The influence of basis set on the ab initio prediction of internal rotation barrier heights in ethene thiol

In this report the effects of basis set size and electron correlation on the internal rotation barrier heights in ethene thiol are investigated and compared with experimental data. At all levels of theory reasonable agreement is obtained for the barrier tosyn/anti rotation (experimental value: 9.6 kJ/mol), however, theanti barrier (experimental value: 0.14 kJ/mol) is consistently overestimated by approximately a factor of 10. A comparison of ab initio predictions of torsional energy distributions and rotational constant variations as a function of torsional state with the corresponding experimental quantities is presented.     

Cation mobility upon adsorption of methanol in NaY faujasite type zeolite: A molecular dynamics study compared to dielectric relaxation experiments

Molecular Dynamics simulations have been carried out to address the question of cation migration upon adsorption of methanol in NaY Faujasite system as a function of the loading. It has been shown that at low and intermediate loadings, SII cations can migrate toward the center of the supercage due strong interaction with the adsorbates, followed by hopping of SI' cations from the sodalite cage into the supercage to fill vacant SII sites. SI cations mainly remain trapped in their initial sites whatever the loading. At higher loading, only limited motion is observed for SII cations due to steric effects induced by the adsorbates within the supercage. These simulated results are in good agreement with those extracted by Complex Impedance Spectroscopy measurements, which provided the evolution of the number of extraframework cations in the different crystallographic sites as a function of the treatment temperature.     

Two New Saponins from Lysimachia davurica

Two new saponins named davuricoside I (1) and davuricoside E (2) were isolated from the whole plants ofLysimachia davurica. Their structures were determined by 1D and 2D NMR, FAB-MS techniques, and chemical methods.     

The NMR spectra of porphyrins 20—proton and 13C characterization of porphyrin atropisomers

The preparation, isolation and characterization by proton and ¹³C NMR of the four possible atropisomers of meso-tetra(2-methoxy-1-naphthyl)porphyrin is described. Chemical shift differences due to atropisomerization effects are observed in the porphyrin and naphthyl rings. Comparison of the naphthyl chemical shifts with those of the model compound 1-isopropenyl-2-methoxynaphthalene allows the shifts due to the porphyrin ring current to be isolated. The observed Δδ values of the naphthyl protons agree well with those calculated from the previously described porphyrin ring current model, and allow both the angle of tilt of the naphthyl ring and the dihedral angle of the 2-methoxy substituent to be estimated. In contrast, the Δδ values for the naphthyl carbons bear no relationship to the calculated ring current shifts. Calculations of the total ring current contribution (porphyrin plus naphthyl rings) at the different naphthyl rings of the unsymmetric type III isomer show that at least part of the observed atropisomerism effects are due to the long-range current shifts of the naphthyl rings. The results also provide a clear demonstration of the identity of the porphyrin ring current in the free base and porphyrin dication.     

A colorimetric and fluorometric fluoride sensor based on a BODIPY-phenol conjugate

A boradiazaindacenes (BODIPY)-phenol conjugate,1,can act as a colorimetric and fluorometric sensor for sensitive and se-lective measurement of F-over AcO-and H2PO-4 in CH3CN. Sensor 1 gives response to F-in a 1:1 ratio via the deprotonation of the phenolic OH proton,which results in color change from pale yellow to light green and quenching of bright green fluo-rescence.     

Temperature dependence of optical and structural properties of ferroelectric B3.15Nd0.85Ti3O12 thin film derived by sol–gel process

We report the annealing temperature dependence of optical properties in ferroelectric B_3.15Nd_0.85Ti₃O₁₂ (BNdT) thin film for the first time. BNdT thin films are prepared by a sol–gel/spin coating method. Structural properties of BNdT thin films upon different thickness and annealing temperatures are characterized using the X-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The BNdT thin film annealed at 650 °C exhibits a well defined perovskite crystalline structure with high c-axis orientation, which leads to a saturated polarization–electric field (PE) hysteresis with a remanent polarization of 2P _r = 39.6 μC/cm² and coercive field of 85 kV/cm at 5 V. Little fatigue degradation (<5%) is demonstrated upon 1 × 10¹⁰ switching cycles indicating a good fatigue endurance. Additionally, a superior optical transparency T(λ) of >80% is observed for wavelengths from 250 to 2,000 nm. Fundamental optical parameters of BNdT material such as refractive index n, extinction coefficient k, and band gap energy E _g are extracted from an ellipsometry measurement. Microstructure and annealing temperature dependence of T(λ), n, k, and E _g variation are also investigated and explained in detail.     

Production of high-quality agarwood in Aquilaria sinensis trees via whole-tree agarwood-induction technology

We used whole-tree agarwood-induction technology to produce agarwood from Aquilaria sinensis trees within 20 months,and evaluated the quality of this agarwood.The results showed its characteristics were similar to those of high-grade wild agarwood in terms of texture,chemical constituents,essential oil content,and ethanol-soluble extract content,with the lattermost quality far surpassing the requirement of traditional Chinese medicine agarwood,as indicated in Chinese Pharmacopoeia 2010.To the best of our knowledge,this is first study to show that high-quality agarwood can be produced in whole A.sinensis trees via a chemically induced technology.