Structural Filiation Research Articles

Polymorphism and Structural Filiations in Five New Organic–Inorganic Hybrid Salts of the Heteroleptic Cationic Iridium(III) Complex and Polyoxometalates

Five new hybrid compounds ionically associating the phosphorescent heteroleptic cationic iridium(III) complex [IrIII(ppy)2(bpy)]+ ([Ir]+) (ppy = 2-phenylpyridine, bpy = 2,2′-bipyridine) and anionic...

CaSn(OH)6 hydroxides, CaSnO3 oxides and CaSnF6 fluorides: Synthesis and structural filiation. Cationic environment impact on Pr3+ doped compounds luminescence

CaSn(OH)6, CaSnO3 and CaSnF6 compounds were elaborated from a “one-batch” synthesis route: the coprecipitation of the pure double hydroxide leads to pure double oxide or fluoride after annealing treatments under air or HF as anhydrous gas, respectively. Structural and morphological features of the three matrices were carefully investigated by X Ray Diffraction analysis and Scanning Electron Microscopy, respectively. In addition, the luminescent properties of the Pr-doped compounds were performed and compared. The nanometric size of the double hydroxide inhibits the luminescence. The interpretation of the emission spectra obtained for Pr-doped CaSnO3 and CaSnF6 compounds is based on the covalence/ionic balance of the M–O or M–F bonds.

Formation of new polymorphs without any nucleation step. Desolvation of the rimonabant monohydrate: directional crystallisation concomitant to smooth dehydration.

Rimonabant monohydrate can be dehydrated at 100 °C or above with complete loss of structural information; in this case the amorphous material can lead to nucleation and crystal growth. The water molecules can also be removed by a smooth process below Tg (78 °C) of the anhydrous phase. In that latter process there is a structural filiation between the mother phase and the daughter phase. The solvent molecules escape from the mother structure by using a network of specific channels; the new non-solvated material undergoes a relaxation process similar to a directional crystallization. By this soft mode of desolvation inside a material which has a very limited mobility, the nucleation of a non-solvated material can be avoided. The structural information contained in the mother phase is not used as a template for crystal growth but it is more a progressive rearrangement of the new desolvated material towards the nearest well in energy. Thus, a metastable new polymorph of a non-solvated component can be obtained by: (i) the crystallization of the component as a solvate and (ii) a smooth desolvation at T < Tg. Other parameters liable to interfere with that transmission of structural information are discussed.

Physical transformations of the active pharmaceutical ingredient BN83495: enantiotropic and monotropic relationships. Access to several polymorphic forms by using various solvation–desolvation processes

BN83495 is an API in development, used in the treatment of hormone dependent cancers. This molecule exhibits an interesting polymorphic landscape consisting of three polymorphic forms (I, II, and III), three 〈1:1〉 DMSO solvate polymorphs, and one 1,4-dioxane hemi-solvate. Among the three DMSO solvates, one can only be obtained in the presence of an inorganic impurity: the letovicite. Between the two polymorphic forms I and III, an enantiotropic transition has been highlighted. This solid–solid transition (Form I → Form III) seems to be controlled by the mosaicity of the particles, where both polymorphic form domains cohabit and this could remain unchanged for months. The reverse transition has not been detected in the solid state; slurrying in a solvent appears necessary to return to Form I. Each of the three polymorphs can be obtained by soaking in cold water the appropriate solvated compound. The crystal structure of each phase was determined from single crystal X-ray diffraction, except for Form II (the monotropic form under normal pressure). The analyses of the starting and final crystal structures involved in a desolvation process led to the proposal of mechanisms with and without transmission of structural information from the mother phase (i.e. the initial solvate) to the daughter phase. The presence of direct hydrogen bonds between BN83495 molecules in DMSO-I and 1,4-dioxane hemi-solvate seems to ensure the structural filiations during the desolvation mechanisms leading respectively to Form III and Form II.

New Hybrid Layered Molybdates Based on 2/∞[MonO3n+1]2– Units (n = 7, 9) with Systematic Organic–Inorganic Interfaces

