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  • Zeolitic metal azolate frameworks (MAFs) from ZnO/Zn(OH) and monoalkyl-substituted imidazoles and 1,2,4-triazoles: Efficient syntheses and properties

    • 摘要:

      Acid-base neutralization reaction between monoalkyl-substituted azole derivatives and ZnO/Zn(OH) can be effectively activated by aqueous ammonia to synthesize a series of metal azolate frameworks (MAFs) including SOD-[Zn(mim) ] (MAF-4, Hmim = 2-methylimidazole), ANA-[Zn(eim) ] (MAF-5, Heim = 2-ethylimidazole), SOD-[Zn(mtz) ] (MAF-7, Hmtz = 3-methyl-1,2,4-triazole), dia-[Zn(mim) ] (MAF-31), qtz-[Zn(eim) ] (MAF-32), and dia-[Zn(etz) ] (MAF-33, Hetz = 3-ethyl-1,2,4-triazole). The porous zeolitic MAFs obtained by this reaction possess high stability and can be easily activated. Their high porosity, unique pore size/surface characteristic, and framework flexibility were demonstrated by gas and solvent vapor (water, methanol, and benzene) sorption measurements. The imidazolate frameworks MAF-4 and MAF-5 are highly hydrophobic adsorbents with exceptional organic/water selectivity, while the triazolate framework MAF-7 containing uncoordinated nitrogen donor on the pore surface exhibits higher sorption affinity and lower stability. Despite the very small aperture sizes (3.2-3.4 Å), the SOD frameworks can readily adsorb large organic molecules by temporary distortion of the structure. © 2011 Elsevier Inc. All rights reserved.

    • 作者:

      Zhu Ai-Xin    Ruibiao Lin    Qi Xiao-Lin    Liu Yan    Yanyong Lin    Jiepeng Zhang    陈小明    

    • 刊名:

      Microporous and Mesoporous Materials

    • 在线出版时间:

      2012

  • Low-dimensional porous coordination polymers based on 1,2-bis(4-pyridyl) hydrazine: From structure diversity to ultrahigh CO /CH selectivity

    • 摘要:

      Solvothermal reactions of metal salts, benzenedicarboxylic acids, and 4,4′-azopyridine (azpy) in different conditions produced four coordination polymers, namely, [Zn (bdc) (bphy) ] ·2DMF·10H O (3; H bdc = 1,4- benzenedicarboxylic acid, bphy = 1,2-bis(4-pyridyl)hydrazine, and DMF = N,N-dimethylformamide), [Ni(bdc)(bphy)]·DMF·3.5H O (4), [Zn(nipa)(bphy)]·EtOH (5; H nipa = 5-nitroisophthalic acid), and [CoBr(bdc) (bphy)]·2DMA·H O (6; DMA = N,N-dimethylacetamide), in which the azpy ligand was in situ reduced. Structural determination reveals that 3-5 consist of the same metal/ligand ratio and similar coordination modes, as well as similar two-dimensional square-grid networks, but differ from their packing/interpenetration modes. 3 consists of alternately arranged single layers and interweaved double layers. Single layers in 4 directly stack in an offset fashion, while 5 is constructed of interdigitated double layers. 6 is a one-dimensional ladderlike structure, which could be regarded as that half of the bridging benzenedicarboxylate ligands in 3-5 are replaced by monodentate bromide ions. Interestingly, the crystal structures of these low-dimensional coordination polymers contain considerable solvent-accessible voids. Thermogravimetric curves, powder X-ray diffraction, and gas sorption experiments were used to study the potential porosity of these structures, which indicated that they can all reversibly desorb and adsorb solvent molecules. In particular, 4 showed gated sorption behavior and high CO /CH selectivity because of its flexible structure. © 2012 American Chemical Society.

    • 作者:

      Xiaomin Liu    Ruibiao Lin    Jiepeng Zhang    陈小明    

    • 刊名:

      Inorganic Chemistry

    • 在线出版时间:

      2012

  • Highly-connected, porous coordination polymers based on [M (μ -OH) ] (M = Co and Ni ) clusters: Different networks, adsorption and magnetic properties

    • 摘要:

      Two new 3D coordination polymers based on tetranuclear clusters, {[Co (ina) (μ -OH) (H O)(EtOH)]-NO ·2EtOH·4H O} (1) (Hina = isonicotinic acid) and {[Ni (ina) (μ -OH) (EtCOO)] ·6EtOH·2H O} (2), were obtained by the solvothermal reactions from Hina and different metal salts. The [M (μ -OH) ] cores act as 7- and 9-connected nodes and are extended through ina linkers to highly-connected frameworks with vmr net for 1 and bct-9-P2 /c net for 2. Both the desolvated frameworks display effective gas sorption capacities of N and H with Langmuir surface areas of 546 and 917 m g for 1 and 2, respectively. Magnetic studies show spin canting and spin-glass behaviours with T = 6.0 and 15.0 K for 1 and 2, respectively. The intra- and inter-tetramer coupling interactions and cooperative magnetic correlation greatly influence the bulk magnetic behaviours in this system. © The Royal Society of Chemistry 2012.

