Construction of Ideal One-Dimensional Spin Chains by Topochemical Dehydration/Rehydration Route.

One-dimensional (1D) Heisenberg antiferromagnets are of great interest due to their intriguing quantum phenomena. However, the experimental realization of such systems with large spin S remains challenging because even weak interchain interactions induce long-range ordering. In this study, we present an ideal 1D S = 5/2 spin chain antiferromagnet achieved through a multistep topochemical route involving dehydration and rehydration. By desorbing three water molecules from (2,2'-bpy)FeF3(H2O)·2H2O (2,2'-bpy = 2,2'-bipyridyl) at 150 °C and then intercalating two water molecules at room temperature (giving (2,2'-bpy)FeF3·2H2O 1), the initially isolated FeF3ON2 octahedra combine to form corner-sharing FeF4N2 octahedral chains, which are effectively separated by organic and added water molecules. Mössbauer spectroscopy reveals significant dynamical fluctuations down to 2.7 K, despite the presence of strong intrachain interactions. Moreover, results from electron spin resonance (ESR) and heat capacity measurements indicate the absence of long-range order down to 0.5 K. This controlled topochemical dehydration/rehydration approach is further extended to (2,2'-bpy)CrF3·2H2O with S = 3/2 1D chains, thus opening the possibility of obtaining other low-dimensional spin lattices.

Anomalous Dynamics of a Nanoconfined Gas in a Soft Metal-Organics Framework.

Dynamics of confined molecules within porous materials is equally important as local structural order, and it is necessary to quantify it and to reveal the microscopic mechanisms ruling it for better control of adsorption applications. In this study, molecular dynamics simulations were carried out to investigate the translational and the rotational dynamics of methanol trapped into the flexible NH2-MIL-53(Al) metal-organics framework (MOF). Indeed, atomistic simulation is nowadays a relevant tool to explore matter at the nanoscale. Very recently it has been shown that the NH2-MIL-53(Al) MOF material was capable to undergo a reversible structural transition (breathing phenomenon) by combining adsorption and thermal stimuli. This flexibility can drastically affect the dynamics of confined molecules and therefore the successful conduct of adsorption applications such as gas storage and separation. Rotational and translational dynamics of confined methanol through nanoporous flexible NH2-MIL-53(Al) MOF were then deeply investigated by exploring a broad range of dynamical properties to extract the molecular mechanisms ruling them. This study allowed us to shed light on the interplay of dynamics of confined fluids and flexibility of porous material and to highlight the physical insights in diffusion mechanisms of confined molecules. Anomalous translational diffusion was evidenced due to a dynamical heterogeneity caused by a combination of a localized dynamics at the subnanometric scale and translational jumps between nanodomains in a zigzag scheme between the hydroxide group of the NH2-MIL-53(Al). Actually, the non-Fickian dynamics of methanol is the result of the specific host-guest interactions and the MOF flexibility involving the pore opening. Eventually, decoupling between both rotational and translational dynamics related to breaking in the Stokes-Einstein relation was highlighted.

Synthesis, structural determination and antimicrobial evaluation of two novel CoII and ZnII halogenometallates as efficient catalysts for the acetalization reaction of aldehydes.

BACKGROUND: Complexes of imidazole derivatives with transition metal ions have attracted much attention because of their biological and pharmacological activities, such as antimicrobial, antifungal, antiallergic, antitumoural and antimetastatic properties. In addition, imidazoles occupy an important place owing to their meaningful catalytic activity in several processes, such as in hydroamination, hydrosilylation, Heck reaction and Henry reaction. In this work, we describe the crystallization of two halogenometallate based on 2-methylimidazole. Their IR, thermal analysis, catalytic properties and antibacterial activities have also been investigated. RESULTS: Two new isostructural organic-inorganic hybrid materials, based on 2-methyl-1H-imidazole, 1 and 2, were synthesized and fully structurally characterized. The analysis of their crystal packing reveals non-covalent interactions, including C/N-H···Cl hydrogen bonds and π···π stacking interactions, to be the main factor governing the supramolecular assembly of the crystalline complexes. The thermal decomposition of the complexes is a mono-stage process, confirmed by the three-dimensional representation of the powder diffraction patterns (TDXD). The catalytic structure exhibited promising activity using MeOH as solvent and as the unique source of acetalization. Moreover, the antimicrobial results suggested that metal-complexes exhibit significant antimicrobial activity. CONCLUSION: This study highlights again the structural and the biological diversities within the field of inorganic-organic hybrids.

