Synthesis and crystal structures of a new (2,3-(CH3)2C6H3NH3)H2XO4 (X=P,As)

The aim of encapsulation of 2,3-dimethylanilinium cation in (H₂XO₄)_n polymeric anion chains is to build acentric frameworks that are efficient for non-linear optical (NLO) applications. The synthesis and structures of two new inorganic–organic NLO crystals with general formula (2,3-(CH₃)₂C₆H₃NH₃)H₂XO₄ (X=P, As) are reported. The magnitude of their second harmonic generations (SHG) responses was found to be between the KDP and urea. They crystallize with monoclinic unit-cells and are isotopic. We have determined the structure of phosphoric salt. The following unit-cell parameters were found: a=8.866(3) Å, b=5.909(6) Å, c=10.644(5) Å, β=112.44(1)°, V=515.5(5) Å³ and D_X=1.412 g cm⁻³. The space group is P2₁ with Z=2. The structure was refined with R=0.041 (R_w=0.057) for 1652 reflections with I≥3σ(I). It exhibits infinite (H₂PO₄)_nⁿ⁻ chains. The organic groups (2,3-(CH₃)₂C₆H₃NH₃)⁺ are anchored between adjacent polyanions through multiple hydrogen bonds. Chemical preparation, crystal structure, calorimetric and spectroscopic investigation are described.     

Crystal structure of a new organic dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2

Chemical preparation, X-ray single-crystal, thermal behavior, and IR spectroscopy investigations are given for a new organic cation dihydrogenomonophosphate (C₆H₈N₃O)₂(H₂PO₄)₂ (denoted IAHP) in the solid state. This compound crystallizes in the orthorhombic space group P2₁2₁2₁. The unit cell dimensions are: a = 7.422(3) Å, b = 12.568(5) Å, c = 20.059(8) Å with V = 1871.1(13) Å³ and Z = 4. The structure has been solved using direct method and refined to a reliability R factor of 0.029. The atomic arrangement can be described as inorganic layers of H₂PO₄⁻ anions between which are located the organic groups (C₆H₈N₃O)⁺ through multiple hydrogen bonds.     

Characterization of M(H2PO4)2·2H2O (M = Mn,Co, Ni) and their in situ thermal decomposition by magnetic measurements

It has been established that M(H₂PO₄)₂·2H₂O (M = Mn, Co, Ni) are paramagnetics between 173 and 353 K with weak antiferromagnetic exchange interaction between the metal ions. In situ magnetic measurements during the thermal decomposition of the salts show that the oxidation state and the octahedral coordination of M²⁺ are preserved. From the data obtained it could be supposed that in M(H₂PO₄)₂·2H₂O (M = Co, Ni) this process is topotactic with no long-range diffusion transport. In Mn(H₂PO₄)₂·2H₂O, the formation of the large variety of intermediate products probably requires more drastic rearrangement and diffusion of the manganese ions during the complex transformations, which reflect on both the value and the sign of the θ constants. M₂P₄O₁₂ (M = Mn, Co, Ni), which are the final decomposition products of the corresponding dihydrogen phosphates are paramagnetics in the temperature range of 295–573 K with antiferomagnetic interactions between the metal ions. The lattice parameters of Ni(H₂PO₄)₂·2H₂O have been calculated. It crystallizes in the monoclinic system with a = 7.228(1) Å; b = 9.778(1) Å; c = 5.306(1) Å; β = 94.50(1)°, SG P2₁/n with Z = 2.     

Structural,thermal, spectroscopic and magnetic studies of the (C2N2H10)0.5[FexV1−x(HPO3)2] (x = 0.26, 0.52, 0.74) solid solution

