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van der Waals (vdW) magnets are receiving ever-growing attention nowadays due to their significance in both fundamental research on low-dimensional magnetism and potential applications in spintronic devices. The high crystalline quality of vdW magnets is the key to maintaining intrinsic magnetic and electronic properties, especially when exfoliated down to the two-dimensional limit. Here, ultrahigh-quality air-stable vdW CrSBr crystals are synthesized using the direct solid-vapor synthesis method. The high single crystallinity and spatial homogeneity have been thoroughly evidenced at length scales from submm to atomic resolution by X-ray diffraction, second harmonic generation, and scanning transmission electron microscopy. More importantly, specific heat measurements of ultrahigh-quality CrSBr crystals show three thermodynamic anomalies at 185, 156, and 132 K, revealing a stage-by-stage development of the magnetic order upon cooling, which is also corroborated with the magnetization and transport results. Our ultrahigh-quality CrSBr can further be exfoliated down to monolayers and bilayers easily, providing the building blocks of heterostructures for spintronic and magneto-optoelectronic applications.

Four complex metal antimony tartrates have been synthesized in single crystal form by slowly evaporating aqueous solutions of potassium antimony tartrate (tartar emetic) and metal nitrates or chlorides. Crystal structures of these compounds all contain infinite layers formed by linking antimony tartrate dimers with M–O bonds, with M = Li, La, Ce or Nd. Dehydration of the La and Ce compounds at elevated temperatures led to new layered structures via single-crystal to single-crystal transformations.

Seven complex metal antimony tartrates have been synthesized in single crystal form by slowly evaporating aqueous solutions of potassium antimony tartrate (tartar emetic) and divalent metal nitrates or perchlorates. Crystal structures of these compounds all contain infinite chains formed by linking antimony tartrate dimers with divalent metal ions. While infinite chains of antimony tartrate dimers bridged by single Zn2+ ions or by double Mg2+ ions were reported previously, new types of chains with alternating single and double bridging cations are observed in this work.

Transition metal-based compounds with new two-dimensional, triangle-based topology are rare but are of considerable interest because of their unusual magnetic properties. Here we report the synthes...

Materials with two-dimensional, geometrically frustrated, spin-1/2 lattices provide a fertile playground for the study of intriguing magnetic phenomena such as quantum spin liquid (QSL) behavior, b...

Two diamond-shaped and partially fluorinated dehydrobenz[18]annulene macrocycles have been synthesized through a one-pot synthesis relying on fourfold Sonogashira coupling. Single crystal structures of the prepared macrocycles show continuous columnar stacks of these molecules that are mediated by the fluoroarene–alkyne, arene–alkyne, fluoroarene–fluoroarene, and alkyne–alkyne [π···π] interactions instead of the expected fluoroarene–arene [π···π] interaction.

The geometrically frustrated diamond spin chain system has yielded materials with a diversity of interesting magnetic properties but is predominantly limited to compounds with single-spin components. Here, we report the compound [(CH

Author(s): Huang, J; Li, S; Yoon, C; Oh, JS; Wu, H; Liu, X; Dhale, N; Zhou, YF; Guo, Y; Zhang, Y; Hashimoto, M; Lu, D; Denlinger, J; Wang, X; Lau, CN; Birgeneau, RJ; Zhang, F; Lv, B; Yi, M | Abstract: Quasi-one-dimensional (1D) materials provide a superior platform for characterizing and tuning topological phases for two reasons: (i) existence for multiple cleavable surfaces that enables better experimental identification of topological classification and (ii) stronger response to perturbations such as strain for tuning topological phases compared to higher dimensional crystal structures. In this paper, we present experimental evidence for a room-temperature topological phase transition in the quasi-1D material Bi4I4, mediated via a first-order structural transition between two distinct stacking orders of the weakly coupled chains. Using high-resolution angle-resolved photoemission spectroscopy on the two natural cleavable surfaces, we identify the high-temperature β phase to be the first weak topological insulator with two gapless Dirac cones on the (100) surface and no Dirac crossing on the (001) surface, while in the low-temperature α phase, the topological surface state on the (100) surface opens a gap, consistent with a recent theoretical prediction of a higher-order topological insulator beyond the scope of the established topological materials databases that hosts gapless hinge states. Our results not only identify a rare topological phase transition between first-order and second-order topological insulators but also establish a novel quasi-1D material platform for exploring unprecedented physics.

