Showing papers by "Susumu Kitagawa published in 2016"
TL;DR: The structural change by photochemical transformation of this PCP via [2 + 2] photodimerization leads to the removal of inverse CO2/C2H2 selectivity, verifying the mechanism of the guest discriminatory gate effect.
Abstract: The adsorptive separation of C2H2 and CO2 via porous materials is nontrivial due to the close similarities of their boiling points and kinetic diameters. In this work, we describe a new flexible porous coordination polymer (PCP) [Mn(bdc)(dpe)] (H2bdc = 1,4-benzenedicarboxylic acid, dpe = 1,2-di(4-pyridyl)ethylene) having zero-dimensional pores, which shows an adsorbate discriminatory gate effect. The compound shows gate opening type abrupt adsorption for C2H2 but not for CO2, leading to an appreciable selective adsorption of CO2 over C2H2 at near ambient temperature (273 K). The origin of this unique selectivity, as unveiled by in situ adsorption-X-ray diffraction experiments and density functional theory calculations, is due to vastly different orientations between the phenylene ring of bdc and each gas in the nanopores. The structural change by photochemical transformation of this PCP via [2 + 2] photodimerization leads to the removal of inverse CO2/C2H2 selectivity, verifying the mechanism of the guest discriminatory gate effect.
316 citations
TL;DR: The recent progress in the accommodation of IPs in the nanochannels of PCPs and the remarkable functions of the composite materials are described.
Abstract: Porous coordination polymers (PCPs) have been recently highlighted because of their high synthetic designability in structure and functions. Because of their ordered nanoporous structures with a large surface area and tunable pore surface functionality, PCPs have emerged as a significant class of nanoporous materials with potential applications in gas storage, separation, catalysis, and chemical sensing. Recent research has shown the utility of PCPs as host materials for the confinement of nanoparticles of inorganic polymers (IPs), such as metals, metal oxides, and metal chalcogenides. The fabrication of IP nanoparticles in PCPs (PCP⊃IP) has been studied for manifesting specific nanosized-dependent properties and host-guest synergistic functions. In this review, we describe the recent progress in the accommodation of IPs in the nanochannels of PCPs and the remarkable functions of the composite materials.
198 citations
TL;DR: The PCP-Ru(II) composite showed improved CO2 adsorption behavior at ambient temperature and catalytic activity was maintained even under a 5 % CO2 /Ar gas mixture, revealing a synergistic effect between the Adsorption and catalytically active sites within the PCP -Ru( II) composite.
Abstract: Direct use of low pressures of CO2 as a C1 source without concentration from gas mixtures is of great interest from an energy-saving viewpoint. Porous heterogeneous catalysts containing both adsorption and catalytically active sites are promising candidates for such applications. Here, we report a porous coordination polymer (PCP)-based catalyst, PCP-Ru(II) composite, bearing a Ru(II) -CO complex active for CO2 reduction. The PCP-Ru(II) composite showed improved CO2 adsorption behavior at ambient temperature. In the photochemical reduction of CO2 the PCP-Ru(II) composite produced CO, HCOOH, and H2 . Catalytic activity was comparable with the corresponding homogeneous Ru(II) catalyst and ranks among the highest of known PCP-based catalysts. Furthermore, catalytic activity was maintained even under a 5 % CO2 /Ar gas mixture, revealing a synergistic effect between the adsorption and catalytically active sites within the PCP-Ru(II) composite.
184 citations
TL;DR: By controlling the amount of EDOT loaded into the host framework, it was possible to modulate the conductivity as well as the porosity of the composite, which yields materials with a reasonable electronic conductivity while maintaining high porosity.
Abstract: A series of conductive porous composites were obtained by the polymerization of 3,4-ethylenedioxythiophene (EDOT) in the cavities of MIL–101(Cr). By controlling the amount of EDOT loaded into the host framework, it was possible to modulate the conductivity as well as the porosity of the composite. This approach yields materials with a reasonable electronic conductivity (1.1 × 10−3 S·cm–1) while maintaining high porosity (SBET = 803 m2/g). This serves as a promising strategy for obtaining highly nanotextured conductive polymers with very high accessibility for small gas molecules, which are beneficial to the fabrication of a chemiresistive sensor for the detection of NO2.