    • 作者:

      Chen Qing    Xue Wei    Jianbin Lin    Ruibiao Lin    Minghua Zeng    陈小明    

    • 刊名:

      Dalton Transactions

    • 在线出版时间:

      2012

  • Strong and dynamic CO sorption in a flexible porous framework possessing guest chelating claws

    • 摘要:

      Using a bis-triazolate ligand and tetrahedral Zn(II) ion, we synthesized a flexible porous coordination polymer functionalized with pairs of uncoordinated triazolate N-donors that can be used as guest chelating sites to give very high CO adsorption enthalpy and CO /N selectivity. The dynamic CO sorption behavior could be monitored well by single-crystal X-ray diffraction. © 2012 American Chemical Society.

    • 作者:

      聊培钦    Zhou Dong-Dong    Zhu Ai-Xin    Jiang Lu    Ruibiao Lin    Jiepeng Zhang    陈小明    

    • 刊名:

      Journal of the American Chemical Society

    • 在线出版时间:

      2012

  • Layer-by-layer evolution and a hysteretic single-crystal to single-crystal transformation cycle of a flexible pillared-layer open framework

    • 摘要:

      Two hypothetical crystal-growth intermediates of a new pillared-layer framework have been isolated. The seemingly rigid pillared-layer framework also undergoes temperature-induced, time-dependent, hysteretic framework distortion. © 2012 The Royal Society of Chemistry.

    • 作者:

      Wang Xiao-Feng    Wang Yu    Yuebiao Zhang    Xue Wei    Jiepeng Zhang    陈小明    

    • 刊名:

      Chemical Communications

    • 在线出版时间:

      2012

  • Copper(I) and silver(I) 2-methylimidazolates: Extended isomerism, isomerization, and host-guest properties

    • 摘要:

      Syntheses, structures, and properties of univalent coinage metal 2-methylimidazolate supramolecular isomers [M(mim)] (1, M = Cu; 2, M = Ag) were investigated in detail. In addition to the known isomers, namely, zigzag chains [Cu(mim)] (1a) and [Ag(mim)] (2a), molecular octagon [Cu (mim) ]̇C H (1b), decagon [Cu (mim) ]̇C H (1c), helical chain [Ag (mim) ]̇C H (2b), and S-shaped chain [Ag (mim) ]̇C H (2c), two new structures including a polyrotaxane [Cu (mim) ]̇[Cu(mim)] (1d, C2/m, a = 14.452(4) Å, b = 27.712(7) Å, c = 11.427(3) Å, β = 125.899(4)°, V = 3707(2) Å ) and a new octagon [Ag (mim) ]̇Me CO (2d, C2/c, a = 21.852(3) Å, b = 12.101(2) Å, c = 20.907(3) Å, β = 90.875(2)°, V = 5528(2) Å ) were discovered. The potential porous properties of guest-containing [M(mim)] isomers were studied by thermogravimetry, X-ray powder diffraction, vacuum thermal desorption, and CO sorption experiments. The isomers show distinctly different guest removal behaviors depending on their pore structures. By heating, the guest-containing isomers, 1b-1c and 2b-2d, undergo irreversible, two-step, crystal-to-crystal structural transformations to form the guest-free isomers 1a or 2a, respectively. Except 1b, other guest-containing isomers can retain their porous structures after removal of the template molecules, which were confirmed by CO sorption experiments. © 2012 American Chemical Society.

    • 作者:

      Wang Yu    Chunting He    Liu Yi-Jiang    Zhao Tian-Qi    Lu Xiao-Min    Zhang Wei-Xiong    Jiepeng Zhang    陈小明    

    • 刊名:

      Inorganic Chemistry

    • 在线出版时间:

      2012

  • Metal azolate frameworks: From crystal engineering to functional materials

    • 摘要:

      With a series of selected examples, the recent progress in the chemistry of MAFs has been discussed. As we can see in the previous sections, MAFs indeed represent a unique and interesting class of coordination polymers and the investigations have been very active in recent years. Some important advances in this multifaceted field are summarized and highlighted here. The well-defined coordination geometries of azolates have largely simplified the difficulty of design and synthesis. Compared to other metalligand systems, many MAFs possess highly predictable coordination geometries and connectivities. Nevertheless, some rational molecular design and synthetic strategies have been developed. A particularly interesting and unique one is the use of uncoordinated side groups to direct the relative orientations of adjacent building blocks and extended framework structures, which has led to a series of novel structures not easily obtained from other metalligand systems. Besides intriguing structures, MAFs also exhibit very interesting properties. As a result of their unique bonding characters, MAFs, especially those based on the diazolates, usually have very high thermal and chemical stability, which is remarkable because stability is a very important issue for practical applications. On the other hand, framework flexibility is also widely observed, particularly in those with simple connectivity (e.g., single metal ions and single bonds) and/or flexible, uncoordinated side groups. So far, MAFs have been mostly explored as porous materials, while other properties have also been topics of some investigations. Highly stable porous MAFs usually possess weak adsorption affinity due to their inert pore surface. Another structural feature of many porous MAFs is the combination of large nanometer-sized cages and very small apertures with diameter similar to or smaller than those of the common gas molecules, which is useful for molecular sieving. Therefore, porous MAFs are useful for separation applications. Nevertheless, porous MAFs can also have good storage and delivery performance when their pore surface, pore shape, and/or framework flexibility are properly engineered and the application condition is well selected. For example, the sorption affinity can be improved/tuned by judicious introduction of active sites on the pore surface. While crystal engineering on azolate-based coordination frameworks has been very fruitful, future research will certainly focus more on developing new applications and improving the performance of either already documented or newly designed MAFs. Some intriguing approaches such as the use of mixed ligands and polyazolates deserve further attention. As we anticipated a few years ago,15b research on MAFs has been largely expanded. Nevertheless, further exploration on MAFs will certainly contribute to the chemistry of coordination polymers in the development of functional materials for practical applications.

