Synthesis of Double Uranyl Phthalates of the M4[(UO2)4(μ3-O)2(C6H4C2O4)4] ⋅ nH2O Type with M = NH4, K, and Cs. Crystal Structure of K4[(UO2)4O2(C6H4C2O4)4] ⋅ 3H2O

Double U(VI) phthalates with NH ₄ ⁺ , K⁺, and Cs⁺ ions in the outer sphere were synthesized. The X-ray phase analysis shows that their structures are similar. Single crystals were prepared and the structure of K₄[(UO₂)₄(μ₃-O)₂(C₆H₄C₂O₄)₄] ? 3H₂O was solved. In the [(UO₂)₄O₂(C₆H₄C₂O₄)₄]^4? anions forming the main structural motif, each bridging oxygen atom μ₃-O combines one pentagonal and two hexagonal bipyramids, which, in turn, are combined in centrosymmetrical tetramers. The phthalate ions have coordination capacity equal to 3; each ligand coordinates U(1) in the bidentate fashion via one carboxy group and U(2) in the bidentate fashion to form a planar seven-membered chelate ring.     

Complexes with substituted 2,5-dihydroxy-p-benzoquinones: The inclusion compounds [Y(H2O)3]2 (C6Cl2O4)3·6.6H2O and [Y(H2O)3]2 (C6Br2O4)3·6H2O

Single crystal of [Y(H₂O)₃]₂ (C₆Br₂O₄)₃·6H₂O and [Y(H₂O)₃]₂ (C₆Cl₂O₄)₃·6.6H₂O were grown in aqueous silicagel. The compounds are in principle isostructural. In Y chloranilate one additional water site is occupied as verified by X-ray single crystal structure analysis. Y³⁺ is nine-coordinated by three water molecules and six oxygen atoms of the bischelating (C₆X₂O₄)²⁻ ions (XCl, Br). The coordination polyhedron is an only slightly distorted tri-capped trigonal prism. The connection of Y³⁺ with the dianions leads to infinite, corrugated layers. The layer stacking yields cage-like cavities in which water molecules are accomodated. Hydrogen bonds interlink adjacent layers. Further hydrogen bonds involve the entrapped water molecules. DSC measurements indicated a complicated dehydration process which caused right at the start destruction of the single crystals.     

Crystal Structure of Neptunium(V) Phthalate (NpO2)2(OOC)2C6H4·4H2O

The crystal structure of (NpO₂)₂(OOC)₂C₆H₄·4H₂O [rhombic cell: a = 15.937(3), b = 26.922(5), c = 8.020(2) Å, space group Pbcn, Z = 8, V = 3441.0(12) ų, d _calc = 2.988 g cm^{- 3}, CAD4, MoK , graphite monochromator, 2934 independent reflections; R ₁ = 0.0352, wR ₂ = 0.0951] was studied. The structure consists of NpO₂ ⁺ cations, H₄C₆(COO)₂ ^{2 -} anions, and molecules of coordinated and crystallization water. The crystal lattice involves neutral layers [(NpO₂)₂(OOC)₂C₆H₄(H₂O)₃] _n parallel to the {101} plane. The dioxocations in these layers are bonded to each other to form cationic networks [the Np···Np distance is 3.911(1)-4.202(1) Å]. The coordination polyhedra of Np(1) and Np(2) are pentagonal bipyramids (CN 7). The point group of the neptunyl(V) groups is close to D _h. These groups are bidentate ligands in the cation-cation interaction. The Np = O bond lengths are 1.852(6) [Np(1)-O(1)], 1.849(7) [Np(1)-O(2)], 1.845(7) [Np(2)-O(3)], and 1.841(7) Å [Np(2)-O(4)]; the O = Np = O bond angles are 178.6(3)° [O(2)-Np(1)-O(1)] and 177.4(3)° [O(3)-Np(2)-O(4)]. The equatorial plane of the Np(1) bipyramid consists of two oxygen atoms of adjacent Np(2)O₂ ⁺ dioxocations, two water molecules, and a single oxygen atom of the phthalate anion. The equatorial plane of the Np(2) bipyramid consists of two oxygen atoms of adjacent Np(1)O₂ ⁺ dioxocations, two oxygen atom of the phthalate anion, and a single water molecule. The bond lengths in the equatorial plane of the bipyramid lie in the following ranges: Np-Oyl 2.373(7)-2.437(7) Å (average 2.397 Å) , Np-Ophth 2.360(7)-2.474(7) Å (average 2.431 Å), and Np-Owater 2.534(8)-2.558(9) Å (average 2.544 Å). The phthalate anions are tridentate bridging ligands binding neptunium atoms only within a single cationic network.     

