First alkyl radical additions to (eta(6)-arene)tricarbonylmanganese complexes

[reaction: see text] Reactions of alkylmercury chlorides with arene manganese tricarbonyl complexes in the presence of NaI led to the formation of the addition-reduction products. The mechanism was postulated to be the alkyl radical addition to ArMn(CO)3+ cation to form the corresponding 17 valence electron intermediate, which was then reduced by alkylmercury chloride via a singlet electron transfer process to afford the product and regenerate an alkyl radical.     

含苯氧基萘并萘醌和偶氮苯双变色基化合物的合成和性质

通过６－氯－５，１２－萘并萘醌与４－羟基偶氮苯及其衍生物的反应合成了３种含苯氧基萘并萘醌和偶氮苯光致变色基的双变色基化合物，６－［４－（苯偶氮基）苯氧基］－５，１２－萘并萘醌（５），６－［４－（ｐ－乙氧基苯偶氮基）苯氧基］－５，１２－萘并萘醌（６）和６－［４－（ｐ－硝基苯偶氮基）苯氧基］－５，１２－萘并萘醌（７）．这些化合物的苯氧基萘并萘醌变色基的ＵＶ诱导光致变色性较弱；基于氨与苯氧基萘并萘醌ａｎａ显色体的不可逆反应，化合物５和６ＤＭＳＯ溶液在３６５ｎｍ紫外光辐照光稳态（ＰＳＳ）下的ａｎａ醌式摩尔分数估计分别为２２％和１７％．这些结果说明，苯偶氮基对苯氧基萘并萘醌变色基的光致变色性质有着极强的影响．另一方面，与４－羟基偶氮苯母体不同，这些双变色基化合物在ＤＭＳＯ中偶氮苯变色基的顺式异构体是相对稳定的     

Molecularly imprinted sol-gel nanotubes membrane for biochemical separations

In this study, we report a simple procedure for applying molecular imprinting functional groups to the inner surfaces of the template-synthesized sol-gel nanotubes for chemical separation of estrone. The silica nanotubes were synthesized within the pores of nanopore alumina template membranes using a sol-gel method by simultaneous hydrolysis of a silica monomer-imprinted molecule complex and tetraethoxysilane (TEOS). A covalent imprinting strategy was employed by generating a sacrificial spacer through the reaction of the isocyanate group of 3-(triethoxysilyl)propyl isocyanate and a phenol moiety of estrone to form a thermally cleavable urethane bond. This allowed us to remove the imprinted estrone by simple thermal reaction and to simultaneously introduce functional groups into the cavity formed by the silica nanotubes. Experiments indicated that estrone could be bound selectively by such an approach and have a binding affinity of 864 +/- 137 (n = 3).     

An efficient method for constructing nonorthogonal localized molecular orbitals

A new method for constructing nonorthogonal localized molecular orbitals (NOLMOs) is presented. The set of highly localized NOLMOs is obtained by minimization of the spread functional starting from an initial set of canonical orthogonal molecular orbitals. To enhance the stability and efficiency, the centroids of the NOLMOs are constrained to be those of the corresponding orthogonal localized molecular orbitals (OLMOs), which are obtained with the Boys criterion in advance. In particular, these centroid constraints make the optimization for each NOLMO independent of the others, which is an attractive feature for application to large systems. The minimization with the constraints incorporated through the multiplier-penalty function method is stable and efficient in convergence. While exhibiting the classical bonding pattern in chemistry and sharing a spatial distribution similar to that of the corresponding OLMOs, the obtained NOLMOs are more compact than the corresponding OLMOs with about 10%-28% reduction in the value of the spread functional and devoid of the troublesome "orthogonalization tails."     

Breakup of a Multiple Emulsion Drop in a Uniform Electric Field

The steady deformation and breakup of emulsion drops in a uniform electric field are considered experimentally. Due to the low volume fraction of inner drops, the emulsions can be effectively assumed as Newtonian fluids with spatial nonuniformity. The measurements of the electrical properties show that the oil-in-water (o/w) emulsion drop behaves like a conducting drop. On the other hand, the water-in-oil (w/o) emulsion drops can be regarded as inhomogeneous leaky dielectric drops. It is found that the viscosity ratio is not an important parameter within the small deformation limit and breakup mode of the o/w emulsion drops. In the case of w/o emulsion drops, however, the breakup mode depends on the viscosity ratio. Inherent nonuniformity of the emulsion drops makes drop more deformable and unstable. The tip-streaming is the dominant breakup mode of o/w emulsion drops when the nonuniformity of drop phase is appreciable. Copyright 1999 Academic Press.     

Synthesis and Second‐Order Nonlinearities of Chiral Prolinol‐Substituted Chromophores

A new series of thiophene‐ and furan‐containing chromophores with a chiral prolinol donor and a sulfone acceptor has been synthesized. The UV‐vis absorptions, second‐order nonlinear optical properties, and X‐ray crystal structures are described.     

菲林B近红外分光光度法测定维生素C

在pH 3的三氯乙酸酸性介质中,菲林B可以定量地将还原型维生素C氧化成脱氢型维生素C,利用脱氢型维生素C在920 nm处有最大吸光度,测定其含量,建立了一种测定维生素C的新方法,并研究了影响反应的各种因素。该方法对维生素C的检出限为0.17 mg/L;线性范围为0.5~10 mg/L,对水果中维生素C含量测定的RSD<2.31%;回收率为99.7%~101.1%,比2,4-二硝基苯肼分光光度法测定结果的相对偏差<±1.6%。     

Remarkably efficient oxidative coupling of N,N-dialkylarylamines in water mediated by cerium(IV) ammonium nitrate

A highly effective, economical, and environmentally friendly method using of CAN as oxidant and water as solvent for oxidative coupling of N,N-dialkylarylamines was reported.     

Asymmetric Diels-Alder Reactions of Chiral Menthyl α-Sulfinylacrylates

Introducing two chiral auxiliaries, sulfoxide and menthol, into an acrylate would have either matched or mismatched pair systems. The presence of chiral menthol in α-sulfinylacrylates can change the diastereoselectivity from 24% d.e. to a single diastereomer by manipulation of the double asymmetric strategy.     

乙苯脱氢铁系催化剂的穆斯堡尔谱研究

用穆斯堡尔法对乙苯脱氢铁系催化剂在反应条件下进行了研究。结果表明,反应前催化剂中的铁主要以α-Fe_2O_3和α-FeOOH的形式存在,在反应中主要组分为Fe_3O_4。用K_2CO_3和α-Fe_2O_3在高温下加热可以生成KFeO_2,后者在室温下很不稳定,在同样条件下很容易转化为Fe_3O_4。但钾的存在可促进催化剂中Fe~(3+)还原为Fe~(2+),有利于电子的交换,对催化活性起着助催作用。