Synthesis of multifunctional metal-organic frameworks and tuning the functionalities with pendant ligands.

A series of multifunctional metal-organic frameworks (MOFs), SNU-170-SNU-176, has been synthesized using ligands, in which various functional pendants such as -NH2, -SMe, -OMe, -OEt, -OPr, and -OBu are attached to the phenyl ring of 4-(2-carboxyvinyl)benzoic acid. The MOFs are isostructural but the interpenetration depends on the pendant group of the ligand. The MOFs exhibit high adsorption capacities for H2, CO2, and CH4 gases, ligand-based photoluminescence, and chemical sensing abilities, all being affected by the pendant group.

50 Years as a Woman Chemist in South Korea.

In her guest editorial, Prof. Myunghyun Paik Suh reflects on her 50-year-long career devoted to chemistry, and the many challenges she had to overcome in order to become a world-leading scientist in South Korea. Furthermore, she gives some advice to young faculty members and students based on her experience.

Modeling adsorption properties of structurally deformed metal-organic frameworks using structure-property map.

Structural deformation and collapse in metal-organic frameworks (MOFs) can lead to loss of long-range order, making it a challenge to model these amorphous materials using conventional computational methods. In this work, we show that a structure-property map consisting of simulated data for crystalline MOFs can be used to indirectly obtain adsorption properties of structurally deformed MOFs. The structure-property map (with dimensions such as Henry coefficient, heat of adsorption, and pore volume) was constructed using a large data set of over 12000 crystalline MOFs from molecular simulations.

Copper-Organic Framework Fabricated with CuS Nanoparticles: Synthesis, Electrical Conductivity, and Electrocatalytic Activities for Oxygen Reduction Reaction.

To apply electrically nonconductive metal-organic frameworks (MOFs) in an electrocatalytic oxygen reduction reaction (ORR), we have developed a new method for fabricating various amounts of CuS nanoparticles (nano-CuS) in/on a 3D Cu-MOF, [Cu (BTC) ⋅(H O) ] (BTC=1,3,5-benzenetricarboxylate). As the amount of nano-CuS increases in the composite, the electrical conductivity increases exponentially by up to circa 10 -fold, while porosity decreases, compared with that of the pristine Cu-MOF. The composites, nano-CuS(x wt %)@Cu-BTC, exhibit significantly higher electrocatalytic ORR activities than Cu-BTC or nano-CuS in an alkaline solution.

Metal-Organic Frameworks Incorporating Various Alkoxy Pendant Groups: Hollow Tubular Morphologies, X-ray Single-Crystal Structures, and Selective Carbon Dioxide Adsorption Properties.

Eight porous metal-organic frameworks (MOFs) incorporating various alkoxy pendant groups (-OC(n)H(2n+1); n=1-8) in the channels have been synthesized. All MOFs have macrosized, hollow, single-crystal morphologies independent of the type of alkoxy pendant groups. The X-ray single-crystal structures indicate that the MOFs have doubly interpenetrated 3D frameworks that generate clover-shaped 1D channels, the window sizes of which reduce as the length of the alkoxy pendant groups increases from -OCH3 to -OC8H17.

Hydrogen storage in a potassium-ion-bound metal-organic framework incorporating crown ether struts as specific cation binding sites.

To develop a metal-organic framework (MOF) for hydrogen storage, SNU-200 incorporating a 18-crown-6 ether moiety as a specific binding site for selected cations has been synthesized. SNU-200 binds K(+), NH4(+), and methyl viologen (MV(2+)) through single-crystal to single-crystal transformations. It exhibits characteristic gas-sorption properties depending on the bound cation.

Enhancing CO(2) separation ability of a metal-organic framework by post-synthetic ligand exchange with flexible aliphatic carboxylates.

A series of porous metal-organic frameworks having flexible carboxylic acid pendants in their pores (UiO-66-ADn: n=4, 6, 8, and 10, where n denotes the number of carbons in a pendant) has been synthesized by post-synthetic ligand exchange of terephthalate in UiO-66 with a series of alkanedioic acids (HO2 C(CH2 )n-2 CO2 H). NMR, IR, PXRD, TEM, and mass spectral data have suggested that a terephthalate linker in UiO-66 was substituted by two alkanedioate moieties, resulting in free carboxyl pendants in the pores. When post-synthetically modified UiO-66 was partially digested by adjusting the amount of added HF/sample, NMR spectra indicated that the ratio of alkanedioic acid/terephthalic acid was increased with smaller amounts of acid, implying that the ligand substitution proceeded from the outer layer of the particles.

