Tahar Mhiri

Potassium gadolinium polyphosphate, KGd(PO3)4

Potassium gadolinium polyphosphate, KGd(PO(3))(4), was synthesized using the flux method. The atomic arrangement consists of an infinite long-chain polyphosphate organization. Two types of chains, with a period of eight PO(4) tetrahedra, run along the [101] direction. The Gd atoms have an eightfold coordination, while the K atoms have nine O-atom neighbours.

Crystal structure, vibrational studies, optical properties and DFT calculation of bis 2-aminobenzothiazolium tetrachloridocuprate.

The zero dimensional organic-inorganic hybrid compound (C7H7N2S)2CuCl4 was synthesized and characterized by X-ray diffraction, infrared absorption, Raman spectroscopy scattering and optical transmission measurements. The title compound crystallizes in the monoclinic system with P21/c space group. The unit cell parameters are a=7.060 (5) Å, b=9.748 (5) Å, c=14.037 (5) Å, β=98.520 (5)° and Z=2. The copper (II) ion has square planar coordination environment and the structure is built up from isolated [CuCl4](2)(-) anion surrounded by organic cations connected together via N-H⋯Cl hydrogen bonding. Room temperature IR and Raman spectra of the title compound were recorded and analyzed. The theoretical geometrical parameters in the ground state have been investigated by density functional theory (DFT) with the B3LYP/LanL2DZ level of theory. The organic-inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the (C7H7N2S)2CuCl4 compound and it showed characteristic absorptions of Cu-Cl based layered perovskite centered at 288 and 400 nm.

X-ray structural, vibrational and calorimetric studies of a new rubidium pentahydrogen arsenate RbH5(AsO4)2

Abstract Synthesis, crystal structure, Raman, IR and DSC characterization are given for a pentahydrogen arsenate of rubidium. X-ray investigations showed that the title compound (abbreviated RPA) crystallizes in an orthorhombic structure, space group Pbca and lattice parameters a =7.9403(8) A, b =9.8218(6) A, c =20.4244(6) A, V =1592.9(2) A 3 , Z =8 and ρ cal =3.072 g cm −3 . The structure was solved from 1568 independent reflections with R 1 =0.047 and WR 2 =0.067, refined with 106 parameters. The structure is different from RbH 5 (PO 4 ) 2 (abbreviated RPP). It can be regarded as consisting of isolated AsO 4 tetrahedra connected by strong H-bonds [2.432(6)–2.638(6) A] to an infinite network. The AsO 4 3− groups are located in layers parallel to the ab plane, and interleaved rubidium cations ensure cohesion between the sheets. The short hydrogen bond [2.432(6) A] is probably not symmetric. The Raman and infrared spectra at room temperature were investigated in the frequency ranges 15–1000 and 250– 4000 cm −1 , respectively. An assignment of all the bands is given. Differential scanning calorimetry showed that RPA crystals do not exhibit any phase transition in the range 100–575 K.

Crystal structure of N-benzylmethylammonium dihydrogen-monophosphate monohydrate, [C6H5CH2NH2CH3]H2PO4.H2O

The salt N-benzylmethylammonium dihydrogenmonophosphate monohydrate is monoclinic with the following unit cell dimensions: a = 6.356(1)Å, b = 8.385(7)Å, c = 11.472(5)Å, β = 104.32(1)°, space group P21 with Z = 2. The structure consists of infinite parallel two-dimensional [110] planes built of mutually connected ions and water molecules by strong O–H···O and N–H···O hydrogen bonding. There are no contacts other than normal van der Waals interactions between the layers.

Crystal structure, vibrational studies and optical properties of a new organic–inorganic hybrid compound (C10H28N4)CuCl5Cl⋅4H2O

A new organic-inorganic hybrid material, 1,4-bis(3-ammoniumpropyl) piperazinium pentachloridocuprate(II) chloride tetrahydrate [(C₁₀H₂₈N₄)CuCl₅Cl⋅4H₂O], has been synthesized and characterized by X-ray diffraction, UV-visible absorption, Infrared and Raman spectroscopy. The compound crystallizes in the orthorhombic system and Pnma space group with a=8.18 (3)Å, b=10.96 (5)Å, c=21.26 (9)Å, V=2254.3 (15)Å(3). In this structure, the Cu(2+) ion, surrounded by five chlorides, adopts the square pyramidal coordination geometry. The structure of this compound consists of tetraprotonated 1,4-bis(3-ammoniumpropyl) piperazinium cations and the anionic sublattice is built up of isolated, square pyramid [CuCl₅](3)(-) units, chloride ion Cl(-) and water molecules connected with each other by hydrogen bonds. Organic and inorganic entities are interconnected by means of hydrogen bonding contacts [NH⋯O(Cl), O(W)H⋯Cl and O(W)H⋯O]. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed on the basis of literature data. The optical study was also investigated by UV-Vis absorption. In fact, the organic-inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the (C₁₀H₂₈N₄)CuCl₅Cl⋅4H₂O hybrid compound and it showed absorptions characteristics of CuCl based layered compounds centered at 275 and 374 nm.

