Structural Chemistry - Experimental and computational studies were performed to determine the antioxidant activities of harmine, harmaline, harmalol, harmane, and... 相似文献
Research on Chemical Intermediates - The objective of this work is to test the effectiveness of hydrotalcite as an adsorbent for the retention of nitrate and nitrite ions and to study the influence... 相似文献
Amino-acyl-quinoxalinone yellow dyes are cyclised analogues of the yellow azomethine dyes developed for, and still used in, silver halide colour photography. Unlike image azomethine dyes, which are rapidly deactivated in their excited states by torsion about the azomethine bond, amino-acyl-quinoxalinone dyes have an interesting photophysics because torsion is not possible due to their cyclised structure. We report results from studies on singlet and triplet state properties, and singlet oxygen yields, of the yellow dye, 7-diethylamino-3-(2,2-dimethyl-propionyl)-5-methyl-1-phenyl-1H-quinoxalin-2-one, in polar and nonpolar solvents. The dye photophysics is characterised by a weak fluorescence, with a solvent dependent emission yield (ΦF?≈?0.002–0.004), and short singlet state lifetime (τexpt?≈?20–50 ps), both increasing by a factor of ≈2 in going from polar acetonitrile to non-polar dioxane as solvent. DFT ZINDO calculations show a transition involving significant electron transfer from the diethyl-amino group into the carbonyl region of the molecule. In solution, in the presence of oxygen, the triplet state decays almost exclusively by oxygen quenching, and singlet oxygen is produced in high yield (Φ??≈?0.5–0.55). The triplet state absorbs across the 450–750 nm region with maxima around 480 and 650 nm, and moderate molar absorption coefficients (ca. 6000–8000 M?1 cm?1). In a glass at 77 K, triplet decay gives a red phosphorescence, with λmax?≈?640–650 nm, and a ?≈?0.25 s lifetime. If singlet oxygen yields are a good indication of triplet yields, then internal conversion and intersystem crossing occur with roughly equal efficiency.
Structural Chemistry - A combined experimental and theoretical study is presented to predict and analyze the inhibition efficiency and adsorption mechanism of 4-aminobenzoic acid molecule for... 相似文献
Research on Chemical Intermediates - A series of D–π–A architectures dyes with Coumarin-based derivatives as difluorenylaminocoumarin (DF) and diphenylaminocoumarin (DP) have been... 相似文献
The photocatalytic activity of titanium dioxide and gold modified TiO2 (Au/TiO2), supported on polymethylmethacrylate (PMMA) thin film, was evaluated in the photodegradation of Trypan Blue (TB) under sunlight
irradiation. The effect of parameters such as the photocatalyst amount and pH on TiO2 photocatalytic activity is investigated. Oxygen flow stream was applied to enhance the decomposition process of TB. The maximum
photoactivity was attained using Au/TiO2-PMMA thin film at pH 2. 相似文献
ZnO/ZnS heterostructures were synthesized by a two steps electrochemical deposition method. Firstly, ZnS layer was deposited from an aqueous solution containing Na2S2O3 and ZnSO4 onto indium-doped tin oxide (ITO) coating glass substrate at two deposition potentials. Then, ZnO nanostructures were deposited from an aqueous solution of Zn(NO3) onto ZnS surface. The as-obtained samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman and UV-visible analysis. The results indicate that the electrodeposition of ZnS layer at ?0.9 V give the best proprieties of ZnO/ZnS heterostructures. Homogeneous and uniform surface of ZnO/ZnS heterostructure was confirmed by AFM images. The XRD patterns indicates a high crystallinity of ZnO/ZnS. A high transmittance of 65% was also noted from UV-Visible spectra and band gap energy as large as 3.6?eV was found. 相似文献