Two new hybrid organic-inorganic molybdates based on layered (2/∞)[Mo(n)O(3n+1)](2-) blocks and organoammonium cations (+)(Me(x)H(3-x)N)(CH(2))(6)(NH(3-x)Me(x))(+) (x = 0-1), namely, (H(3)N(CH(2))(6)NH(3))[Mo(7)O(22)]·H(2)O (1) and (MeH(2)N(CH(2))(6)NH(2)Me)[Mo(9)O(28)] (2), have been synthesized under hydrothermal conditions. The (2/∞)[Mo(9)O(28)](2-) unit in 2 is an unprecedented member of the (2/∞)[Mo(n)O(3n+1)](2-) family with the n value extended to 9. The structural filiation between the (2/∞)[Mo(n)O(3n+1)](2-) (n = 5, 7, 9) blocks is well established, and their structural similarity with the (2/∞)[MoO(3)] slabs in α-MoO(3) is also discussed. Single-crystal X-ray analyses show that the (2/∞)[Mo(n)O(3n+1)](2-) layers in 1 and 2 are pillared in the three-dimensional networks by the organic cations with a similar connection at the organic-inorganic interface. In addition, a correlation between the topology of the (2/∞)[Mo(n)O(3n+1)](2-) blocks in 1 and 2 and the overall sizes of the associated organic cations is pointed out. Finally, the efficiency of Fourier transform Raman spectroscopy to easily discriminate the different (2/∞)[Mo(n)O(3n+1)](2-) blocks (n = 5, 7, 9) in hybrid organic-inorganic layered molybdate materials is clearly evidenced.

Syntheses and crystal structures of new vanadium(IV) oxyphosphates M(VO) 2(PO 4) 2 with M = Co, Ni

We have extended our research interest on titanium oxyphosphates (M II(TiO) 2(PO 4) 2, with M II = Mg, Fe, Co, Ni, Cu, Zn) to vanadium oxyphosphates M II(V IVO) 2(PO 4) 2 (M II = Co, Ni). For each compound two phases, named α and β according to synthesis conditions, have been stabilized at room temperature, then characterized. The four crystal structures M(VO) 2(PO 4) 2 (α and β for M = Co, Ni) have been determined in monoclinic P2 1/ c space group using X-ray single crystals diffraction data. Structure of the α phase is derived from the Li(TiO)(PO 4) (orthorhombic Pnma) and LiNi 0.50(TiO) 2(PO 4) 2 (monoclinic P2 1/ c) types, with cell parameters: a = 6.310(1) Å, b = 7.273(1) Å, c = 7.432(1) Å, β = 90.43(1)° for M = Co, and a = 6.297(2) Å, b = 7.230(2) Å, c = 7.421(2) Å, β = 90.36(2)° for M = Ni. Structure of the β phase is derived from the Ni(TiO) 2(PO 4) 2-type (monoclinic P2 1/ c) with cell parameters: a = 7.2742(2) Å, b = 7.2802(2) Å, c = 7.4550(2) Å, β = 120.171(2)° for M = Co, and a = 7.2691(2) Å, b = 7.2366(2) Å, c = 7.4453(2) Å, β = 120.231(2)° for M = Ni. All these structures consist of a three dimensional (3D) framework built up of infinite chains of tilted corner-sharing [VO 6] octahedra, cross-linked by corner-sharing [PO 4] tetrahedra. The M 2+ ion (M = Co, Ni) is located in a triangular based antiprism which shares faces with two [VO 6] octahedra. Structural filiation is discussed based on a common structural unit, a sheet where divalent cations M 2+ (M = Co, Ni) are inserted. A thermal study of the α ↔ β transition is also presented.

Structure solution and refinement from powder or single-crystal diffraction data? Pros and cons: An example of the high-pressureβ′-polymorph of glycine

The structure of a high-pressure polymorph of glycine (theβ′-polymorph formed reversibly at 0.8 GPa from theβ-polymorph) was determined from high-resolution X-ray powder diffraction data collectedin situin a diamond anvil cell at nine pressure points up to 2.6 GPa. X-ray powder diffraction study gave a structural model of at least the same quality as that obtained from a single-crystal diffraction experiment. The difference between the powder-diffraction and the single-crystal models is related to the orientation of the NH3-tails and the structure of the hydrogen-bonds network. The phase transition between theβ- andβ′-polymorphs is reversible and preserves a single crystal intact. No transformations were observed between theβ-,α-, andβ′-polymorphs on compression and decompression, although theα- andβ′-polymorphs belong to the same space group (P21/c). The instability of theβ- andγ-forms with pressure can be predicted easily when considering the densities of their structures versus pressure. The direction of the transformation (i.e., which of the high-pressure polymorphs is formed) is determined by structural filiation between the parent and the high-pressure phases because of the kinetic control of the transformations.