We report a combined experimental and theoretical study of the ${\mathrm{PdSe}}_{2\ensuremath{-}x}{\mathrm{Te}}_{x}$ system. With increasing Te fraction, structural evolutions, first from an orthorhombic phase (space group Pbca) to a monoclinic phase (space group $C2/c)$ and then to a trigonal phase (space group $P\text{\ensuremath{-}}3m1)$, are observed accompanied with clearly distinct electrical transport behavior. The new monoclinic phase $(C2/c)$ belongs to the very rare Verbeekite polymorphism and is discovered within a narrow range of Te composition $(0.3\ensuremath{\le}x\ensuremath{\le}0.8)$. Electronic calculations and detailed transport analysis of the Verbeekite polymorphic ${\mathrm{PdSe}}_{1.3}{\mathrm{Te}}_{0.7}$ phase are presented. In the trigonal phase region, superconductivity with enhanced critical temperature is also observed within a narrow range of Te content $(1.0\ensuremath{\le}x\ensuremath{\le}1.2)$. The rich phase diagram, new polymorphic structure, and abnormally enhanced superconductivity could further stimulate interest to explore new types of polymorphs and investigate their transport and electronic properties in the family of transition metal dichalcogenides, which are of significant interest.

Five extensively fluorinated tetraphenylethylene (TPE) derivatives have been synthesized using Cu-catalyzed C–H functionalization reactions and Stille couplings. Surprisingly, in contrast to the parent TPE, these compounds show little to no aggregation-induced emission (AIE). Instead, photocyclization into fluorinated phenanthrene products occurs.

Cyclotetrabenzoin esters form porous solid-state structures with infinite one-dimensional channels and a Brunauer–Emmett–Teller surface area of ∼570 m2 g–1. Their assembly appears not to involve any strong covalent or noncovalent bonds between individual molecules. The isobutyric ester of cyclotetrabenzoin includes molecules of CS2 within its central cavity in an arrangement resembling an insulated wire.

A porous molecular crystal (PMC) assembled by macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for CO

A porous molecular crystal (PMC) assembled by close-packing of macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for selective CO2 capture. The 7.1´7.1 Å square pore of PMC and its ester C=O group play important roles in improving its affinity for CO2 molecules. Thermodynamically, the benzene walls of macrocycle strongly promote CO2 adsorption via [p···p] interactions at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0´5.0 Å square, which offers kinetic selectivity for CO2 capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. In mixed-gas breakthrough experiments, it exhibits efficient CO2/N2 and CO2/CH4 separations under kinetic flow conditions. Most importantly, the moderate adsorbate–adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption (PSA) processes. The eluted N2 and CH4 are obtained with over 99.9% and 99.8% purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, these properties make cyclotetrabenzoin acetate a promising adsorbent for CO2 separations from flue and natural gases.

Nitriles and terminal alkynes are important compounds in industrial and academic settings. Their supramolecular binding has been challenging without the intervention of metals, because of the small dimensions of their linear –C≡N and –C≡CH groups. Using a combination of crystallography and computation, we have shown that cyclotetrabenzoin esters can host terminal triple bonds of alkynes and nitriles in their electron-poor cavities. Within these cavities, π-clouds of triple bonds can establish favorable and virtually equidistant interactions with the four aromatic walls of the cyclotetrabenzoin skeleton. Binding is selective for aliphatic nitriles and terminal alkynes, with their aromatic counterparts residing outside of the cyclotetrabenzoin cavity. These findings are of relevance in the binding, separations, and activation of these and other linear molecular guests.

