Mechanically induced polyamorphism in a one-dimensional coordination polymer.

We created different amorphous structures of a coordination polymer by applying mechanical shear forces. One-dimensional Cu(TfN)(bip) (1, TfN = bis(trifluoromethanesulfonyl)imide, bip = 1,3-bis(1-imidazolyl)propane) melted at 245 °C and underwent a glass transition at -10 °C by a static cooling process. 1 formed another amorphous state with a distinct glass transition point of 70 °C under oscillatory shear stress.

Entropically driven melting of Cu-based 1D coordination polymers.

We investigated the melting behavior of four CPs with one-dimensional structures from a thermodynamic point-of-view. The difference in melting points depending on the crystal structures is observed. The interactions within the crystals were analyzed using DFT calculations.

Solution State-Like Reactivity of a Flexible Crystalline Werner-Type Metal Complex.

Flexible crystalline solids exhibit unique properties in response to external stimuli like heat and light. However, challenges exist in developing crystalline solids that have similar degrees of flexibility as in solution. Herein, we report the preparation of the new flexible crystalline metal complex [Cd(CFSO)(4-spy)] (4-spy=4-styrylpyridine), which contains photoreactive 4-spy ligand.

Selective Gas Sensing under a Mixed Gas Flow with a One-Dimensional Copper Coordination Polymer.

Structural changes of the coordination polymer associated with gas adsorption (gate opening-type adsorption) can be linked to bulk physical properties such as magnetism, electrical conductivity, and dielectric properties. To enable real-space sensing applications, it is imperative to have a system where the selective adsorption of mixed gases can be correlated with physical properties. In this report, we demonstrate that a crystalline sample of one-dimensional (1D) coordination polymer exhibits selective CO adsorption while simultaneously displaying dielectric switching behavior in a mixed N/CO gas environment.

Composite with a Glassy Nonporous Coordination Polymer Enhances Gas Adsorption Selectivity.

A glass-crystal composite (g-NCP/PCP), comprising a glassy nonporous coordination polymer (g-NCP) and a crystalline porous coordination polymer (PCP)/metal-organic framework, was synthesized by using a melt-quenched method. Compared to that of the PCP itself, g-NCP/PCP has an enhanced gas adsorption selectivity. The results should stimulate further studies of the chemistry of g-NCP/PCP glass-crystal composites.

Influence of carbohydrate polymer shaping on organic dye adsorption by a metal-organic framework in water.

A number of studies have been conducted to develop new metal-organic frameworks (MOFs) as adsorbents for the removal of contaminants from polluted water. However, few reports exist describing detailed and thorough examinations of the effects of shaping on the adsorption properties of MOFs. In this study, a thorough analysis and comparison was conducted of the Orange II and Rhodamine B dye adsorption properties of unshaped MIL-100(Fe) (MIL) particles and alginate polymer-shaped MIL beads (MIL-alg).

Mechanical Force Induced Formation of Extrinsic Micropores in Coordination Polymers.

Mechanical force can be employed not only to efficiently synthesize new materials under environmentally friendly conditions but also to change the macroscopic and microscopic properties of materials. Although coordination polymers (CPs) are attractive functional materials because they possess high structural designability and diversity, mechanical force-induced structural and functional changes of CPs are challenging issues. In this study, two one-dimensional CPs, one a densely packed nonporous CP [Cu(bza)(pyr)] () and the other a porous CP [Cu(1-nap)(pyr)] () (bza = benzoate, 1-nap = 1-naphthoate and pyr = pyrimidine), were subjected to ball-milling to assess the effect of mechanical force on their porosities.

One-Step Preparation of Fe/N/C Single-Atom Catalysts Containing Fe-N Sites from an Iron Complex Precursor with 5,6,7,8-Tetraphenyl-1,12-Diazatriphenylene Ligands.

Fe/N/C single-atom catalysts containing Fe-N sites prepared by pyrolysis are promising cathode materials for fuel cells and metal-air batteries due to their high oxygen reduction reaction (ORR) activities. We have developed iron complexes containing N2- or N3-chelating coordination structures with preorganized aromatic rings in a 1,12-diazatriphenylene framework tethering bromo substituents as precursors to precisely construct Fe-N sites in an Fe/N/C catalyst. One-step pyrolysis of the iron complex with carbon black forms atomically dispersed Fe-N sites without iron aggregates.

