Interaction between tetramethylcucurbit[6]uril with α-furaldehyde-isonicotinyl-hydrazone hydrochloride

Interaction between tetramethylcucurbit[6]uril (TMeQ[6], host) and the hydrochloride salt of α-furaldehyde-isonicotinyl-hydrazone hydrochloride (FIHH⁺, guest) was investigated using X-ray crystallography and spectroscopic methods. X-ray crystallography showed that the π–π stacking effect and hydrogen bonding resulted in the formation of a dumbbell-shaped supramolecule which contained two FIHH⁺@TMeQ[6] host–guest inclusion complexes. The host–guest interaction provided identifiable changes in the vibrational frequencies in the IR spectra. ¹H NMR spectral analysis established a similar interaction model and revealed that TMeQ[6] preferred to include the furan moiety over the pyridine moiety of the FIHH⁺ guest molecule. Absorption spectrophotometric analysis suggested that the host and guest interact in a ratio of 1:1 with a stability constant K _s = (3.52 ± 0.74) × 10⁶ l mol^? 1.pH titration confirmed that the host–guest interaction led to a clear change in the protonation constant of the title guest. Quantum chemical calculations were used to determine the possible mechanism of formation of the dumbbell-shaped complex.     

Development of an information-intensive structure–activity relationship model and its application to human respiratory chemical sensitizers

Structure–activity relationship (SAR) models are recognized as powerful tools to predict the toxicologic potential of new or untested chemicals and also provide insight into possible mechanisms of toxicity. Models have been based on physicochemical attributes and structural features of chemicals. We describe herein the development of a new SAR modeling algorithm called cat-SAR that is capable of analyzing and predicting chemical activity from divergent biological response data. The cat-SAR program develops chemical fragment-based SAR models from categorical biological response data (e.g. toxicologically active and inactive compounds). The database selected for model development was a published set of chemicals documented to cause respiratory hypersensitivity in humans. Two models were generated that differed only in that one model included explicate hydrogen containing fragments. The predictive abilities of the models were tested using leave-one-out cross-validation tests. One model had a sensitivity of 0.94 and specificity of 0.87 yielding an overall correct prediction of 91%. The second model had a sensitivity of 0.89, specificity of 0.95 and overall correct prediction of 92%. The demonstrated predictive capabilities of the cat-SAR approach, together with its modeling flexibility and design transparency, suggest the potential for its widespread applicability to toxicity prediction and for deriving mechanistic insight into toxicologic effects.     

Theory of docking scores and its application to a customizable scoring function

In general, the docking scoring tends to have a size dependence related to the ranking of compounds. In this paper, we describe a novel method of parameter optimization for docking scores which reduce the size dependence and can efficiently discriminate active compounds from chemical databases. This method is based on a simplified theoretical model of docking scores which enables us to utilize large amounts of data of known active and inactive compounds for a particular target without requiring large computational resources or a complicated procedure. This method is useful for making scoring functions for the identification of novel scaffolds using the knowledge of active compounds for a particular target or a customized scoring function for an interesting family of drug targets.     

Various shaped-ZnO nanocrystals via low temperature synthetic methods: Surfactant and pH dependence

ZnO nanocrystals, rod-, carnation-, and flower-like structures, have been synthesized in a high yield through low-temperature synthetic methods. Well-aligned ZnO nanorods having hexagonal wurtzite structure were grown on the ZnO thin films assembled by a spin-coating method. The morphologies of ZnO seed films are affected by pHs of sol–gel solutions, resulting smaller sizes and homogeneous roughness at higher pHs and higher number of spin-coating times. The carnation-like structures, average size of about 2–3 μm, were assembled by tens of uniform ZnO nanosheet petals of ∼50 nm in thickness when a different volume ratio of the precursory solution was used. ZnO nanocrystals on the facets of the compact ZnO nanorods have grown to linear nanorods having an average diameter of ∼500 nm and length of ∼2 μm. Furthermore, a noticeable difference in the growth of ZnO nanocrystals in the presence of various surfactants, polyvinylpyrrolidone, polyvinylsulphonic acid, and polyethyleneimine, has been observed and discussed.     