Cyclobenzoins are shape-persistent macrocycles of interest in the preparation of optoelectronic and porous materials. New cyclotetrabenzoins derived from biphenyl, naphthalene, and tolane skeletons were synthesized using

Cyclobenzoins are stable and shape-persistent macrocycles which offer promise as components of optoelectronic and porous materials. We report three new cyclotetrabenzoins, derived from biphenyl, naphthalene, and tolane skeletons. Their synthesis relied on the N-heterocyclic carbene-catalyzed benzoin condensation. Isolated as their acetic esters, these compounds are characterized by structures similar in shape, but larger in size than the parent cyclotetrabenzoin. Alkyne groups of the tolane-based cyclotetrabenzoin were post-synthetically functionalized with Co2(CO)6 moieties under mild reaction conditions.

Materials with two-dimensional, geometrically frustrated, spin

In this work, we have thoroughly studied the effects of flux composition and temperature on the crystal growth of the BaCu2As2 compound. While Pb and CuAs self-flux produce the well-known {\alpha}-phase ThCr2Si2-type structure (Z=2), a new polymorphic phase of BaCu2As2 (\b{eta} phase) with a much larger c lattice parameter (Z=10), which could be considered an intergrowth of the ThCr2Si2- and CaBe2Ge2-type structures, has been discovered via Sn flux growth. We have characterized this structure through single-crystal X-ray diffraction, transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) studies. Furthermore, we compare this new polymorphic intergrowth structure with the {\alpha}-phase BaCu2As2 (ThCr2Si2 type with Z=2) and the \b{eta}-phase BaCu2Sb2 (intergrowth of ThCr2Si2 and CaBe2Ge2 types with Z=6), both with the same space group I4/mmm. Electrical transport studies reveal p-type carriers and magnetoresistivity up to 22% at 5 K and under a magnetic field of 7 T. Our work suggests a new route for the discovery of new polymorphic structures through flux and temperature control during material synthesis., Comment: 15 pages, 4 figures

We report two new quaternary BaCu6Sn2As4−x and BaCu6Sn2P4−x phases with a new structure type, which are fully characterized by single crystal X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These two phases crystallize in tetragonal cell with space group I4/mmm (#139) and Pearson symbol tI26. The refined lattice parameters are a = 4.164(1) A, c = 24.088(3) A for BaCu6Sn2As4−x, and a = 4.053(2) A, c = 24.08(1) A for BaCu6Sn2P4−x, respectively. They possess a distinct layered feature composed of Cu6Sn2Pnx (Pn = P, As) layers sandwiched by the Ba atoms. The Cu-Sn framework of the Cu6Sn2Pnx layer is closely related to the well-known Cu2Sb-type structure, and Pn atoms are found occupying two interstitial sites caused by close packing of Cu and Sn atoms or capped on the top of square nets formed by Cu atoms. The compounds are also characterized by electrical transport measurements down to 2 K.

Two new Cu(II) coordination compounds, [Cu2(cca)(phen)4](ClO4)2(H2O)5.5, 1, and [Cu2(OH)(oda)(phen)2)](ClO4), 2, where cca = 4-carboxycinnamate; phen = 1,10-phenanthroline; oda = octanedioate, have been synthesized and their structures determined by single-crystal X-ray diffraction. Compound 1 contains cationic Cu2(cca)(phen)4 dimers, in which two copper(II) centers are bridged by a 4-carboxycinnamate ligand. Compound 2 consists of polymeric Cu2(OH)(oda)(phen)2 chains in which Cu2(OH)(phen)2 dimers are linked by bridging oda ligands. The compounds were evaluated for in vitro anticancer efficacy and were found to exhibit significant activities against human-derived pancreatic and liver cancer cells.