The (C₂N₂H₁₀)_0.5[Fe_xV_1−x(HPO₃)₂] (x = 0.26, 0.52 0.74) compounds have been obtained by mild solvothermal conditions in the form of micro-crystalline powder with brown color. The crystal structures were refined by X-ray powder diffraction data using the Rietveld method. The compounds crystallize in the monoclinic system, space group P2/c with the unit-cell parameters, a = 9.262(5) Å, b = 8.823(5) Å, c = 9.714(6) Å, β = 120.84(3)°; a = 9.245(1) Å, b = 8.823(1) Å, c = 9.698(1)Å, β = 120.80(1)° and, a = 9.254(4)Å, b = 8.822(4)Å, c = 9.702(4)Å, β = 120.73(3)° for (C₂N₂H₁₀)_0.5[Fe_0.26V_0.74 (HPO₃)₂] (1), (C₂N₂H₁₀)_0.5[Fe_0.52V_0.48(HPO₃)₂] (2), and (C₂N₂H₁₀)_0.5[Fe_0.74V_0.26(HPO₃)₂] (3). The compounds show an open crystalline structure with three-dimensional character, whose formula for the anionic inorganic skeleton is [M(HPO₃)₂]²⁻. The inorganic framework is formed by [MO₆] octahedra inter-connected by phosphite groups. The structure of the compounds exhibits channels extended along the [1 0 0] and [0 0 1] directions and the ethylendiammonium cations are located inside these channels, linked through hydrogen bonds and ionic interactions. The infrared spectra show the bands corresponding to the stretching (P–H) vibration of the phosphite group and the band corresponding to the deformation mode of the ethylendiammonium cation, δ(NH₃⁺). The thermal and thermodiffractometric behavior show that the compounds are stable up to approximately 300 °C, at higher temperatures the decomposition of the crystal structure by calcination of the organic cation starts. The diffuse reflectance spectra show bands of the V³⁺ ion (d²), and a band of the Fe³⁺ ion (d⁵), in a slightly distorted octahedral symmetry. The values of the Dq and Racah parameters (B and C) have been calculated for the V(III) cation. Magnetic measurements were performed on a powdered sample from 5 to 300 K at magnetic fields 1000, 500 and 100 G, in the ZFC and FC modes. At the magnetic field of 1000 G antiferromagnetic interactions were observed, but at 100 G have been detected higher values of the χ_m in the FC mode than those observed in the ZFC one, indicating the existence of a dominant ferromagnetic component at low temperature. The magnetization measurements show hystheresis loops at 5 K, with values of the remanent magnetization and coercive field of 1.91 emu/mol and 23 Gauss for (1), 25 emu/mol and 300 Gauss for (2), and 3 emu/mol and 50 Gauss for the compound (3).     

Synthesis and structure determination of new open-framework chromium carboxylate MIL-105 or CrIII(OH)·{O2C–C6(CH3)4–CO2}·nH2O

Two new three-dimensional chromium(III) dicarboxylate, MIL-105 or Cr^III(OH)·{O₂C-C₆(CH₃)₄-CO₂}·nH₂O, have been obtained under hydrothermal conditions, and their structures solved using X-ray powder diffraction data. Both solids are structural analogs of the known Cr benzenedicarboxylate compound (MIL-53). Both contain trans corner-sharing CrO₄(OH)₂ octahedral chains connected by tetramethylterephthalate di-anions. Each chain is linked by the ligands to four other chains to form a three-dimensional framework with an array of 1D pores channels. The pores of the high temperature form of the solid, MIL-105ht, are empty. However, MIL-105ht re-hydrates at room temperature to finally give MIL-105lt with pores channels filled with free water molecules (lt: low temperature form; ht: high temperature form). The thermal behaviour of the two solids has been investigated using TGA. Crystal data for MIL-105ht: monoclinic space group C2/c with a = 19.653(1) Å, b = 9.984(1) Å, c = 6.970(1) Å, β = 110.67(1)° and Z = 4. Crystal data for MIL-105lt: orthorhombic space group Pnam with a = 17.892(1) Å, b = 11.165(1) Å, c = 6.916(1) Å and Z = 4.     

Synthesis and characterization of a one-dimensional inorganic–organic hybrid iron phosphate: [Fe(bipy)(HPO4)(H2PO4)] (bipy = 2,2′-bipyridyl) with anti-ferromagnetic property

A coordinated iron phosphate, Fe(bipy)(HPO₄)(H₂PO₄) (I), has been hydrothermally synthesized and characterized by elemental analysis, thermogravimetric analysis, and single crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P2₁/n (No. 14), with cell parameters M = 405.00, a = 10.904(4) Å, b = 6.4210(2) Å, c = 19.294(9) Å, β = 101.24(4) ų, V = 1324.9(9) ų, Z = 4, R₁ [I > 2((I)) = 0.0357, wR₂ [I > 2((I)) = 0.0717. This compound displays a new structure of ladder-like chains, in which each one-dimensional chain is constituted by the distorted octahedral units of Fe³⁺ bridged through PO₄ tetrahedra. The bipy ligands in the compound bind in a bidentate fashion to the iron atoms and the ladder-like structure of the compound extends into a three-dimensional supramolecular array via π–π stacking interactions of bipy ligands and strong hydrogen bonding between the chains. Mössbauer spectroscopy shows the presence of Fe³⁺ in the octahedral coordination. Magnetic susceptibility measurements show that this material may model as anti-ferromagnetic.     