Role of structural and macrocrystalline factors in the desolvation behaviour of cortisone acetate solvates

A combined analysis of structural data and experimental results (DSC, temperature-resolved XRPD and hot stage optical microscopy) revealed that the dehydration mechanism of cortisone acetate monohydrate (CTA·H2O) involves a collective and anisotropic departure of water molecules followed by a cooperative structural reorganization toward the anhydrous polymorph CTA (form 2). In spite of the lack of crystal structure data, it can be postulated from experimental data that thermal decomposition of the dihydrated form (CTA·2H2O) and of the tetrahydrofuran solvate (CTA·THF) toward another polymorph (CTA (form 3)) also proceeds according to a cooperative mechanism, thus giving rise to probable structural filiations between these crystalline forms of CTA. The crystal structure determination of two original solvates (CTA·DMF and CTA·DMSO) indicates that these phases are isomorphous to the previously reported acetone solvate. However, their desolvation behaviour does not involve a cooperative mechanism, as could be expected from structural data only. Instead, the decomposition mechanism of CTA·DMF and CTA·DMSO starts with the formation of a solvent-proof superficial layer, followed by the partial dissolution of the enclosed inner part of crystals.

Synthesis, structure, and characterization of hybrid materials: [Ce(H2O)]2[O2C(CH2)2CO2]3 and [Sm(H2O)]2[O2C(CH2)2CO2]3·H2O

The rare-earth dicarboxylate hybrid materials [Ce(H2O)]2[O2C(CH2)2CO2]3 ([Ce(Suc)]) and [Sm(H2O)]2[O2C(CH2)2CO2]3·H2O ([Sm(Suc)]) have been hydrothermally synthesized (200°C, 3 days) under autogenus pressure. [Ce(Suc)] is triclinic, a=7.961 (3)Å, b=8.176 (5)Å, c=14.32 (2)Å, α=97.07° (7), β=96.75° (8), γ=103.73° (6), and z=2. The crystal structure of this compound has been determined using 3120 unique single crystal data. The final refinements let the agreement factors R1 and wR2(F2) converge to 0.0138 and 0.0363, respectively. [Ce(Suc)] is built up from infinite chains of edge-sharing nine-fold coordinated cerium atoms running along [100]. These chains are interconnected by the carbon atoms of the succinate anions, leading to a three-dimensional hybrid framework. The cell constants of [Sm(Suc)], isotypic with monoclinic C2/c [Pr(H2O)]2[O2C(CH2)2CO2]3·H2O ([Pr(Suc)]), were refined starting from X-ray powder data: a=20.275 (3)Å, b=7.919 (6)Å, c=14.130 (3)Å, and β=121.45° (1). Despite its lower symmetry, [Ce(Suc)] presents an important structural filiation with [Sm(Suc)]

Crystal Structure of BiZn2PO6. Filiation between Related Compounds

The BiZn2PO6 room-temperature crystal structure was determined from powder X-ray data using the Rietveld method. This compound crystallizes in space group Pnma, with Z=4, a=11.897(2) Å, b=5.277(1) Å, c=7.819(2) Å. The structure contains ZnO5 square pyramids associated by edge in dimers which are connected by corners to form infinite independent [ZnO4−3]∞ zigzag double chains. The interconnection is achieved by PO3−4 tetrahedra creating six-sided tunnels parallel to the b axis containing Bi3+ cations. An intensive discussion about the structural filiation between the different members of the BiM2XO6 series (M=Mg, Ca, Cu, Cd, Pb; X=P, V, As) is given. A thermal investigation showed that BiZn2PO6 undergoes a P-to-B phase transition at about 325°C while this isostructural BiCu2PO6 remains structurally unchanged until 750°C.

The soft chemistry of molybdenum and tungsten oxides: a review

Through various examples the potential of soft chemistry is illustrated. Using the structural filiation between a mother and a daughter phase, supermetastable and metastable oxides have been obtained. Studies have shown that these oxides are good materials for comparative studies of intercalation chemistry. These studies have been performed in order to compare the intercalation effects of hydrogen and lithium in the metastable and supermetastable oxides in accordance with their structures (ID or 3D tunnels) and with the Mo/W ratio. It can be concluded that the more isotrope the structures are (3D tunnels of the pyrochlore structure for example), the less distorted they are. Lithium leads to an amorphization at high intercalation rates, which is not observed in the case of hydrogen. Molybdenum compounds allow high intercalation rates but deintercalation is difficult to perform; it is the reason why it is difficult to consider their use as electrochromic displays.

Soft chemical synthesis of a high-pressure phase of molybdenum trioxide: MoO 3-II

Topotactic dehydration of either the white molybdenum trioxide monohydrate, MoO 3 · H 2O, or the hemihydrate, MoO 3 · 1 2 H 2O, provides a convenient synthetic route to a high-pressure phase of molybdenum trioxide, MoO 3-II. The structural filiations between the various molybdenum trioxide and trioxide hydrate phases are delineated, and simple mechanistic models for the transformations are proposed.