169 citations
TL;DR: It is concluded that the defect sites provide space for mobile uncoordinated H3PO4, H2PO4(-), and H2O, which play a key role in expanding the proton-hopping path and promoting the mobility of protons in the coordination framework, leading to high proton conductivity and fuel cell power generation.
Abstract: We describe the encapsulation of mobile proton carriers into defect sites in nonporous coordination polymers (CPs). The proton carriers were encapsulated with high mobility and provided high proton conductivity at 150 °C under anhydrous conditions. The high proton conductivity and nonporous nature of the CP allowed its application as an electrolyte in a fuel cell. The defects and mobile proton carriers were investigated using solid-state NMR, XAFS, XRD, and ICP-AES/EA. On the basis of these analyses, we concluded that the defect sites provide space for mobile uncoordinated H3PO4, H2PO4–, and H2O. These mobile carriers play a key role in expanding the proton-hopping path and promoting the mobility of protons in the coordination framework, leading to high proton conductivity and fuel cell power generation.
136 citations
TL;DR: The glassy state of a two-dimensional (2D) Cd(2+) coordination polymer crystal was prepared by a solvent-free mechanical milling process and displays superior properties compared to the crystalline state; specifically, it shows anhydrous proton conductivity and a dielectric constant two orders of magnitude greater than the crystallines material.
Abstract: The glassy state of a two-dimensional (2D) Cd(2+) coordination polymer crystal was prepared by a solvent-free mechanical milling process. The glassy state retains the 2D structure of the crystalline material, albeit with significant distortion, as characterized by synchrotron X-ray analyses and solid-state multinuclear NMR spectroscopy. It transforms to its original crystal structure upon heating. Thus, reversible crystal-to-glass transformation is possible using our new processes. The glass state displays superior properties compared to the crystalline state; specifically, it shows anhydrous proton conductivity and a dielectric constant two orders of magnitude greater than the crystalline material. It also shows material flexibility and transparency.
102 citations
TL;DR: Divergent and convergent synthesis of coordination star polymers (CSP) by using metal-organic polyhedrons (MOPs) as a multifunctional core is reported, which allows instant access to a wide variety of multicomponent starpolymers that conventionally have required highly skilled and multistep syntheses.
Abstract: We herein report the divergent and convergent synthesis of coordination star polymers (CSP) by using metal–organic polyhedrons (MOPs) as a multifunctional core. For the divergent route, copper-based great rhombicuboctahedral MOPs decorated with dithiobenzoate or trithioester chain transfer groups at the periphery were designed. Subsequent reversible addition–fragmentation chain transfer (RAFT) polymerization of monomers mediated by the MOPs gave star polymers, in which 24 polymeric arms were grafted from the MOP core. On the other hand, the convergent route provided identical CSP architectures by simple mixing of a macroligand and copper ions. Isophthalic acid-terminated polymers (so-called macroligands) immediately formed the corresponding CSPs through a coordination reaction with copper(II) ions. This convergent route enabled us to obtain miktoarm CSPs with tunable chain compositions through ligand mixing alone. This powerful method allows instant access to a wide variety of multicomponent star polymers...
81 citations
TL;DR: The synthesis of a new family of metal-organic cuboctahedra is demonstrated by connecting dirhodium units through 1,3-benzenedicarboxylate and assembling cuboct ahedra as porous solids.
Abstract: The upbuilding of dirhodium tetracarboxylate paddlewheels into porous architectures is still challenging because of the inertness of equatorial carboxylates for ligand-exchange reaction. Here we demonstrate the synthesis of a new family of metal–organic cuboctahedra by connecting dirhodium units through 1,3-benzenedicarboxylate and assembling cuboctahedra as porous solids. Carbon monoxide and nitric oxide were strongly trapped in the internal cavity thanks to the strong affinity of unsaturated axial coordination sites of dirhodium centers.
78 citations
TL;DR: In this article, a new family of 2-fold interpenetrated primitive cubic (pcu) networks of formula [M(L)2(Cr2O7)]n (M = Co2+, Ni2+, Cu2+ and Zn2+; L = 4,4′-azopyridine), DICRO-3-M-i, has been synthesized and their structures, permanent porosity and gas sorption properties were comprehensively characterised.
