Energy funneling of IR photons captured by dendritic antennae and acceptor mode specificity: anti-stokes resonance raman studies on iron(III) porphyrin complexes with a poly(aryl ether) dendrimer framework

A series of poly(aryl ether) dendrimer chloroiron(III) porphyrin complexes (LnTPP)Fe(III)Cl (number of aryl layers [n]=3 to 5) were synthesized, and their Boltzmann temperatures under IR irradiation were evaluated from ratios of Stokes to anti-Stokes intensities of resonance Raman bands. While the Boltzmann temperature of neat solvent was unaltered by IR irradiation (LnTPP)Fe(III)Cl (n=3 to 5), all showed a temperature rise that was larger than that of the solvent and greater as the dendrimer framework was larger. Among vibrational modes of the metalloporphyrin core, the temperature rise of an axial Fe-Cl stretching mode at 355 cm-1 was larger than that for a porphyrin in-plane mode at 390 cm-1. Although most of the IR energy is captured by the phenyl nu8 mode at 1597 cm-1 of the dendrimer framework, an anti-Stokes Raman band of the phenyl nu8 mode was not detected, suggesting the extremely fast vibrational relaxation of the phenyl mode. From these observations, it is proposed that the energy of IR photons captured by the aryl dendrimer framework is transferred to the axial Fe-Cl bond of the iron porphyrin core and then relaxed to the porphyrin macrocycle.     

杂合型全局优化法优化水分子团簇结构

基于遗传算法、快速模拟退火及共轭梯度方法提出了一种快速的杂合型全局优化方法(fast hybrid global optimization algorithm, FHGOA),并将这一方法应用于TIP3P和TIPS2模型水分子团簇(H2O)n结构的优化.在进行TIP3P模型水分子团簇结构的优化过程中,发现了能量比文献值更低的团簇结构,且执行效率有较大提高.把该方法应用到优化TIPS2模型的水分子团簇,发现最优结构和采用TTM2-F模型优化的水分子团簇结构在n < 17时完全相同,为全表面结构;而在n=17、19、22时为单中心水分子笼状结构;在n=25、27时为双中心水分子笼状结构.说明随着团簇中水分子个数的增加,采用TIPS2和TTM2-F势能函数优化的团簇最优结构有相同的变化趋势.     

Separation and preconcentration of ultratrace lead in biological organisms and its determination by graphite furnace atomic absorption spectrometry

A biological organism (chitosan) was utilized to preconcentrate lead ions from tap water. This preconcentration was achieved by mixing 0.8 ml of chitosan slurry with 10-50 ml of lead-containing solution and subsequently separating by centrifugation. The chitosan paste was then dissolved in 1 ml of 0.2% nitric acid and analysed by graphite furnace atomic absorption spectrometry. The extraction efficiency can approach 100% in the pH range 4-10. The amount of chitosan used was not critical. The effect of some impurities was also investigated. If six samples were prepared simultaneously, the time needed to preconcentrate each sample was less than 3 min. Two different modes of standard addition (the standard lead solutions being added before and after preconcentration) were used for analysis of tap water samples, and the results obtained by the two modes were found to be quite consistent.     

PEO／PBHE共混体系X射线散射研究

在聚环氧乙烷(PEO)/聚双酚A羟基醚(PBHE)共混体系中PEO是一个强质子受体,而PBHE是一个强质子给体,两者极易形成氢键,十分有利于形成互容对。笔者研究了PEO/PBHE共混体系的相容性,等温及非等温结晶动力学,本文根据Vonk提出的一维电子密度相关函数,分析了PEO/PBHE的SAXS现象,求得了共混体系的结晶度,片晶层厚度,过渡层厚度及长周期等结构参数。     

