Synchrotron Powder Diffraction Data Research Articles

Powder X-ray diffraction of bendamustine hydrochloride monohydrate, C16H22Cl2N3O2Cl·H2O

Bendamustine hydrochloride monohydrate (marketed as Treanda®) is a nitrogen mustard purine analog alkylator used in the treatment of chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphomas. Commercial bendamustine hydrochloride monohydrate crystallizes in the monoclinic space group P21/c (14), with a = 4.71348(4) Å, b = 47.5325(3) Å, c = 8.97458 (5) Å, β = 96.6515(8)°, V = 1997.161(23) Å3, and Z = 4. A reduced cell search in the Cambridge Structural Database yielded a previously reported crystal structure (Allen, 2002), which did not include hydrogens (Reck, 2006). In this work, the sample was ordered from Santa Cruz Biotechnology, and analyzed as received. The room-temperature crystal structure was refined using synchrotron (λ = 0.413896 Å) powder diffraction data, density functional theory (DFT), and Rietveld refinement techniques. Hydrogen positions were included as part of the structure, and recalculated during the refinement. The diffraction data were collected on beamline BM-11 at the Advanced Photon Source, Argonne National Laboratory. Figure 1 shows the powder X-ray diffraction pattern of the compound. The pattern is included in the Powder Diffraction File as entry 00-064-1508.

The Influence of Isomerism on Crystallization in Aluminum Pyridinedicarboxylate Coordination Compounds

The reactions of three isomeric pyridinedicarboxylic acid linkers – 2,4‐, 2,6‐, and 3,5‐pyridinedicarboxylic acid – with various aluminum salts were investigated by high‐throughput solvothermal synthesis. Two coordination compounds were obtained from the symmetrical linkers (2,6‐ and 3,5‐pyridinedicarboxylic acid). The former is based on molecular Al–O dimers, similar to those reported in the coordination polymer CAU‐16. The latter forms a porous extended framework and is a member of the CAU‐10 family of compounds. Full characterization of both compounds is reported. Crystal structures were determined from high‐resolution synchrotron powder diffraction data. The number of guest water molecules determined crystallographically is in excellent agreement with the number found by thermogravimetric and elemental analyses. It was found that the CAU‐10 analogue undergoes a reversible, displacive phase transition from a non‐centrosymmetric to a centrosymmetric space group on loss of guest water molecules, due to guest‐framework interactions.

Ab initio structure determination of [Eu5(C2H4O2)6(CH3CO2)3] n by X-ray powder diffraction

The compound [Eu5(C2H4O2)6(CH3CO2)3] n was synthesized by dissolving acetate europium salt in ethylene glycol solvent and heating under reflux for a short time. Its structure was solved ab initio from synchrotron powder diffraction data using optimization methods in direct space. The compound has a very large unit-cell volume of 23679 Å3 and the highest centred cubic symmetry space group, Ia{\bar 3}d (No. 230). The porous metal–organic framework structure is similar to those usually observed in zeolites, with pores volumes of 82 Å3, which is of potential interest for gas storage.

AI SeC2 H (AI =K, Rb, Cs): Crystalline Compounds with the Elusive - Se-C≡C-H Anion.

By reaction of alkali metal acetylides, AI C2 H (AI =K, Rb, Cs), with elemental selenium in liquid ammonia highly crystalline powders of AI SeC2 H were obtained. The structure analysis based on the resulting synchrotron powder diffraction data revealed that all compounds crystallize in an orthorhombic unit cell (Cmc21 , Z=4) exhibiting the elusive - SeC2 H anion, which is unprecedented in a crystalline compound up to now. Elemental analysis and IR spectroscopic data confirm this finding. Upon heating, AI SeC2 H compounds release acetylene based on DSC/TGA experiments resulting in powders with the proposed composition AI 2 Se2 (C2 ). The resulting powders were indexed with small cubic unit cells, but a reasonable structural model could not be developed up to now. Upon exposure of AI SeC2 H compounds to water elemental selenium is formed again.

Ca12[Mn19N23] and Ca133[Mn216N260]: Structural Complexity by 2D Intergrowth

AbstractTwo new calcium nitridomanganates, Ca12[Mn19N23] (P3, a=11.81341(3) Å, c=5.58975(2) Å, Z=1) and Ca133[Mn216N260] ( , a=39.477(1) Å, c=5.5974(2) Å, Z=1), were obtained by a gas–solid reaction of Ca3N2 and Mn with N2 at 1273 K and 1223 K, respectively. The crystal structure of Ca12[Mn19N23] was determined from high‐resolution X‐ray synchrotron powder diffraction data, whereas single‐crystal X‐ray diffraction was employed to establish the crystal structure of the Ca133[Mn216N260] phase, which classifies as a complex metallic alloy (CMA). Both crystal structures have 2D nitridomanganate layers containing similar building blocks but of different levels of structural complexity. Bonding analysis as well as magnetic susceptibility and electron spin resonance measurements revealed that only a fraction of the Mn atoms in both structures carries a localized magnetic moment, while for most Mn species the magnetism is quenched as a result of metal–metal bond formation.