The vanadium analog of MIL-69, V(OH)ndc·H2O (ndc = 2,6-naphthalenedicarboxylate) was prepared solvothermally and the structure determined by single crystal X-ray diffraction (Space Group P21/c (#14), a = 6.7936(2) A, b = 14.6816(4) A, c = 23.9156(6) A, β = 91.734(2)°, V = 2394.3(1) A3). Anhydrous V(OH)ndc was obtained from V(OH)ndc·H2O by heating under nitrogen flow at 378 K in situ the crystal used to determine the structure of the as synthesized hydrated compound. The water molecules are removed on heating in a crystal to crystal transformation. Minor changes in the structure occur with no change in the V3+ oxidation state though the space group symmetry changes from P21/c to C2/c. (Space Group C2/c (#15), a = 24.684(4) A, b = 7.079(2) A, c = 6.853(1) A, β = 104.35(1)°, V = 1160.2(4) A3). The structure of VOndc (Space Group C2/c (#15), a = 24.628 (2) A, b = 7.1434(5)A, c = 6.7428(4) A, β = 104.637(3)°, V = 1147.8 A3) obtained by heating V(OH)ndc·H2O in air at 573 K, in contrast shows a change in oxidation state from V3+ to V4+ evidenced by bond valence sum calculations and by the appearance of a characteristic distorted VO6 octahedron and an O⋯V(IV) = O chain.

Porous molecular crystals are an emerging class of porous materials that is unique in being built from discrete molecules rather than being polymeric in nature. In this study, we examined the effects of molecular structure of the precursors on the formation of porous solid-state structures with a series of 16 rigid aromatics. The majority of these precursors possess pyrazole groups capable of hydrogen bonding, as well as electron-rich aromatics and electron-poor tetrafluorobenzene rings. These precursors were prepared using a combination of Pd- and Cu-catalyzed cross-couplings, careful manipulations of protecting groups on the nitrogen atoms, and solvothermal syntheses. Our study varied the geometry and dimensions of precursors, as well as the presence of groups capable of hydrogen bonding and [π···π] stacking. Thirteen derivatives were crystallographically characterized, and four of them were found to be porous with surface areas between 283 and 1821 m2 g–1. Common to these four porous structures were (a...

A new compound KLi[Sb2(C4H2O6)2]·4H2O, 1, was synthesized in single crystal form by slowly evaporating an aqueous solution of potassium antimony tartrate and lithium nitrate. The structure of 1 consists of homochiral layers of antimony tartrate dimers linked by LiO4 tetrahedra. The interlayer water molecules can be reversibly driven out by heating or exchanged by small alcohol molecules under ambient conditions, occurring via single-crystal to single-crystal transformations. To accommodate different interlayer molecules, the interlayer space is changed by adjusting the relative lateral shift of neighboring layers. A similar adjustment in the layer stacking also occurs in a structural phase transition caused by order-disorder transformation of the arrangement of interlayer methanol molecules at low temperature.

Creating stimuli-responsive materials with switchable solid-state luminescence remains a challenge. We report that the solvation of a novel organic fluorophore can be utilized to prepare such a material, which emits in the blue (442-446 nm) region when wet and in the green (497-503 nm) region when dry.

Two new amine-templated transition metal-based sulfates, [(CH3)2NH2]17.4 [SO4]0.7 [MIII8(μ2-OH)8(μ2-SO4)16] where M = Cr and Fe, have been synthesized via mild solvothermal synthesis. The compounds...

Recent reported very high thermal conductivities in the cubic boron arsenide (BAs) and boron phosphide (BP) crystals could potentially provide a revolutionary solution in the thermal management of high power density devices. To fully facilitate such application, compatible coefficient of thermal expansion (CTE) between the heat spreader and device substrate, in order to minimize the thermal stress, need to be considered. Here we report our experimental CTE studies of BAs and BP in the temperature range from 100K to 1150K, through a combination of X-ray single crystal diffraction and neutron powder diffraction. We demonstrated the room temperature CTE, 3.6 $\pm$ 0.15 $\times$ 10E-6 /K for BAs and 3.2 $\pm$ 0.2 $\times$ 10E-6 /K for BP, are more compatible with most of the semiconductors including Si and GaAs, in comparison with diamond, and thus could be better candidates for the future heat spreader materials in power electronic devices., Comment: 13 pages, 3 figures, accepted by applied physics letters

A large spin, magnetically anisotropic, octanuclear vanadium(iii) wheel-like cluster has been synthesized. The coupling between adjacent VIII ions is ferromagnetic giving a ground state of St = 8, the largest known for a vanadium-based complex.