Abstract: A new family of 2-fold interpenetrated primitive cubic (pcu) networks of formula [M(L)2(Cr2O7)]n (M = Co2+, Ni2+, Cu2+ and Zn2+; L = 4,4′-azopyridine), DICRO-3-M-i, has been synthesised and their structures, permanent porosity and gas sorption properties were comprehensively characterised. Molecular simulations indicate that CO2 molecules occupy both of the two distinct ultramicropores that run through this isostructural series. The orientation of the Cr2O72− pillars is thought to contribute to high isosteric enthalpy of adsorption (Qst) towards CO2 and temperature programmed desorption experiments reveal that DICRO-3-Ni-i selectively adsorbs CO2 from gas mixtures that simulate flue gas. Performance in this context is among the highest for physisorbents measured to date and these materials are readily regenerated at 50 °C.
56 citations
TL;DR: The findings show that the encapsulation of polymer chains in host materials is a facile method for understanding the intrinsic properties of conjugated polymers, along with controlling and enhancing their functions.
Abstract: Strong interchain interactions render unsubstituted polythiophene un-fusible, non-melting, and insoluble. Therefore, control of the packing structure, which has a profound effect on the optical and electronic properties of the polymer, has never been achieved. Unsubstituted polythiophene was prepared in the one-dimensional channels of [La(1,3,5-benzenetrisbenzoate)]n, where polymer chains form unprecedented assembly structures mediated by the host framework. It is noteworthy that the emission and carrier transport properties were drastically changed by varying the number of chains within a particular assembly. The response of the composite to additional guests is also examined as a method to use the composites as low-concentration sensors. Our findings show that the encapsulation of polymer chains in host materials is a facile method for understanding the intrinsic properties of conjugated polymers, along with controlling and enhancing their functions.
52 citations
TL;DR: In this article, the 1,3-butadiene-selective sorption profile of SD-65 was elucidated by adsorption isotherms, in-situ PXRD, and SSNMR studies.
Abstract: The separation of 1,3-butadiene from C4 hydrocarbon mixtures is imperative for the production of synthetic rubbers, and there is a need for a more economical separation method, such as a pressure swing adsorption process. With regard to adsorbents that enable C4 gas separation, [Zn(NO2ip)(dpe)]n (SD-65; NO2ip=5-nitroisophthalate, dpe=1,2-di(4-pyridyl)ethylene) is a promising porous material because of its structural flexibility and restricted voids, which provide unique guest-responsive accommodation. The 1,3-butadiene-selective sorption profile of SD-65 was elucidated by adsorption isotherms, in situ PXRD, and SSNMR studies and was further investigated by multigas separation and adsorption–desorption-cycle experiments for its application to separation technology.
TL;DR: Detailed experimental studies on a twofold entangled MOF (f-MOF-1) are reported, which unveil its structural response toward external stimuli such as temperature, pressure, and guest molecules.
Abstract: An understanding of solid-state crystal dynamics or flexibility in metal–organic frameworks (MOFs) showing multiple structural changes is highly demanding for the design of materials with potential applications in sensing and recognition. However, entangled MOFs showing such flexible behavior pose a great challenge in terms of extracting information on their dynamics because of their poor single-crystallinity. In this article, detailed experimental studies on a twofold entangled MOF (f-MOF-1) are reported, which unveil its structural response toward external stimuli such as temperature, pressure, and guest molecules. The crystallographic study shows multiple structural changes in f-MOF-1, by which the 3 D net deforms and slides upon guest removal. Two distinct desolvated phases, that is, f-MOF-1 a and f-MOF-1 b, could be isolated; the former is a metastable one and transformable to the latter phase upon heating. The two phases show different gated CO2 adsorption profiles. DFT-based calculations provide an insight into the selective and gated adsorption behavior with CO2 of f-MOF-1 b. The gate-opening threshold pressure of CO2 adsorption can be tuned strategically by changing the chemical functionality of the linker from ethanylene (−CH2−CH2−) in f-MOF-1 to an azo (−N=N−) functionality in an analogous MOF, f-MOF-2. The modulation of functionality has an indirect influence on the gate-opening pressure owing to the difference in inter-net interaction. The framework of f-MOF-1 is highly responsive toward CO2 gas molecules, and these results are supported by DFT calculations.
