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Benzene, cyclohexane, and cyclohexene are essential raw materials in the petrochemical industry. Their separation and purification rely on traditional distillation processes that consume a large amount of energy due to their close boiling points. Here, we describe a new microporous metal azolate framework for mild adsorptive and kinetic separation of the three hexacyclic hydrocarbons. This metal azolate framework exhibits ultrafast benzene adsorption in a short saturation time within seconds and ultrafast kinetic adsorptive separation of benzene/cyclohexane and benzene/cyclohexene. Investigation into the adsorption kinetics of benzene, cyclohexane and cyclohexene reveals a two-step adsorption process, including steps of intraparticle diffusion and surface adsorption, respectively. Also, by adjusting the sample particle size, the adsorption behaviour can be significantly controlled. The large-particle sample achieves a high selectivity for benzene/cyclohexene (94.3) and an inverse selectivity for cyclohexane/cyclohexene, being opposite to the small-particle sample. This highlights the feasibility of controlling adsorption selectivity by manipulating the kinetic steps in porous materials. [ABSTRACT FROM AUTHOR]

An air-stable iron(II) chain compound [Fe(phen)(Cl)2]n (1, phen = 1,10-phenanthroline) was prepared and exhibits intrachain ferromagnetic interactions as well as competing interchain antiferromagnetic interactions that are mediated by π-π stacking of the phen ligands, resulting in metamagnetic behaviour. The interchain interactions can be altered by changing the external magnetic field, and disparate magnetic dynamics was thus observed from zero to the critical field of 1500 Oe. Zero-field cooled (ZFC) and fieldcooled (FC) magnetization and heat capacity measurements indicate that long-range antiferromagnetic ordering occurs at lower fields, and this ordering disappears when the external field is larger than 1500 Oe. The low-frequency ac susceptibility data are consistent with the exponential increase of the temperature- dependent dc data, indicating a Glauber-type dynamics under the field of 1500 Oe. Thus, 1 is considered as a metamagnetic single-chain magnet. For further analysis, a discrete hexametallic segment of the chain, [Fe6(phen)6(Cl)12] (2), was also isolated and was shown to possess a high-spin ground state and display slow magnetic relaxations like single-molecule magnets. Magnetic analysis using CONDON suggests weak ferromagnetic interactions between the metal centres. The polymeric compound 1 can be viewed as being constructed using the hexametallic unit 2 which is of a low energy barrier, suggesting the significance of intrachain ferromagnetic interactions in enhancing the spin-reversal energy barrier of the short chains. [ABSTRACT FROM AUTHOR]

X-Ray single-crystal diffraction has been the most straightforward and important technique in structural determination of crystalline materials for understanding their structure-property relationships. This powerful tool can be used to directly visualize the precise and detailed structural information of porous coordination polymers or metal-organic frameworks at different states, which are unique for their flexible host frameworks compared with conventional adsorbents. With a series of selected recent examples, this review gives a brief overview of single-crystal X-ray diffraction studies and single-crystal to single-crystal transformations of porous coordination polymers under various chemical and physical stimuli such as solvent and gas sorption/desorption/exchange, chemical reaction and temperature change. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of Cu(NO3)2 and 4,4'-([3,4'-bipyridine]-2',6'-diyl)dibenzoic acid (H2L1), 3,3'-([4,4'-bipyridine]-2,6-diyl)dibenzoic acid (H2L2), or 4,4'-([4,4'-bipyridine]-2,6-diyl)dibenzoic acid (H2L3) yielded three new metal-carboxylate frameworks (MCF-28, MCF-29 and MCF-30) with a common formula [Cu2(L)2] (H2L = pyridyldicarboxylic acid). X-ray crystallography showed that MCF-28, MCF-29, and MCF-30 are three-dimensional (3,6)-connected rtl, eea and pyr networks, respectively, based on 3-connected tripodal ligands and 6-connected Cu2(RCOO)4(py)2 units (RCOO and py denote carboxylate and pyridyl groups, respectively). Thermogravimetry, powder X-ray diffraction, and gas adsorption measurements indicated that the three compounds became shrunk and amorphous structures after guest removal. Interestingly, single-crystal X-ray diffraction showed that MCF-28 exhibited drastic temperature-induced framework breathing. [ABSTRACT FROM AUTHOR]

The article discusses a research that investigated the induction of structural phase transition behavior by ligand motion in a polar coordination polymer and a distinct phase behavior in an isomorphic compound when ligand motion was restrained. Topics discussed include displacement of thiocyanate group passing through the copper thiocyanate chain, modulation in the size and geometry of the motional units and role of steric hindrance in the transition behavior of isomorphic compound.

