基于有机硼化合物的氟离子化学传感器的研究进展

有机硼化合物中硼原子空的pπ轨道使其作为路易斯酸能够选择性的结合氟离子,其与氟离子的结合破坏了硼中心与芳香取代基的pπ-π共轭,引起有机硼化合物光物理性质的变化。因此,有机硼化合物能够用作高选择性的氟离子化学传感器材料。本文从具有三芳基硼结构及硼酸或硼酸酯结构的这两类有机硼化合物出发,综述了它们在氟离子化学传感器领域的研究进展。     

基于有机硼化合物的氟离子化学探针

本文综述了有机硼化合物在氟离子探针领域的研究进展.介绍了基于三芳基硼化合物、硼酸和硼酸酯的有机硼化合物在氟离子检测中的应用,评述了这些化合物的结构和检测性能之间的关系,讨论了检测机理,即有机硼化合物中硼原子空的pπ轨道使其作为路易斯酸能够选择性地结合氟离子,硼原子与氟离子的结合破坏了硼中心与芳香取代基的pπ-π共轭,引起有机硼化合物光物理性质的变化,从而实现对氟离子的高选择性检测.最后提出了有机硼化合物作为氟离子探针存在的一些问题,并展望了有机硼化合物在氟离子探针领域的研究和发展方向.     

介离子化合物的合成与生物活性研究进展

介离子化合物代表了一类在杂环化学中非常重要的分子,在医药和农药等领域有着广泛的应用.自1935年该类化合物被发现以来,因其有着独特的反应活性和物活性,人们对其合成、应用和性质等方面一直进行研究,不少文献报道了该类化合物的合成及相关活性.综述了几类介离子化合物的合成方法和部分重要机理,并探讨了介离子化合物作为一种优势活性结构在未来的应用前景.     

吡唑含能离子盐的合成研究进展

吡唑环上有三个可修饰的碳位点和一个可修饰的NH位点,通过对这四个位点的修饰(主要是引入硝基、硝胺基、氨基、羟基以及形成稠环等),可设计出种类丰富的吡唑含能化合物.同时,相对于2,4,6-三硝基甲苯(TNT)、黑索金(RDX)、奥克托今(HMX)等常规含能化合物,吡唑含能化合物具有氮含量高、生成焓高及感度低等优势.近年来,国内外基于吡唑骨架设计并合成了大量吡唑含能离子盐,其中很多种化合物表现出高能及钝感等特性.按单环吡唑含能离子盐、联环吡唑含能离子盐及稠环吡唑含能离子盐,分类综述了近年来所报道的吡唑含能离子盐的合成及性能,并对该类化合物的应用前景进行了展望.     

两类大戟二萜的高分辨ESI-MS/MS质谱裂解规律及诊断离子解析

采用高分辨电喷雾串联质谱技术研究了15种大戟二萜的二级质谱裂解行为,总结了这些化合物的基本裂解规律并归纳了其诊断离子。所研究的二萜均为多酯类化合物,根据其二萜骨架的不同分为曼西烷型(化合物1～9)和前曼西烷型(化合物10～15)。研究结果发现,这些化合物先断裂酰氧基和/或脱水等得到二萜骨架离子,接着在骨架上发生裂解生成一系列特征的诊断离子,这些离子集中在m/z 200～320区域。化合物1～7的骨架离子为m/z 311(离子A)和m/z 293(离子B),化合物8～9的骨架离子为m/z 295(离子C)和m/z277(离子D),而化合物10～15的骨架离子为m/z 313(离子E)和m/z 295(离子F)。根据这些关键的诊断离子可以鉴别化合物的结构类型。此外,关键诊断离子丢失H₂O、HCHO、CO、C₃H₄和/或丙酮等中性分子,可分别证明前体离子存在羟基、四氢呋喃环、羰基、异丙烯基和/或CH₃C(OH)CH₃片段或官能团。上述诊断离子和特征的中性丢失既可表征这些化合物的化学结...     

某些西佛碱类化合物的质谱重排反应

研究了十四种西佛碱类化合物的电子轰击质谱，利用碰撞诱导解离(CID)和B/E联动扫描技术，证实了特殊重排产物的离子结构及生成机理，并利用亚稳离子测定方式对这类化合物的主要离子进行了归属。     

铜离子的偶氮苯化合物探针的制备、应用及实验教学研究

以邻苯二胺为原料,在超氧化钾的氧化作用下合成了偶氮化合物--2,2′-二氨基偶氮苯,并通过紫外可见分光光度法分析2,2′-二氨基偶氮苯与铜离子的配位作用及定量关系,将合成的偶氮化合物制备成检测试纸,应用于实际水样中的铜离子检测。在实验基础上设计综合实验,实验内容按主题分为3部分:偶氮化合物的合成,偶氮化合物与铜离子配合物的组成及稳定常数的测定,铜检测试纸的制备与水样中铜离子的可视检测。实验涵盖有机化学、无机化学、分析化学的相关知识点与实验操作,适用对象为本科高年级学生。     

一类以光度法进行检测的新型阴离子敏感化合物

对6种带羟基的分子内电荷转移化合物(其中化合物1,4,5,6含氰基基团)及与不同阴离子间的相互作用及其分子识别进行了研究.发现化合物2,3,5,6均对F^-离子有优良的检测能力,并对H₂PO₄^-有一定的响应能力,其中化合物2对AcO^-离子也有一定的响应.对实验结果进行了初步讨论,并对提高敏感化合物的灵敏度和选择性提出了看法.     