TL;DR: The use of calcium carbonate as a metal source is explored and its versatility as a precursor to several known frameworks, as well as a new flexible compound based on the 2,5-dihydroxybenzoquinone (H2dhbq) linker, are demonstrated.
Abstract: The emergence of metal-organic frameworks (MOFs) as potential candidates to supplant existing adsorbent types in real-world applications has led to an explosive growth in the number of compounds available to researchers, as well as in the diversity of the metal salts and organic linkers from which they are derived. In this context, the use of carbonate-based precursors as metal sources is of interest due to their abundance in mineral deposits and their reaction chemistry with acids, resulting in just water and carbon dioxide as side products. Here, we have explored the use of calcium carbonate as a metal source and demonstrate its versatility as a precursor to several known frameworks, as well as a new flexible compound based on the 2,5-dihydroxybenzoquinone (H2dhbq) linker, Ca(dhbq)(H2O)2. Furthermore, inspired by the ubiquity and unique structures of biomineralized forms of calcium carbonate, we also present examples of the preparation of superstructures of Ca-based MOFs via the coordination replication technique. In all, the results confirm the suitability of carbonate-based metal sources for the preparation of MOFs and further expand upon the growing scope of coordination replication as a convenient strategy for the preparation of structuralized materials.
TL;DR: The regulated structure of Pglc prepared using the PCP led to a remarkable improvement in the processability and thermal stability of PGlc, which is useful in applications as a bioplastic.
TL;DR: The radical polymerization of vinyl monomers was performed in a tetrahedral imine-linked organic cage with extrinsic porosity (CC3) and was promoted by amorphization of the host in a cooperative manner, which is not possible with conventional rigid porous materials.
Abstract: The radical polymerization of vinyl monomers was performed in a tetrahedral imine-linked organic cage with extrinsic porosity (CC3). Because of its dynamic and responsive packing structure, CC3 endowed the polymerization with specific behaviors. The adsorption of styrene triggered a change in the CC3 assembly, resulting in a monomer arrangement that was suitable for polymerization within the host matrix. The polymerization reaction was strongly dependent on the crystallinity of CC3 and was promoted by amorphization of the host in a cooperative manner, which is not possible with conventional rigid porous materials. Furthermore, CC3 can recognize the polarity of substrates, and thus polar monomers, such as methyl methacrylate and acrylonitrile, could not induce the structural changes in CC3 that are required for polymerization. This monomer specificity governed by the flexibility of CC3 is useful to the prevent incorporation of unfavorable monomers into the polymeric products.
TL;DR: Results indicate that the electrochemical oxidation of the dihydropyridine moiety in the NADH-type ligand was independent of the π system, including the Ru polypyridyl framework.
Abstract: An NAD/NADH-functionalized ligand, benzo[b]pyrido[3,2-f][1,7]-phenanthroline (bpp), was newly synthesized. A Ru compound containing the bpp ligand, [Ru(bpp)(bpy)2](2+), underwent 2e(-) and 2H(+) reduction, generating the NADH form of the compound, [Ru(bppHH)(bpy)2](2+), in response to visible light irradiation in CH3CN/TEA/H2O (8/1/1). The UV-vis and fluorescent spectra of both [Ru(bpp)(bpy)2](2+) and [Ru(bppHH)(bpy)2](2+) resembled the spectra of [Ru(bpy)3](2+). Both complexes exhibited strong emission, with quantum yields of 0.086 and 0.031, respectively; values that are much higher than those obtained from the NAD/NADH-functionalized complexes [Ru(pbn)(bpy)2](2+) and [Ru(pbnHH)(bpy)2](2+) (pbn = (2-(2-pyridyl)benzo[b]-1.5-naphthyridine, pbnHH = hydrogenated form of pbn). The reduction potential of the bpp ligand in [Ru(bpp)(bpy)2](2+) (-1.28 V vs SCE) is much more negative than that of the pbn ligand in [Ru(pbn)(bpy)2](2+) (-0.74 V), although the oxidation potentials of bppHH and pbnHH are essentially equal (0.95 V). These results indicate that the electrochemical oxidation of the dihydropyridine moiety in the NADH-type ligand was independent of the π system, including the Ru polypyridyl framework. [Ru(bppHH)(bpy)2](2+) allowed the photoreduction of oxygen, generating H2O2 in 92% yield based on [Ru(bppHH)(bpy)2](2+). H2O2 production took place via singlet oxygen generated by the energy transfer from excited [Ru(bppHH)(bpy)2](2+) to triplet oxygen.
