The influence of concentration and supersaturation ratio of CuI·HI on CuI crystal growth by decomplexation method

The fundamental role of solubility and supersaturation of solute for crystal growth from solution has been widely realized. In order to optimize the process of CuI crystal growth by CuI·HI decomplexation in HI acid, the solubility and supersaturation curves of CuI in HI‐H₂O mixed solvent were measured, and then a modified concentration programming scheme was designed, which could grow high quality CuI single crystals of 2.5 mm on edge successfully. In this scheme, the concentration distribution of CuI·HI complex and HI acid in silica gel along their diffused direction were measured with spectrophotometer, and the evolution of CuI·HI complex supersaturation ratio was analysed. It was found that the excess CuI·HI complex concentration would lead to the high supersaturation ratio and the formation CuI dendrites. The condition for regular CuI single crystal growth in silica gel was measured as follow: when the crystal nuclei appears, the CuI·HI complex concentration in HI‐H₂O solvent should be kept in the range of 0.033–0.050 mol/L and its corresponding supersaturation ratio is 1.24–1.45, and then they should be respectively declined to a range of 0.025–0.033 mol/L and 1.14–1.26 at the stage of crystal growth. The results may provide a useful clue for further improvement of the experimental scheme. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Rapid Eco-Friendly Synthesis and Structure of 3-Hydroxy-3-nitromethyl-1,3-dihydro-indol-2-one

Abstract  

3-Hydroxy-3-nitromethyl-1,3-dihydro-indol-2-one was synthesized from isatin by Henry reaction using an eco-friendly method and characterized by NMR and MS. The crystal structure was determined from single-crystal X-ray diffraction data. It crystallizes in the orthorhombic space group, Pbca, with unit cell dimensions a = 10.515 (2) Å, b = 7.3736 (14) Å, and c = 23.261 (4) Å. The two rings are coplanar and the angle between hydroxyl group and nitromethyl group is 109.07(9)°. In the crystal structure, intermolecular N–H···O and O–H···O hydrogen bonds are responsible for the formation of a 3-dimensional network. No intramolecular hydrogen bond exists.     

A general model for non-autocatalytic zymogen activation in the presence of two different and mutually exclusive inhibitors. II. Relative weight of activation and inhibition processes

The kinetic study carried out in paper I of this series (preceding article) on enzyme systems involving zymogen activation and the simultaneous action of two different, mutually exclusive inhibitors (Scheme 1) allows, new dimensionless kinetic parameters to be suggested. These parameters furnish quantitative information about the relative weight of the activation and inhibition routes, i.e. the conditions under which the activation prevails over the inhibition and vice versa, as well as the absolute and relative contributions to overall inhibition of each of the inhibition routes and their synergistic effect. These results can be easily and directly applied to any of the thousands of particular cases of the model. Examples are given for different particular cases.     

Enhanced proton conductivity of polymer electrolyte membrane doped with titanate nanotubes

Nafion-titanate nanotubes composite membranes were prepared through a casting process. With the addition of 5 wt.%, the nanotubes were homogenously distributed in Nafion solution. The formed composite membrane showed a comparable mechanical strength to Nafion membrane. The proton conductivity of the composite membrane without external humidification is higher than that of the Nafion membrane, reaching 0.034 Scm^?1 and 0.01 Scm^?1 at 100 °C and 120 °C, respectively. The improved proton conductivity was attributed to the great water retention ability of the doped nanotubes.     

New fluorescent sensor for antimony and transition metal cations based on rhodamine amide-arm homotrioxacalix[3]arene

A new fluorescent sensor 1 based on the rhodamine amide-armed homotrioxacalix[3]arene was synthesized, and its sensing behavior toward metal ions was investigated by UV–vis and fluorescence spectroscopies. Upon the addition of metal cations (Sb³⁺, Fe³⁺, Ni²⁺), a significant fluorescent enhancement in the range of 500–600 nm and colorimetric change was observed.     