A supramolecular double sulfate salt with a lamellar type: crystal structure and thermal behavior.

The synthesis of a series of supramolecular double sulfate salts using transition metals and the aromatic amine α-methylbenzylamine afforded an unexpected hybrid lamellar structure type. (C8H12N)2[M(H2O)4(SO4)2]·2H2O (M = Fe to Zn) crystallizes with a monoclinic structure (S.G. P21/n), with a significant interlamellar distance of more than 16 Å. While comparable to common clay materials, the crystal structure is actually supramolecular; in particular, the mineral layer is built from hydrogen bonds only. The interlayer space is filled with aromatic amines that form chains through C-H···π interactions. The thermal study of all metal compounds revealed good stability of the filled compounds up to 200 °C. The dehydration proceeds differently according to the metal incorporated into the structure. In particular, the stepped release of water drastically modifies the interlayer space, which is able to vary from 14.8 to 18.8 Å, in an opposite way for the Zn-related compound compared to other metals.

Conductivity study of a new protonic conductor Rb1.12(NH4)0.88SO4·Te(OH)6

Abstract Single crystals of Rb 1.12 (NH 4 ) 0.88 SO 4 ·Te(OH) 6 were obtained by slow evaporation at 300 K. Differential scanning calorimetry showed an anomaly at 418 K, two shoulders at 482 and 510 K and one strong peak at 517 K. X-ray diffraction shows that the first DSC peak at 418 K passes the material from paraelectric to ferroelectric phase. A conductivity study shows that the shoulder at 482 (which masks a second one at about 458 K) can be attributed to a superprotonic phase transition. Dielectric constant and dissipation factor evolutions indicate that the peak at 458 K is probably due to a ferroelectric–paraelectric phase transition. The strong peak at 517 K was attributed to the decomposition of the salt.

Ferroelectric transition in Cs1−X(NH4)xHSO4 solid solutions

Abstract Dielectric investigations show three anomalies for some Cs1−x(NH4)xHSO4 (x = 0.05, 0.1 and 0.25) compositions. The paraelectric-ferroelectric phase transition is well defined in the 280–320 K temperature range. A dipolar-type relaxation is observed only for x = 0.25. The high-temperature phase transition is a plastic phase with highly orientational disorder.

Structural, vibrational and thermal studies of a new nonlinear optical crystal tetrapropylammonium dihydrogenmonoarsenate bis arsenic acid

Single crystals of tetrapropylammonium dihydrogenmonoarsenate bis arsenic acid [CH3CH2CH2]4N (H2AsO4) (H3AsO4)2, a potential new nonlinear optical (NLO) material of interest were prepared by the slow evaporation technique and characterized by means of single-crystal X-ray diffraction, thermal analysis, FT-IR and Raman spectroscopy. The title compound belongs to the monoclinic space group Ia with the following unit cell dimensions: a=8.116(2) Ǻ, b=33.673(4) Ǻ, c=8.689(2) Ǻ, β=95.34(2)°. The structure consists of infinite parallel two-dimensional planes built of mutually [H2AsO4(-)] and [H3AsO4] tetrahedra connected by strong O-H⋯O hydrogen bonding giving birth to trimmers. The planes of inorganic groups are alternated with those of the organic cations. The geometry, first hyperpolarizability and harmonic vibrational wavenumbers were calculated by means of density functional theory DFT with the B3LYP/6-31G(d) level of theory. Good consistency was found between the calculated results and the experimental structure, IR, and Raman spectra. The detailed interpretation of the vibrational modes was carried out building on the proposed DFT calculations as primary source of assignment and by comparison with the spectroscopic studies of similar compounds. The first hyperpolarizability βtot of the title compound is about 14.6 times more than that of the reference crystal KDP, which may explain the importance of the compound under study.

Synthesis, Crystal Structure, and Characterization of Na7Cu4(AsO4)5

Abstract Sodium copper (II) arsenate Na7Cu4(AsO4)5 has been grown by conventional high-temperature, solid-state methods in molten-salt media. It was characterized by single crystal X-ray diffraction (XRD), thermal analysis (DTA–TGA), scanning electron microscopy (SEM), semiquantitative energy dispersive spectroscopy analysis (EDS), and vibrational spectroscopy. Na7Cu4(AsO4)5 exhibits a three-dimensional framework built up of CuO5, CuO4, and AsO4 polyhedra, with intersecting channels in which the Na+ cations are located. The three-dimensional cohesion of the framework results from Cu–O–As bridges. CuO5 and CuO4 polyhedra are elongated due to the Jahn–Teller effect, whereas AsO4 tetrahedra are almost regular. This new structural model is validated by the charge distribution (CD) analysis. The infrared and Raman spectra confirmed the presence of AsO4 tetrahedra. [Supplementary materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional tables and figures.] GRAPHICAL ABSTRACT