Crystallographic studies into the role of exposed metal ions on pore surfaces of a porous gadolinium 1,3,5-bezenetricarboxylate have been performed. High-quality single crystals of [Gd(btc)] (1) were readily obtained by heating the dichloromethane-exchanged single crystals of [Gd(btc)(H2O)]·(DMF)(H2O)0.5(1–H2O·DMF), since the latter always crack during direct heating. Crystal structure analyses revealed that the Gd3+ions were exposed on the channel surface of 1, although the coordination environments were slightly changed from the as-synthesized phase. 1is able to adsorb and exchange some small molecules reversibly, but the PXRD patterns give very limited information about the sorption mechanism. Single-crystal structures of the guest-loaded phases [Gd(btc)(H2O)]·(H2O)5(1–H2O·H2O), [Gd(btc)(EtOH)]·(EtOH) (1a–EtOH·EtOH), and [Gd(btc)(EtOH)]·(MeCN) (1–EtOH·MeCN) have been successfully determined, which revealed that Gd3+ions coordinate with the oxygen donors of guest molecules. After the metal sites are saturated, other adsorbed guests were stabilized by hydrogen-bonding interactions with the coordinated guests or carboxylate O atoms on the channel walls. The exposed Gd3+ions are preferentially coordinated by ethanol molecules, even though ethanol has a much lower concentration than that of acetonitrile in the mixture. Loading pure EtOH distorts the framework to a low symmetry (P41), while all other phases have a higher symmetry (P4122). The stabilities against heating and humidity, and gas adsorption properties have also been studied for the related compounds. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of Zn(NO3)2, 1,4-benzenedicarboxylic acid (H2bdc), and 4,4′-azopyridine (azpy) in different conditions yielded [Zn(bdc)(bphy)]·DMF·H2O (1a, bphy = 1,2-bis(4-pyridyl)hydrazine, DMF = N,N-dimethylformamide) and [Zn(bdc)(bphy)]·EtOH·H2O (1b) with two-fold interpenetrated dmptopology and [Zn2(bdc)2(bphy)]·1.5EtOH·H2O (2a) and [Zn2(bdc)2(bphy)]·DMA·1.5H2O (2b, DMA = N,N-dimethylacetamide) with two-fold interpenetrated pcutopology. The in situreduction of azpy to bphy was confirmed by single-crystal structures and LC-MS analyses of the acid-digested crystalline samples, as well as controlled solvothermal experiments. Removal of the guest molecules in 1a/1band 2a/2bconverts the materials to guest-free phases [Zn(bdc)(bphy)] (1) and [Zn2(bdc)2(bphy)] (2), respectively, which were identified by PXRD. CO2sorption experiments performed at 195 and 298 K showed low porosity for 1and gated sorption behavior for 2. At 298 K, 2exhibits high selectivity for adsorbing CO2over CH4. [ABSTRACT FROM AUTHOR]

Heterotrinuclear Zn2Ln (Ln = Nd 2, Eu 3, Tb 4, Er 5, Yb 6) clusters [(Znq2)2](μ-CH3COO){Ln(hfac)2} (q= 8-hydroxylquinolinate, hfac = hexafluoroacetylacetonate) have been synthesized. The Zn2Ln framework is ligated by two q ligands featuring μ-phenoxo and two q ligands featuring μ3-phenoxo coordination modes, and one μ-CH3COO−anions. Since the short intramolecular separations of ZnLn (ca.3.354–3.373 Å) allow energy transfer from Znq2-based sensitizers to the LnIIIcentres through two energy transfer pathways, the lanthanide luminescence is indeed “lighted up” by excitation of the Znq2-based chromopores. Photophysical measurements revealed that these Zn2Ln complexes exhibit the so-called “dual emission” originating from both Znq2-based luminophores and lanthanide emitters. By virtue of the dual luminescence with complementary colours, the Znq2-based cyan emission and EuIII-centred red luminescence are combined to generate a white-light emission in the Zn2Eu (3) complex. [ABSTRACT FROM AUTHOR]