Ca12 [Mn19 N23 ] and Ca133 [Mn216 N260 ]: Structural Complexity by 2D Intergrowth.

Two new calcium nitridomanganates, Ca12 [Mn19 N23 ] (P3, a=11.81341(3) Å, c=5.58975(2) Å, Z=1) and Ca133 [Mn216 N260 ] (P3‾ , a=39.477(1) Å, c=5.5974(2) Å, Z=1), were obtained by a gas-solid reaction of Ca3 N2 and Mn with N2 at 1273 K and 1223 K, respectively. The crystal structure of Ca12 [Mn19 N23 ] was determined from high-resolution X-ray synchrotron powder diffraction data, whereas single-crystal X-ray diffraction was employed to establish the crystal structure of the Ca133 [Mn216 N260 ] phase, which classifies as a complex metallic alloy (CMA). Both crystal structures have 2D nitridomanganate layers containing similar building blocks but of different levels of structural complexity. Bonding analysis as well as magnetic susceptibility and electron spin resonance measurements revealed that only a fraction of the Mn atoms in both structures carries a localized magnetic moment, while for most Mn species the magnetism is quenched as a result of metal-metal bond formation.

Hexagonal Perovskite Ba4Fe3NiO12 Containing Tetravalent Fe and Ni Ions.

BaFe xNi1- xO3 with end members of BaNiO3 ( x = 0) and BaFeO3 ( x = 1), which, respectively, adopt the 2H and 6H hexagonal perovskite structures, were synthesized, and their crystal structures were investigated. A new single phase, Ba4Fe3NiO12 ( x = 0.75), that adopts the 12R perovskite structure with the space group R3̅ m ( a = 5.66564(7) Å and c = 27.8416(3) Å), was found to be stabilized. Mössbauer spectroscopy results and structure analysis using synchrotron and neutron powder diffraction data revealed that nominal Fe3+ occupies the corner-sharing octahedral site while the unusually high valence Fe4+ and Ni4+ occupy the face-sharing octahedral sites in the trimers, giving a charge formula of Ba4Fe3+Fe4+2Ni4+O11.5. The magnetic properties of the compound are also discussed.

New 2D and 3D Coordination Polymers by Dehydration of 1∞[MII(tF‐BDC)(H2O)4] (MII = Zn2+, Co2+, Ni2+ and tF‐BDC2– = Tetrafluoroterephthalate)

By dehydration of the known coordination polymers 1∞[MII(tF‐BDC)(H2O)4] (MII = Co2+, Zn2+ and tF‐BDC2– = tetrafluoroterephthalate) the homoleptic anhydrous coordination networks 3∞[MII(tF‐BDC)] were obtained as polycrystalline powders. Their crystal structures (C2/c, Z = 4) were solved and refined by means of synchrotron powder diffraction data. These structures are characterized by [MIIO4] tetrahedra, which are connected by the tF‐BDC2– linkers to form a 3D non‐porous coordination network. The dehydration leads to a change from a [MIIO6] octahedral coordination in the hydrate to a tetrahedral coordination sphere in the anhydrous compound. For the cobalt compounds this leads to a color change from pale rose to deep blue upon heating and dehydration, which was analyzed by means of UV/Vis/NIR spectroscopy and measurements of the magnetic susceptibilities. In contrast, 1∞[NiII(tF‐BDC)(H2O)4] can only partly be dehydrated to form 2∞[NiII(tF‐BDC)(H2O)2] (P1, Z = 1) with retention of the octahedral [NiIIO6] coordination in both compounds. At higher temperatures the tF‐BDC2– linker starts to decompose, before a complete dehydration can take place.