Brushite (CaHPO4·2H2O) to octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O) transformation in DMEM solutions at 36.5 °C

The purpose of this study was to investigate the transformation of brushite (dicalcium phosphate dihydrate, DCPD, CaHPO₄·2H₂O) powders at 36.5 °C in DMEM (Dulbecco's Modified Eagle Medium) solutions. Two sets of brushite powders with different particle shapes were synthesized to use in the above DMEM study. The first of these brushite powders was prepared by using a method which consisted of stirring calcite (CaCO₃) powders in a solution of ammonium dihydrogen phosphate (NH₄H₂PO₄) from 6 to 60 min at room temperature. These powders were found to consist of dumbbells of water lily-shaped crystals. The second one of the brushite powders had the common flat-plate morphology. Both powders were separately tested in DMEM-immersion experiments. Monetite (DCPA, CaHPO₄) powders were synthesized with a unique water lily morphology by heating the water lily-shaped brushite crystals at 200 °C for 2 h. Brushite powders were found to transform into octacalcium phosphate (OCP, Ca₈(HPO₄)₂(PO₄)₄·5H₂O) upon soaking in DMEM (Dulbecco's Modified Eagle Medium) solutions at 36.5 °C over a period of 24 h to 1 week. Brushite powders were known to transform into apatite when immersed in synthetic (simulated) body fluid (SBF) solutions. This study found that DMEM solutions are able to convert brushite into OCP, instead of apatite.     

Ceramics Based on CaSO4⋅2H2O Powder Synthesized from Ca(NO3)2 and (NH4)2SO4

Inorganic Materials - Ceramics consisting of anhydrous calcium sulfate, CaSO4, after firing in the range 800–1000°C have been prepared from calcium sulfate dihydrate (CaSO4?2H2O)...     

纳米微孔杂多化合物Na[Fe2(O2H3)Mo2O8](Ⅰ)和(NH4)[Fe(MoO4)2](Ⅱ)的结构特征

通过采用水热合成法得到了二种具有纳米筛孔的氧簇化合物Na[Fe2(O2H3)Mo2O8](Ⅰ)和(NH4)[Fe(Mo O4)2](Ⅱ).晶体(Ⅰ)属于单斜晶系,空间群为C2/m,晶胞参数为:a=9.5450(17),b=6.4381(9),c=0.76405(12)nm;β=116.128(4),Z=2,R1=0.0219,Rw=0.0756.晶体(Ⅱ)属于正交晶系,空间群为Pnma,晶胞参数为:a=1.4782(3),b=0.56774(11),c=0.87653(18)nm;Z=4,R1=0.0212,Rw=0.0513.     

Phase-matched UV generation at 0.1774 μm in KB(5)O(8) ·4H(2)O

Sixth-harmonic generation of the Nd:YAG laser frequency at 1.0642 μm has been achieved in KB(5) O(8) ˙ 4H(2) O by type-1 mixing the fundamental and fifth harmonic at room temperature. The phase-matching angles were measured to be (θ = 90°, φ = 68.5 ± 0.5°) and (θ = 80.0 ± 0.5 °, φ = 90°) in the x - y and y -z planes, respectively. Improved Sellmeier equations of this crystal are presented.     

X-ray powder diffraction and IR study of NaMg(H2O)2[BP2O8]·H2O and NH4Mg(H2O)2[BP2O8]·H2O

NaMg(H₂O)₂[BP₂O₈]·H₂O was prepared by hydrothermal synthesis and was characterized by X-ray powder difraction and IR method. The title compound was synthesized from MgCl₂·6H₂O, NaBO₃·4H₂O, and (NH₄)₂HPO₄ with variable molar ratios using hydrothermal method by heating at 165 °C for 3 days. The X-ray powder diffraction data was indexed in hexagonal system, the unit cell parameters were found to be as a = 9.428, c = 15.82 Å, Z = 4 and the space group is P6₁22. It is isostructural with M^lM^ll(H₂O)[BP₂O₈] type compounds where M^l = Na, K; M^ll = Mg, Mn, Fe, Co, Ni and Zn. In addition NH₄Mg(H₂O)₂[BP₂O₈]·H₂O was also synthesized the first time in this research. Its unit cell parameters and hkl values were in good agreement with the sodium magnesium compound. The unit cell parameters are a = 9.529, c = 15.736 Å. The indexed X-ray powder diffraction data of both compounds which were not reported in the literature is presented in this work. The IR data of NaMg(H₂O)₂[BP₂O₈]·H₂O is also reported.     