高效液相色谱与原子荧光光谱联用分析汞化合物形态的研究

建立了高效液相色谱与原子荧光光谱联用测定汞化合物形态的分析方法。实验对淋洗液组分浓度、氧化剂和还原剂浓度、载气流速及紫外消解管长度等操作条件进行了优化,获得了令人满意的分析结果。在优化的分离检测条件下,20μg/L的汞化合物标准溶液平行7次进样分析,甲基汞、无机汞和乙基汞的色谱峰高的相对标准偏差(RSD)分别为2.0%、2.9%和2.4%;3种汞化合物的线性范围为10~1000μg/L,25μL进样检出限分别为3、2和4μg/L。用建立的方法测定了脉红螺样品中甲基汞的含量,甲基汞和乙基汞的加标回收率分别为90%和92%。     

丙烯和甲苯的超共轭效应的理论研究

用从头算对丙烯和甲苯2个超共轭体系进行计算,结果表明甲基上氢原子参与超共轭时,其碳氢键键长增大,氢上集居数减少,丙烯、甲苯的甲基旋转势垒为7.61及0.096 kJ/mol.超共轭基作用相当于一带有孤对电子参与共轭之杂原子,超共轭体系不同构型稳定性可用M=sum from i=1 to 3(sinθ_i[sin(θ_i-α)+sinα])来表征。     

阳极溶出催化伏安法的理论研究 Ⅱ.不可逆电极溶出

本文对在玻璃碳电极上不可逆溶出催化的理论进行了研究,推导了溶出催化过程的电流方程,峰电流和峰电势方程,并用微计算机模拟出各种关系曲线,从理论方程得知溶出催化伏安法所得的峰电流比溶出伏安法的峰电流提高了二个数量级。本文还用钯的溶出催化实验验证理论方程,所得的实验结果均与理论方程相吻合。     

In situ Fe K-edge X-ray absorption fine structure of a nitrosyl adduct of iron phthalocyanine irreversibly adsorbed on a high area carbon electrode in an acidic electrolyte

Key aspects of the microenvironment surrounding the Fe center in the nitrosyl adduct of iron phthalocyanine, [Fe(Pc)(NO)], have been elucidated from the analysis of the Fe K-edge extended X-ray absorption fine structure (EXAFS) of the material adsorbed on the surface of a high area carbon electrode recorded in situ, in 0.5 M H(2)SO(4). Statistical best fits to the EXAFS data place the Fe center in a five-coordinated square pyramidal configuration shifted away from the Pc plane toward the axially bound NO bent at an angle of ca. 40 degrees with respect to the normal to the Pc plane. This environment is analogous to that of Fe in the nitrosyl adduct of crystalline [Fe(TPP)], where TPP = meso-tetraphenylporphyrinato(2-), determined from X-ray diffraction.     

A study of solar erythema radiation doses

Abstract —Using semi-empirical analytic formulas for the transmitted and scattered ultraviolet spectral irradiance at the ground (Green, A. E. S., T. Sawada and E. P. Shettle, Photochem. Photobiol. 19 , 251–259, 1974), we calculate erythema dose rates and daily erythema doses. Results are illustrated graphically, and for the purpose of photobiological applications are given in terms of approximate analytic forms, with parameters presented in tabular form. The relative erythema data assembled by W. W. Coblentz and R. Stair (U.S. Bureau of Standards J. Res. 12 , 13–14, 1934), as fit by an analytic form, is taken as a standard spectrum in our calculations. Other forms of erythema spectra are also compared.     

牛血清蛋白对手性物质的毛细管电泳拆分

采用聚氧乙烯涂层毛细管柱，以牛血清蛋白(BSA)为手性添加剂，运用毛细管电泳电导检测对手性药物沙丁胺醇和多沙唑嗪以及DL-组氨酸、色氨酸、苏氨酸进行拆分。考察了涂层柱的稳定性和重现性。对影响手性分离的主要因素：缓冲溶液的浓度和酸度、BSA的浓度、有机溶剂的种类和浓度以及分离电压进行了系统的研究。结果表明：在选择的最佳实验条件下，各对映异构体在22min内得到基线分离。