TL;DR: In this paper, the particle size of a flexible MOF, specifically the as-synthesised form of [Cu(bcppm)H2O]·S (H2BCppm = bis(4-(4-carboxyphenyl)-1H-pyrazolyl)methane, S = solvent) (1), correlates with the rate of structural reorganisation from a "kinetically-trapped" 3D form of this MOF to an "open" 2D structure.
Abstract: The application of metal–organic frameworks (MOFs) for gas storage, molecular separations and catalysis necessitates careful consideration of the particle size and structuralisation (e.g. pelletisation, surface-anchoring) of a material. Recently, particle size has been shown to dramatically alter the physical and structural properties of certain MOFs, but overall there is limited information on how the particle size affects the properties of flexible MOFs. Here we demonstrate that the particle size of a flexible MOF, specifically the as-synthesised form of [Cu(bcppm)H2O]·S (H2bcppm = bis(4-(4-carboxyphenyl)-1H-pyrazolyl)methane, S = solvent) (1), correlates with the rate of structural reorganisation from a “kinetically-trapped”, activated 3D form of this MOF to an “open” 2D form of the structure. We also outline two methods for synthetically reducing the particle size of 1 at room temperature, using 0.1 M NaOH (for two reaction times: 0.5 and 16 h) and with the sodium salt of the ligand Na2bcppm, producing crystals of 85 ± 15, 280 ± 14 and 402 ± 41 nm, respectively.
TL;DR: Investigation was conducted by solid state (113)Cd nuclear magnetic resonance (NMR) spectroscopy that unambiguously advocates the reversible transformation "pentagonal-bipyramidal CdO6N → octahedral C dO5N" geometry in the desolvated state.
Abstract: Two new isomorphous three-dimensional porous coordination polymers, {[Cd(bpe)0.5(bdc)(H2O)]·EtOH}n (1) and {[Cd(bpe)0.5(bdc)(H2O)]·2H2O}n (2) [bpe = 1,2-bis(4-pyridyl)ethane, and H2bdc = 1,4-benzenedicarboxylic acid], have been synthesized by altering the solvent media. Both structures contain one-dimensional channels filled with metal-bound water and guest solvent molecules, and desolvated frameworks show significant changes in structure. However, exposure to the solvent vapors (water and methanol) reverts the structure back to the as-synthesized structure, and thus, the reversible flexible nature of the structure was elucidated. The flexibility and permanent porosity were further reinforced from the CO2 adsorption profiles (195 and 273 K) that show stepwise uptake. Moreover, a high selectivity for O2 over N2 at 77 K was realized. The framework exhibits interesting solvent vapor adsorption behavior with dynamic structural transformation depending upon the size, polarity, and coordination ability of the s...
TL;DR: The photoactivatable CO release from the engineered protein crystals activates nuclear factor kappa B (NF-κB) upon stimulation by visible light irradiation with suppression of cytotoxicity of the Mn complex.
TL;DR: In this paper, the conductivities of various organic cations involved in a one-dimensional zinc sulfate framework were studied, and the optimized structure (EMIm)2[Zn(SO4)2] exhibited an ionic conductivity of 3.8 × 10-3 S cm-1 at 210 °C, which is comparable to that of highly conductive organic ionic plastic crystals.
Abstract: We demonstrated a new method of synthesizing crystalline organic cation conductors. The conductivities of various organic cations involved in a one-dimensional zinc sulfate framework were studied. The optimized structure (EMIm)2[Zn(SO4)2] exhibited an ionic conductivity of 3.8 × 10–3 S cm–1 at 210 °C, which is comparable to that of highly conductive organic ionic plastic crystals. The high ionic conductivity is attributable to the defect structures of the organic cations in the inorganic frameworks. The pulsed-field gradient solid-state NMR technique revealed that the self-diffusion coefficient of organic cations in the zinc sulfate at 80 °C is comparable to that of the popular ionic liquid EMIm-BF4 at 30 °C, which indicates that liquid-like fast transporting of organic cation is achieved in the robust crystal structure.
