Vibrational Spectroscopic Investigation and Theoretical Calculations of (E)-3-Phenyl-N-[4-(Phenyl-Amino) Quinazoline-7-yl] Acrylamide

ABSTRACT

Optimized geometrical structure and harmonic vibration frequencies of prior synthesized (E)-3-phenyl-N-[4-(phenyl-amino) quinazoline-7-yl] acrylamide were computed by ab initio HF and DFT/B3LYP methods using both 6-31G* and 6-311G** basis sets and the Moller–Plesset second-order perturbation (MP2) method merely at the 6-31G* level. The infrared (IR) spectrum of the title compound has been measured in the range of 400–4000 cm^?1. Complete vibrational assignments of the IR spectra were proposed. Moreover, the calculated wavenumbers of the title compound were compared with the experimental data. The correlation analyses indicate that good linearity relationships exist between the scaled theoretical vibration frequencies and the experimental values. Additionally, the atoms in molecules (AIM) method was applied to explore the possible intramolecular interactions in the title compound.     

Spectroscopic Investigation of Tungsten Ions in Lead Scandium Phosphate Glass System

Lead scandium phosphate glasses (PbO-Sc₂O₃-P₂O₅) containing different concentrations of tungsten oxide (WO₃) ranging from 0 to 5 mol% were prepared. A number of studies, viz. differential thermal analysis (DTA), infrared spectra, optical absorption, and electron spin resonance (ESR) spectra, have been carried out. The results of DTA indicated the highest glass forming ability for the glass containing 5 mol% of WO₃. The results of spectroscopic studies have been analyzed in light of different oxidation states of tungsten ions.     

An EPR Study on the Chemical form of Mn2+ in the Chinese Loess Samples

Electron paramagnetic resonance (EPR) spectroscopy in combination with thermal methods were used to identify and characterize Mn²⁺ in the Chinese loess that is a multimineral system. EPR spectra of the loess samples from the classic loess-paleosol section in central China show the presence of trace amounts of Mn²⁺; whereas paleosol samples present no Mn²⁺ EPR signal. The spectral changes upon step heating from room temperature to 1000 °C suggest that this EPR signal in the loess arises from Mn substituted into CaCO₃. This study provides a direct evidence that the loess-paleosol profiles were formed under the changing redox conditions caused by a past climatic change.     

NMR Analysis of a Complex Spin System from a Siruo-Chamigrene

The compound 2,10-dibromo-3-chloro-8-hydroxy-β-chamigrene was analysed in detail by NMR Spectroscopy. the complete assignment of the signals in the ¹H and ¹³C NMR spectra and the determination of the relative configurations were achieved by 2D NMR techniques, AM1 data and ¹H spectrum simulation. Comparisons of the results with related spiro chamigrene systems are also presented.     

Preconcentration and Separation of Gold(III) from Ore Samples by Solid-Phase Extraction Prior to Its Catalytic Fluorescent Determination

ABSTRACT

A new catalytic kinetic fluorescent quenching method for the determination of trace gold(III) was investigated. The method was based on the catalytic effect of gold on oxidation of 3-(3′-methylphenyl)-5- (2′-arsenoxylphenylazo) rhodanine by hydrogen peroxide in potassium hydrogen phthalate–hydrochloric acid (pH = 3.4). Under the optimum conditions, the great decrease of fluorescence intensity has a linear relationship against the concentration of gold in the range of 0 to 12.0 µg·L^?1 with a detection limit of 6.0 × 10^?10g·L^?1. The coexistent metal ions can be separated, and gold can be enriched by TBP resin of solid-phase extraction, which greatly improves the selectivity and sensitivity of the system. The method can be used to determine trace amounts of gold in ore samples successfully with satisfactory results.     

Rotational Analysis of the 1–4 Band of the B 2Σ+–X 2Σ+ System of 14C16O+

ABSTRACT

High-resolution emission spectrum of the 1–4 band of the B ²Σ⁺–X ²Σ⁺ transition of ¹⁴C¹⁶O⁺ was observed for the first time by conventional emission spectroscopy. The band spectrum was excited in a water-cooled Geissler lamp filled with commercial gaseous carbon monoxide enriched in about 80% of the radiocarbon ¹⁴C. A rotational analysis has been carried out and obtained molecular constants have been merged with previously published data for the B ²Σ⁺–A ²Π_i and A ²Π_i–X ²Σ⁺ transitions. The principal equilibrium constants for the ground X ²Σ⁺ state obtained from this work are ω_e = 2121.7726(98), ω_e x _e = 13.9055(27), B _e = 1.815290(30), α_e = 1.6594(33) × 10^?2, and γ_e = ? 0.377(73) × 10^?4 cm^?1. Also, presently known experimental equilibrium molecular constants of the X ²Σ⁺ states of the CO⁺ isotopic molecules are summarized and isotopic dependence of the B _e and ω _e constants is discussed.     

Femtosecond Diffuse-Reflectance Spectroscopy of Various Commercially Available TiO2 Powders

The transient absorption properties of several commercially available TiO₂ photocatalysts were investigated by femtosecond diffuse-reflectance spectroscopy. Using femtosecond diffuse-reflectance spectroscopy, the quantities and rates of the initial trapping processes of holes and electrons generated by the photoexcitation of TiO₂ photocatalysts were investigated. It was found that the total amounts of trapped electrons for the pure-anatase and pure-rutile TiO₂ became smaller with increasing particle size, but increased again when the particles’ diameters were larger than 50 nm. The anatase–rutile mixed TiO₂ photocatalysts were found to have smaller amounts of trapped electrons compared with pure-anatase and pure-rutile TiO₂ photocatalysts. The lifetimes of trapped holes of various TiO₂ photocatalysts were also investigated, and it was found that the lifetimes were proportional to the anatase–rutile mixed ratios.     

Interpretation of Polarized Absorption and Emission Spectra of Molecules Incorporated in Stretched Polymer Films

Different methods for the interpretation of linear dichroic spectra of molecules incorporated in uniaxial matrices are discussed. A method based on the combination of both polarized absorption and emission measurements is described for the resolution of absorption and emission spectra into their different polarized components, and for the investigation of molecular distributions in the oriented matrix. The distributions of some planar molecules of different shapes incorporated in stretched polyethylene films are presented.     

Fiber Optic Spectrophotometer for Noninvasive Transmission and Diffuse Reflection Studies

We describe the construction of a simple but versatile single-beam spectrophotometer that uses no sample holder at all; one arm of a bifurcated fiber optic bundle illuminates the specimen, while the other receives the remitted light. Though designed with an eye to recording the diffuse reflection spectra of scattering-and-absorbing substances, it can also be used for conventional studies (ie transmission spectroscopy) by merely placing a plane mirror behind the cuvette. The performance of the instrument is evaluated and representative spectra of several powders, solutions, and biomaterials are presented.     

Normal Coordinates Analysis for The M(NH3)2+ 4 Complex Ions in D4h and Td Symmetries. Simplified Molecular Models

A normal coordinates analysis for the M(NH₃)²⁺ ₄ complex ions in T_d symmetry (M = Zn, Cd, Co) and in D_4h symmetry (M = Cu, Pd, Pt) has been undertaken on the basis of a General Valence Force Field (GVFF), using simplified molecular models. Throughout the course of the present work, we have relaxed the point mass approximation for the NH₃-ligands in order to investigate, on a quantitative basis, some relevant ligand - framework coupling vibrations. The simplest molecular model able to accomplish this purpose is to treat the ammino group, in a linear ligator approximation. We show that these model calculations provide a satisfactory set of vibrational frequencies as well as consistent sets of force constants.