Growth,thermal and optical properties of Yb:GdYAl3(BO3)4 crystal

Single crystal of Yb:GdYAl₃(BO₃)₄(Yb:GdYAB) has been grown by the flux method. The structure of Yb:GdYAB crystal has been determined by X-ray diffraction analysis. The experiment show that the crystal has the same structure as that of YAl₃(BO₃)₄ crystal and its unit cell constants have been measured to be a = 9.30146 Å, c = 7.24164 Å, Vol = 542.59 Å³. The absorption and fluorescence spectrum of Yb:GdYAl₃(BO₃)₄ crystal have also been measured at room temperature. In the absorption spectra, there are two absorption bands at 938 nm and 974 nm, respectively, which is suitable for InGaAs diode laser pumping. In the fluorescence spectra, there are two fluorescence peaks at 992 and 1040 nm. The thermal properties of Yb:GdYAl₃(BO₃)₄ crystal have been studied for the first time. The thermal expansion coefficient along c-axis is almost 5.4 times larger than that along a-axis. The specific heat of the crystal has been measured to be 0.77 J/g °C at room temperature. The calculated thermal conductivity is 5.26 Wm⁻¹ K⁻¹ along a-direction.     

Synthesis and tunable luminescence of RbCaGd(PO4)2:Ce3+, Mn2+ phosphors

RbCaGd(PO₄)₂ doped with Ce³⁺, Mn²⁺ was synthesized by the sol-gel method. The crystal structure and crystallographic location of Ce³⁺ in RbCaGd(PO₄)₂ were identified by Rietveld refinement. Powder X-ray diffraction (XRD) revealed that the structure of RbCaGd(PO₄)₂:Ce³⁺ compounds is hexagonal structure which is similar to that of hexagonal LnPO₄ with the lattice constant of a = b = 7.005(57) Å, c = 6.352(05) Å, and V (cell volume) = 269.980 Å³. The photoluminescence behavior and emission mechanism were studied systematically by doping activators in the RbCaGd(PO₄)₂ host. The Mn²⁺ incorporated RbCaGd(PO₄)₂:Ce³⁺, Mn²⁺ compounds exhibited blue emission from the parity- and spin-allowed f-d transition of Ce³⁺ and orange-to-red emission from the forbidden ⁴T₁ → ⁶A₁ transition of Mn²⁺. The emission chromaticity coordinates of RbCaGd(PO₄)₂:0.10Ce³⁺, xMn²⁺ (x = 0.16, 0.25) are close to the white region due to an energy transfer process and the energy transfer mechanism from Ce³⁺ to Mn²⁺ in the RbCaGd(PO₄)₂ host was dominated by dipole-dipole interactions.     

Hydrothermal synthesis,crystal structure and characterization of LiCoP5O14·H2O: A new condensed layered penta phosphate crystals

A new family of condensed hydrated lithium cobalt penta phosphate (LiCoP₅O₁₄·H₂O) crystals were synthesized by hydrothermal technique and characterized by X-ray diffraction method. The compound crystallizes in monoclinic system with space group P21/c and cell parameters a = 10.788(4) Å, b = 9.761(3) Å, c = 9.788(5) Å, β = 101.249(1) Å, Z = 4, exhibiting layer type polymeric structure. DTA study indicates that this compound has low thermal stability and magnetically frequency dependent paramagnetic behaviour.     

X-ray powder diffraction,vibration and thermal studies of [A0.92(NH4)0.08]2TeCl4Br2 with A = Cs,Rb: Influence of mixed cationic and anionic substitutions

The crystal structures of [A_0.92(NH₄)_0.08]₂TeCl₄Br₂ with A = Cs, Rb have been determined using X-ray powder diffraction techniques. The two compounds crystallize in the tetragonal space group P4/mnc, with the unit cell parameters: a = 7.452(1) Å, c = 10.544(3) Å, Z = 2 and a = 7.315(2) Å, c = 10.354(4) Å, Z = 2 in the presence of Cs and Rb, respectively. These two compounds have an antifluorite-type arrangement of NH₄⁺/Rb⁺/Cs⁺ and octahedral TeCl₄Br₂^2? anions. The stability of these structure is by ionic and hydrogen bonding contacts: A?Cl, A?Br and N–H?Cl, N–H?Br. The different vibrational modes of these powders were analysed by FTIR and Raman spectroscopic studies. A DTA/TGA experiment reveals one endothermic peak at 780 K implicating the decomposition of the sample. At low temperature, one endothermic peak in thermal behavior is detected at around 213 K by DSC experiment. This transition was confirmed by dielectric measurements.     

