A Porous Coordination Polymer with an Interdigitated Structure for Enhanced Inverse Separation of C2H6 and C2H4.

Two new, homochiral, porous metal-organic coordination polymers [Zn(2)(ndc){(R)-man}(dmf)]⋅3DMF and [Zn(2)(bpdc){(R)-man}(dmf)]⋅2DMF (ndc=2,6-naphthalenedicarboxylate; bpdc=4,4'-biphenyldicarboxylate; man=mandelate; dmf=N,N'-dimethylformamide) have been synthesized by heating Zn(II) nitrate, H(2)ndc or H(2)bpdc and chiral (R)-mandelic acid (H(2)man) in DMF. The colorless crystals were obtained and their structures were established by single-crystal X-ray diffraction. These isoreticular structures share the same topological features as the previously reported zinc(II) terephthalate lactate [Zn(2)(bdc){(S)-lac}(dmf)]⋅DMF framework, but have larger pores and opposite absolute configuration of the chiral centers. The enhanced pores size results in differing stereoselective sorption properties: the new metal-organic frameworks effectively and stereoselectively (ee up to 62 %) accommodate bulkier guest molecules (alkyl aryl sulfoxides) than the parent [Zn(2)(bdc){(S)-lac}(dmf)]⋅DMF, while the latter demonstrates decent enantioselectivity toward precursor of chiral anticancer drug sulforaphane, CH(3)SO(CH(2))(4)OH. The new homochiral porous metal-organic coordination polymers are capable of catalyzing a highly selective oxidation of bulkier sulfides (2-NaphSMe (2-C(10)H(7)SMe) and PhSCH(2)Ph) that could not be achieved by the smaller-pore [Zn(2)(bdc){(S)-lac}(dmf)]⋅DMF. The sorption of different guest molecules (both R and S isomers) into the chiral pores of [Zn(2)(bdc){(S)-lac}(dmf)]⋅DMF was modeled by using ab initio calculations that provided a qualitative explanation for the observed sorption enantioselectivity. The high stereo-preference is accounted for by the presence of coordinated inner-pore DMF molecule that forms a weak C-H...O bond between the DMF methyl group and the (S)-PhSOCH(3) sulfinyl group.

Three porous coordination polymers, {[Nd(dpdo)2(H2O)5(CH3OH)2](PMo12O40)(CH3OH)-(H2O)5} n (1), {[Tb(dpdo)4(H2O)3](PMo12O40)(H2O)2CH3CN} n (2) and {[Tb(dpdo)4(H2O)3]H(SiMo12O40)(dpdo)0.5(CH3CN)0.5(H2O)4} n (3) (where dpdo is 4,4′-bipyridine-N,N′-dioxide), templated by single- or double-Keggin polyanions were synthesized and characterized by single crystal X-ray diffraction. The compounds exhibit three different 3D non-interwoven frameworks with large cavities occupied by the single- or double-Keggin-type anions. Thermogravimetric analyses suggest different stability for the three metal-organic frameworks. The SHG (second harmonic generation) efficiency of 1 confirms its noncentric framework.

The widely studied porous coordination polymers, possessing large pores to adsorb waste carbon dioxide gas and further transform it into valuable chemical products, have been attracting research interest, both industrially and academically. The active silver(I) ions endow the specific alkynophilicity to activate C≡C bonds of alkyne-containing molecules via π activation. Incorporating catalytic Ag metal sites into the porous frameworks represents a promising approach to construct heterogeneous catalysts that cyclize propargylic alcohols with CO2, which is highly desirable for the environmentally benign conversion of carbon dioxide to fine chemicals. We report the preparation of porous coordination polymers (PCPs) with active silver sites and efficient silver–silver bond formation by carefully modifying the coordination geometries of the silver sites. The decentralized silver(I) chains in the porous frameworks enable the efficient conversion of CO2 and derivatives of acetylene to α-alkylidene cyclic carbona...