Dipole fluctuation and structural phase transition in hydrogen-bonding molecular assemblies of mononuclear Cu complexes with polar fluorobenzoate ligands.

A series of mononuclear Cu complexes, [Cu(4-FBA)(py)(HO)] (1), [Cu(3-FBA)(py)(HO)] (2), and [Cu(3,4-FBA)(py)(HO)] (3), where 4-FBA = 4-fluorobenzoate, 3-FBA = 3-fluorobenzoate, 3,4-FBA = 3,4-difluorobenzoate, and py = pyridine, respectively, was synthesized and the complexes crystallographically identified. All the Cu complex crystals share a one-dimensional O-H⋯O hydrogen-bonding chain substructure, although the mutual alignment of fluorinated benzoate (FBA) ligands exhibits subtle differences among the various compounds, , FBA ligands align in an antiparallel fashion in crystals 1 and 3, while 3-FBA ligands in crystal 2 are interdigitated with a tilt along the axis. Reversible phase transitions were found upon heating at 170.

Reversible hydrogen adsorption at room temperature using a molybdenum-dihydrogen complex in the solid state.

Reversible H storage under mild conditions is one of the most important targets in the field of materials chemistry. Dihydrogen complexes are attractive materials for this target because they possess moderate adsorption enthalpy as well as adsorption without cleavage of the H-H bond. In spite of these advantages, H adsorption studies of dihydrogen complexes in the solid state are scarce.

A Temporarily Pore-Openable Porous Coordination Polymer for Guest Adsorption/Desorption.

Flexible porous coordination polymers (PCPs)/metal-organic frameworks are unique materials that have potential applications as components of highly efficient separation, sensor, and actuator systems. In general, the structures of flexible PCPs drastically change upon guest loading. In this investigation, we uncovered the rare one-dimensional PCP [Cu(bza)(2-apyr)] (; bza = benzoate and 2-apyr = 2-aminopyrimidine), which exhibits a unique type of flexibility involving temporary pore opening.

Gas sorption of nano-porous supramolecules formed by multi-hydrogen bonded coordination capsules.

[{Re(CO)(Hbim)}(tpta)] (1, Hbim = 2,2'-biimidazolate monoanion, tpta = 2,4,6-tripyridyl-1,3,5-triazine) was prepared as a nano-space supramolecule by using a new group of H-bonded coordination capsules. The hamburger bun-shaped half unit [{Re(CO)(Hbim)}(tpta)] contains six intermolecular H-bonds of Hbim ligands with complementary dual NHN types, and three [Re(CO)(Hbim)] are coordinated by bridging tridentate tpta. Interestingly, mechanical grinding easily would convert single crystals of 1 to an amorphous state with minor crystallinity while maintaining the nano-space pores.

A hydrogen-bonded organic framework based on redox-active tri(dithiolylidene)cyclohexanetrione.

Redox-active hexakis(4-carboxyphenyl) tri(dithiolylidene)cyclohexanetrione (CPDC) was synthesized. The CPDC-based porous framework, constructed via anomalistic helical hydrogen-bonding, exhibites permanent porosity and photoconductivity.

Understanding the interactions between the bis(trifluoromethylsulfonyl)imide anion and absorbed CO using X-ray diffraction analysis of a soft crystal surrogate.

The selective carbon dioxide (CO) absorption properties of ionic liquids (ILs) are highly pertinent to the development of methods to capture CO. Although it has been reported that fluorinated components give ILs enhanced CO solubilities, it has been challenging to gain a deep understanding of the interactions occurring between ILs and CO. In this investigation, we have utilized the soft crystalline material [Cu(NTf)(bpp)] (NTf = bis(trifluoromethylsulfonyl)imide, bpp = 1,3-bis-(4-pyridyl)propane) as a surrogate for single-crystal X-ray diffraction analysis to visualize interactions occurring between CO and NTf, the fluorinated IL component that is responsible for high CO solubility.

Structural Phase Transitions of a Molecular Metal Oxide.

The structural phase of a metal oxide changes with temperature and pressure. During phase transitions, component ions move in multidimensional metal-oxygen networks. Such macroscopic structural events are robust to changes in particle size, even at scales of around 10 nm, and size effects limiting these transitions are particularly important in, for example, high-density memory applications of ferroelectrics.

