四硫富瓦烯衍生物/硬脂酸LB膜的导电性研究

报导了14种四硫富瓦烯衍生物／硬脂酸LB膜的导电性，并解释了硬脂酸量和碘蒸气掺杂对LB膜导电性的影响．     

Ar离子束作用下C60薄膜的结构稳定性研究

利用XPS和AES研究了在Ar离子束作用下C60薄膜的分子结构的稳定性．研究发现C60分子与Ar离子束作用后，C1s结合能从284．7eV逐步下降到284．4eV，CKLL俄歇动能从270．0eV增加到271．3eV．并且C60薄膜在与氩离子束作用后，其C60分子结构特征的C1s携上峰及价带峰均消失．表明Ar离子束可以促使C60分子的C＝C双键断裂，离域π键消失，C60分子分解为单质碳．C＝C双键断裂过程与离子束的能量和辐照时间有一定的函数关系．     

耐盐性聚丙烯酸盐类高吸水树脂的制备

耐盐性聚丙烯酸盐类高吸水树脂的制备宋彦凤，崔占臣，陈欣芳（吉林大学材料科学系长春１３００２３）关键词丙烯酸钠，丙烯酰胺，丙烯酸羟乙酯，共聚物，吸水树脂，耐酸性高吸水树脂是一种应用比较广的功能性高分子材料［１～５］．它的吸水率可高达几百倍乃至几千倍。但...     

两种荧光LB膜的制备和光谱性能

制取了４－二氰基亚甲基－２－甲基－６－对二甲胺基苯乙烯基－４Ｈ－吡喃（ＤＣＭ）和１，２－双（５－甲基苯并恶唑）基乙烯（ＤＴ）两种荧光分子的ＬＢ膜以及两者的混合膜，以吸收光谱和荧光光谱探讨了膜中分子的构型，微环境，发光性能等特征，发现在ＬＢ膜的缀密排布环境中ＤＣＭ顺式构型的含量较之在溶液中大为增加。     

单臂冠醚液晶LB膜的相变研究

研究了两种单臂冠醚液晶及配合物(1, 2及1.Eu^3^+)的LB膜的成膜特性,实验发出它们均可在气-液界面形成单分子膜, 但不易转移, 化合物1在压膜过程中出现一维相变。用CPK模型对成膜分子构型和面积进行估算, 其结果与实验相一致, 并讨论了冠醚液晶结构对LB膜相变的影响。     

Determination of hydroxycarbamates in aqueous matrices by direct derivatization and GC-MS analysis in chemical ionization mode

A rapid and effective procedure, developed for the determination of polar compounds in water, has been applied to hydroxycarbamates. In few minutes, it is possible to perform a catalyzed derivatization of such compounds directly in the aqueous medium, using n-hexyl chloroformate. Extraction with n-hexane and injection into a benchtop GC-MS system are the only two further steps to complete the analysis. Chemical ionization proved to be more effective than electron impact to produce valuable mass spectra in terms of selectivity and sensitivity. Linear quantitative responses were demonstrated over a two-order-of-magnitude range. The minimum detectable concentration was 3 ppb for acetohydroxamic acid and 10 ppb for hydroxyurethane, obtained from Po river water samples spiked with the two hydroxycarbamate standards.     

Improved method for the determination of sulfur components in natural gas

Determination of trace concentrations of sulfur components in natural gas is a true analytical challenge. Only analytical procedures based on gas chromatography can meet the sensitivity and accuracy requirements dictated by environmental regulation institutions and modern chemical industry. In the present contribution the sample pretreatment and chromatographic separation steps have been evaluated and optimized based on the use of a flamebased sulfur chemiluminescence detector (SCD) for target compound detection. The proposed instrument consists of a programmed temperature vaporizing (PTV) injector employing a liner packed with Chromosorb 104, a 4 μm thick film apolar column and a flame-based SCD. Using a 13 mL sample loop the detection limit achievable with the new method is 3 μg S/m³. The precision of replicate measure. ments is generally in the range of 5–15% relative standard deviation. Lower detection limits can be achieved by preconcentrating larger sample volumes, e.g. 100 mL.     