A novel rhodamine-based thiacalix[4]arene fluorescent sensor for Fe3+ and Cr3+

The novel fluorescent sensor 1, which is comprised of two rhodamine B lactams as fluorophores that are 1,3-alternately linked to a thiacalix[4]arene, behaves as a highly sensitive ion-induced fluorescent sensor for Fe³⁺ and Cr³⁺. This compound was synthesized, and its recognition of metal ions was evaluated by fluorescence and absorption spectroscopy. The possible mechanism of Fe³⁺- and Cr³⁺-induced spirocycle opening of 1 leads to fluorescent and colorimetric enhancement, and these properties were investigated by spectroscopy, ¹H NMR and IR. The stoichiometric ratios and association constants of the complexes between 1 and these ions have been measured and calculated, and showed that the presence of Fe³⁺ or Cr³⁺ induced sensor 1 to form a stable 1:1 complex.     

Nanoindentation testing of SiO<Subscript>2</Subscript>-PMMA hybrid films on acrylic substrates with variable coupling agent content

In this work we report the influence of the molar composition of the coupling agent, as well as the curing conditions on the mechanical properties of SiO₂-PMMA (polymethyl methacrylate) hybrid films deposited on organic acrylic substrates. The SiO₂-PMMA hybrid films were deposited by the sol–gel method from hybrid precursor solutions with fixed molar ratio of 1:0.25 for TEOS/MMA (Tetraethyl-orthosilicate/Methylmethacrylate) and TEOS/TMSPM (3-trimethoxysilyl propyl methacrylate) molar ratios ranging from 1:0.05 to 1:0.2. The organic compound TMSPM was used as coupling agent to enhance the bond between the organic and inorganic molecules. The wear resistance, hardness and elastic modulus of the hybrid films were determined by nanoindentation techniques and compared to the substrate mechanical behaviour. The chemical bonding in the hybrid films was analyzed by Fourier Transform Infrared spectroscopy and their transparency by optical transmission and reflection spectroscopy. The friction coefficient and sliding life of the hybrid films were also measured with a pin-on-disc tribometer. The surface morphology and roughness were determined from atomic force microscopy images. The hybrid films with lowest content of coupling agent showed the best mechanical performance in terms of hardness, friction coefficient and wear resistance keeping high optical transparency.     

Structure of Glancing Incidence Deposited TiO2 Thin Films as Revealed by Grazing Incidence Small‐Angle X‐ray Scattering

For the first time, grazing incidence small‐angle X‐ray scattering (GISAXS) analysis is used to characterize the morphology of TiO₂ thin films grown by glancing angle physical vapor deposition (GLAD). According to cross‐section scanning electron microscopy (SEM) images, the films consist of near isotilted TiO₂ columns of different length and width depending on film thickness. The obtained GISAXS patterns show a characteristic asymmetry with respect to the incidence plane, which is associated with the tilted geometry of the TiO₂ columns. The patterns also show the existence of two populations of columns in these GLAD‐TiO₂ films. The population of the thinnest columns appears related to the first grown layer and is common for all the films investigated, while the second population of columns grows with the thickness of the films and has been related to wider columns formed by shadowing at the expense of the initially formed columns.     

Preparation and properties of water‐soluble chitosan and polyvinyl alcohol blend films as potential bone tissue engineering matrix

The blend film was prepared by casting solutions of water‐soluble hydroxyethyacryl‐chitosan (HEA‐CS) and polyvinyl alcohol (PVA) and cross‐linked by glutaraldehyde. The structure and properties of the blend films were estimated by wide‐angle X‐ray diffraction (WXRD), contact angle measurements with water, and scanning electron microscopy (SEM). The tensile properties of the blend films were investigated and the tensile strength (TS) and the elongation increased with the increased amount of PVA. The thermal stability (thermogravimetric (TG) and derivative thermogravimetric (DTG)) was evaluated and HEA‐CS was more thermally‐stable than that of PVA. The water swelling properties analysis indicated that HEA‐CS in the blends promoted the water absorption owing to its porous structure and the antimicrobial ability of the blend films was retained. Indirect cytotoxicity assessment of the blend films with human bone sarcoma cell (SW1353) indicated that the biomaterials were non‐toxic and did not release substances harmful to living cells. Copyright © 2009 John Wiley & Sons, Ltd.     

On the nature of the transition metal-main group metal bond: synthesis and theoretical calculations on iridium gallyl complexes

The iridum-gallyl complex MeIr(PCy(3))(2)(GaMe(2))(Cl*GaMe(3)) exhibits a short Ir-Ga bond length of 2.381(1)-2.389(2) ?. Theoretical calculations (ZORA BP86/TZ2P) support the presence of a Ir-Ga single bond but highlight a π orbital contribution.