Coexistence of ferroelectric phases and electric field induced structural transformation in sodium potassium bismuth titanate ceramics

Lead-free sodium potassium bismuth titanate (1−x)[Na0.5Bi0.5TiO3]-x[K0.5Bi0.5TiO3] (NKBTx) ceramics have been believed to be a rhombohedral crystal system with R3c symmetry up to x = 0.16 mole fraction, right now. For the first time, on the contrary, we have disclosed the existence of a low-symmetry (MA)-type monoclinic phase (69%) along with rhombohedral R3c (31%) in the NKBT0.10 sample from Rietveld studies on conventional and high-energy synchrotron powder diffraction data in the unpoled state. The peak splitting and reduced FWHM of {110}pc and {111}pc reflections after poling indicate the field-induced structural transformation. Rietveld analysis reveals that the monoclinic (Cc) phase is partially transformed to rhombohedral (R3c) at 50 kV/cm. Two distinct dielectric anomalies are noticed in the dielectric curve at 120 and 310 °C corresponding to freezing temperature (Tf) and glass-like transition temperature (Tm), respectively. The dielectric diffusivity (γ) estimated from the modified Curie-Weiss law reveals that the sample has a relaxor behavior. Structural inhomogeneity in the nanoscale region due to cation disorder in the A-site causes relaxing nature. A well-saturated square-like ferroelectric hysteresis loop is obtained with a remnant polarization and a coercive field of 35.8 μC/cm2 and 47 kV/cm, respectively. A piezoelectric constant (d33) of 85 pC/N is obtained for the sample which is somewhat higher than that of pure Na0.5Bi0.5TiO3 ceramics.

Ba4[Mn3N6], a Quasi-One-Dimensional Mixed-Valent Nitridomanganate (II, IV)

The mixed-valent nitridomanganate Ba4[Mn3N6] was prepared using a gas–solid high temperature route. The crystal structure was determined employing high resolution synchrotron powder diffraction data: space group Pbcn, a = 9.9930(1) Å, b = 6.17126(8) Å, c = 14.4692(2) Å, V = 892.31(2) Å3, Z = 4. The manganese atoms in the structure of Ba4[Mn3N6] are four-fold coordinated by nitrogen forming infinite corrugated chains of edge-sharing [MnN4] tetrahedra. The chains demonstrate a complete charge order of Mn species. Magnetization measurements and first principle calculations indicate quasi-one dimensional magnetic behavior. In addition, chemical bonding analysis revealed pronounced Mn–Mn interactions along the chains.

Determining the Crystal Structures of Peptide Analogs of Boronic Acid in the Absence of Single Crystals: Intricate Motifs of Ixazomib Citrate Revealed by XRPD Guided by ss-NMR

Uncertainties in the structure determination of peptide analogs of boronic acid, exacerbated by the many coordination modes of boron, represent an obstacle in understanding their role in living organisms and thus also in developing the next generation of anticancer drugs. For that reason, we present here a general experimental-computational strategy allowing structure determination of complex boronic acid derivatives with extensive conformational variability. We demonstrate successful solution of the crystal structures of two nonsolvated polymorphs of ixazomib citrate directly from synchrotron powder diffraction data, which is challenging because the two molecules in the asymmetric unit cell that exhibit 32 degrees of conformational freedom push the limits of current solution procedures. We used a novel two-step Rietveld refinement based on DFT-D restraints to improve information quality derived from powder diffraction data to be comparable with that of single-crystal solutions. NMR crystallography was ap...

The Smaller the Better: Hosting Trivalent Rare-Earth Guests in Cu–P Clathrate Cages

Summary The most striking difference between the trivalent rare-earth cations and their alkali and alkaline-earth peers is the presence of localized 4 f electrons. Placing trivalent rare-earth cations inside fullerene molecules or in between blocks of intermetallics has given rise to a plethora of fascinating properties and materials. A long-sought-after yet undiscovered material is a semiconducting compound with rare-earth cations situated inside the oversized polyhedral cages of a three-dimensional framework. In this work, we present a synthesis of unconventional clathrates, Ba 8−x R x Cu 16 P 30 , with the smallest pentagonal dodecahedral cages encapsulating La 3+ and Ce 3+ . Their composition and crystal structure were unambiguously determined by a combination of synchrotron powder diffraction, time-of-flight neutron powder diffraction, scanning transmission electron microscopy, and electron energy-loss spectroscopy. Our quantum-mechanical calculations and experimental characterizations show that the incorporation of the rare-earth cations significantly enhances hole mobility and reduces hole concentration, resulting in a drastic (700%) increase in the thermoelectric performance.

Phenytoin sodium monohydrate, C15H11N2O2Na(H2O)

The crystal structure of phenytoin sodium monohydrate at 295 K has been refined using synchrotron powder diffraction data, and optimized using density functional techniques.