High-pressure synthesis and magnetic properties of complex oxide Y2Cd2/3Re4/3O7

A new complex oxide Y₂Cd_2/3Re_4/3O₇ with hexagonal cell parameters a = 7.3564(2) Å, c = 17.7092(5) Å (space group P3₁21, z = 6, zirkelite structure type) was synthesized from Y₃ReO₈, ReO₂, metallic Re and CdO under pressure 6 GPa and temperature 1500 °C. Magnetic susceptibility measured in the temperature range from 2 to 300 K depends little on temperature above ∼50 K and is indicative of a delocalized or intermediate character of d electrons of Re⁵⁺ cations.     

Fluorine intercalation in the n = 1 and n = 2 layered manganites Sr2MnO3.5+x and Sr3Mn2O6

Fluorine insertion into the oxygen defect superstructure manganite Sr₂MnO_3.5+x has been shown by transmission electron microscopy (TEM) to result in two levels of fluorination. In the higher fluorine content sections, the fluorine anions displace oxygen anions from their apical positions into the equatorial vacancies, thus destroying the superstructure and reverting to a K₂NiF₄-type structure (a = 3.8210(1) Å and c = 12.686(1) Å). Conversely, lower fluorine content sections retain the Sr₂MnO_3.5+x defect superstructure, crystallising in the P2₁/c space group. Fluorine intercalation into the reduced double-layer manganite Sr₃Mn₂O₆ occurs in a step-wise fashion according to the general formula Sr₃Mn₂O₆F_y with y = 1, 2, and 3. It is proposed that the y = 1 phase (a = 3.815(1) Å, c = 20.29(2) Å) is produced by the filling of all the equatorial oxygen vacancies by fluorine atoms whilst the y = 2 phase (a = 3.8222(2) Å, c = 21.2435(3) Å) has a random distribution of fluorine anions throughout both interstitial rocksalt and equatorial sites. Neutron powder diffraction data suggest that the fully fluorinated y = 3 phase (a = 3.8157(6) Å, c = 23.666(4) Å) corresponds to the complete occupation of all the equatorial oxygen vacancies and the interstitial sites by intercalated fluorine.     

Ba2La2TiNb2O12: A new microwave dielectric of A4B3O12-type cation-deficient perovskites

A new A₄B₃O₁₂-type cation-deficient perovskite Ba₂La₂TiNb₂O₁₂ was prepared by the conventional solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The compound crystallizes in the trigonal system with unit cell parameter a = 5.6726(3) Å, c = 27.740(2) Å, V = 773.04(9) ų and Z = 3. The microwave dielectric properties of the ceramic were studied using a network analyzer, and it shows a high dielectric constant of 42.70, a high quality factor with Q × f of 31,130 GHz, and a small negative τ_f of − 4.2 ppm °C^− 1.     

(C2N2H10)[FexV1−x(HPO3)F3] (x = 0.44, 0.72): Two new organically templated phosphites: Solvothermal synthesis and structural,thermal, spectroscopic and magnetic studies

(C₂N₂H₁₀)[Fe_xV_1−x(HPO₃)F₃] (x = 0.44, 0.72) have been synthesized using mild solvothermal conditions under autogenous pressure and the ethylenediamine molecule as templating agent. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds crystallize in the orthorhombic P2₁2₁2₁ space group with Z = 4 and unit-cell parameters a = 12.8494(9), b = 9.5430(6), c = 6.4372(5) Å, and a = 12.8578(1), b = 9.5342(1), c = 6.4370(7) Å for (C₂N₂H₁₀)[Fe_0.44V_0.56(HPO₃)F₃] and (C₂N₂H₁₀)[Fe_0.72V_0.28(HPO₃)F₃], (1) and (2), respectively. These isostructural compounds exhibit a monodimensional crystal structure formed by pillared double anionic chains with the formula [M(HPO₃)F₃]²⁻, extended along the [0 0 1] direction. These doubled ionic chains are the result of the linking of two simple chains in which there are alternating octahedral [MO₃F₃] and tetrahedral groups [HPO₃]. The ethylendiammonium cations are placed in the space delimited by three different chains. The metallic ions are interconnected by the pseudo-pyramidal (HPO₃)²⁻ phosphite oxoanions, adopting a slightly distorted octahedral geometry. The IR spectra show bands corresponding to the phosphite oxoanion and the ethylendiamonium cation at 2400 and 1600 cm⁻¹, respectively. The thermogravimetric analyses show that these phases are stable up to ca. 280 °C, at higher temperatures, the decomposition of the crystal structure begins by calcination of the organic cation and the elimination of the fluoride anions. The diffuse reflectance spectra show bands of the V³⁺ ion (d²) in octahedral symmetry. The values of the Dq (1540, 1540 cm⁻¹), and Racah parameters, B (560, 535 cm⁻¹) and C (3055, 3140 cm⁻¹) for (1) and (2), respectively, correspond with those usually found for octahedrically coordinated V(III) compounds. Magnetic measurements, performed on a powered sample from 5.0 to 300 K at 1000 G, in the ZFC and FC modes, indicate the existence of antiferromagnetic interactions.     

