两种四苯基卟啉衍生物的表观质子化常数测定

卟啉类试剂质子化常数的测定对于研究其显色性能有着重要的意义。用光度法测得两种四苯基卟啉衍生物的表观质子化常数,探讨了取代基的电子效应与空间位阻效应对表观质子化常数的影响。取代基三氟甲基的间位引入降低了两种四苯基卟啉衍生物的表观质子化常数,与四苯基卟啉相比其显色灵敏度稍微降低,但增强了其空间位阻效应,在显色研究中有望提高其选择性。     

亚碘酰苯氧化锰卟啉反应的取代基效应研究

报道了锰卟啉系列化合物被ＰｈＩＯ氧化开环的反应动力学和取代基效应对反应的影响规律，研究结果表明，单锰卟啉被ＰｈＩＯ氧化反应在动力学上为一级反应，且反应动力学常数ｋ与取代基特性常数σ之间存在线性关系。     

羟丙基-β-环糊精包埋性能研究

以复合物稳定常数为指标对羟丙基-β-环糊精（HPCD）与不同客体形成复合物的性能进行了研究。HPCD的取代度和取代基分布由甲基化分析测定。选取苯甲酸乙酯、甲基红和酚酞分别作为大小和构型不同的客体模型与HPCD作用,结合HPCD的结构特性,总结出了HPCD对不同客体的包埋规律。对于“较小”分子,HPCD的包埋能力远高于母体β-环糊精,羟丙基的“增溶”效应特别明显;对于“中等”分子,HPCD的包埋能力高于母体β-环糊精,低取代度时,羟丙基以“增溶”效应为主;对于“较大”分子,空间位阻是主导效应,HPED包埋能力低于β-环糊精。     

钛（Ⅳ）与四种荧光酮的显色反应

研究了四种２，３，７－三羟基荧光酮－９－取代物（水杨基、邻硝基苯基、邻氯苯基和二溴羟基苯基）在新两性表面活性剂Ｎ－［Ｎ＇－（羧甲基）－Ｎ＇－（２－羟乙基）氨乙基］月桂酰胺钠盐（ＣＭＨＥＡＥＬＡ）和十二醇聚氧乙烯２３醚存在下与钛的显色反应。结果发现，钛与水杨基荧光酮（ＳＡＦ）在０．０２５－０．０８ｍｏｌ／Ｌ盐酸介质中形成１：３络合物，λｍａｘ为５３２ｎｍ，表观摩尔吸光系数ε５３２＝２．０２×１０＾５     

天然香豆素衍生物^13C—NMR化学位移研究：Ⅰ.取代基效应因子与…

通过模型化合物＾１３Ｃ－ＮＭＲ化学位移的经验取代基参数，对天然香豆素衍生＾１３Ｃ－ＮＭＲ化学位移，进行了系统的研究。结果表明，模型化合物的取代基参数，与香豆素衍生物的化学位移具有良好的线性关系。从而提出了香豆素取代基效应因子，建立了香豆素衍生物＾１３Ｃ－ＮＭＲ化学位移与取代基效应因子的定量关系式。用于计算和预测香豆素的化学位移。     

非水溶性卟啉显色体系中表面活性剂及助络剂作用机理的初步探讨

本文结合ｍｅｓｏ－四－（４－甲氧苯基）卟啉与金属离子的显色反应,对非水溶性卟啉显色体系中非离子型表面活性剂增溶增敏机理和辅助络合剂的催化作用机理进行了探讨,用“氢键增溶模型”、“催化场模型”和“过渡络合物模型”对上述增溶、增敏和助络催化作用分别进行了解释。     

N2,N3-亚乙烯基鸟嘌呤核苷的荧光性质及与牛血清白蛋白结合作用的研究

本文合成了新型鸟苷衍生物N~2,N_3-亚乙烯基鸟嘌呤核苷(εG),研究了它在不同pH下的紫外、荧光性质,分析了εG质子化、非质子化以及去质子化型体间的分布情况。εG的荧光性质决定于它的非质子化的型体,不同介质下荧光性质研究表明εG与水存在着氢键作用,进一步增强了它的荧光强度。利用其对牛血清白蛋白(BSA)的荧光猝灭作用,探讨了二者之间的作用机理,测得其结合常数K_B=3．891×10~3L/mol,结合位点数n=1,并为εG作为荧光试剂提供了理论依据。     

新显色剂meso—四(3-溴-4-羟基—5-甲氧基苯)卟啉分光光度法测定痕量钯的研究

本文研究了在混合表面活性剂SDBS和聚乙二醇辛基苯基醚(OP)共存下,meso-四(3-溴—4-羟基—5-甲氧基苯)卟啉T(BHMOP)P与钯的显色反应.并以该反应为基础建立了高灵敏度的痕量钯的光度分析法.钯与该显色剂形成1:2的配合物,其表观摩尔吸光系数在422nm处为1.27×10~5L·mol~(-1)·cm~(-1).钯量在0.0-12μg/25ml范周内服从比尔定律.本法用于合成样品中钯的测定,结果满意.     