The crystal structure of MoO2(O2)H2O

The crystal structure of MoO2(O2)H2O has been solved by analogy with the WO2(O2)H2O structure and refined with synchrotron powder diffraction data obtained from beamline 08B1-1 at the Canadian Light Source. Rietveld refinement, performed with the software package GSAS, yielded monoclinic lattice parameters of a = 12.0417(4) Å, b = 3.87003(14) Å, c = 7.38390(24) Å, and β = 78.0843(11)° (Z = 4, space group P21/n). The structure is composed of double zigzag molybdate chains running parallel to the b-axis. The Rietveld refined structure was compared with density functional theory (DFT) calculations performed with CRYSTAL14, and show strong agreement with the DFT optimized structure.

Impact of Fluorination on Phase Stability, Crystal Chemistry, and Capacity of LiCoMnO4 High Voltage Spinels

Fluorinated LiCoMnO4–yFy (y = 0, 0.05, 0.1) spinel electrodes, electrochemically active at 5–5.3 V versus Li/Li+, show enhanced phase purity and enhanced capacity with increasing y. We disclose the impact of fluorination on the phase purity and reversible capacity of LiCoMnO4 via joint Rietveld refinement of neutron and synchrotron powder diffraction data, combined with micro-Raman spectroscopy. It is found that fluorination stabilizes the spinel phase and hinders precipitation of Li2MnO3 as a secondary phase, which controls the cation distribution on tetrahedral and octahedral sites in spinel. That is to say, for higher fluorine content the cobalt occupancy at the tetrahedral site in spinel decreases, and the lithium occupancy increases. Accordingly, the number of lithium sites that are available for electrochemical extraction and insertion of lithium ions is raised so that the capacity is increased. Further investigation of the lithium ion diffusion by means of cyclic voltammetry at different scan rates...

Cluster Formation in the Superconducting Complex Intermetallic Compound Be21Pt5.

Materials with the crystal structure of γ-brass type (Cu5Zn8 type) are typical representatives of intermetallic compounds. From the electronic point of view, they are often interpreted using the valence electron concentration approach of Hume-Rothery, developed previously for transition metals. The γ-brass-type phases of the main-group elements are rather rare. The intermetallic compound Be21Pt5, a new member of this family, was synthesized, and its crystal structure, chemical bonding, and physical properties were characterized. Be21Pt5 crystallizes in the cubic space group F4̅3m with lattice parameter a = 15.90417(3) Å and 416 atoms per unit cell. From the crystallographic point of view, the binary substance represents a special family of intermetallic compounds called complex metallic alloys (CMA). The crystal structure was solved by a combination of synchrotron and neutron powder diffraction data. Besides the large difference in the scattering power of the components, the structure solution was hampered by the systematic presence of very weak reflections mimicking wrong symmetry. The structural motif of Be21Pt5 is described as a 2 × 2 × 2 superstructure of the γ-brass structure (Cu5Zn8 type) or 6 × 6 × 6 superstructure of the simple bcc structural pattern with distinct distribution of defects. The main building elements of the crystal structure are four types of nested polyhedral units (clusters) with the compositions Be22Pt4 and Be20Pt6. Each cluster contains four shells (4 + 4 + 6 + 12 atoms). Clusters with different compositions reveal various occupation of the shells by platinum and beryllium. Polyhedral nested units with the same composition differ by the distance of the shell atoms to the cluster center. Analysis of chemical bonding was made applying the electron localizability approach, a quantum chemical technique operating in real space that is proven to be especially efficient for intermetallic compounds. Evaluations of the calculated electron density and electron localizability indicator (ELI-D) revealed multicenter bonding, being in accordance with the low valence electron count per atom in Be21Pt5. A new type of atomic interactions in intermetallic compounds, cluster bonds involving 8 or even 14 atoms, is found in the clusters with shorter distances between the shell atoms and the cluster centers. In the remaining clusters, four- and five-center bonds characterize the atomic interactions. Multicluster interactions within the polyhedral nested units and three-center polar intercluster bonds result in a three-dimensional framework resembling the structural pattern of NaCl. Be21Pt5 is a diamagnetic metal and one of rather rare CMA compounds revealing superconductivity (Tc = 2.06 K).

Completing the Series: New Coordination Networks of Composition 3∞[RE2(ADC)3(H2O)6]·2H2O with RE = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Y and ADC2– = Acetylenedicarboxylate (–O2C–C≡C–CO2–)

The crystal structures of 3∞[RE2(ADC)3(H2O)6]·2H2O (RE = Pr, Nd, Sm, Eu, Tb, Dy) were solved and refined from X‐ray single crystal data. They crystallize in a structure type already known for RE = La, Ce and Gd (P1, no. 2, Z = 2), which is characterized by REO9 polyhedra forming dimeric units being the nodes of a 3D framework structure linked by ADC2– anions (–O2C–C≡C–CO2– = acetylenedicarboxylate). From synchrotron powder diffraction data it was shown that isostructural coordination networks are formed for RE = Ho, Er, Y, whereas for RE = Tm, Yb, Lu a new structure type crystallizing in a highly complex crystal structure with a large orthorhombic unit cell is found. All compounds are obtained by slow evaporation of an aqueous solution containing RE(OAc)3·xH2O and acetylenedicarboxylic acid (H2ADC). The coordination networks of composition 3∞[RE2(ADC)3(H2O)6]·2H2O were thoroughly investigated by thermal analysis and for RE = Eu, Tb, a strong red and green photoluminescence was observed and investigated by means of UV/Vis spectroscopy.