Multinuclear NMR as a tool for studying local order and dynamics in CH3NH3PbX3 (X = Cl, Br, I) hybrid perovskites.

We report on 207Pb, 79Br, 14N, 1H, 13C and 2H NMR experiments for studying the local order and dynamics in hybrid perovskite lattices. 207Pb NMR experiments conducted at room temperature on a series of MAPbX3 compounds (MA = CH3NH3+; X = Cl, Br and I) showed that the isotropic 207Pb NMR shift is strongly dependent on the nature of the halogen ions. Therefore 207Pb NMR appears to be a very promising tool for the characterisation of local order in mixed halogen hybrid perovskites. 207Pb NMR on MAPbBr2I served as a proof of concept. Proton, 13C and 14N NMR experiments confirmed the results previously reported in the literature. Low temperature deuterium NMR measurements, down to 25 K, were carried out to investigate the structural phase transitions of MAPbBr3. Spectral lineshapes allow following the successive phase transitions of MAPbBr3. Finally, quadrupolar NMR lineshapes recorded in the orthorhombic phase were compared with simulated spectra, using DFT calculated electric field gradients (EFG). Computed data do not take into account any temperature effect. Thus, the discrepancy between the calculated and experimental EFG evidences the fact that MA cations are still subject to significant dynamics, even at 25 K.

Hydride in BaTiO2.5H0.5: A Labile Ligand in Solid State Chemistry.

In synthesizing mixed anion oxides, direct syntheses have often been employed, usually involving high temperature and occasionally high pressure. Compared with these methods, here we show how the use of a titanium perovskite oxyhydride (BaTiO2.5H0.5) as a starting material enables new multistep low temperature topochemical routes to access mixed anion compounds. Similar to labile ligands in inorganic complexes, the lability of H(-) provides the necessary reactivity for syntheses, leading to reactions and products previously difficult to obtain. For example, BaTiO2.5N0.2 can be prepared with the otherwise inert N2 gas at 400-600 °C, in marked contrast with currently available oxynitride synthetic routes. F(-)/H(-) exchange can also be accomplished at 150 °C, yielding the oxyhydride-fluoride BaTi(O, H, F)3. For BaTiO2.4D0.3F0.3, we find evidence that further anionic exchange with OD(-) yields BaTiO2.4(D(-))0.26(OD(-))0.34, which implies stable coexistence of H(+) and H(-) at ambient conditions. Such an arrangement is thermodynamically unstable and would be difficult to realize otherwise. These results show that the labile nature of hydride imparts reactivity to oxide hosts, enabling it to participate in new multistep reactions and form new materials.

A supramolecular double sulfate salt with a lamellar type: crystal structure and thermal behavior.

The synthesis of a series of supramolecular double sulfate salts using transition metals and the aromatic amine α-methylbenzylamine afforded an unexpected hybrid lamellar structure type. (C8H12N)2[M(H2O)4(SO4)2]·2H2O (M = Fe to Zn) crystallizes with a monoclinic structure (S.G. P21/n), with a significant interlamellar distance of more than 16 Å. While comparable to common clay materials, the crystal structure is actually supramolecular; in particular, the mineral layer is built from hydrogen bonds only. The interlayer space is filled with aromatic amines that form chains through C-H···π interactions. The thermal study of all metal compounds revealed good stability of the filled compounds up to 200 °C. The dehydration proceeds differently according to the metal incorporated into the structure. In particular, the stepped release of water drastically modifies the interlayer space, which is able to vary from 14.8 to 18.8 Å, in an opposite way for the Zn-related compound compared to other metals.

1,4,8,11-Tetra-azonia-cyclo-tetra-decane tetra-kis-(hydrogensulfate).

In the title salt, C10H28N4 (4+)·4HSO4 (-), the cation lies about an inversion center. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

Poly[1H-imidazol-3-ium [di-µ-nitrato-sodium]].

In the title compound {(C3H5N2)[Na(NO3)2]} n , the Na(I) ion is coordinated by eight O atoms from three bidentate nitrate anions and two O atoms from two monodentate nitrate anions, displaying a bicapped trigonal-prismatic geometry. The imidazolium cation is essentially planar (r.m.s. deviation for all non-H atoms = 0.0018 Å). In the crystal, the Na(I) ions are connected by bridging nitrate ligands, forming layers parallel to (010). The imidazolium cations are sandwiched between these layers. Weak C-H⋯O hydrogen bonds link the layers into a three-dimensional network. In addtion, π-π inter-actions between the imidazolium rings [centroid-centroid distance = 3.588 (3) Å] are observed.