Novel two-dimensional metal-organic framework with unprecedented trimeric building unit constructed from bridging water molecules

A novel two-dimensional nickel trimesate (1,3,5-benzenetricarboxylate), Ni₃(C₉O₆H₃)₂(H₂O)₈, has been obtained by solvothermal route. Its structure is built up from linear trimers of nickel, {Ni₃O₈(μ₂–OH₂)₂(H₂O)₆}, connected by trimesate anions. It crystallizes in the triclinic system, space group P-1, with a = 6.6960(3), b = 9.6446(3), c = 10.1114(3) Å, α = 112.638(1)°, β = 94.008(1)°, γ = 106.476(1)°, V = 565.99(4) Å³. Synthesis, X-ray structure determination, thermogravimetric analysis and magnetic properties are presented.     

Two 2-D 36 tessellated metal–organic frameworks constructed from trimetallic clusters and dicarboxylate ditopic links

Two metal–organic framework compounds, [Zn₃(1,4-BDC)₃(Py)₂]·2(1,4-dioxane) (MOF-CJ6) and [Cd₃(bpdc)₃(H₂O)₂] (MOF-CJ7), have been solvothermally synthesized and characterized by single crystal X-ray diffraction, X-ray powder diffraction, ICP, IR and photoluminescence spectroscopy analyses, respectively. MOF-CJ6 crystallizes in monoclinic, space group P2(1)/n (no. 14) with a = 14.6886(14) Å, b = 9.6194(6) Å, c = 15.9161(16) Å and β = 105.687(6)°. Its framework can be described as a 2-D 3⁶ tessellated net based on the assembly of trimeric Zn₃(CO₂)₆ clusters and 1,4-benzenedicarboxylates ditopic links. The 2-D nets can be further linked into a novel 3-D supramolecular hexagonal lattice (hex) network through π–π packing interaction. MOF-CJ7 crystallizes in trigonal, space group R-3 (no. 148) with a = 14.1129(8) Å, b = 14.1129(8) Å, c = 20.1168(13) Å and γ = 120°. MOF-CJ7 exhibits analogous framework topology with that of MOF-CJ6, consisting of trimeric Cd₃(CO₂)₆ clusters and 4,4′-biphenyldicarboxylate links.     

Preparation,characterization and dielectric properties of Ba5LnZnTa9O30 (Ln=La,Sm) ceramics

Ba₅LnZnTa₉O₃₀ (Ln=La, Sm) ceramics were prepared by high temperature solid-state reaction route. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) methods. They belong to paraelectric phase of filled tetragonal TB structure at room temperature with unit cell a=12.5909(4) Å, c=3.9622(2) Å for Ba₅LaZnTa₉O₃₀; and a=12.5777(4) Å, c=3.9544(2) Å for Ba₅SmZnTa₉O₃₀. At 1 MHz, Ba₅LaZnTa₉O₃₀ has high dielectric constants of 89 with low dielectric loss 0.0067, and temperature coefficients of the dielectric constant (τ_ε) −811 ppm °C⁻¹; Ba₅LaZnTa₉O₃₀ has dielectric constants of 74 with low dielectric loss 0.0035, and τ_ε −474 ppm °C⁻¹.     

Synthesis and characterization of Bi2S3 nanorods by solvothermal method in polyol media

Bi₂S₃ nanorods were synthesized via a simple solvothermal process in polyol media through the reaction between Bi(NO₃)₃·5H₂O, urea and CS₂ at 150 °C for 15 h using diethylene glycol as solvent. The nanorods were characterized by XRD, TEM and SAED. The results showed that the products were well-crystallized orthorhombic phase with lattice parameters a = 11.15 Å, b = 11.3 Å and c = 3.984 Å, which are consistent with the value in standard JCPDS card No. 17-0320. DEG served as an excellent solvent and structure director. Besides, compared to water and EG as solvents, the DEG system can provide a mild and homogenous condition, which is favorable to anisotropic growth and increases the yield of high quality Bi₂S₃ nanorods. Based on the experimental results, the growth mechanism was discussed.