Crystal Structures of Z and E ortho‐Tetrafluoroazobenzene

AbstractThe crystal structures of Z‐ (Pna21, Z=4; single‐crystal X‐ray diffraction data) and E‐ortho‐tetrafluoroazobenzene (Pna21, Z=4; synchrotron powder diffraction data) were solved and refined. These structural analyses reveal that the phenyl rings are almost coplanar in the E isomer, whereas a tilting by 67.8(5)° was found in the Z isomer. This leads to significantly different molecular shapes (longest elongations 13.2 Å x 8.1 Å x 4.0 Å for the E isomer vs. 9.6 Å x 7.0 Å x 6.9 Å for the Z isomer). A comparison of the supramolecular structures of Z‐ and E‐ortho‐tetrafluoroazobenzene with other known fluorinated azobenzenes shows that mainly H…F interactions occur in both isomers of ortho‐tetrafluoroazobenzene, whereas H…F and F…F interactions exist in E‐4H,4H’‐octafluoroazobenzene, only F…F interactions in E‐perfluoroazobenzene, and N…C, F…C as well as F…F interactions in Z‐perfluoroazobenzene.

Local Disorder and Tunable Luminescence in Sr1-x/2Al2-xSixO4 (0.2 ≤ x ≤ 0.5) Transparent Ceramics.

Eu-doped Sr1-x/2Al2-xSixO4 (x = 0.2, 0.4, and 0.5) transparent ceramics have been synthesized by full and congruent crystallization from glasses prepared by aerodynamic levitation and laser-heating method. Structural refinements from synchrotron and neutron powder diffraction data show that the ceramics adopt a 1 × 1 × 2 superstructure compared to the SrAl2O4 hexagonal polymorph. While the observed superstructure reflections indicate a long-range ordering of the Sr vacancies in the structure, 29Si and 27Al solid-state NMR measurements associated with DFT computations reveal a significant degree of disorder in the fully polymerized tetrahedral network. This is evidenced through the presence of Si-O-Si bonds, as well as Si(OAl)4 units at remote distances of the Sr vacancies and Al(OAl)4 units in the close vicinity of Sr vacancies departing from local charge compensation in the network. The transparent ceramics can be doped by europium to induce light emission arising from the volume under UV excitation. Luminescence measurements then reveal the coexistence of Eu2+ and Eu3+ in the samples, thereby allowing tuning the emission color depending on the excitation wavelength and suggesting possible applications such as solid state lighting.

Observation of Vacancies, Faults, and Superstructures in Ln5Mo2O12 (Ln = La, Y, and Lu) Compounds with Direct Mo-Mo Bonding.

Among oxide compounds with direct metal-metal bonding, the Y5Mo2O12 (A5B2O12) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral B2O10 dimers arranged in one-dimensional edge-sharing chains along the direction of the metal-metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal-metal bonding have integer oxidation states resulting from the lifting of orbital degeneracy typically induced by the metal-metal bonding. Although a monoclinic C2/m structure has been previously proposed for Ln5Mo2O12 (Ln = La-Lu and Y) members of this family based on prior single crystal diffraction data, it is found that this structural model misses many important structural features. On the basis of synchrotron powder diffraction data, it is shown that the C2/m monoclinic unit cell represents a superstructure relative to a previously unrecognized orthorhombic Immm subcell and that the superstructure derives from the ordering of interchangeable Mo2O10 and LaO6 building blocks. The superstructure for this reason is typically highly faulted, as evidenced by the increased breadth of superstructure diffraction peaks associated with a coherence length of 1-2 nm in the c* direction. Finally, it is shown that oxygen vacancies can occur when Ln = La, producing an oxygen deficient stoichiometry of La5Mo2O11.55 and an approximately 10-fold reduction in the number of unpaired electrons due to the reduction of the average Mo valence from +4.5 to +4.05, a result confirmed by magnetic susceptibility measurements. This represents the first observation of oxygen vacancies in this family of compounds and provides an important means of continuously tuning the magnetic interactions within the one-dimensional octahedral chains of this system.