A new magnesium antimony tartrate perchlorate [Mg2Sb2(C4H2O6)2(H2O)8](ClO4)2·5H2O, 1, was synthesized in single crystal form by slowly evaporating an aqueous solution of potassium antimony tartrate and magnesium perchlorate. In the temperature interval 298 K–123 K, the compound undergoes two reversible structural phase transitions. The transition from phase I to phase II at ca. 236 K is second order and the transition from phase II to phase III at ca. 144 K is first order. Phase I has an orthorhombic structure, P21212, a=11.8658(4) Å, b=16.464(1) Å, c=8.3895(4) Å at 298 K, containing infinite chains of antimony tartrate dimeric clusters bridged by MgO2(H2O)4 octahedra. The ClO4 − anions occupying the interchain space show pronounced dynamic disorder. Phase II is monoclinic, P21, a=8.3813(8) Å, b=11.760(1) Å, c=16.289(2) Å, β=92.442(2)° at 153 K. Phase III has an orthorhombic unit cell with quadrupled cell volume, P212121, a=11.6914(8) Å, b=16.176(1) Å, c=33.426(2) Å at 123 K. While the infinite chains in phases II and III are closely similar to those in phase I, the ClO4 − anions show different orientations and gradual disappearance of dynamic disorder as the temperature is lowered.

The nanoporous frameworks VO(bdc), MIL-47, and M(OH)(bdc), MIL-53; bdc=1,4-benzenedicarboxylate, can absorb various guest species in their channels. As synthesized, the channels are filled with H2bdc molecules that have been reported to be disordered, except for [In(OH)bdc](H2bdc)3/4, 1, which has a inorganic-organic hybrid Vernier structure with the H2bdc molecules forming an ordered sublattice. Based on X-ray data from large single crystals grown by hydrothermal techniques, similar Vernier structures have been found for MIL-47, [VO(bdc)](H2bdc)5/7, 2, MIL-53Al, [Al(OH)(bdc)](H2bdc)11/16, 3, and MIL-53Ga, [Ga(OH)(bdc)](H2bdc)12/17, 4. The Vernier structures of 2–4 at room temperature were determined based on superstructure unit cells that index both host and guest sublattices: 2, space group P21, a=23.903(2), b=17.191(2), c=25.722(2) A, β=105.914(8)°; 3, P21/n, a=105.224(4), b=12.2441(5), c=17.0143(6) A, β=89.99(1)°; 4, P21, a=114.562(5), b=12.1503(5), c=17.4275(7) A, β=89.99(1)°. The number of guest H2bdc molecules per framework metal ion is determined by the ratio of the repeat distances of the two sublattices which depends on the size of the metal ion in the octahedral chain. The octahedral chains are parallel to [201] in 2, and to [100] in 3 and 4. Remarkably, all atoms in 3 and 4 show significant sinusoidal modulations transverse to the chain axis.

Deformation of the microporous MIL-47 framework VO(bdc), bdc = 1,4-benzenedicarboxylate, upon absorption of carbon disulfide, tetrahydrothiophene, thiomorpholine and thioxane is investigated by single crystal X-ray diffraction. Intercalation of CS 2 significantly expands the channel opening by a breathing deformation mode of the framework characterized solely by a cooperative translation of the octahedral chains, in contrast to intercalation of many other molecules that usually cause contraction of the channel opening. Upon loading of CS 2 the short diagonal of the rhombic channel expanded by 0.91 A and the maximum spherical void diameter increases to 8.0 A from 7.6 A of VO(bdc) with empty channels. Loading of the three cyclic organosulfur molecules all results in a strong twisting deformation of the framework featured by cooperative rotation of the octahedral chains by 21.3°–28.2°, bending of the bdc ligand and lowering of the space group symmetry from P nma to P2 1 2 1 2 1 . The maximum spherical void diameter of the framework decreases to 6.8 A from 7.6 A upon intercalation of tetrahydrothiophene or thiomorpholine, and to 6.0 A upon intercalation of thioxane. Intercalation of thioxane leads to the highest degree of twisting known for the VO(bdc) framework combined with a substantial breathing contraction of the channel. The host–guest interactions are predominantly van der Waals in nature and the framework deformations are presumably driven by maximizing the van der Waals contacts.