Acid-leaching of sodium brannerite: synthesis and structure of Na 0.13(V 0.13Mo 0.87)O 3 · nH 2O

In dilute hydrochloric acid NaVMoO 6, which has a layered “brannerite” structure, participates in an acid-leaching reaction that results in the formation of a metastable compound with the stoichiometry Na 0.13(V 0.13Mo 0.87)O 3 · nH 2O and the structure of “hexagonal” MoO 3. The locations of the sodium ions and water molecules in the channels of this structure, space group P6 3 with a = 10.628(1) Å and c = 3.6975(7) Å, were determined through Rietveld refinement of powder neutron diffraction data collected on deuterated samples. The water molcules are important in providing a stable environment for the sodium ions, which are octahedrally coordinated by four framework oxygen atoms and two water molecules. In an attempt to understand the mechanistic aspects of the acid-leaching reaction, samples of the hexagonal phase were formed with a range of V : Mo contents from aqueous NaVMo solutions via conventional precipitation methods. Although phases could be stabilized with the same crystallography as the brannerite-derived products, the solution precipitates contained vacancies in the transition metal framework and a higher concentration of sodium in the channels. These compositional differences led to a significant reduction in the apparent high-temperature stability of the solution-derived phases compared to that of their brannerite-derived counterparts. There is some evidence to suggest that the structural filiation between brannerite and hexagonal MoO 3 may be responsible for the unique stoichiometry and stability of the products of the acid-leaching reactions and that the acid-leaching reactions do not proceed through a simple dissolution/precipitation mechanism.

Impact of regularity in structure-property relationships

The regular evolution of properties with structural modification is quantitatively formulated. It is defined in a structural space which is exhaustive, ordered, flexible and explicit. It is detected along the ordered pathways of structural filiations by inference tools, which take into account the experimental precision and proceed by a heuristic modulation of the initial representation space. The introduction of nuances in the quantitative formulation of regularity leads to diverse tools for setting up and exploiting the relationships. These latter constitute a prediction law, which is both simple and as precise as the measurements. The detected regularities make for a generalization of certain structural effects and suggest a fruitful interpretation. Zeroth- and first-order regularities, characteristic of strongly linear variation, are used to safely extrapolate the prediction range and to orient experimental planning.

Synthesis of vanadium bronzes M xV 2O 5 through sol-gel processes II - orthorhombic bronzes (M = Ba 2+, Ni 2+, Al 3+, Fe 3+)

The bronzes M xV 2O 5 (M=Ba 2+,Ni 2+,Al 3+,Fe 3+) are synthesized via a sol-gel process (SGP bronzes). New compounds have been prepared: they have an α orthorhombic structure which differs considerably from the structures of the same compounds prepared by solid state reaction (SSR bronzes). The thin layers which have been obtained show preferred orientation. The orientation-type depends on the cation: the layers parallel to the substrate are either parallel to the V 2O 5 orthorhombic layers plane (case of Fe 3+ and Al 3+), either perpendicular to it (case of Ba 2+), either parallel or perpendicular to it (case of Ni 2+). The interpretation in terms of a structural filiation between the hydrate phase and the oxide phase can be applied to the exchanged xerogel and the bronze.

Structural filiation between a new hydrate [formula omitted] and a new monoclinic form of MoO 3 obtained by dehydration

A new hydrate MoO 3· 1 3 H 2O has been prepared byhydrothermal at 110°C of aqueous solution of molybdic acid. From X-ray powder data, the structure of this hydrate has been established by analogy with WoO 3 1 3 H 2O , and confirmed by IR spectroscopy (orthorhombic cell, a=12.647(3), b=7.697(2), c=7.338(2), Z=12). By dehydration, an entirely new MoO 3 oxide with ReO 3-type structure is formed (monoclinic cell, a=7.118(1), b=5.366(1), c=5.568(1), β=91.99(1), z=4). This monoclinic MoO 3 is metastable and transforms in the orthorhombic MoO 3 at about 400°C. These tungsten and molybdenum hydrates are isostructural; in both cases, the dehydration proceeds via an oriented oxide/hydrate nucleation which occurs respectively on the (001) and (100) planes. These different nucleations explain why the two hydrates engender two structurally different metastable oxides: hexagonal WO 3 and monoclinic MoO 3.

Etude cristallographique du systeme ternaire [formula omitted] Á 700°C

The study of the ternary system obtained from LiVWO 6 phase by the substitutions V 5++ Li + = W 6+ + □ and et 2V 5+ = W 6+ + V 4+ has allowed to delimit at 700°C the homogeneity ranges of two phases, one of the brannerite type, the other of the columbite type. A complete structural study shows a disordered distribution for the vanadium and tungsten atoms in the crystallographic sites except for a random composition of LiV 1 2 W 3 2 O 6 where a crystallographic order has been determined. The authors show the structural filiation between the PbO 2α, columbite and LiV 1 2 W 3 2 O 6 phases.