Metal-containing amorphous microporous polymers are an emerging class of functional porous materials in which the surface properties and functions of polymers are dictated by the nature of the metal ions incorporated into the framework. In an effort to introduce coordinatively unsaturated metal sites into the porous polymers, we demonstrate herein an aqueous-phase synthesis of porous coordination polymers (PCPs) incorporating bis(o-diiminobenzosemiquinonato)-Cu(II) or -Ni(II) bridges by simply reacting hexaminotriptycene with CuSO4·5H2O [Cu(II)-PCP] or NiCl2·6H2O [Ni(II)-PCP] in H2O. The resulting polymers showed surface areas of up to 489 m2 g-1 along with a narrow pore size distribution. The presence of open metal sites significantly improved the gas affinity of these frameworks, leading to an exceptional isosteric heat of adsorption of 10.3 kJ·mol-1 for H2 at zero coverage. The high affinities of Cu(II)- and Ni(II)-PCPs toward CO2 prompted us to investigate the removal of CO2 from natural and landfill gas conditions. We found that the higher affinity of Cu(II)-PCP compared to that of Ni(II)-PCP not only allowed for the tuning of the affinity of CO2 molecules toward the sorbent, but also led to an exceptional CO2/CH4 selectivity of 35.1 for landfill gas and 20.7 for natural gas at 298 K. These high selectivities were further verified by breakthrough measurements under the simulated natural and landfill gas conditions, in which both Cu(II)- and Ni(II)-PCPs showed complete removal of CO2. These results clearly demonstrate the promising attributes of metal-containing porous polymers for gas storage and separation applications.

The development of highly efficient CO2 separation materials is very important for environmental preservation and energy conservation. Crystalline porous coordination polymers (PCPs)/metal-organic frameworks are one of a number of promising types of porous materials for CO2 separation because of their controllable pore size, shape and surface function. Simultaneously, the unique structural flexibility of PCPs affords both high CO2 selectivity and inexpensive regeneration. However, this family of materials suffers from the coexistence of water that destroys the framework of PCPs and its adsorption in the pores is greater than that of CO2 , which results in a deterioration in CO2 -separation performance. Herein, a flexible and hydrophobic CuII PCP that is stable towards water has been designed and synthesised. This PCP has extremely high adsorption selectivity for CO2 over CH4 , derived from its structural flexibility. Furthermore, the obtained water-tolerant flexible PCP, under CO2 /CH4 mixed-gas conditions, exhibits highly selective CO2 adsorption over CH4 , even in the presence of water.

A three-dimensional (3D) porous coordination polymer, [Pb(4-bpdh)(NO3)(H2O)]n (HMTI-1), has been synthesized under microwave-irradiation (MW) of identical reaction mixtures of Pb(II) salt and 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (4-bpdh) at different powers. The microwave synthesis of HMTI-1 has been compared to its conventional synthesis. It has been found that by using MW synthesis HMTI-1 can be obtained in a much shorter synthesis time with improved yield and physical properties. Compound HMTI-1 is stable up to 300 °C in the static atmosphere of nitrogen and useful for loading and unloading of guests. In this compound, we successfully loaded the porous crystals and nano-HMTI-1 with I2 by suspending them in a solution of I2 in cyclohexane. The delivery of I2 from HMTI-1⊃3I2 performed in ethanol, a nonaromatic solvent, at room temperature was determined by UV/vis spectroscopy. A comparison of adsorption and desorption rates of iodide between nano and bulk compounds was also conducted.

Three MIL-100-type porous coordination polymers were synthesized using different types of anions and their water sorption properties were investigated. All of the compounds adsorbed huge amounts of water (0.6 g g−1) at a moderate humidity (P/P0 < 0.6), and one of the compounds showed the same adsorption property even after two thousand replicate water sorption tests. In addition, the pressure of water adsorption was found to be controlled by counter anions incorporated in the structure, which was attributed to the hydration energy of the anions.

Effective separation of hexane (C6) isomers is critical for a variety of industrial applications but conventional distillation methods are energy-intensive. Adsorptive separations based on porous coordination polymers (PCPs) offer a promising alternative due to their exceptional porosity and tunable properties. However, there is still an urgent need to develop PCPs with high stability and separation performance. This study investigates how substituting a methyl (-CH3) group with a trifluoromethyl (-CF3) group can regulate pores and hydrophobicity in PCPs. This precise adjustment aims to enhance stability and improve the kinetic separation performance of hydrophobic C6 isomers by considering the size and hydrophobicity of the trifluoromethyl group. Two isostructural PCPs with pcu topology, PCP-CH3 and PCP-CF3, were synthesized to vary pore diameters and hydrophobicity based on the presence of -CH3 or -CF3 groups. PCP-CF3 showed greater stability in water compared to PCP-CH3. While PCP-CH3 had high adsorption capacities, it lacked selectivity, whereas PCP-CF3 demonstrated improved selectivity, particularly in excluding dibranched isomers. Dynamic column separation experiments revealed that PCP-CF3 could selectively adsorb linear and monobranched isomers over dibranched isomers at room temperature. These findings highlight the potential of fluorine-modified PCPs for efficient isomer separation and underscore the importance of stability improvement strategies.