Synthesis and structure of actinide(VII) compounds Rb3NpO4(OH)2·3H2O and Rb3PuO4(OH)2·3H2O

Actinide(VII) salts Rb₃[NpO₄(OH)₂]·3H₂O (I) and Rb₃[PuO₄(OH)₂]·3H₂O (II) were prepared as single crystals and examined by X-ray diffraction. The compounds are isostructural and crystallize in the monoclinic system, space group C2/c, Z = 4; unit cell parameters: a = 12.1544(3), b = 10.9942(2), c = 7.789(2) ?, ?? = 91.0930(11)° for I and a = 12.1254(3), b = 10.9506(2), c = 7.7699(2) ?, ?? = 90.8253(12)° for II. The main structural elements of I and II are centrosymmetrical anions [AnO₄(OH)₂]^3? forming together with water molecules, owing to strong hydrogen bonding, chains oriented along [101]. In [AnO₄(OH)₂]^3? anions, the central An(VII) atom has a tetragonal-bipyramidal oxygen surrounding. The An-O(OH) interatomic distances decrease in going from I to II owing to actinide contraction by a factor of ??2 more strongly than the An-O bond lengths in the equatorial planes of the bipyramids. The previously studied structure of Cs₃[NpO₄(OH)₂]·3H₂O (III) was refined.     

Reaction of Cd(NO3)2·4H2O with 4,4'–bipyridine (bpy) in MeOH solvent: synthesis and characterization of T-shaped [Cd(bpy)1.5(NO3)2]·3H2O,square grid [Cd(bpy)2(H2O)2](NO3)2·4H2O and linear polymeric [Cd(bpy)(H2O)2(NO3)2]

The influence of concentration of water and metal salt in the reaction between Cd(NO₃)₂·4H₂O and 4,4′–bipyridine in MeOH has been studied and three compounds namely, T-shaped [Cd(bpy)_1.5(NO₃)₂]·3H₂O, 1 square grid [Cd(bpy)₂(H₂O)₂](NO₃)₂ 4H₂O, 2 and one dimensional linear polymer, [Cd(bpy)(H₂O)₂(NO₃)₂], 3 were isolated quantitatively in this process. Compound 1 forms in MeOH at high dilution of the metal salt (5.0 mg/mL or less) and for the metal-to-ligand ratio 1:(1.5–2.0). Compound 2 forms exclusively in the concentration range, 17–33% for water in MeOH by volume and 12–28 mg/mL for the metal salt of the solution. Outside these limits, mixtures of 2 and 3 were isolated. For 1:1 ratio of metal salt to bpy, the linear polymer, 3 was obtained in major quantity and its formation was found to be independent of concentration of water or the metal salt. Compounds 1 and 2 have been characterized by X-ray crystallography. On heating all the compounds decompose through a common intermediate [Cd(bpy)(NO₃)₂] and finally to CdO as monitored by TG.     

Cobalt-mediated synthesis of 2-(4-pyridyl)benzimidazole. x-ray structures of Co[2-(4-pyridyl)benzimidazole]2(H2O)2(NO3)2 and [Co(isonicotinate)(4-pyridiniumcarboxylate)(H2O)(NO3)]∞

We have observed an unusual example of cobalt-mediated cyclization of 4-pyridinecarboxaldehyde and 2-nitroaniline to afford 2-(4-pyridyl)benzimidazole under hydro(solvo)thermal conditions. Reaction of Co(NO₃)₂·6H₂O with 4-pyridinecarboxaldehyde and 2-nitroaniline in ethanol at 120°C gave a cobalt(II) coordination compound, Co[2-(4-pyridyl)benzimidazole]₂(H₂O)₂(NO₃)₂, 1. In contrast, when the hydro(solvo)thermal reaction was carried out between Co(NO₃)₂·6H₂O and isonicotinic acid in the presence of 2-nitroaniline at 110°C, a one-dimensional Co(II) coordination polymer with the formula of [Co(isonicotinate)(4-pyridiniumcarboxylate)(H₂O)(NO₃)]_∞, 2, resulted. The X-ray single crystal structures of both 1 and 2 are described. Interestingly, the isonicotinic acid in 2 exists as a 4-pyridiniumcarboxylate tautomer, and the pyridinium hydrogen atom forms a very strong hydrogen bond to the carboxylate oxygen of the 4-pyridiniumcarboxylate on an adjacent metal center. 1 forms a three-dimensional polymeric network through hydrogen bonding interactions, while 2 exists as a 2-D bilayer polymeric network through hydrogen bonding interactions.     