Moving the heat aside with BAs Thermal management becomes increasingly important as we decrease device size and increase computing power. Engineering materials with high thermal conductivity, such as boron arsenide (BAs), is hard because it is essential to avoid defects and impurities during synthesis, which would stop heat flow. Three different research groups have synthesized BAs with a thermal conductivity around 1000 watts per meter-kelvin: Kang et al. , Li et al. , and Tian et al. succeeded in synthesizing high-purity BAs with conductivities half that of diamond but more than double that of conventional metals (see the Perspective by Dames). The advance validates the search for high-thermal-conductivity materials and provides a new material that may be more easily integrated into semiconducting devices. Science , this issue p. 575 , p. 579 , p. 582 ; see also p. 549

Reactions of hydrated rare earth nitrates with formamide under mild solvothermal reaction conditions give three different rare earth formate structure types Ln(HCOO)3, Ln(HCOO)3·(HCONH2)2, and [CH(NH2)2][Ln(HCOO)4]. The conditions for the formation of a specific structure type were determined as a function of the size of the rare earth cation, the reaction time, and the reaction temperature. Thirteen previously unreported rare earth formates were obtained; nine were isostructural compounds with the composition Ln(HCOO)3·(HCONH2)2 (denoted by LnFA, Ln = Y (1Y), Sm (2Sm), Eu (3Eu), Gd (4Gd), Tb (5Tb), Ho (6Ho), Tm (7Tm), Yb (8Yb), and Lu (9Lu)), and four were isostructural compounds with the composition [CH(NH2)2][Ln(HCOO)4] (denoted by LnFMD, Ln = Sm (10Sm), Ho (11Ho), Tm (12Tm), and Lu (13Lu)). All compounds contain metal ions that are eight coordinated by oxygen atoms and are connected by anti–anti bridging formato ligands to form frameworks. The coordination geometry is bisdisphenoid in LnFA and square ...

Reduction of cyclotribenzoin with sodium borohydride produces a cone-shaped hexaol. Crystals of this hexaol, obtained from wet tetrahydrofuran, encapsulate clusters of five water molecules in an idealized hydrogen-bonded arrangement. The water pentamer is stabilized by hydrogen bonding with the -OH groups of the hexaol, and [O-H⋅⋅⋅π] interactions with the benzene rings of the reduced cyclotribenzoin.

The dehydration behavior of the microporous copper silicate Na2(Cu2Si5O13)·3H2O conventionally denoted as CuSH-6Na was studied using single crystal X-ray data collected at temperatures –150, 25, 40, 50, 60, 70 and 120 °C. Reversible dehydration of CuSH-6Na starts at ambient temperatures under dry nitrogen flow and is complete at 70 °C. The water molecules initially present in both ordered and disordered sites were simultaneously driven out beginning at ambient temperature. The dehydration is accompanied by a negative thermal expansion of the crystal caused by a slight progressive narrowing of the channels along the direction perpendicular to the silicate layers. The fully dehydrated structure has framework copper metal sites with open coordination spheres directly exposed to the space inside the accessible channels.

