A highly selective fluorescent sensor for Cu based on 2-(2′-hydroxyphenyl)benzoxazole in a poly(vinyl chloride) matrix

This paper describes a copper selective optical chemical sensor based on static quenching of the fluorescence of 2-(2′-hydroxyphenyl)benzoxazole entrapped in a poly(vinyl chloride) (PVC) membrane. The effect of the composition of the sensing membrane was studied, and experimental conditions were optimized. The sensors exhibit stable response over the concentration range from 4.0 × 10⁻⁸ M to 5.0 × 10⁻⁵ M Cu²⁺ at pH 4.0-6.5, and a high selectivity. The response time for Cu²⁺ with concentration ≤5 × 10⁻⁶ M is less than 7 min. The optode can be regenerated using 0.1 M HCl and acetate buffer solution. The sensor has been used for direct measurement of copper content in river water samples with a relative error less than 4% with reference to that obtained by atomic absorption spectrometry.     

贫电子环丙烷衍生物与胂叶立德的反应研究

The reaction of electron-deficient cyclopropane derivatives, cis-1-methoxycarbonyl-2-aryl-6,6-dimethyl-5,7dioxospiro[2,5]octa-4,8-diones with benzoylmethylenetriphenylarsorane (2) and methoxycarbonylmethylenetriphenylarsorane (4) was found to form cis,trans-l-methoxycarbonyl-2-aryl-3-benzoyl-7,7-dimethyl-6,8-dioxospiro[3,5]nona-5,9-dione (3a-3e) and trans,cis,trans-5-[2‘-methoxycarbonyl-2‘-(triphenylarsoranylidene)acetyl]-6oxo-3-aryl-tetrahydro-pyran-2,4-dicarboxylic acid dimethyl esters (5a-5c) respectively with high stereoselectivity. The possible reaction mechanisms for the formation of the different products were also orooosed.     

Simple test system for single molecule recognition force microscopy

We have established an easy-to-use test system for detecting receptor-ligand interactions on the single molecule level using atomic force microscopy (AFM). For this, avidin-biotin, probably the best characterized receptor-ligand pair, was chosen. AFM sensors were prepared containing tethered biotin molecules at sufficiently low surface concentrations appropriate for single molecule studies. A biotin tether, consisting of a 6 nm poly(ethylene glycol) (PEG) chain and a functional succinimide group at the other end, was newly synthesized and covalently coupled to amine-functionalized AFM tips. In particular, PEG₈₀₀ diamine was glutarylated, the mono-adduct NH₂-PEG-COOH was isolated by ion exchange chromatography and reacted with biotin succinimidylester to give biotin-PEG-COOH which was then activated as N-hydroxysuccinimide (NHS) ester to give the biotin-PEG-NHS conjugate which was coupled to the aminofunctionalized AFM tip. The motional freedom provided by PEG allows for free rotation of the biotin molecule on the AFM sensor and for specific binding to avidin which had been adsorbed to mica surfaces via electrostatic interactions. Specific avidin-biotin recognition events were discriminated from nonspecific tip-mica adhesion by their typical unbinding force (∼40 pN at 1.4 nN/s loading rate), unbinding length (<13 nm), the characteristic nonlinear force-distance relation of the PEG linker, and by specific block with excess of free d-biotin. The convenience of the test system allowed to evaluate, and compare, different methods and conditions of tip aminofunctionalization with respect to specific binding and nonspecific adhesion. It is concluded that this system is well suited as calibration or start-up kit for single molecule recognition force microscopy.     

The influence of preparation method of OC1OC6-PPV films on the photo-oxidation process

Poly(p-phenylene vinylene) (PPV) derivatives are well known for their applications in polymer light emitting diodes (PLEDs). PPV derivatives are highly susceptible to photo-oxidation though, which is mainly caused by the scission of the vinyl double bond on the polymer backbone. In this work, we show that Langmuir-Blodgett (LB) films are less degraded than cast films of a PPV derivative (OC₁OC₆-PPV). Both films had similar thickness (∼50 nm) to allow for a more realistic comparison. Degradation was monitored with UV-vis and FTIR spectroscopies. The results indicated that cast films were completely degraded in ca. 400 min, while LB took longer time, i.e. about four times the values for the cast films. The differences can be attributed to the more compact morphology in the LB than in the cast films. With a compact morphology the diffusion of oxygen in the LB film is hampered and this causes a delay in the degradation process.     