纳米xCuFe2O4·(1-x)Fe3O4固溶体的制备与表征

合成了4种不同铜含量的间苯二甲酰二茂铁二乙酰腙配位聚合物(PFZCu),然后在高温(600～800℃)热解制得粒径为10～25nm的固溶体xCuFe2O4·(1-x)Fe3O4(0相似文献   

Study of coercive force for yZnFe2O4–(1 − y)CoFe2O4 magnetic nanoparticles system

The coercive forces are taken out from the loops of magnetisation cycle for yZnFe₂O₄–(1 ? y)CoFe₂O₄ mixed magnetic nanoparticles system (y is the volume fraction of ZnFe₂O₄ particles in yZnFe₂O₄–(1 ? y)CoFe₂O₄ magnetic nanoparticles mixed system). The results show that the coercive force of the system is increasing with the y decreasing and is interpreted by using particles chain model. The number of chains of particles under magnetic field is obtained by comparing the coercive force of the experiment and the theory of chain model. In yZnFe₂O₄–(1 ? y)CoFe₂O₄ magnetic nanoparticles mixed system, the coercive force comes from ferrimagnetic CoFe₂O₄ nanoparticles, and paramagnetic ZnFe₂O₄ nanoparticles make the chain length of the mixed magnetic system shorter than single CoFe₂O₄ nanoparticles system.     

Crystal structure of a double Np(V) ammonium propionate, NH4[(NpO2)3(C2H5COO)4(H2O)]·3H2O

The structure of NH₄[(NpO₂)₃(C₂H₅COO)₄(H₂O)]·3H₂O was studied by single crystal X-ray diffraction. The single crystals were prepared by hydrothermal synthesis. In the structure, there are three crystallographically independent Np atoms with different equatorial surrounding. All of them have CN 7; the coordination polyhedron is a distorted pentagonal bipyramid. Each NpO ₂ ⁺ cation is bonded to four other cations, acting simultaneously as a bidentate ligand and a coordination center for two other dioxocations. The cation-cation interactions result in formation of trigonal-hexagonal cationic networks.     

Phase Relations in the NiFe2O4–NiCr2O4–CuCr2O4System

The phase relations in the NiFe₂O₄–NiCr₂O₄–CuCr₂O₄system were investigated experimentally and theoretically. X-ray diffraction data were used to construct the phase diagram of the system and elucidate the structural mechanisms of the transitions from the cubic spinel structure to the tetragonal (I42d, c/a< 1 and I4₁/amd, c/a> 1) and orthorhombic (Fdd2) structures.     

A single crystal X-ray diffraction study of Na4(UO2)4(i-C4H9COO)11(NO3)·3H2O

Synthesis and the results of IR and single crystal X-ray diffraction study of Na₄(UO₂)₄(i-C₄H₉COO)₁₁·(NO₃)·3H₂O are reported. The crystals are monoclinic; the unit cell parameters at 100 K are as follows: a = 13.697(2), b = 20.285(3), c = 15.991(3) Å, β = 103.760(3)°, space group P2₁, Z = 2, R = 0.0650. The uraniumcontaining structural units are mononuclear moieties [UO₂(i-C₄H₉COO)₃]^? and [UO₂(NO₃)(i-C₄H₉COO)₂]^?, belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = i-C₄H₉COO^? and NO ₃ ^? ) of uranyl complexes. The IR data are consistent with the results of the single crystal X-ray diffraction study. The influence of the carboxylate ligand volume on the structure of Na[UO₂L₃]·nH₂O crystals (L = acetate, n-butyrate, isovalerate ion) is analyzed.     

Synthesis of maghemite (γ-Fe2O3) nanoparticles by thermal-decomposition of magnetite (Fe3O4) nanoparticles

In this research work, we prepared γ-Fe₂O₃ nanoparticles by thermal-decomposition of Fe₃O₄. The Fe₃O₄ nanoparticles were synthesized via co-precipitation method at room temperature. This simple, soft and cheap method is suitable for preparation of iron oxide nanoparticles (γ-Fe₂O₃; Fe₃O₄). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer and differential scanning calorimeter (DSC). The XRD and FT-IR results indicated the formation of γ-Fe₂O₃ and Fe₃O₄ nanoparticles. The TEM images showed that the γ-Fe₂O₃ and Fe₃O₄ were spherical, and their size was 18 and 22 nm respectively. Magnetic properties have been measured by VSM at room temperature. Hysteresis loops showed that the γ-Fe₂O₃ and Fe₃O₄ nanoparticles were super-paramagnetic.     

Mixed-Cation Molybdate Complex of Neptunium(V), Li2Na[NpO2(MoO4)2]·4H2O

Radiochemistry - A new mixed-cation complex Li2Na[NpO2(MoO4)2]·4H2O with NpO2+ : MoO42– = 1 : 2 has been synthesized and structurally characterized. The coordination environment of Np(V)...