A series of layered divalent metal formate compounds, [M(HCOO)2(HCONH2)2] (M = Mn (1Mn), Ni (2Ni), Cu(3Cu), Zn(4Zn), Mg(5Mg)), have been prepared by solvothermal synthesis and their room temperature (RT) and low-temperature (LT) crystal structures, and thermal and magnetic properties determined. All the compounds contain octahedral metal ions connected by four anti-anti formato ligands to form (4,4) nets with the composition of M(HCOO)2. The oxygen atoms from two coordinating formamide ligands above and below the layer complete the MO6 distorted octahedral coordination. Order-disorder phase transformations involving the formamide ligands were observed in the 1Mn, 2Ni, and 4Zn compounds. Like transitions in related formate structures with perovskite like topology, the transitions correspond to the ordering of the amine groups of the terminating formamide ligands which are disordered at ambient temperature. The magnetic properties of the three magnetic members of the series 1Mn, 2Ni, and 3Cu were investigated using microcrystalline samples, over the temperature range of 2 K-300 K under different applied fields. All compounds belong to antiferromagnetic square lattices with S = 5/2, 1, and 1/2. Exchange constants for a nearest neighbor model are presented here. Specific heat measurements indicate magnetic long-range order at lower temperatures, S = 5/2 (antiferromagnetic) and S = 1 (ferrimagnetic).

Neutron powder diffraction was used to characterize the layered perovskite PrBaCo 2 O 5 + δ (PBCO) under in-situ conditions from 573 to 852 °C and at p O 2 = 10 − 1 –10 − 4 atm. The data were fit to a tetragonal model in space group P4/mmm . The oxygen vacancies were found to be localized within the Pr layer, with total oxygen stoichiometry between 5.57(1) and 5.17(2). This was verified by coulometric titration. The location of these vacancies and the anisotropic displacement of the surrounding oxygen anion sites indicate that ion transport occurs via a hopping mechanism between O sites in the Pr layer and the nearest neighbor sites in the Co layer. While the direct hopping distance between these sites was found to be greater for PBCO than previously reported for NdBaCo 2 O 5 + δ , the larger radius of Pr 3 + stabilizes a higher concentration of mobile anions within the Ln layer.

The syntheses and crystal structures of compounds based on the ligand 1,4-phenylenebis (hydroxyacetic acid) (H2L) are reported for the first time. Three chain structures based on H2L and divalent metal cations were synthesized and characterized and their structures determined by single-crystal X-ray diffraction. The compounds PbL (1), CoL(H2O)2·2H2O (2), and ZnL(H2O)2·2H2O (3) have similar infinite chains of metal centers bridged by 1,4-phenylenebis(hydroxyacetic acid). The coordination spheres of the transition metal ions are completed by coordinating water molecules in the isostructural compounds 2 and 3. The non-covalent secondary bonding requirement of Pb2+ in 1 and interchain hydrogen bonds in 2 and 3 lead to different packing of the chains.

Two new strontium tin hydroxy polyselenides [Sr2Sn(OH)6(H2O)6]Se4 (1) and [Sr2Sn(OH)6(H2O)5]Se3·H2O (2) were synthesized from hydrothermal reactions. Their structures were determined from single-crystal X-ray data measured at 218 K. Compound 1 crystallized in the space group P with a = 5.935(1), b = 8.440(1), c = 9.464(2) A, α = 97.292(2)°, β = 104.957(2)°, γ = 110.328(2)°. Compound 2 crystallized also in the space group P with a = 10.658(2), b = 11.082(2), c = 15.797(2) A, α = 73.303(4)°, β = 74.942(4)°, γ = 64.627(3)°. Both compounds have structures containing infinite cationic layers of hydrated metal hydroxides built from Sn(OH)6 octahedra and Sr(OH, H2O)n polyhedra. Molecular Se42– and Se32– anions are located in the interlayer spaces of 1 and 2, respectively. The Se42– anions of 1 adopt a flat zigzag conformation with a torsion angle of 0°.

Two new manganese phosphate-silicates Na3Mn2Si2PO10, (1), and CsNa8[Mn5Mn0.8 Si12O32.6(OH)5.4](PO4)(H2O)4 (2) were synthesized under mild hydrothermal conditions. The structure of 1 contains Si4O12 vierer single rings that interconnect chains of MnO6 octahedra to form slabs. The slabs are cross-linked by PO4 tetrahedra to form a framework with channels filled by sodium ions. Compound 2 consists of silicate single layers that are interconnected by complex chains of MnOn polyhedra to form a 3D framework. The framework has channel systems filled by Naþ, Csþ, (PO4) ions and water molecules. The silicate single layer of 2 is an unbranched sechser single layer and contains both secondary Q2 and tertiary Q3 tetrahedra with a Q/Q ratio 2 :1. The valence states of the Mn atoms in 2 are derived from bond valence calculations and are supported by XPS measurement.

