2,3,8,9-Dibenzo-5,6-(substituted)benzo-1,4-dithio-7-azacyclonona-2,5,8-trienes. Synthesis and mechanistic study

5-(2-Acetamidoaryl)thianthreniumyl perchlorates reacted with potassium hydroxide in methanol at reflux giving 2,3,8,9-dibenzo-5,6-(substituted)benzo-1,4-dithio-7-azacyclonona-2,5,8-trienes 4 in 43 to 75% yields, whereas the reactions of the same compounds with sodium hydride in the absence or in the presence of dimethyl sulfate in refluxing tetrahydrofuran gave N-acetylated and N-methylated 4 in 68 to 96% and 27 to 56% yields, respectively. The mechanism of the formation of the products might be explained by a nucleophilic attack of amide ions 10, 12, and 14 at the ipso-position of the thianthrene ring. A sulfuranyl radical mechanism might be involved in these reactions.     

C60哌嗪加成物的结构及光谱研究

用ＩＮＤＯ系列方法研究了Ｃ６０的哌嗪衍生物Ｃ６０Ｎ２（Ｃ２Ｈ４）２的结构。结果表明［６，６］，异构体具有Ｃ２ｖ对称性［６，５］，异构体具有Ｃｓ对称性，前者能量较低。以优化构型为基础，计算两种加成产物的ＵＶ谱，结果表明，［６，６］异构体的特征吸收与实验值相符，同时对［６，５］异构体的ＵＶ谱进行理论预测，对电子跃迁进行了理论指认，并分析了光谱红移的原因。     

Establishment of heterodinuclear replacement complexation and its application to direct determination of iron in natural water with dibromo-o-nitrophenylfluorone

The chromophore dibromo-o-nitrophenylfluorone (DBNPF) was used to complex Fe(III) and Cu(II) at pH 5.88. Fe(III) can competitively replace Cu(II) from its dinuclear complex Cu(DBNPF)Cu, and forms the Cu(DBNPF)Fe heterodinuclear complex. The Fe-DBNPF and Cu-DBNPF complexes were also characterized by the spectral correction technique. The heterodinuclear replacement complexation (HRC) is proposed and first used for the quantitative detection of iron in trace level with high sensitivity and good selectivity by the light-absorption ratio variation approach. The limit of detection of Fe is 1.0 μg L⁻¹. The method has been successfully applied to the direct determination of Fe(II, III) dissolved and bound to suspended substances in natural water.     

Novel Reaction of Nitroxide with Hantzsch Dihydropyridines

Nitroxides have been found to be the intermediate in the in vivo metabolism of hydroxamic acid, a well-known biological molecule1. Structural modification of some antitumor drugs by introducing nitroxides can lower toxicity remarkably with retention or even increase of the antitumor activity2. Furthermore, the use of nitroxides as spin probes makes it possible to get information regarding the microenvironment of the reaction. 4-Substituted Hantzsch 1,4-dihydropyridines (DHP) are analogs …     

Synthesis and Characterization of a Novel Cyclomatrix Phosphazene Polymer

Novel phosphazene cyclomatrix network polymers were synthesized via the nucleophilic displacement of activated nitro groups of tri(4-nitrophenoxy)tri(phenoxy)cyclotriphosphazene and hexa(p-nitrophenoxy) cyclotriphosphazene with hydroxyls of bisphenol A. Both monomers and polymers were characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, and elemental analysis measurements, and their structures were identified. Thermal properties of polymers were investigated using dynamic thermogravimetric analysis in air. The results demonstrated that both cyclomatrix phosphazene polymers 4 and 6 were of excellent thermal stability, and their char yields in air at 800°C were 45.1 and 43.2%, respectively. According to combustion phenomenon, polymer 4 was supposed to be processed with a good flame-retardant property because of its excellent crosslinked structure during pyrolysis or combustion. However, polymer 6 yielded the opposite result. Translated from the Journal of Beijing University of Chemical Technology, 2005, 32(2) (in Chinese) This study was supported by the National High Technology Research and Development Foundation (2002AADF3202)     

Insertion reactions of phenyl isocyanate into hafnium nitrogen bonds: synthesis and reactivity of hafnium complexes bearing substituted pyrrolyl ligands

A bis(diethylamido)hafnium compound [C₄H₃N(CH₂NMe₂)-2]₂Hf(NEt₂)₂ (1) has been prepared in 79% yield by reacting Hf(NEt₂)₄ with 2 equiv. of [C₄H₃NH(CH₂NMe₂)-2] in heptane via deamination. Reacting compound 1 with 2 equiv. of phenyl isocyanate at room temperature in diethyl ether results in the PhNCO being inserted seletively into hafnium-NEt₂ bonds to generate [C₄H₃N(CH₂NMe₂)-2]₂Hf[PhNC(NEt₂)O]₂ (2) in 56% yield. Similarly, while reacting 1 with 2 equiv. of phenyl isocyanate for a week in toluene produces a mixture of 2 and [C₄H₃N(CH₂NMe₂)-2]Hf[PhNC(NEt₂)O]₃ (3). For comparison, reacting Hf(NEt₂)₄ with 4 equiv. of PhNCO in a toluene solution at room temperature results in the PhNCO inserted into Hf-N bonds, and forms a tetrakis-ureato hafnium compound Hf[PhNC(NEt₂)O]₄ (4) in 88% yield. A theoretical calculation found that the unpaired electrons of the ureato fragments of 2 are resonance delocalized between the C-O, C-NPh, and C-NEt₂ bonds, which are all partially doubly bonded.     

Diphenylamino end-capped oligofluorenes with enhanced functional properties for blue light emission: synthesis and structure-property relationships

A novel series of monodisperse asymmetrically and symmetrically substituted diphenylamino end-capped oligofluorenes, OF(2)-NPhR, R = H or An (An = 9-anthryl) and OF(n)-NPh, n = 2-4, has been synthesized by a convergent approach using palladium-catalyzed Suzuki cross-coupling. End-capping of oligofluorenes with diphenylamino group(s) has been shown to offer advantages in terms of lowering their first ionization potentials, enhancing thermal stability, and inducing good amorphous morphological stability. By tuning the number of diphenylamino end-caps and the chain length, the optimal conjugated length for optical and luminescence properties has been determined. Of all the hitherto reported oligofluorenes capable of serving as non-doped blue emitters, OF(3)-NPh, with an optimal conjugated length, exhibits some of the best hole-transport and blue-emitting properties. A maximum luminance of 7500 cd m(-2) and a luminance efficiency up to 1.8 cd A(-1) have been achieved.     

超声波专题实验的设计与教学

本文介绍了自制超声波实验仪器的基本工作原理以及用该实验仪器开设的超声波专题实验,概述了实验教学效果。     

时间敏感型货物两阶段集装箱舱位分配问题研究

本文旨在探索如何对时间敏感型货物的集装箱舱位分配和动态定价问题进行研究。考虑到时间敏感型货物对配送时间的要求,本文提出一种新的定价机制,即在该类货物的运费制定时,考虑时间敏感型货物的配送时效及港口拥挤对其存在的影响,建立运价和配送时间之间的关系。另外,以船舶公司总运费收益最大化为目标,构建两阶段随机整数规划模型,运用机会约束规划方法对模型进行求解。最后,通过算例研究,验证了模型及算法的有效性。结果表明,本文针对时间敏感型货物所提出的定价机制能够显著提高船公司收益。