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]·10DMA·7H2O (SNU-150) and [Zn5(NTN)4(DEF)2][NH2(C2H5)2]2·8DEF·6H2O (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 m(2) g(-1)) and SNU-151' (BET: 1563 m(2) 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.

High CO2-capture ability of a porous organic polymer bifunctionalized with carboxy and triazole groups.

A new porous organic polymer, SNU-C1, incorporating two different CO2 -attracting groups, namely, carboxy and triazole groups, has been synthesized. By activating SNU-C1 with two different methods, vacuum drying and supercritical-CO2 treatment, the guest-free phases, SNU-C1-va and SNU-C1-sca, respectively, were obtained. Brunauer-Emmett-Teller (BET) surface areas of SNU-C1-va and SNU-C1-sca are 595 and 830 m(2) g(-1), respectively, as estimated by the N2-adsorption isotherms at 77 K.

Fabrication of metal nanoparticles in metal-organic frameworks.

In this review, we highlight various preparative strategies and characterization methods for metal nanoparticles fabricated in porous metal-organic frameworks (MOFs) or porous coordination polymers (PCPs), and their applications in hydrogen storage and heterogeneous catalysis.

Magnesium nanocrystals embedded in a metal-organic framework: hybrid hydrogen storage with synergistic effect on physi- and chemisorption.

Hexagonal-disk-shaped magnesium nanocrystals (MgNCs) are fabricated within a porous metal-organic framework (MOF, see picture). The MgNCs@MOF stores hydrogen by both physi- and chemisorptions, exhibiting synergistic effects to decrease the isosteric heat of H(2) physisorption compared with that of pristine MOF, and decrease the H(2) chemisorption/desorption temperatures by 200 K compared with those of bare Mg powder.

Selective CO2 adsorption in a metal-organic framework constructed from an organic ligand with flexible joints.

A metal-organic framework (SNU-110) constructed from an organic ligand with flexible joints exhibits selective CO(2) adsorption over N(2), O(2), H(2) and CH(4) gases.

Control of interpenetration and gas-sorption properties of metal-organic frameworks by a simple change in ligand design.

In metal-organic framework (MOF) chemistry, interpenetration greatly affects the gas-sorption properties. However, there is a lack of a systematic study on how to control the interpenetration and whether the interpenetration enhances gas uptake capacities or not. Herein, we report an example of interpenetration that is simply controlled by the presence of a carbon-carbon double or single bond in identical organic building blocks, and provide a comparison of gas-sorption properties for these similar frameworks, which differ only in their degree of interpenetration.

Enhanced isosteric heat of H2 adsorption by inclusion of crown ethers in a porous metal-organic framework.

Inclusion of 18-crown-6 or 15-crown-5 in a porous MOF increased the isosteric heats of H(2) adsorption significantly, which are comparable to MOFs containing open metal sites.

A highly porous metal-organic framework: structural transformations of a guest-free MOF depending on activation method and temperature.

A doubly interpenetrating porous metal-organic framework (SNU-77) has been synthesized from the solvothermal reaction of the extended carboxylic acid tris(4'-carboxybiphenyl)amine (H(3)TCBPA) and Zn(NO(3))(2)⋅6H(2)O in N,N-dimethylacetamide (DMA). SNU-77 undergoes single-crystal-to-single-crystal transformations during various activation processes, such as room-temperature evacuation, supercritical CO(2) drying, and high temperature evacuation, to afford SNU-77R, SNU-77S, and SNU-77H, respectively. These guest-free MOFs exhibited different fine structures with different window shapes and different effective window sizes at room temperature.

Selective CO2 adsorption in a flexible non-interpenetrated metal-organic framework.