A chiral cluster compound, dipotassium bis-(μ-tartrato)-diantimony(III), K2Sb2L2 (H4L = l-tartaric acid), was used as a secondary building unit to react with Fe(III) perchlorate and Fe(II) sulfate in water and DMF (DMF = dimethylformamide) in the presence of NaN(CN)2 or 4,4′-bipyridine. Three distinct homochiral structures have been obtained: H3Na7[Fe4Sb6(μ4-O)6(μ3-O)2(l-tartrate)6]·14H2O (1), H5K3[(CH3)2NH2]2[Fe7Sb6(μ4-O)6(μ3-O)2(l-tartrate)6]2·28H2O (2), and Na3K5[(CH3)2NH2]4[Fe6Sb6(μ4-O)6(μ3-O)2(l-tartrate)6]2·30H2O (3). All of these compounds contain iron oxo-clusters sandwiched by Sb3(μ3-O)(l-tartrate)3 SBUs. 1 consists of isolated [Fe4Sb6(μ4-O)6(μ3-O)2(l-tartrate)6]10– clusters, which are interconnected by Na+ ions into 2D homochiral layers. The structure of 2 features [Fe7Sb6(μ4-O)6(μ3-O)2(l-tartrate)6]5– clusters; the clusters are further linked into negatively charged honeycomb layers. Both types of clusters are found in 3 and are also assembled into negatively charged honeycomb layers. The acces...

A chiral cluster compound, dipotassium bis(μ-tartrato)diantimony(III), K(2)Sb(2)L(2) (H(4)L = L-tartaric acid), was used as a secondary building unit to react with lanthanide ions. Three series of homochiral coordination compounds were obtained: 0D [La(H(2)L)(H(2)O)(4)](2)[Sb(2)L(2)]·7H(2)O (0D-La), 1D Ln(Sb(2)L(2))(H(2)O)(5)(NO(3))·H(2)O (1D-Ln) (Ln = La-Lu or Y, expect Pm), 2D(I) [(Ln(H(2)O)(5))(2)(Sb(2)L(2))(3)]·5H(2)O (2D(I)-Ln) (Ln = La, Ce, Pr), and 2D(II) [(La(H(2)O)(5))(2)(Sb(2)L(2))(3)]·6H(2)O (2D(II)-La). Single-crystal X-ray diffraction studies indicated that 0D-La crystallizes in space group P1, and the structure contains isolated Sb(2)L(2)(2-) units located between chains of composition La(H(2)L)(H(2)O)(4). The series of 1D-Ln compounds is isostructural and crystallizes in space group P2(1)2(1)2(1). In the structure, Sb(2)L(2)(2-) units are coordinated to two Ln ions by two out of the four free tartrate oxygen atoms to form a linear chain. To the best of our knowledge, this is the first example of a homochiral structure that can be formed for the whole lanthanide series. In the 2D(I)-Ln structure series, which crystallizes in space group P2(1), the Sb(2)L(2)(2-) units have two distinct coordination modes: one is the same as that found in the 1D structure, while in the other all four free tartrate oxygen atoms are coordinated to four Ln ions in a very distorted tetrahedral arrangement. The connectivity between Sb(2)L(2)(2-) secondary units and LnO(9) polyhedra gives rise to infinite layers. 2D(II) [(La(H(2)O)(5))(2)(Sb(2)L(2))(3)]·6H(2)O, which crystallizes in space group C2, has a similar network to the 2D(I)-Ln compounds. The trends in lattice parameters, bond lengths, and ionic radii in the 1D-Ln series were analyzed to show the effect of the lanthanide contraction.