechains. Most significantly, the adsorption quantities and selectivity were found to depend strongly upon the type of sidechains attached to the framework scaffold.     

Supramolecular Open‐Framework of a Bipyridinium‐Carboxylate Based Copper Complex with High and Reversible Water Uptake

The rigid zwitterionic ligand 1,1′‐bis(4‐carboxylatphenyl)‐(4,4′‐bipyridinium) (pc1) and copper(II) ions give rise to a linear complex [Cu(pc1)₂(H₂O)₄]²⁺, which self assembles in a pseudo tetragonal supramolecular arrangement leading to the supramolecular open‐framework [Cu(pc1)₂(H₂O)₄](Cl)₂ · 8H₂O exhibiting an open structure including water molecules and chlorides in pores. The dehydration of this material occurs at relatively low temperature (70 °C) and results in structure modification accompanied by shrinking of the crystals. Characterization of the obtained material by FT‐IR spectroscopy reveals appearance of coordinated carboxylates groups, which may indicate the formation of coordination polymer after dehydration. Water adsorption (maximum uptake 0.23 g H₂O per g) on dehydrated material allows to restore the initial structure. A large hysteresis in water adsorption‐desorption isotherm is characteristic of a significant modification of the structure during the hydration‐dehydration cycle which is in line with the structural transition determined from thermodiffractometry and FT‐IR spectroscopy.