We have prepared a flexible metal-organic framework and demonstrated that when activated by supercritical CO(2) it has greater gas sorption capacities than that activated by the heat-evacuation method, and it selectively adsorbs CO(2) over N(2) at room temperature.

High gas sorption and metal-ion exchange of microporous metal-organic frameworks with incorporated imide groups.

Metal-organic frameworks (MOFs), {[Cu(2)(bdcppi)(dmf)(2)]·10DMF·2H(2)O}(n) (SNU-50) and {[Zn(2)(bdcppi)(dmf)(3)]·6DMF·4H(2)O}(n) (SNU-51), have been prepared by the solvothermal reactions of N,N'-bis(3,5-dicarboxyphenyl)pyromellitic diimide (H(4)BDCPPI) with Cu(NO(3))(2) and Zn(NO(3))(2), respectively. Framework SNU-50 has an NbO-type net structure, whereas SNU-51 has a PtS-type net structure. Desolvated solid [Cu(2)(bdcppi)](n) (SNU-50'), which was prepared by guest exchange of SNU-50 with acetone followed by evacuation at 170 °C, adsorbs high amounts of N(2), H(2), O(2), CO(2), and CH(4) gases due to the presence of a vacant coordination site at every metal ion, and to the presence of imide groups in the ligand.

Post-synthetic reversible incorporation of organic linkers into porous metal-organic frameworks through single-crystal-to-single-crystal transformations and modification of gas-sorption properties.

The porous metal-organic framework (MOF) {[Zn(2)(TCPBDA)(H(2)O)(2)]⋅30 DMF⋅6 H(2)O}(n) (SNU-30; DMF = N,N-dimethylformamide) has been prepared by the solvothermal reaction of N,N,N',N'-tetrakis(4-carboxyphenyl)biphenyl-4,4'-diamine (H(4)TCPBDA) and Zn(NO(3))(2)⋅6 H(2)O in DMF/tBuOH. The post-synthetic modification of SNU-30 by the insertion of 3,6-di(4-pyridyl)-1,2,4,5-tetrazine (bpta) affords single-crystalline {[Zn(2)(TCPBDA)(bpta)]⋅23 DMF⋅4 H(2)O}(n) (SNU-31 SC), in which channels are divided by the bpta linkers. Interestingly, unlike its pristine form, the bridging bpta ligand in the MOF is bent due to steric constraints.

Stepwise and hysteretic sorption of N(2), O(2), CO(2), and H(2) gases in a porous metal-organic framework [Zn(2)(BPnDC)(2)(bpy)].

A doubly interpenetrated 3D porous metal-organic framework (SNU-9) exhibits high gas uptake capacities for N(2), O(2), CO(2), and H(2) gases, with uncommon stepwise adsorption and hysteretic desorption behaviors, while not adsorbing CH(4) gas.

Selective gas adsorption in a magnesium-based metal-organic framework.

A doubly interpenetrated magnesium-based porous metal-organic framework exhibits thermal stability up to 500 degrees C and selective gas sorption properties for H2 and O2 gases over N2, and CO2 gas over CH4.

Selective gas adsorption in a microporous metal-organic framework constructed of CoII4 clusters.

A porous metal-organic framework, [Co(II)(4)(micro-OH(2))(4)(MTB)(2) x (H(2)O)(4)](n) x 13nDMF x 11nH(2)O (SNU-15), has been prepared; the X-ray crystal structure reveals a CaF(2)-like structure that generates 3D channels and the desolvated solid [Co(II)(4) (micro-OH(2))(4)(MTB)(2)](n) (SNU-15') exhibits selective gas sorption properties for H(2) and O(2) gases over N(2) at 77 K, with exceptionally high O(2) density, as well as for CO(2) over CH(4) at 195 and 273 K, suggesting its potential application in gas separation processes.

Enhanced hydrogen storage by palladium nanoparticles fabricated in a redox-active metal-organic framework.

Quick on the uptake: Palladium nanoparticles were fabricated simply by immersing {[Zn(3)(ntb)(2)(EtOH)(2)]4 EtOH}(n) (1) in an MeCN solution of Pd(NO(3))(2) at room temperature, without any extra reducing agent. 3 wt % PdNPs@[1](0.54+)(NO(3)(-))(0.