生物降解ε—己内酯／d,l—丙交酯共聚物的合成与表征

采用一种新型的稀土配位化合物Ｙ（ＣＦ３ＣＯＯ）３／Ａｌ（ｉ－Ｂｕ）３为催化剂，制备了不同组成的ε－己内酯／ｄ，ｌ－丙交酯共聚物，并用ＧＰＣ、ＮＭＲ和ＤＳＣ表征了共聚物的结构．结果表明通过改变初始投料中两种单体的比例，可以调节共聚酯的化学结构，而共聚物的形态则受结构影响很大．     

A novel[2 + 3]cycloaddition reaction: singlet oxygen mediated formation of 1,3-dipole from iminodiacetic acid dimethyl ester and its addition to maleimides

Sensitized photolysis of iminodiacetic acid methyl ester and maleimides follows a [2 + 3] cycloaddition pathway yielding pyrrolidine derivatives. This is similar to the photochemical reaction between C(60) and amines. A series of pyrrolidine derivatives are prepared by the method including multipyrrolidines from bis- and tris-maleimide starting materials. The yields range from 13% to 85%. The reaction is highly stereoselective. All the isolated products have the 1,3-dimethoxycarbonyl groups in the cis configuration. Various sensitizers may be used with slightly different yields. A plausible mechanism is proposed that involves the singlet oxygen abstraction of two alpha hydrogen atoms from the iminodiacetate and formation of a 1,3-dipole with a structure similar to the classical thermally generated 1,3-dipole.     

线性变位极谱法研究（Ⅸ）——CAEM过程配位吸附溶出可逆波理论

本文报道CAEM过程配位吸附溶出可逆波理论，用铟（Ⅲ）－铜铁试剂－醋酸和醋酸钠缓冲体系进行验证，实验结果与理论相符。     

Fabrication and Characterization of a New Self-Assembled Monolayer of Fullerene Dicarboxylic Acid Derivative and Its Photoelectric Conversion Property

A new fullerene self-assembled monolayer (SAM) which has the property of photoelectric conversion is reported here. The SAM was fabricated on hydrophilic substrates by an esterification reaction. The SAM is characterized by contact angle, AFM, UV spectrum, and cyclic voltammetry. A cathodic photocurrent of 226 nA/cm(2) was obtained. Copyright 2000 Academic Press.     

Self-assembly of PcOC8 and its sandwich lanthanide complex Pr(PcOC8)(2) with oligo(phenylene-ethynylene) molecules

Self-assemblies of octakis(octyloxy) phthalocyanine (PcOC8) and its sandwich lanthanide complex, substituted praseodymium bis(phthalocyanine) (Pr(PcOC8)(2)), with oligo(phenylene-ethynylene) (OPE) have been investigated by scanning tunneling microscopy (STM) on a highly oriented pyrolytic graphite (HOPG) surface. The assemblies were prepared by dissolving the molecules in phenyloctane solution. It was found that both PcOC8 and Pr(PcOC8)(2) can form 4-fold or 6-fold symmetrical adlayers on HOPG. The intramolecular structure of Pr(PcOC8)(2) molecule was revealed by a high-resolution STM image. When OPE molecules are added into phenyloctane solvent, Pr(PcOC8)(2) molecules prefer to form an ordered adlayer at the top of the OPE adlayer, while PcOC8 molecules adsorb on HOPG surface directly and form separated domains with OPE. These results may be helpful to construct surface assemblies and develop molecular electronic devices in the future.     

Regiochemistry of [70]fullerene: preparation of C70(OOtBu)n (n = 2, 4, 6, 8, 10) through both equatorial and cyclopentadienyl addition modes

[reaction: see text] tert-Butylperoxy radicals add to [70]fullerene to form a mixture of adducts C(70)(OO(t)()Bu)(n)() (n = 2, 4, 6, 8, 10). Four isomers were isolated for the bis-adduct with the two tert-butylperoxo groups attached at 1,2-, 5,6-, 7,23-, and 2,5-positions, respectively. Two isomers were isolated for the tetrakis-adduct with the tert-butylperoxo groups located along the equator in C(s)() symmetry and on the side in C(1) symmetry, respectively. Similarly, two isomers were isolated for the hexakis-adducts with a structure related to the tetrakis-adducts, one of which has the cyclopentadienyl substructure. No isomer was detected for the octakis- and decakis-adducts. The C(s)()-symmetric octakis- and C(2)-symmetric decakis-adducts have all the tert-butylperoxo groups located along the equator. The decakis-adduct is the major product under optimized conditions. The compounds were characterized by their spectroscopic data. Chemical correlation through further addition of tert-butylperoxy radicals to isolated pure derivatives confirmed the structure assignment. Mechanisms of the tert-butylperoxy radical addition to C(70) follow two pathways: equatorial addition along the belt and cyclopentadienyl addition on the side.     

Two novel procedures for automatic resolution of two-way data from coupled chromatography

In order to deal with the problem of simultaneous qualitative and quantitative analysis of the complicated samples in analytical chemistry, two novel procedures for automatic resolution of two-way data from coupled chromatography were developed in this work. The first can be used to determine automatically the number of components involved in a certain peak cluster. The second method is an iterative resolution procedure named the stepwise key spectrum selection which has also been developed to resolve automatically the spectra and chromatographic profiles of every component in the peak cluster investigated. The results obtained from simulated and real data show that the proposed methods perform fairly well.     

Photoelectron spectra of the gauche and trans conformers of 1,2-dibromoethane

The He I photoelectron spectra of the gauche and trans conformers of 1,2-dibromo-ethane have been obtained. Time-averaged spectra of 1,2-dibromoethane recorded at different temperatures have been analyzed by a spectrum-stripping procedure to give resulting spectra which represent each of the two stable conformers. The correlation of the ionization potentials of the two conformers is consistent with data obtained from MO calculations. In comparison with the case of 1,2-dichloroethane, 1,2-dibromoethane shows different non-bonded Br—Br interactions and generally larger resonance splittings of the ethane orbitals.     

Trace analysis of aluminum in natural waters with rubeanic acid by adsorption chronopotentiometry

The determination of trace levels of aluminum in natural waters with rubeanic acid (RA) by adsorption chronopotentiometry is developed in this paper. Optimum experimental conditions include an accumulation potential of -0.40 V, accumulation time of 60 s, and a RA concentration of 6x10(-6) M in 0.2 M NaAc-HAc buffer solution (pH 4.6). The response is linear over the 1x10(-8) approximately 4x10(-7) M concentration range. The detection limit is 5.6x10(-9) M and the relative S.D. (at the 3x10(-7) M level) is 2.6%. Possible interferences are evaluated. The method has been applied to the determination of trace levels of Al in various real samples. Direct determination of toxic forms of Al in surface waters by this technique is also explored.