DFT-assisted structure determination of α1- and α2-VOPO4: new insights into the understanding of the catalytic performances of vanadium phosphates.

Structural investigations on vanadium phosphates, which are extensively used as catalysts in industry, often resulted in important advances in the understanding of the mechanisms driving the catalytic oxidation of light hydrocarbons. Layer translations in the two lamellar vanadium phosphates α1- and α2-VOPO4 phases identified during the catalysis were investigated by the combination of first-principles calculations, synchrotron X-ray powder diffraction, single-crystal X-ray diffraction and solid-state NMR. This analysis reveals an important feature: the α1-form is the only polymorph of VOPO4 to exhibit layer translations that prevent the formation of infinite VO6 chains. A detailed investigation of this structural characteristic in vanadium phosphates reveals the correlation between the presence of infinite VO6 chains and the catalytic performances of related phases.

Ethyl-enediammonium tetra-aqua-disulfato-cadmate.

The crystal structure of the title compound, [NH(3)(CH(2))(2)NH(3)][Cd(SO(4))(2)(H(2)O)(4)], consists of [Cd(SO(4))(2)(H(2)O)(4)](2-) anions that are built from octa-hedral Cd(H(2)O)(4)O(2) and SO(4) tetra-hedral units linked by corner sharing. The ethyl-ene-diamminium cations are linked to the anions via N-H⋯O hydrogen bonds. The asymmetric unit contains one-half of the compound, the other half being related to the first by an inversion centre. The crystal structure presents alternate stacking of the inorganic and organic layers along the crystallographic b axis. The structure cohesion and stability is further assured by O(water)-H⋯O hydrogen bonds.

Poly[[µ-aqua-tetraaquabis(µ-2-hydroxy-4-oxocyclobut-1-ene-1,3-diolato)strontium] hemihydrate].

In the title coordination polymer, {[Sr(C(4)HO(4))(2)(H(2)O)(5)]·0.5H(2)O}(n), the Sr(2+) ion is coordinated by three monodentate hydrogensquarate (hsq) anions and six aqua ligands in a distorted SrO(9) monocapped square-anti-prismatic geometry. The hsq anions and water mol-ecules bridge the metal ions into infinite sheets lying parallel to (100). The O atom of the uncoordinated water mol-ecule lies on a crystallographic twofold axis. The packing is stabilized by numerous O-H⋯O hydrogen bonds.

Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][M(II)(H2O)6](SO4)2, (M(II) = Mn, Fe, Co, Ni).

A series of novel organically templated metal sulfates, [C(5)H(14)N(2)][M(II)(H(2)O)(6)](SO(4))(2) with (M(II) = Mn (1), Fe (2), Co (3) and Ni (4)), have been successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, thermogravimetric analysis and magnetic measurements. All compounds were prepared using a racemic source of the 2-methylpiperazine and they crystallized in the monoclinic systems, P2(1)/n for (1, 3) and P2(1)/c for (2,4). Crystal data are as follows: [C(5)H(14)N(2)][Mn(H(2)O)(6)](SO(4))(2), a = 6.6385(10) Å, b = 11.0448(2) Å, c = 12.6418(2) Å, ß = 101.903(10)°, V = 906.98(3) Å(3), Z = 2; [C(5)H(14)N(2)][Fe(H(2)O)(6)](SO(4))(2), a = 10.9273(2) Å, b = 7.8620(10) Å, c = 11.7845(3) Å, ß = 116.733(10)°, V = 904.20(3) Å(3), Z = 2; [C(5)H(14)N(2)][Co(H(2)O)(6)](SO(4))(2), a = 6.5710(2) Å, b = 10.9078(3) Å, c = 12.5518(3) Å, ß = 101.547(2)°, V = 881.44(4) Å(3), Z = 2; [C(5)H(14)N(2)][Ni(H(2)O)(6)](SO(4))(2), a = 10.8328(2) Å, b = 7.8443(10) Å, c = 11.6790(2) Å, ß = 116.826(10)°, V = 885.63(2) Å(3), Z = 2. The three-dimensional structure networks for these compounds consist of isolated [M(II)(H(2)O)(6)](2+) and [C(5)H(14)N(2)](2+) cations and (SO(4))(2-) anions linked by hydrogen-bonds only. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers. The magnetic measurements indicate that the Mn complex (1) is paramagnetic, while compounds 2, 3 and 4, (M(II) = Fe, Co, Ni respectively) exhibit single ion anisotropy.