Coordination polymers have been emerging as a topical research field in crystal engineering, solid-state chemistry, and materials science. Considering the wide occurrence of structural and compositional diversity during self-assembly and crystallization, supramolecular isomerism represents an indication of composition control and structure prediction. Actually, supramolecular isomerism is not just an obstacle or challenge, but also a good opportunity for developing novel materials and a better understanding of self-assembly and crystal growth. This critical reviewprovides an overview of the developing knowledge, in the context of supramolecular isomerism, of the design, synthesis, and properties of coordination polymers (97 references). [ABSTRACT FROM AUTHOR]

Nine new coordination polymers: [Cu3(ipO)2(pyz)2] (5), [Cu3(ipO)2(4-phpy)(H2O)2] (6), [Cu(ip)(4-phpy)2] (7), [Cu3(ipO)2(H2O)2] (8), [Co(phen)(ip)(H2O)] (9), [Co3(1,2,3-btc)2(4,4'-bpy)2(H2O)2]·2H2O (10), [Ni(1,2,3-btcH)(4,4'-bpy)(H2O)]·H2O (11), [Cd5(1,2,3-btc)2(1,2,3-btcH)2(4,4'-bpy)3(H2O)2] (12) and (1,2,3-btcH3)(4,4'-bpy) (13) (1,2,3-btcH3 = 1,2,3-benzenetricarboxylic acid, ipO = 2-hydroxyisophthalate, 4,4'-bpy = 4,4'-bipyridine, pyz = pyrazine, 4-phpy = 4-phenyl-pyridine and phen = o-phenanthroline) have been hydrothermally synthesized. This family of compounds show the role of the N-containing heterocyclic ligands and Cu(II) ions in the metal-ligand reactions. These results suggest that the hydroxylation requires Cu(II) ions as the oxidant, rather than the presence of N-containing heterocyclic ligands, while the decarboxylate procedure requires high temperature and basic condition rather than the participation of Cu(II) ions. The obtained compounds show versatile structures and magnetic properties due to the flexibility of the carboxylate ligands. Compound 5 shows dominated antiferromagnetic interaction in the [Cu2(μ-ipO)2] unit, and no long-range magnetic ordering behaviour. Compound 10 has a topologically ferrimagnetic chain with alternating CooctIICotetIICooctII (oct = octahedral, tet = tetrahedal) spin arrangement. The Cotet II and CooctII ions are bridged by similar syn-anti carboxylates (CotetII · · · CooctII 4.616 and 4.735 Å). Such a chain shows ferro- and antiferro- magnetic interactions and no long-range magnetic ordering behaviour was observed. Compound 11 has a antiferromagnetic coupled syn-anti carbxylate-bridged Ni(II) chain (J = 1.48(2) K), and shows long-range magnetic order below 2.6 K due to the extensive hydrogen bonds between the chains. [ABSTRACT FROM AUTHOR]

Nine new coordination polymers: [Cu3(ipO)2(pyz)2] (5), [Cu3(ipO)2(4-phpy)(H2O)2] (6), [Cu(ip)(4-phpy)2] (7), [Cu3(ipO)2(H2O)2] (8), [Co(phen)(ip)(H2O)] (9), [Co3(1,2,3-btc)2(4,4′-bpy)2(H2O)2]·2H2O (10), [Ni(1,2,3-btcH)(4,4′-bpy)(H2O)]·H2O (11), [Cd5(1,2,3-btc)2(1,2,3-btcH)2(4,4′-bpy)3(H2O)2] (12) and (1,2,3-btcH3)(4,4′-bpy) (13) (1,2,3-btcH3= 1,2,3-benzenetricarboxylic acid, ipO = 2-hydroxyisophthalate, 4,4′-bpy = 4,4′-bipyridine, pyz = pyrazine, 4-phpy = 4-phenyl-pyridine and phen = o-phenanthroline) have been hydrothermally synthesized. This family of compounds show the role of the N-containing heterocyclic ligands and Cu(ii) ions in the metal–ligand reactions. These results suggest that the hydroxylation requires Cu(ii) ions as the oxidant, rather than the presence of N-containing heterocyclic ligands, while the decarboxylate procedure requires high temperature and basic condition rather than the participation of Cu(ii) ions. The obtained compounds show versatile structures and magnetic properties due to the flexibility of the carboxylate ligands. Compound 5shows dominated antiferromagnetic interaction in the [Cu2(μ-ipO)2] unit, and no long-range magnetic ordering behaviour. Compound 10has a topologically ferrimagnetic chain with alternating CoIIoctCoIItetCoIIoct(oct = octahedral, tet = tetrahedal) spin arrangement. The CoIItetand CoIIoctions are bridged by similar syn–anticarboxylates (CoIItetCoIIoct4.616 and 4.735 ). Such a chain shows ferro- and antiferro- magnetic interactions and no long-range magnetic ordering behaviour was observed. Compound 11has a antiferromagnetic coupled syn–anticarbxylate-bridged Ni(ii) chain (J= 1.48(2) K), and shows long-range magnetic order below 2.6 K due to the extensive hydrogen bonds between the chains. [ABSTRACT FROM AUTHOR]

