Study on the hydrogen donating abilities of benzofuranones as chain-breaking antioxidants using laser flash photolysis technique

The hydrogen donation kinetics of four 3-aryl-benzofuranones with different chemical structures toward tert-butoxyl radicals were studied using laser flash photolysis (LFP) technique. The rate constants of hydrogen reactions, which can be used to evaluate the hydrogen donating abilities of 3-aryl-benzofuranones toward radicals, were obtained. The results showed that the position of substituted methyl group has a very important effect on the hydrogen donating ability of benzofuranone toward tert-butoxyl radicals, i.e. if the methyl group is on 2′-position, the hydrogen donation of 3-aryl-benzofuranone toward tert-butoxyl radicals will be prevented and the hydrogen donating ability will be weakened.     

金属氯化醇盐的红外光谱分析

金属氯化醇盐作为一种溶胶．凝胶法新型前驱体,其分子结构较为复杂,但关于它们结构的红外光谱分析却很少。为此,文章分别对四氯化钛和三氯化铝与乙醇、异丙醇及正丁醇的反应产物——金属氯化醇盐进行了红外光谱测试分析。结果发现,由于四氯化钛中钛的反应活性参数Rn较小,同时三氯化铝中离子键较少,因此,它们与醇之间只发生了部分亲核取代反应,导致产物中残余一定量的Ti-Cl和Al-Cl键合,即反应产物为铝、钛氯化醇盐,这样造成铝氯化醇盐的红外图谱中存在Al-Cl键合振动吸收峰,而钛氯化醇盐中C-O-Ti键合的C-O伸缩振动吸收峰峰位也明显有别于纯的金属钛醇盐。     

Analysis of thermal reactions of photochromic species in glassy matrices based on the concept of dispersive processes

Thermal decoloration reactions of photochromic spiroindolinonaphthoxazine in glassy polymer matrices have been studied. The non-exponential kinetic behaviour in these systems was analyzed using the phenomenological equation with an exp(-t^α) dependency describing dispersive processes in glassy solids. The dispersive parameter α represents the molecular environmental characteristics of matrix polymers.     

Synthesis and electrical properties of Vanadyl(V)chloride complexes of N-2(4,5,6-monosubstituted pyridyl)-N′-aryl substituted thioureas

VOCl₃ formed six-coordinated complexes with N-aryl-N′-2(4,5,6-mono-substituted pyridyl)thioureas of the general formula [VOCl₃(RNHCSNHR′)], where R = pyridyl, 5-nitropyridyl, 4-methylpyridyl, 6-methylpyridyl groups and R′ = —C₆H₅, o-C₆H₅(CH₃) and p-C₆H₄(CH₃). The complexes have been characterized by means of elemental analysis, molar conductance, magnetic susceptibility, IR, UV—VIS, and ¹H NMR spectral data. The thermally stimulated depolarization effect was studied in samples polarized under different conditions. The results indicate two distinct transitions in the temperature range 92–100°C and 120–125°C for the ligands, whereas the VOCl₃-complexes show no breaks. The polarization—depolarization phenomena were correlated with the physicochemical changes occurring in the matrix. Depolarization kinetic data such as activation energy (E_a) and relaxation time (τ) of the electrets are reported.     

光热协同催化去除挥发性有机化合物和CO的研究进展

随着社会和经济的快速发展,环境污染和能源短缺等问题,尤其是空气污染,已经影响了人类的可持续发展.挥发性有机化合物(VOCs),如苯、甲苯、甲醛和丙酮是主要的空气污染物,它们主要来源于油漆、有机化学品、石油化工产品、药物和工业生产过程.大多VOCs具有特殊的气味,而且具有一定的毒性、致畸性和致癌作用,尤其是苯、甲苯和甲醛...     

Comparison of a very high frequency 148 MHz inductively coupled plasma to a 27 MHz ICP

Physical parameters and analytical performance are determined for an analytical ICP operated at 148 MHz, a frequency nearly three times higher than any previously reported. The iron(I) excitation temperatures are approximately 1.5 times lower and the electron densities are five times lower than at 27 MHz. The consequences of these changes are lower analyte and background continuum emission intensities, such that the signal to background ratios are decreased at the higher frequency. Freedom from interferences and working curve linearity are unaffected while ease of sample introduction is improved. A shift towards atomic emission indicates a deviation farther from LTE at 148 MHz. These effects are attributed to the decrease in skin depth with increasing frequency.