A charge-transfer challenge: combining fullerenes and metalloporphyrins in aqueous environments

A series of truly water-soluble C(60)/porphyrin electron donor-acceptor conjugates has been synthesized to serve as powerful mimics of photosynthetic reaction centers. To this end, the overall water-solubility of the conjugates was achieved by adding hydrophilic dendrimers of different generations to the porphyrin moiety. An important variable is the metal center of the porphyrin; we examined zinc(II), copper(II), cobalt(II), nickel(II), iron(III), and manganese(III). The first insights into electronic communication between the electron donors and the electron acceptors came from electrochemical assays, which clearly indicate that the redox processes centered either on C(60) or the porphyrins are mutually affected. Absorption measurements, however, revealed that the electronic communication in terms of, for example, charge-transfer features, remains spectroscopically invisible. The polar environment that water provides is likely to be a cause of the lack of detection. Despite this, transient absorption measurements confirm that intramolecular charge separation processes in the excited state lead to rapid deactivation of the excited states and, in turn, afford the formation of radical ion pair states in all of the investigated cases. Most importantly, the lifetimes of the radical ion pairs were found to depend strongly on several aspects. The nature of the coordinated metal center and the type of dendrimer have a profound impact on the lifetime. It has been revealed that the nature/electronic configuration of the metal centers is decisive in powering a charge recombination that either reinstates the ground state or any given multiplet excited state. Conversely, the equilibrium of two opposing forces in the dendrimers, that is, the interactions between their hydrophilic regions and the solvent and the electronic communication between their hydrophobic regions and the porphyrin and/or fullerene, is the key to tuning the lifetimes.     

A reliable and efficient first principles-based method for predicting pKa values. III. Adding explicit water molecules: Can the theoretical slope be reproduced and pKa values predicted more accurately?

A popular method for predicting pK(a) values for organic molecules in aqueous solution is to establish empirical linear least-squares fits between calculated deprotonation energies and known experimental pK(a) values. In virtually all such calculations, the empirically observed slope of the pK(a) vs. ΔE fit is significantly less than the theoretical value, 1/(2.303RT) (which is 0.73 mol/kcal at room temperature). In our own continuum solvation calculations (Zhang et al., J Phys Chem A 2010, 114, 432), the empirical slope for carboxylic acids was only 0.23 mol/kcal, despite the excellent fit to the experimental pK(a) values. There has been much speculation about the reason for this phenomenon. Although the ΔE - pK(a) relation neglects entropic effects, these are expected to largely cancel. The most likely cause for the strange behavior of the fitted slope is explicit solute-solvent (water) interactions, especially involving the ions, which cannot be described accurately by continuum solvation models. We used our previously developed pK(a) protocol (OLYP/6-311+G(d,p)//3-21G(d) with the COSMO solvation model) to investigate the effect of adding one or two explicit water molecules to the system. The slopes for organic acids (especially carboxylic acids) are much closer to the theoretical value when explicit water molecules are added to both the neutral molecule and the anion. However, explicit water molecules have almost no effect on the slopes for organic bases. Adding explicit water molecules to the ions only produces intermediate results. Unfortunately, linear fits involving explicit water molecules have much larger errors than with continuum solvation models alone and are also much more expensive. Consequently, they are not suitable for large-scale pK(a) calculations. The results compared with literature values showed that our predicted pK(a) s are more accurate.     

高效液相色谱法同时测定稻田中苄嘧磺隆和苯噻酰草胺残留

建立了同时测定稻田(稻田土壤、水和植株)中苄嘧磺隆和苯噻酰草胺残留量的高效液相色谱(HPLC)分析方法。稻田水样品用二氯甲烷直接萃取;稻田土壤样品用碱性乙腈-二氯甲烷(1:1, v/v)混合液直接提取;水稻植株样品用碱性二氯甲烷提取后,二氯甲烷提取液经弗罗里硅土柱净化。上述样品溶液采用C18不锈钢色谱柱(150 mm×4.6 mm, 5 μm)分离,流动相为水-甲醇(30:70, v/v),流速为0.5 mL/min,柱温为30 ℃,紫外检测波长为238 nm,外标法定量。苄嘧磺隆和苯噻酰草胺在0.05～5.00 mg/L范围内的线性关系均很好(r＞0.9999)。在稻田水、土壤和水稻植株中添加3个水平(0.05, 0.10, 1.00 mg/kg)的苄嘧磺隆和苯噻酰草胺,两者的回收率均在85.39%～113.33%之间,相对标准偏差为0.91%～10.24%。这表明该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求。