Three new coordination polymers, namely, {[Cu2(bcpmba)(μ4-OH)]·2H2O}n (1), [Mn(Hbcpmba)]n (2), and [Co2(bcpmba)(μ3-OH)·H2O]n (3) (H3bcpmba = 3,5-bi(4-carboxy-phenylene-methylene-oxy)-benzoic acid) have been prepared under solvothermal conditions. The complexes were characterized by physico-chemical and spectroscopic methods. All of the compounds 1–3 contain one-dimensional (1D) chains extended via the bcpmba3− bridge to generate 2D porous layers which are further connected by bcpmba3− ligands to form 3D porous coordination polymers. The result shows configurations of the ligand have an important influence on the structure. Magnetic susceptibility measurements indicate that compounds 1–3 exhibit antiferromagnetic coupling between adjacent metal ions, with the corresponding J value of − 2.76 cm−1 for compound 2. Three porous coordination polymers, namely, {[Cu2(bcpmba)(μ4-OH)]·2H2O}n (1), [Mn(Hbcpmba)]n (2) and [Co2(bcpmba)(μ3-OH)·H2O]n (3) have been synthesized by employing a semi-rigid aromatic multicarboxylate acid (3,5-bi(4-carboxy-phenylene-methylene-oxy)-benzoic acid, H3bcpmba) under solvothermal conditions. Porous coordination polymers 1–3 consisted of 1D chain extended via the bridge of bcpmba3– to generate 2D porous layers and further connected by bcpmba3– to provide a 3D porous frameworks. The results reveal that different coordination modes of the ligand play an important role in the self-assembly processes to form metal-organic frameworks with different structures. Moreover, compounds 1–3 exhibited antiferromagnetic properties.

The crystal phase change in an amino-functionalized 3D FeII spin crossover compound hosting different guests involves the emergence of large regions of bi-stability whose origin has been interpreted relying on an exhaustive structural study.

Hollow microspheres with pores in their shells have received much attention owing to their hierarchically porous structures and advanced applications in electrochemical capacitive energy storage, hydrogen storage, drug delivery, sensing, and catalysis. For example, Lou et al. reported that hollow SnO2 nanospheres with nanoporous shells showed high reversible charge capacity and good cycling performance. Zhu et al. investigated the drug-delivery properties of hollow silica spheres with mesoporous shells and found that the hollow microspheres were able to store significantly more molecules with higher release rates than conventional mesoporous silica. Template synthesis is one of the most-used strategies to prepare hierarchically hollow microspheres, especially for pores inside the shells. Braun and co-workers have prepared hollow ZnS microspheres with mesoporous shells using dual templates assembled by lyotropic liquid crystals on the surfaces of silica or polystyrene colloidal templates. Liu et al. have produced organic–inorganic hybrid hollow nanospheres with microwindows on the shells templated by tricopolymer aggregates. The template method is general to prepare hollow microspheres with pores in the shells, but expensive and tedious post-treatment processes, such as solvent extraction, thermal pyrolysis, or chemical etching, and resultant fragile frameworks, limit or even impair its applicability. 3, 4] As a result, it remains an important challenge to develop a convenient and template-free method to prepare hollow microspheres with porous shells. Porous coordination polymers are highly ordered porous multifunctional materials prepared by linking metal ions or metal oxide clusters with multidentate organic ligands without any additional template. Construction of shells of hollow materials with porous coordination polymers is an especially promising approach to design hollow microspheres with porous shells through a template-free method and to endow materials with multifunctionality, such as electric, magnetic, and optical properties. Herein, we report the formation of hollow coordination polymer microspheres with microporous shells by a one-pot solvothermal reaction without any additional template; the shells are constructed of iron-based ferrocenyl coordination polymers. We confirm that the Ostwald ripening mechanism is responsible for the formation of hollow cavities with controllable size. Hollow iron-based ferrocenyl coordination polymer microspheres (Fe-Fc-HCPS) were synthesized by a solvothermal reaction of FeCl3·6H2O with 1,1’-ferrocenedicarboxylic acid (H2FcDC) in N,N-dimethyl formamide (DMF; Figure 1a). The precipitate was collected by centrifugation and washed several times with DMF and CHCl3. The reaction temperature, reaction time, and molar ratio of reactants play important roles in the formation of hollow spherical particles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy (OPM) were