TL;DR: In this article, a continuous-wave electron paramagnetic resonance (EPR) study of a metal-organic framework based on the kagome topology is presented, where the main structural unit of this compound is a copper paddlewheel (PW) consisting of two Cu2+ ions interconnected via four carboxylate groups in the syn-syn fashion.
Abstract: We present a continuous-wave electron paramagnetic resonance (EPR) study of Cu(ipa)(H2O) (ipa stands for isophthalate ligand) metal–organic framework (MOF) that is based on the kagome topology. The main structural unit of this compound is a copper paddle-wheel (PW) consisting of two Cu2+ ions interconnected via four carboxylate groups in the syn–syn fashion. X- and Q-band EPR measurements of this MOF allow us to probe distinct magnetic interactions of different magnitudes that originate from these dinuclear units. EPR experiments performed at different temperatures reveal that two Cu2+ ions in a single PW are antiferromagnetically coupled to the total spin S = 0 state with the exchange coupling constant J = −285 cm–1. The fine structure pattern observed in the spectra indicates the thermal population of the excited triplet S = 1 spin states of the Cu2+ pairs. Spectral simulations are used to determine the fine and hyperfine structure tensors of the PW units. At higher temperatures a collapse of the fine s...
TL;DR: Three Ru-CO complexes, [Ru(pbn)2(CO)2]2+, [Ru-(pyridin-2-yl)-5,10-dihydrobenzo[b]-1,5-naphthyridine], exist as equilibrium mixtures in aqueous solutions.
Abstract: Three Ru–CO complexes, [Ru(pbn)2(CO)2]2+, [Ru(pbn)2(CO)(COOH)]+, [Ru(pbn)2(CO)(COO)]0 [pbn = 2-(pyridin-2-yl)benzo[b]-1,5-naphthyridine], exist as equilibrium mixtures in aqueous solutions. Thermal decarboxylation of [Ru(pbn)2(CO)(COOH)]+ and/or [Ru(pbn)2(CO)(COO)]0 induces a two-electron reduction of pbn to form [Ru(pbn)(pbnHH)(CO)(OH2)]2+ [pbnHH = 2-(pyridin-2-yl)-5,10-dihydrobenzo[b]-1,5-naphthyridine] in H2O.
TL;DR: The achievement of highly selective NO adsorption through chemical doping in a framework (i.e., solid solution approach) is reported, which is an efficient means of designing purposeful porous frameworks.
Abstract: On-demand design of porous frameworks for selective capture of specific gas molecules, including toxic gas molecules such as nitric oxide (NO), is a very important theme in the research field of molecular porous materials. Herein, we report the achievement of highly selective NO adsorption through chemical doping in a framework (i.e., solid solution approach): the highly electron donating unit [Ru2(o-OMePhCO2)4] (o-OMePhCO2– = o-anisate) was transplanted into the structurally flexible chain framework [Ru2(4-Cl-2-OMePhCO2)4(phz)] (0; 4-Cl-2-OMePhCO2– = 4-chloro-o-anisate and phz = phenazine) to obtain a series of doped compounds, [{Ru2(4-Cl-2-OMePhCO2)4}1–x{Ru2(o-OMePhCO2)4}x(phz)] (x = 0.34, 0.44, 0.52, 0.70, 0.81, 0.87), with [Ru2(o-OMePhCO2)4(phz)] (1) as x = 1. The original compound 1 was made purely from a “highly electron donating unit” but had no adsorption capability for gases because of its nonporosity. Meanwhile, the partial transplant of the electronically advantageous [Ru2(o-OMePhCO2)4] unit wi...
TL;DR: An amorphous and metastable precursor for a Zn two-dimensional coordination framework was synthesised via freeze drying and was accompanied by a change in the coordination geometry of the Zn(2+) ions from tetrahedral to octahedral symmetry.
Abstract: An amorphous and metastable precursor for a Zn two-dimensional coordination framework was synthesised via freeze drying. The precursor comprises randomly packed discrete clusters of a Zn complex. The amorphous-to-crystalline framework transformation, which was triggered by the gentle application of heat or pressure, was accompanied by a change in the coordination geometry of the Zn(2+) ions from tetrahedral to octahedral symmetry.