Responsive Four-Coordinate Iron(II) Nodes in FePd(CN).

Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal-organic frameworks with desirable properties; however, Fe ions are exclusively six-coordinated. Herein, we present a cyanide-bridged three-dimensional (3D) CP, FePd(CN) , bearing four-coordinate Fe ions, which is synthesized by thermal treatment of a two-dimensional (2D) six-coordinate Fe CP, Fe(H O) Pd(CN) ⋅4 H O, to remove water molecules. Atomic-resolution transmission electron microscopy and powder X-ray and neutron diffraction measurements revealed that the FePd(CN) structure is composed of a two-fold interpenetrated PtS topology network, where the Fe center demonstrates an intermediate geometry between tetrahedral and square-planar coordination.

Controlling the gate-sorption properties of solid solutions of Werner complexes by varying component ratios.

Methods relying on the use of solid solutions can be used to produce solid materials having finely controlled physical properties. In the current investigation, we utilized this protocol to prepare solid solutions derived from two different Werner complexes in order to assess the effects of component ratios on acetone vapor adsorption properties. For this purpose, microcrystalline solid solutions with the basic elemental composition α-[Cu(PF6)2(py)4]x[Cu(CF3SO3)2(py)4]1-x (x = 0.

Coordinated Water as New Binding Sites for the Separation of Light Hydrocarbons in Metal-Organic Frameworks with Open Metal Sites.

Metal-organic frameworks with open metal sites are promising materials for gas separations. Particularly, the M(dobdc) (dobdc = 2,5-dioxidobenzenedicarboxylate, M = Co, Mn, Fe, ..

Paddlewheel Complexes with Azulenes: Electronic Interaction between Metal Centers and Equatorial Ligands.

Rhodium dinuclear complexes (1-3) with azulene moieties as equatorial ligands were obtained by reacting Rh (OAc) with guaiazulene-2-carboxylic acid, azulene-2-carboxylic acid, and azulene-1-carboxylic acid, respectively. The molecular structures in their crystalline states were determined by X-ray diffraction to be 1 ⋅ (H O) , 1 ⋅ (MeCN) , 2 ⋅ (MeCN) , and 3 ⋅ (DMF) , which were coordinated with the crystallization solvent at the axial positions. Among these, the crystal packing of 1 ⋅ (H O) , 1 ⋅ (MeCN) , and 3 ⋅ (DMF) revealed the formation of one-dimensional stacked chains nearly along the axial direction and of two-dimensional stacked sheets along the equatorial direction.

A Zn(ii) metal-organic framework with dinuclear [Zn(N-oxide)] secondary building units.

We report the synthesis, structural characterisation, and adsorption properties of a three-dimensional metal-organic framework [Zn(pydcao)(DMF)] (H2-pydcao = 3,5-pyridinedicarboxylic acid N-oxide) that has an unprecedented [Zn2(N-oxide)2] secondary building unit.

Hydrogen-Bonded Polyrotaxane Cation Structure in Nickel Dithiolate Anion Radical Salts: Ferromagnetic and Semiconducting Behavior Associated with Structural Phase Transition.

The pseudo-polyrotaxane structure of [(H-bpy )- (DB-24-crown-8)] (H-bpy = monoprotonated 4,4-bipyridinium; DB-24-crown-8 = dibenzo-24-crown-8) has been incorporated into the anion radical salt [Ni(dmit) ] (dmit = 1,3-dithiole-2-thione-4,5-dithiolate). (H-bpy )(DB-24-crown-8)[Ni(dmit) ] crystallized as two polymorphs, crystals 1 and 2. Crystal 1 was found to have a lower density and looser packing structure in which H-bpy forms a one-dimensional hydrogen-bonding chain that passes though the crown ether ring of DB-24-crown-8.

Chemo-chromism in an orthogonal dabco-based Co(ii) network assembled by methanol-coordination and hydrogen bond formation.

Newly prepared single crystals of [Co(ii)(dabco)(NCS)2(MeOH)2]·dabco (1-pink; dabco: 1,4-diazabicyclo[2.2.2]octane) showed chromotropic behaviour in the solid state, changing from pink to blue upon heating or grinding.