Bis(β-diketonato) Co(II) complex, [Co(dbm)2] (dbm = dibenzoylmethanato or 1,3-diphenyl-propane-1,3-dionato), was examined as a linear building block for the construction of coordination polymers in the combination with a potentially tridentate ligand, 2,6-bis(4′-pyridyl)-4-(3′-pyridyl)pyridine (L1). L1 was expected to work as a conformationally flexible ligand because of the rotation of the terminal 3-pyiridyl moiety. A porous coordination polymer, [Co(dbm)2]3/2(L1)·(G) (Co-1, G = guest molecules) with a fourfold interpenetrating β-hydroquinone framework was obtained from a methanol–nitrobenzene–benzonitrile mixed solution containing [Co(dbm)2(H2O)2] and L1. Single crystal X-ray diffraction analysis reveals that Co-1 crystallizes in a trigonal space group R-3 with unit-cell parameters, a = b = 53.8629(12), c = 14.0649(7) Å, and V = 35338(3) Å3. Solvent molecules were indicated to be included in the large hexagonal channel from thermogravimetry and elemental analyses, while they could not be determined from X-ray analysis because of the severe disorder. Meanwhile, a 2-D (6. 3) coordination polymer (Co-2) was obtained from the nitrobenzene-methanol mixed solution. In Co-2, [Co(dbm)2] and L1 also work as a linear building block and a tridentate ligand, respectively. Moreover, a coordination polymer with a 1-D chain structure (Co-3) was obtained from a hydrothermal synthetic condition. In Co-3 with no guest molecules, [Co(dbm)2] works as a linear building block, while L1 behaves as a bidentate ligand. Comparison of the three structures indicates the templating role of solvent molecules in forming the β-hydroquinone framework of Co-1.

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.

Two -(2D) and three-dimensional (3D) porous coordination polymers have been extensively explored for their porous nature and thus gas separation, but one-dimensional (1D) materials remain much less explored due to their reliance on weaker, non-covalent interactions to sustain the permanent porosity. Recent significant advances on the construction of porous hydrogen-bonded organic frameworks (HOFs) through synergistic weak interactions have provided us with the promise and motivated us to explore porous HOFs using 1D coordination polymers (CPs), and their multifunctional properties. In this work, we present such a HOF, [Cu(bpy)(H2PO4)∙H2O]n (ZNU-30), constructed from a linear CP via hydrogen bonds, C─H⋯π, and π-π interactions. Upon thermal activation at 373K under vacuum, ZNU-30 undergoes a reversible single-crystal-to-single-crystal transformation, yielding ZNU-30a with 1D channels. Notably, ZNU-30a exhibits exceptional hydrophilicity, featuring considerable water uptake at low humidity, rapid adsorption-desorption kinetics, mild regeneration conditions, and outstanding cycling stability over 100 adsorption-desorption cycles. Single-component gas adsorption isotherms reveal unique molecular sieving behavior, with preferential adsorption of water (100mgg-1) over CO2 and C1─C3 alkene/alkanes (CH4, C2H4, C2H6, C3H6, and C3H8) at 298K. Single-crystal structural analysis and DFT calculations indicate that the selective adsorption of H2O is facilitated by multiple hydrogen-bonding interactions within the framework. Breakthrough experiments further confirm the material's ability to efficiently separate trace water vapor from CH4 and other gases.

For the remediation of oil spills and organic solvent leakage into water, it is desirable to develop not only advanced sorbents with a high adsorption capability but also labor- and time-saving apparatuses that can work continuously without human intervention. In this work, we synthesized a novel and highly stable porous coordination polymer (PCP, also called metal-organic framework), University of Science and Technology of China-6 (USTC-6), with a corrugated -CF3 surface that features high hydrophobicity. The uniform growth of USTC-6 throughout a graphene oxide (GO)-modified sponge was achieved and yielded a macroscopic USTC-6@GO@sponge sorbent, which repels water and exhibits a superior adsorption capacity for diverse oils and organic solvents. Remarkably, the sorbent can be further assembled with tubes and a self-priming pump to build a model apparatus that affords consecutive and efficient oil recovery from water. The easy and fast recovery of oils/organic solvents from water based on such an apparatus indicates that it has great potential for future water purification and treatment. A non-stick coordination polymer coating helps sponges absorb and recover up to 40 times their own weight in oil under extreme temperatures. Using passive sorbents to clean up toxic spills normally requires specially engineered materials, such as biomimetic surfaces with nanoscale rough features, to repel water molecules and attract oil particles. Now, Hai-Long Jiang from the University of Science and Technology of China and co-workers have developed a way to achieve these properties using porous coordination polymers containing copper ions and fluorinated organic ligands. After dipping a commercial sponge in graphene oxide to enhance copper binding, the team grew their coordination polymer coating in situ and found it yielded a corrugated surface with high hydrophobicity. Intriguingly, a prototype assembled from the coated sponge and a self-priming pump enabled labor-free cleanup of oil spills from water. A hydrophobic porous coordination polymer (PCP) has been synthesized and its growth throughout the graphene oxide (GO)-modified sponge yields a macroscopic PCP@GO@sponge sorbent, which repels water and exhibits superior adsorption for diverse oils. Remarkably, the sorbent is further assembled with tubes and a self-priming pump to build a model apparatus that can afford consecutive and efficient oil recovery from water.