Yttrium ethyl-enediammonium squarate tetra-hydrate.

The title compound, {(C(2)H(10)N(2))(1.5)[Y(C(4)O(4))(3)(H(2)O)(4)]}(n) {system-atic name: catena-poly[sesqui(ethyl-enediammonium) [[tetra-aquabis-(squarato-κO)yttrium(III)]-µ-squarato-κ(2)O:O']]}, was synthesized by slow evaporation of an acid solution. The asymetric unit contains one yttrium cation in an anti-prismatic environnement, three squarate groups, one and a half protonated ethyl-enediamine mol-ecules and four water mol-ecules. YO(8) polyhedra are connected through bis-(mono-dentate) squarates, leading to infinite zigzag chains, in between which are located ammonium groups. A framework of hydrogen bonds between protonated amine N atoms, water mol-ecules and squarate anions ensures the cohesion of the structure.

A second monoclinic polymorph of ethyl-enediammonium bis-(hydrogen squarate) monohydrate.

The title compound, C(2)H(10)N(2) (2+)·2HC(4)O(4) (-)·H(2)O, a new polymorph of ethyl-enediammonium bis-(hydrogen squarate) monohydrate, was synthesized by slow evaporation of an acid solution. The asymetric unit contains two hydrogen squarate anions, two half-mol-ecules of protonated ethyl-enediamine arranged around a twofold axis and one water mol-ecule. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds between the hydrogen squarate anions, protonated N atoms from the amine group and water mol-ecules lead to a three-dimensional framework. In particular, the cohesion between the squarate groups is ensured by very short intermolecular hydrogen bonds bonds. The title compound crystallized together with the previously reported polymorph [Mathew et al. (2002 ▶). J. Mol. Struct.641, 263-279].

catena-Poly[[{bis-[tetra-aqua-(2-hy-droxy-3,4-dioxocyclo-but-1-en-1-olato-κO)bariumstrontium(0.35/0.65)]di-µ-aqua}-bis-(µ-2-hy-droxy-4-oxocyclo-but-1-ene-1,3-diolato-κO:O)] monohydrate].

The title structure, {[Ba(0.71)Sr(1.29)(C(4)HO(4))(4)(H(2)O)(10)]·H(2)O}(n), is built from dimers of edge-sharing monocapped square anti-prisms [(Ba/Sr)O(3)(H(2)O)(6)], in which barium and strontium are statistically disordered [ratio 0.353 (8):0.647 (8)] on the same crystallographic site. Such dimers are connected via bidentate hydrogen squarate groups [HC(4)O(4)](-), leading to chains that propagate along the b axis. Inter- and intra-molecular O-H⋯O hydrogen bonds maintain the crystal packing through a three-dimensional network.

Ethyl-enediammonium tetraaquadi-sulfatomagnesium(II).

The title compound, [NH(3)(CH(2))(2)NH(3)][Mg(SO(4))(2)(H(2)O)(4)], was synthesized by the slow evaporation method. Its crystal structure can be described as an alternate stacking of inorganic layers of tetra-aqua-bis(sulfato-O)magnesium [Mg(SO(4))(2)(H(2)O)(4)](2-) anions ( symmetry) and organic layers of [NH(3)(CH(2))(2)NH(3)](2+) cations along the crystallographic b axis. The anions, built up from tetrahedral SO(4) units and octahedral Mg(H(2)O)(4)O(2) units, and the cations are linked together through N-H⋯O hydrogen bonds, forming a three-dimensional network. O-H⋯O inter-actions are also present.

A snapshot of a coordination polymer self-assembly process: the crystallization of a metastable 3D network followed by the spontaneous transformation in water to a 2D pseudopolymorphic phase.

A metastable copper(II) 3D hybrid with 4,4'-bipyridine (4,4'-bipy) and P,P'-diphenylethylenediphosphinate (pc2p(2-)) undergoes a spontaneous, quantitative, transformation to a stable 2D polymorphic species either spontaneously in water, or after thermal dehydration followed by hydration.