    • 作者:

      Jiepeng Zhang    Yuebiao Zhang    Jianbin Lin    陈小明    

    • 刊名:

      Chemical Reviews

    • 在线出版时间:

      2012

  • Unprecedented binodal (7,9)-connected network based on distinct tricobalt(ii) clusters: Structure, topology and cooperative magnetism

    • 摘要:

      A new Co(ii)-based coordination polymer, [{Co (ina) (μ -O)}{Co (ina) (μ -OH)(μ-OH)(C H OH) (H O) } ]NO ·3C H OH·24H O (1, also denoted as MCF-39), has been synthesized from the solvothermal reaction of cobalt(ii) nitrate and the ligand isonicotinic acid (Hina) with the presence of hmq (2-(hydroxymethyl)-quinolin-8-ol) as a necessary additive. The crystal structure of 1 consists of the 7- and 9-connected trinuclear clusters, and exhibits the first highly-connected binodal network with (3 ·4 ·5 ·6 ) (3 ·4 ·5 ) topology. Magnetic studies show that the spin canting and spin-glass-like behaviours were found in 1, and the cooperative effect among intra- and inter-trimer could greatly influence the bulk magnetic behaviour of the three-dimensional (3D) framework. © 2012 The Royal Society of Chemistry.

    • 作者:

      Chen Qing    Xue Wei    Wang Bao-Ying    Minghua Zeng    陈小明    

    • 刊名:

      CrystEngComm

    • 在线出版时间:

      2012

  • Chemical/physical pressure tunable spin-transition temperature and hysteresis in a two-step spin crossover porous coordination framework

    • 摘要:

      A two-dimensional (2D) square-grid type porous coordination polymer [Fe(bdpt) ]·guest (1·g, Hbdpt = 3-(5-bromo-2-pyridyl)- 5-(4-pyridyl)-1,2,4-triazole) with isolated small cavities was designed and constructed as a spin-crossover (SCO) material based on octahedral Fe N units and an all-nitrogen ligand. Three guest-inclusion forms were successfully prepared for 1·g (1·EtOH for g = ethanol, 1·MeOH for g = methanol, 1 for g = Null), in which the guest molecules interact with the framework as hydrogen-bonding donors. Magnetic susceptibility measurements showed that 1·g exhibited two-step SCO behavior with different transition temperatures (1·EtOH < 1·MeOH < 1) and hysteresis widths (1·EtOH > 1·MeOH > 1 ≈ 0). Such guest modulation of two-step spin crossover temperature and hysteresis without changing two-step state in a porous coordination framework is unprecedented. X-ray single-crystal structural analyses revealed that all two-step SCO processes were accompanied with interesting symmetry-breaking phase transitions from space group of P2 /n for all high-spin Fe(II), to P1̄ for ordered half high-spin and half low-spin Fe(II), and back to P2 /n for all low-spin Fe(II) again by lowering temperature. The different SCO behaviors of 1·g were elucidated by the steric mechanism and guest-host hydrogen-bonding interactions. The SCO behavior of 1·g can be also controlled by external physical pressure. © 2012 American Chemical Society.

    • 作者:

      Jianbin Lin    Xue Wei    Wang Bao-Ying    Tao Jun    Zhang Wei-Xiong    Jiepeng Zhang    陈小明    

    • 刊名:

      Inorganic Chemistry

    • 在线出版时间:

      2012

  • Single-crystal X-ray diffraction and Raman spectroscopy studies of isobaric N adsorption in SOD-type metal-organic zeolites

    • 摘要:

      The two-step N adsorption behaviour of sodalite-type Zn(ii) 2-methylimidazolate and 3-methyl-1,2,4-triazolate has been comprehensively and accurately elucidated. © 2012 The Royal Society of Chemistry.

    • 作者:

      Jiepeng Zhang    Zhu Ai-Xin    陈小明    

    • 刊名:

      Chemical Communications

    • 在线出版时间:

      2012

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