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The hydrates [Na2(H2O)3(Htba)2] (1) and [Na2(H2O)4(Htba)2] (2), where H2tba is 2-thiobarbituric acid, were obtained under different thermal conditions from aqueous solutions and were structurally characterized. The molecular and supramolecular structures were compared to the known structure of [Na2(H2O)5(Htba)2] (3). In polymeric1–3, the Htba−ions are linked to Na+through O and S forming octahedra. The decrease of the number of coordination water molecules led to an increase of the total number of bridge ligands (μ2-H2O, Htba−) and a change of the Htba−coordination. These factors induced higher distortion of the octahedra. It was assumed that hydrates, with a different number of coordinated water molecules, are more probable when the central metal has weaker bonds with O water molecules and with other ligands. The net topologies of1–3were compared. Thermal decomposition and IR spectra were analyzed for1and2. [ABSTRACT FROM PUBLISHER]

Two new d -element compounds, [Co(H 2 O) 6 ](Detba) 2 ·2H 2 O ( 1 ) and [Ni(H 2 O) 6 ](Detba) 2 ·2H 2 O ( 2 ) (HDetba – 1,3-diethyl-2-thiobarbituric acid) were synthesized and characterized by single-crystal and powder X-ray diffraction analysis, TG–DSC and FT-IR. Structural analysis revealed that ( 1 ) and ( 2 ) are discrete structures, in which M 2+ ion (M = Co, Ni) is six-coordinated by water molecules and it forms an octahedron. The outer-sphere Detba − ions and H 2 O molecules participate in O H⋯(O/S) intermolecular hydrogen bonds which form the 2D layer. Thermal decomposition includes the stage of dehydration and the following stage of oxidation of Detba − with a release of CO 2 , SO 2 , H 2 O, NH 3 and isocyanate gases. [ABSTRACT FROM AUTHOR]

Binuclear [Ni 2 (en) 2 (H 2 O) 6 (pyr)]·4H 2 O complex undergoes dehydration in 325–400 K temperature region, which is accompanied by polymerization. Polymerized product is characterized by chelate coordination of carboxylate group to Ni, as identified by vibrational spectroscopy. XRD and spectroscopic measurements suggest that the resulting dehydration product is two-dimensional layered polymer with weak interconnectivity between the polymer layers. A combination of experimental measurements and DFT calculations was used to identify two reaction mechanisms, as well as the factors determining the change from one mechanism to the other. Reaction mechanism changes with increase in the heating rate, due to slow diffusion of released water inhibiting the polymerization. Polymerization occurs in parallel with dehydration at lower heating rates, while it follows dehydration at higher heating rates, leading to an increase in overall enthalpy of the reaction of around 50 kJ mol −1 and decrease in crystallinity of the polymeric product. Determined isokinetic temperature of the dehydration reaction corresponds to the vibrational frequency of Ni OH 2 bond. [ABSTRACT FROM AUTHOR]

Zofenopril calcium (ZOF) is one of the newest angiotensin-converting enzyme (ACE) inhibitors, highly lipophilic and with low water solubility. This research investigates the interaction between ZOF and a chemically modified derivative of β-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin (HPBCD), in order to prove the formation of an inclusion complex with an enhanced water solubility profile of ZOF. In this research, for the first time, the physicochemical characterization and the solubility profile of an inclusion complex between ZOF and HPBCD are reported. Different spectroscopic techniques (UV absorption spectrometry, powder X-ray diffraction, attenuated total reflectance Fourier transform IR spectroscopy) were applied in order to prove the formation of the ZOF/HPBCD inclusion complex, both in water and in the solid state, backed by thermal analysis (TGA/DTG/HF). The obtained results confirmed that the physicochemical properties of the ZOF/HPBCD binary system, prepared using the kneading method, are different in comparison to both with the parent substances and the corresponding physical mixture, thus suggesting that an inclusion complex was formed. After the formation of the inclusion complex with HPBCD, the solubility test indicated that the water solubility of ZOF was increased 5-fold. [ABSTRACT FROM AUTHOR]

The present paper undertakes the study of a new hybrid compound [2-CH3C6H4NH3]2SeO4 characterized by the X-ray diffraction, IR, DFT calculation, TG-DTA, DSC and electrical conductivity. This new organic-inorganic hybrid compound crystallizes in the monoclinic system with P21/c space group and the following parameters a = 14.821 (5) Å; b = 16.245 (5) Å; c = 6.713 (5) Å; ß = 102.844 (5)°, Z = 4 and V = 1575.8 (14) ų. The atomic arrangement can be described as isolated tetrahedral SeO42- connected with the organic groups by means of NH⋯O hydrogen bonds to form infinite sinusoidal chains in the c-direction. BHHLYP/6-311g** method was used to determine the harmonic frequencies for two optimized cluster structures. The calculated modes were animated using the Molden graphical package to give tentative assignments of the observed IR spectra. Thermal analysis of the title compound does not indicate the occurrence of a phase transition in the temperature range of 300-650 K. Dielectric study of this compound has been measured, in order to determine the conductivity. The conductivity relaxation parameters associated with some H+ conduction have been determined from an analysis of the M"/M"max spectrum measured in a wide temperature range. [ABSTRACT FROM AUTHOR]

Abstract: Renal stone containing calcium oxalate monohydrate as a major component was subjected to microhardness and acoustic studies in order to understand its mechanical properties in vitro and use them to help in the treatment procedures for more effective stone fragmentation. The chemical composition and the crystalline nature of the stone were verified using Fourier Transform Infrared spectroscopy, X-ray diffraction and the stone was also analyzed using thermo gravimetric analysis and by differential thermal analysis. The microhardness values were almost constant around 1000 MNm−2 in the load range of 1.96 N–9.8 N. The values of fracture toughness and brittleness index for the stone in this load range was varying from 1.12 (0.307) MNm−3/2 to 1.48 (0.296) MNm−3/2 and 674.25 m−1/2 to 878.07 m−1/2 respectively. The density of the stone and the ultrasonic longitudinal wave velocity in the stone were found to be 1880 kgm−3 and 3399 ms−1 respectively indicating that the urinary stone under study was a compact one. The acoustic impedance and the dynamic modulus values were calculated as 6.39×106 kgm−2 s−1and 21.72 GNm−2 respectively. [Copyright &y& Elsevier]