TL;DR: The fact that the Co‐stoichiometric compound Nax(H3O)yCoO2 does not exhibit any significant ionic conductivity proves that Co vacancies are essential for the occurrence of superionic conductivity.
Abstract: The layered P2-Nax MO2 (M: transition metal) system has been widely recognized as electronic or mixed conductor. Here, we demonstrate that Co vacancies in P2-Nax CoO2 created by hydrogen reductive elimination lead to an ionic conductivity of 0.045 S cm(-1) at 25 °C. Using in situ synchrotron X-ray powder diffraction and Raman spectroscopy, the composition of the superionic conduction phase is evaluated to be Na0.61 (H3 O)0.18 Co0.93 O2 . Electromotive force measurements as well as molecular dynamics simulations indicate that the ion conducting species is proton rather than hydroxide ion. The fact that the Co-stoichiometric compound Nax (H3 O)y CoO2 does not exhibit any significant ionic conductivity proves that Co vacancies are essential for the occurrence of superionic conductivity.
Patent•
27 Jul 2016TL;DR: In this paper, a proton conductor includes a coordination polymer having stoichiometrically metal ions, oxoanions, and proton coordinating molecules capable of undergoing protonation or deprotonation.
Abstract: A proton conductor includes a coordination polymer having stoichiometrically metal ions, oxoanions, and proton coordinating molecules capable of undergoing protonation or deprotonation. The coordination polymer including coordination entities that are repeatedly coordinated to bond the coordination entities with one another. Each coordination entity is either a first coordination entity or a second coordination entity. The first coordination entity is one metal ion of the metal ions coordinated with either at least one oxoanion of the oxoanions or at least one proton coordinating molecule of the proton coordinating molecules. The second coordination entity is the metal ion coordinated with each of at least one oxoanion of the oxoanions and at least one proton coordinating molecule of the proton coordinating molecules. At least a part of the proton conductor is non-crystalline. The proton conductor has high ion conductivity at high temperature.
TL;DR: The base-assisted oxidation of an aniline-Ru-quinone complex produced a radical complex that resulted in selective C-N bond formation through an intermolecular coupling between nitrogen and carbon atoms at the para-position of the anilinyl ligand.
Abstract: The base-assisted oxidation of an aniline–Ru–quinone complex produced an anilinyl radical–Ru–semiquinone. Furthermore, base-assisted oxidation of the radical complex resulted in selective C–N bond formation through an intermolecular coupling between nitrogen and carbon atoms at the para-position of the anilinyl ligand.
TL;DR: In this article, the authors describe the recent progress in the accommodation of inorganic polymers (IPs) in the nanochannels of PCPs and the remarkable functions of the composite materials.
Abstract: Porous coordination polymers (PCPs) have been recently highlighted because of their high synthetic designability in structure and functions. Because of their ordered nanoporous structures with a large surface area and tunable pore surface functionality, PCPs have emerged as a significant class of nanoporous materials with potential applications in gas storage, separation, catalysis, and chemical sensing. Recent research has shown the utility of PCPs as host materials for the confinement of nanoparticles of inorganic polymers (IPs), such as metals, metal oxides, and metal chalcogenides. The fabrication of IP nanoparticles in PCPs (PCP⊃IP) has been studied for manifesting specific nanosized-dependent properties and host-guest synergistic functions. In this review, we describe the recent progress in the accommodation of IPs in the nanochannels of PCPs and the remarkable functions of the composite materials.
01 Sep 2016
TL;DR: In this article, the adsorption state of water molecules in a porous coordination polymer (PCP) using infrared spectroscopy was studied and two absorbance peaks below 4% relative humidity (RH) that originate from OH stretch modes of adsorbed water molecules were observed.
Abstract: We studied adsorption state of water molecules in a porous coordination polymer (PCP) using infrared spectroscopy. We observed two absorbance peaks below 4% relative humidity (RH) that originate from OH stretch modes of adsorbed water molecules. Their peak frequencies and areas indicate that one of the OH is free, and the other is hydrogen bonded. We also found that Free-OH plays a role of water attraction above 4% RH, and discuss the water adsorption kinetics in detail.