氨基取代四苯基卟啉衍生物的结构剖析

用 HMO 方法计算了5个氨基取代四苯基卟啉的能级、净电荷、自由价和共振能,讨论了这些参数之间的线性关系,并预测了这类大环化合物的酸碱性。     

meso—四（4—烟酰胺基苯基）卟啉分光光度法测定超微量铜的研究

研究新的非水溶性meso—四(4—烟酰胺基苯基)卟啉[简称T(4—NAP)PH_2]在表面活性剂存在下测定Cu(Ⅱ)显色反应的最佳条件。结果表明,该卟啉与Cu(Ⅱ)形成稳定性好、灵敏度高的配合物,其ε_(418)=4.20×10~5,Cu(Ⅱ)在0～3.5μg/25mL范围内遵守比耳定律。用本法测定Cu(Ⅱ)干扰小,可不经分离而直接测定钢铁、自来水中的痕量铜。     

Staphylococcal nuclease: size and specificity of the active site

The dissociation constants and standard free energies of complex formation determined with staphylococcal nuclease and a series of 5'-phosphoryloligothymidyl derivatives of increasing chain length suggest that maximum stability is reached with an oligonucleotide containing three nucleotide units. A proposed model of the active site that contains other knowledge of the specificity and the catalytic mechanism of this enzyme postulates the existence of three nonequivalent phosphate binding subsites and a closely related phosphodiester hydrolytic subsite.     

Mode of Chemical-Degradation of s-Triazines by Montmorillonite

Chemical hydrolysis of the s-triazines after interaction with less than 2-micron (equivalent spherical diameter) montmorillonite clay occurs as a result of protonation at the colloidal surface; protonation occurs even when the exchange sites are occupied by metallic cations. The adsorbed hydrolytic degradation product is not the hydroxy analog, but it is predominantly the keto form of the protonated hydroxy species. This cationic form is held tightly by the clay which may restrict vertical movement and entrance into groundwater. Protonation of the hydroxy analog occurs on the heterocyclic ring nitrogen.     

Ultrafast carbon-carbon single-bond rotational isomerization in room-temperature solution

Generally, rotational isomerization about the carbon-carbon single bond in simple ethane derivatives in room-temperature solution under thermal equilibrium conditions has been too fast to measure. We achieved this goal using two-dimensional infrared vibrational echo spectroscopy to observe isomerization between the gauche and trans conformations of an ethane derivative, 1-fluoro-2-isocyanato-ethane (1), in a CCl4 solution at room temperature. The isomerization time constant is 43 picoseconds (ps, 10(-12) s). Based on this value and on density functional theory calculations of the barrier heights of 1, n-butane, and ethane, the time constants for n-butane and ethane internal rotation under the same conditions are approximately 40 and approximately 12 ps, respectively.     

Band gap fluorescence from individual single-walled carbon nanotubes

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.     

混合三烃基锡有机芳氧乙酸酯化合物的合成及结构表征

混合三烃基锡有机化合物是在锡原子上连结不同有机基因的一类有机锡化合物。由于混合三烃基锡具有独特的生物活性和结构特征，人们对它们研究日趋活跃；成为有机锡化学的一个生长点和有机锡研究的热点。它们被广泛用作防腐剂及防污涂料[1]，在医药上被作为新型抗癌药物而得到开发应用[2－3]，在农业上，许多有机锡化合物是高效杀螨剂[4]，为了开发出高效、广谱，具有多重活性的新型农药，本文在南开大学元素有机所国家重点室及有机锡化合物研究小组所作工作基础上[5]，合成了23个新的混合三烃基锡有机化合物，并对其本身结构特征和生物活性进行了研究。     

荧光猝灭法研究8-烷基黄连碱衍生物对溶菌酶的作用机制

通过测定不同温度(12、24、36℃)下8-烷基黄连碱衍生物(Cop-C8-n,n=4、6、8)对溶菌酶的荧光猝灭常数,并计算热力学参数,研究8-烷基黄连碱衍生物对溶菌酶的作用机制.结果表明:8-烷基黄连碱衍生物对溶菌酶的内源性荧光可产生极强的猝灭作用,猝灭作用过程既有静态猝灭又有动态猝灭;热力学参数证明,黄连碱衍生物...     

Extraction and analysis of organic cations from Acid solution with strong electric fields and mass spectrometry

High electric fields have been used to extract organic cations from solutions of small organic molecules in polyphosphoric acid. The cations have been analyzed by mass spectrometry. Production of ions by this method is shown to be related to ease of protonation by acid rather than to ionization potential.     

Antiarthritic gold compounds effectively quench electronically excited singlet oxygen

Although certain gold [Au(I)] compounds have been used effectively in the treatment of rheumatoid arthritis for some years, the molecular basis for such therapeutic action has been unclear. One possible mechanism of the action of Au(I) compounds is that they protect unsaturated membrane lipids and proteins against oxidative degradation caused by activated phagocytes that are not properly regulated. In this study it has been shown that superoxide ion (O-2.), a product of activated phagocytes, can be oxidized to electronically excited singlet oxygen (O1(2)delta g), an agent that is capable of peroxidation of unsaturated fatty acid derivatives. It has also been shown that antiarthritic Au(I) compounds are effective deactivators of O1(2)delta g with quenching constants on the order of 10(7) M-1 sec-1.     

质子化交联壳聚糖颗粒对水体中硝酸盐的吸附去除作用

以活性炭、交联壳聚糖、质子化交联壳聚糖作为吸附剂,对污水中的硝酸盐进行吸附去除,研究了振荡吸附时间、质子化时间、吸附剂投加量和不同转速等对吸附效果的影响。结果表明,在质子化时间60 min,吸附时间60 min,振荡转速90 rpm,壳聚糖投加量为0.1 g左右的条件下,质子化交联壳聚糖对硝酸盐浓度为20 mg/L的污水的硝酸盐去除效果最好,去除率可达80.74%。对试验数据运用相关数学模型拟合发现,吸附过程符合二级反应动力学,线性相关系数为0.999 8。