Solvothermal and solution reactions of a V-shaped organic ligand 4,4′-oxybis(benzoic acid) (H2oba) and Cu(NO3)2yield two porous coordination polymers, namely [Cu(oba)(dmso)] (MCF-21) and [Cu2(oba)2(dmf)(C2H5OH)]·(dmf)2(H2O) (MCF-22·guest) (dmso = dimethyl sulfoxide, dmf = dimethylformamide), respectively. Single-crystal X-ray analyses reveal that the metal carboxylate backbones of MCF-21and MCF-22·guestare framework-isomeric as two uninodal four-connected nets, i.e.a two-dimensional (2-D) 44layer and a 3-fold interpenetrated lvt (4284) three-dimensional (3-D) network, respectively. After removing the solvent molecules, MCF-21retains a rigid 2-D framework, but MCF-22·guestexhibits either rigid or dynamic behavior depending on the degree of desolvation, which is confirmed by powder X-ray diffraction and sorption isotherms. Meanwhile, the different sorption behavior of the framework-isomeric materials is elucidated by the discrepancies of their pore dimensions and framework rigidities. [ABSTRACT FROM AUTHOR]

Three new chiral metal–organic frameworks, (H2NMe2)[M(tzdc)]·0.5H2O [MCo(II) (1), Mn(II) (2)] and (NH4)[Mn(tzdc)]·2.6H2O (3) (tzdc3−= 1,2,3-triazole-4,5-dicarboxylate), have been solvothermally synthesized. In the frameworks of 1–3, the ratio of metal and tzdc3−is 1 : 1. Each metal ion is chelated by three tzdc3−ligands, and each tzdc3−connects three metal ions, resulting in three-dimensional, 3-connected anionic frameworks. 1and 2are isomorphous, and both crystallize in the cubic space group P213. With the template of H2NMe2+cations, the frameworks of 1and 2have a well-known, porous (10,3)-anetwork. In contrast, 3can be obtained by replacing the H2NMe2+with smaller NH4+cations, which leads to a significant topological change to a unique uniform etd(8,3) network as well as the change of the space group to P61. Magnetic studies show dominated antiferromagnetic interactions in 1–3with = −46.8(1), −22.3(1) and −25.8(1) K for 1, 2and 3, respectively. Due to the triangular arrangement of the metal centres, geometrically spin-frustrated magnetism is a characteristic behaviour of 1–3. For 1, spin-glassy behaviour with a freezing temperature Tfof 2.4 K was distinctly observed, and an empirical factor f= /Tf 20 > 10 indicates strong spin-frustration effect. For both 2and 3, no obvious long-range magnetic ordering and/or spin–glassy behaviour was observed down to 2.0 K, which might indicate the fvalues in them being also larger than 10. By contrast, the observed spin-glassy behaviour above 2.0 K in 1is probably due to the stronger magnetic anisotropy of Co(II) ion and the stronger antiferromagnetic interactions in 1. [ABSTRACT FROM AUTHOR]

Two new microporous metal–organic frameworks, [Zn3(NH2BDC)3(H2O)2]·5DMF (1) and (Me2NH2)2[Cd3(NH2BDC)4]·2DMF·2.5 H2O (2) (NH2BDC = 2-amino-1,4-benzenedicarboxylate), based on linear trinuclear secondary building units of Zn3(COO)6 or Cd3(COO)8 that have different connected numbers, have been synthesized and characterized, which exhibit usual pcu and rare hex-like topologies, respectively. Both 1 and 2 are three-dimensional porous frameworks, having solvent accessible volumes of ca. 53 and 39%, respectively. There are unremovable guest Me2NH2+ cations clogged in the channels of 2. In contrast, being of good thermo-stability, 1 has a Langmuir surface area about 570 m2 g−1 and type I isotherm behaviour for nitrogen gas sorption at 77 K, being typical of microporous material. [ABSTRACT FROM AUTHOR]