Synthesis, crystal structure from single-crystal and powder X-ray diffraction data, and thermal behavior of mixed potassium lanthanide squarates: thermal transformations of layered [Ln(H2O)6]K(H2C4O4)(C4O4)2 into pillared LnK(C4O4)2 (Ln = Y, La, Gd, Er).

A new series of mixed potassium and rare-earth squarates, [Ln(H(2)O)(6)]K(H(2)C(4)O(4))(C(4)O(4))(2) (Ln = Y, La, Gd, Er), has been synthesized and structurally characterized from single-crystal X-ray diffraction and spectroscopic analyses. The yttrium-based compound crystallizes with a monoclinic symmetry, space group C2/c [a = 8.3341(2) A, b = 37.7094(9) A, c = 11.7195(3) A, beta = 90.3959(9) degrees , V = 3683.1(2) A(3), Z = 8]. The structure is built from layers maintained together via hydrogen bonds. Within a layer, squarate ligands act as linkers between lanthanide and potassium cations. The thermal decomposition of the precursors has been studied by powder thermodiffractometry and thermal analyses. It is shown that crystalline intermediate phases are formed during the degradation. Among them, unprecedented mixed anhydrous squarates, LnK(C(4)O(4))(2), could be isolated. The crystal structure of the Y compound has been solved ab initio from X-ray powder diffraction data, using direct-space methods [a = 6.2010(5) A, c = 11.639(1) A, V = 447.55 A(3), Z = 2]. The structure consists of layers of edge-sharing YO(8) and KO(8) antiprisms, pillared by mu(8)-squarate groups. The end of the precursor decomposition is marked by the formation of cubic sesquioxides Ln(2)O(3), including lanthanum oxide.

A rationale for the large breathing of the porous aluminum terephthalate (MIL-53) upon hydration.

Aluminum 1,4-benzenedicarboxylate Al(OH)[O(2)C-C(6)H(4)-CO(2)]. [HO(2)C-C(6)H(4)-CO(2)H](0.70) or MIL-53 as (Al) has been hydrothermally synthesized by heating a mixture of aluminum nitrate, 1,4-benzenedicarboxylic acid, and water, for three days at 220 degrees C. Its 3 D framework is built up of infinite trans chains of corner-sharing AlO(4)(OH)(2) octahedra. The chains are interconnected by the 1,4-benzenedicarboxylate groups, creating 1 D rhombic-shaped tunnels. Disordered 1,4-benzenedicarboxylic acid molecules are trapped inside these tunnels. Their evacuation upon heating, between 275 and 420 degrees C, leads to a nanoporous open-framework (MIL-53 ht (Al) or Al(OH)[O(2)C-C(6)H(4)-CO(2)]) with empty pores of diameter 8.5 A. This solid exhibits a Langmuir surface area of 1590(1) m(2)g(-1) together with a remarkable thermal stability, since it starts to decompose only at 500 degrees C. At room temperature, the solid reversibly absorbs water in its tunnels, causing a very large breathing effect and shrinkage of the pores. Analysis of the hydration process by solid-state NMR ((1)H, (13)C, (27)Al) has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms. The hydrogen bonds between water and the oxygen atoms of the framework are responsible for the contraction of the rhombic channels. The structures of the three forms have been determined by means of powder X-ray diffraction analysis. Crystal data for MIL-53 as (Al) are as follows: orthorhombic system, Pnma (no. 62), a = 17.129(2), b = 6.628(1), c = 12.182(1) A; for MIL-53 ht (Al), orthorhombic system, Imma (no. 74), a = 6.608(1), b = 16.675(3), c = 12.813(2) A; for MIL-53 lt (Al), monoclinic system, Cc (no. 9), a = 19.513(2), b = 7.612(1), c = 6.576(1) A, beta = 104.24(1) degrees.

Hemi(piperazinediium) hexaaquaaluminium(III) bis(sulfate) tetrahydrate: a new double aluminium sulfate salt.

Piperazinium aluminium sulfate decahydrate, (C(4)H(12)N(2))(0.5)[Al(H(2)O)(6)](SO(4))(2).4H(2)O, exhibits a crystal structure built from isolated [Al(H(2)O)(6)](3+), SO(4)(2-), C(4)H(12)N(2)(2+) and H(2)O units connected by a complex hydrogen-bond network. The title compound shows strong similarities to many double aluminium sulfates, such as alums and Tutton's salts. However, since its structure is not derived directly from that of these compounds, it is assumed to be a new structure type.