基于人工神经网络研究芳胺喹唑啉衍生物的抗胃癌活性

基于分子电性距离矢量(M1)表征21个芳胺喹唑啉衍生物的分子结构,并与其对人胃癌细胞的抗癌活性(pI)关联.通过最佳变量子集回归方法建立上述化合物抗胃癌活性的三参数(M15、M18、M82)定量构效关系模型.其交叉验证系数(R2cv)、非交叉验证系数(R2)依次为0.386和0.737.通过R、R2cv.、VIF等检验...     

含氨基酸单元Schiff碱的合成与表征

以谷氨酸为原料合成了四个新型的含糠醛或苯甲醛Schiff碱的氨基酸衍生物,并通过红外光谱、质谱和核磁共振氢谱对化合物的组成及结构进行了表征．     

聚醚-紫外侧基聚硅氧烷的结构表征与膜形态

利用聚甲基氢硅氧烷(PHMS)与4-(β-羟基-γ-烯丙氧)丙氧基-2-羟基二苯甲酮(MUV-O)、α-烯基聚醚(F6)的硅氢化加成反应,合成了一种新型聚醚-二苯甲酮衍生物侧基聚硅氧烷PE-PUVSi,用红外光谱(IR)、紫外光谱(UV)、核磁共振氢谱(1H-NMR)以及原子力显微镜(AFM)等仪器对产物的结构和成膜形态进行了研究。结果表明,新合成的PE-PUVSi对波长为243.6、289.2、325.0nm的紫外光有强吸收作用。在纤维及单晶硅表面,PE-PUVSi均可成膜。但宏观上平滑的PE-PUVSi膜,微观上实则呈非均一、相分离结构,其中UV侧基以纤细尖峰分布在聚硅氧烷膜表面,而亲水性聚醚基团则卷曲堆积成峰包。     

四种5-氟尿嘧啶二肽衍生物的合成、晶体结构和抗癌活性

合成了四种新的5-氟尿嘧啶(5-Fu)二肽衍生物, 它们的结构经过元素分析、IR、1H NMR和13C NMR的表征, 比旋光度[a]D的测定结果表明了它们之间的对映异构关系, 用X射线衍射法测定了其中一对对映异构的晶体结构3a (S)和3b (R), 生物活性测试的结果表明这四种化合物都具有一定的抑制活性, 并且R型产物比S型产物抑制率高. 研究了2a和3a与DNA在Au电极上相互作用的伏安行为, 比较了它们跟5-氟尿嘧啶与双链DNA发生相互作用的差别.     

3-仲氨基氧杂环丁烷-3-腈衍生物的合成

以仲胺、氧杂环丁-3-酮和三甲基氰硅烷为原料,无水甲醇为溶剂,无需催化剂,一步反应合成目标化合物3-仲氨基氧杂环丁烷-3-腈衍生物(1a～1d),产物结构经¹H NMR、¹³C NMR和ESI-MS表征。并以异吲哚啉、氧杂环丁-3-酮和三甲基氰硅烷的反应为模型反应,考察影响产物1a收率的主要因素,优化反应条件为:物料摩尔比为n(异吲哚啉)∶n(氧杂环丁-3-酮)∶n(三甲基氰硅烷)=2.0∶1∶2.5;反应溶剂为无水甲醇,在65℃反应6h,在此反应条件下,化合物1a收率78.3%。化合物1a与苯基溴化镁在四氢呋喃中室温反应5h,可得到2-(3-苯基氧杂环丁烷-3-基)异吲哚啉(4)和[3-(异吲哚啉-2-基)氧杂环丁烷-3-基](苯基)甲酮(5),收率分别为40.1%和31.5%。     

空间-时间分数阶对流扩散方程的数值解法

本文考虑一个空间-时间分数阶对流扩散方程.这个方程是将一般的对流扩散方程中的时间一阶导数用α(0＜α＜1)阶导数代替,空间二阶导数用β(1＜β＜2)阶导数代替.本文提出了一个隐式差分格式,验证了这个格式是无条件稳定的,并证明了它的收敛性,其收敛阶为O(ι h).最后给出了数值例子.