A new perovskite-like compound [N(CH3)4][Cd(N3)3] is reported here, which undergoes a series of reversible phase transitions including an above-room-temperature ferroelastic phase transition. An order-disorder mechanism is found in these structural transitions owing to the sway of the rod-like N3- bridges as well as the rotation of the tetrahedron-like [N(CH3)4]+ guests. [ABSTRACT FROM AUTHOR]

Self-assembly of Ni(ii)/Co(ii) with 4,4′-oxybis(benzoate) and 4,4′-bipyridyl under hydrothermal conditions yielded polyrotaxane ring-and-rod double chains and 6-fold interpenetrated (10,3)-a coordination networks. [ABSTRACT FROM AUTHOR]

The silver(i) isopropylimidazolate crystallizes as three genuine interweaving supramolecular isomers, including a sinusoidal chain, a rare quintuple helix, and an unprecedented chicken-wire pattern. Heating transforms the chicken-wire into the quintuple helix through an interesting mechanism. [ABSTRACT FROM AUTHOR]

An ionic porous coordination polymer possessing partially exposed uncoordinated nitrogens exhibits strong interaction with CO2and high CO2/CH4selectivity, and the adsorption mechanism is illustrated by the structure of its CO2-loaded single-crystal. [ABSTRACT FROM AUTHOR]

Multifunctional heteropentanuclear Al3Ln2 (Ln = Nd, Eu, Yb) clusters with a novel structure exhibit significantly fluorideenhanced lanthanide emission intensity and lifetime in both solid state and solution as well as unusual white-light emitting for an Al3Eu2 complex. [ABSTRACT FROM AUTHOR]

Two new three-dimensional manganese(II) coordination polymers were assembled by 1,2,3-triazole-4,5-dicarboxylate, showing unusual multi-step magnetization jumps at 1.8 K due to the competing interactions between the antiferromagnetic couplings with different amplitudes. [ABSTRACT FROM AUTHOR]

A 1-D chain-like hybrid coordination polymer [(CuBr)2(bpy)]n(bpy = 2,2′-bipyridine) was first synthesized viaa hydrothermal reaction of copper(I) bromide with 2,2′-bipyridine (bpy). The most fascinating feature of [(CuBr)2(bpy)]nis the unusual six-member-(Cu3Br3)-ring motif. The skeleton of copper bromide combined with bpy in [(CuBr)2(bpy)]nhas not been reported. In addition, research on pyrolysis of [(CuBr)2(bpy)]nwas reported in this paper. Oriented growth of single crystalline Cu(111) flake, which is usually prepared through depositing onto the surface of high-quality metal films (substrates), was synthesized by simply pyrolyzing [(CuBr)2(bpy)]nby adjusting the heating procedures. No capping reagent was induced to simplify the system. Since most of the research of pyrolysis of coordination polymers focuses on the relationship between the structure of precursor and sinter, the results of this paper show how the reaction conditions affect the morphology of the product and give a simple method for the synthesis of a Cu(111) flake, which has wide application in industry. [ABSTRACT FROM AUTHOR]

Two novel (3,12)-connected, chiral porous coordination polymers featuring 3D intersecting pore structures, selective sorption and solvothermal resistance properties are constructed by linking 3-connected benzene-1,3,5-tribenzoic acid with two types of 12-connected heptanuclear metal carboxylate clusters. [ABSTRACT FROM AUTHOR]

An unprecedented release of the bridging aqua molecules and conversion of chain helicity within a 3-D chiral cadmium(ii) dicarboxylate coordination polymer was observed in a unique and drastic single-crystal-to-single-crystal transformation of dehydration. [ABSTRACT FROM AUTHOR]

A new perovskite-like compound [N(CH3)4][Cd(N3)3] is reported here, which undergoes a series of reversible phase transitions including an above-room-temperature ferroelastic phase transition. An order-disorder mechanism is found in these structural transitions owing to the sway of the rod-like N3- bridges as well as the rotation of the tetrahedron-like [N(CH3)4]+ guests. [ABSTRACT FROM AUTHOR]