Optical and luminescence properties of Dy3+ ions in phosphate based glasses

Phosphate glasses with compositions of 44P₂O₅ + 17K₂O + 9Al₂O₃ + (30 − x)CaF₂ + xDy₂O₃ (x = 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 4.0 mol %) were prepared and characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier transform infrared (FTIR), optical absorption, emission and decay measurements. The observed absorption bands were analyzed by using the free-ion Hamiltonian (H_FI) model. The Judd–Ofelt (JO) analysis has been performed and the intensity parameters (Ω_λ, λ = 2, 4, 6) were evaluated in order to predict the radiative properties of the excited states. From the emission spectra, the effective band widths (Δλ_eff), stimulated emission cross-sections (σ(λ_p)), yellow to blue (Y/B) intensity ratios and chromaticity color coordinates (x, y) have been determined. The fluorescence decays from the ⁴F_9/2 level of Dy³⁺ ions were measured by monitoring the intense ⁴F_9/2 → ⁶H_15/2 transition (486 nm). The experimental lifetimes (τ_exp) are found to decrease with the increase of Dy³⁺ ions concentration due to the quenching process. The decay curves are perfectly single exponential at lower concentrations and gradually changes to non-exponential for higher concentrations. The non-exponential decay curves are well fitted to the Inokuti–Hirayama (IH) model for S = 6, which indicates that the energy transfer between the donor and acceptor is of dipole–dipole type. The systematic analysis of revealed that the energy transfer mechanism strongly depends on Dy³⁺ ions concentration and the host glass composition.     

Synthesis,spectroscopic and crystal structure analysis of 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)imidazo[2,1-b][1,3,4]thiadiazole and its morpholinomethyl derivative

The preparation of 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)-5-morpholin-1-ylmethyl imidazo[2,1-b][1,3,4]thiadiazole via the intermediate 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)Imidazo[2,1-b][1,3,4] thiadiazole is described. Elemental analysis, IR spectrum, ¹H NMR and X-ray crystal structure analyses were carried out to determine the compositions and molecular structures of the two compounds. The crystal packing exhibits intermolecular C–H?O, C–H?N, C–H?F and π–π stacking interactions leading to the formation of the supramolecular network.     

Synthesis and photocatalytic properties of core–shell TiO~2@ZnIn_2S_4 photocatalyst

A novel core–shell TiO2@ZnIn2S4composite has been synthesized successfully by a simple and flexible hydrothermal route using TiO2as precursors.The as-synthesized samples were characterized by X-ray diffraction,UV–vis diffuse reflectance spectra and transmission electron microscopy.The photocatalytic properties of samples were tested by degradation of aqueous methylene blue（MB）under visible light irradiation.It was found that the as-synthesized TiO2@ZnIn2S4photocatalyst was more effcient than TiO2and ZnIn2S4in the photocatalytic degradation of MB.Moreover,TEM images confrmed the TiO2@ZnIn2S4nanoparticles possessed a well-proportioned core–shell morphology.     

New Look into the Synthesis of Polyhalogenoarylphosphanes

The present study shows new aspects of the synthesis of polyhalogenoarylphosphanes. The sterically hindered anions Ph(R)P-Y^? (1a–c, Y = O, lone pair; R = Ph, Bu^t) have been used to show the complexity of the reaction between phosphorus nucleophiles and hexahalogenobenzenes or 9-bromofluorene (E3). The Ph(Bu^t)P-O^? (1a) anion reacts with hexachlorobenzene (E1), hexafluorobenzene (E2), or E3 to give Ph(R)P(O)X (4a–c, X = F, Cl, Br) with the release of the corresponding carbanion as a nucleofuge, followed by side reactions. In contrast, the lithium phosphides Ph(R)PLi (1b,c) react with hexahalogenobenzenes to give the corresponding diphosphanes 5a,b as the main product and traces of P-arylated products, i.e., Ph(R)P-C₆X₅ (10a,b, X = Cl, F). Unexpectedly, Ph(Bu^t)PLi (1b) reacts with an excess of 9-bromofluorene to give only halogenophosphane Ph(Bu^t)P-X.