以吖啶染料荧光猝灭为基础的卤素阴离子检测研究

合成了两种吖啶及吖啶橙盐类小分子化合物和带有吖啶盐的三元共聚物.研究了它们在溶液中的荧光被卤素离子猝灭的问题.发现它们能强烈地被碘离子所猝灭而不易被氯离子猝灭,表明这类化合物有可能用于在有氯离子存在条件下对碘、溴离子的检测.对荧光猝灭机理进行的研究发现,卤素离子的猝灭能力并不和它们对发光化合物的系间窜越和三重态的生成等有关,而是和阴离子对极化分子的作用减弱了分子内的电荷转移能力相关.     

电喷雾-离子阱-飞行时间质谱联用研究黄酮和异黄酮苷元C环上的裂解规律

采用电喷雾-离子阱-飞行时间串联质谱在负离子模式下分析了4个黄酮苷元和6个异黄酮苷元的质谱数据, 并总结了两类化合物C环上的裂解规律. 黄酮化合物C环以Rretro-Diels-Alder(RDA)裂解断裂为主, 形成A1,3-离子且相对丰度较高; 而异黄酮化合物C环断裂以碳0和碳3键的断裂为主, 形成B0,3-离子, 且相对丰度较高. 说明黄酮化合物的交叉共轭体系和异黄酮的非交叉共轭体系对C环的裂解影响较大, 而且黄酮化合物的B环和异黄酮化合物的A, B环上取代基的类型和位置对生成碎片离子的稳定性也有影响, 导致生成的碎片离子类型及其相对丰度不同, 根据其质谱数据(包括碎片离子的质荷比和相对离子丰度)可以推测黄酮类化合物的结构类型和取代状况, 为快速鉴定黄酮化合物和异黄酮化合物结构奠定了基础.     

Design,synthesis and cytotoxic activity of vitamin E bearing selenium compounds against human breast cancer cell line (MCF-7)

A new series of vitamin E/selenated pyridine, vitamin E/selenated pyridazine, vitamin E/selenated coumarine and vitamin E/selenated nicotine moieties were synthesized and their cytotoxic activity is investigated using the human breast cancer cell line. The newly synthesized compounds were characterized using spectroscopic tools (IR, ¹H NMR, ¹³C NMR, and mass spectroscopy) as well as microanalysis. Our study reveals that compound vitamin E/selenated nicotine moiety has the highest cytotoxic effect than the other synthesized compounds.     

Dynamical properties of the soft sticky dipole-quadrupole-octupole water model: a molecular dynamics study

The dynamical properties of the soft sticky dipole-quadrupole-octupole (SSDQO) water model using SPC/E moments are calculated utilizing molecular dynamics simulations. This new potential for liquid water describes the water-water interactions by a Lennard-Jones term and a sticky potential, which is an approximate moment expansion with point dipole, quadrupole, and octupole moments, and reproduces radial distribution functions of pure liquid water using the moments of SPC/E [Ichiye and Tan, J. Chem. Phys. 124, 134504 (2006)]. The forces and torques of SSDQO water for the dipole-quadrupole, quadrupole-quadrupole, and dipole-octupole interactions are derived here. The simulations are carried out at 298 K in the microcanonical ensemble employing the Ewald method for the long-range dipole-dipole interactions. Here, various dynamical properties associated with translational and rotational motions of SSDQO water using the moments of SPC/E (SSDQO:SPC/E) water are compared with the results from SPC/E and also experiment. The self-diffusion coefficient of SSDQO:SPC/E water is found to be in excellent agreement with both SPC/E and experiment whereas the single particle orientational relaxation time for dipole vector is better than SPC/E water but it is somewhat smaller than experiment. The dielectric constant of SSDQO:SPC/E is essentially identical to SPC/E, and both are slightly lower than experiment. Also, molecular dynamics simulations of the SSDQO water model are found to be about twice as fast as three-site models such as SPC/E.     

Trace level quantification of deuterated 17beta-estradiol and estrone in ovariectomized mouse plasma and brain using liquid chromatography/tandem mass spectrometry following dansylation reaction

A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method coupled with dansylation was developed for the simultaneous quantification of exogenously administered deuterated 17beta-estradiol-d4 (E2-d4) and its metabolite, estrone-d4 (E1-d4), in mouse plasma and brain homogenates. The dansylation reaction was simple, fast, and sensitive, and a lower limit of quantification of 50 pg/mL was achieved by using 50 microL of mouse plasma. Interference from endogenous 17beta-estradiol and estrone in plasma and brain samples was minimized by the use of deuterated-E2 as well by utilizing ovariectomized (OVX) mice. The recovery of dansylated derivative exceeded 83% and the reaction was completed within approximately 3 min. The intra- and inter-day assay precision were better than 12.9% and assay accuracy ranged between 92-104% for E1-d4 and E2-d4 in plasma, respectively. The absorption of E2-d4 at both 1 and 3 mg/kg P.O. was rapid, reaching peak plasma concentrations (Cmax) at 5 min post-dose that was the earliest time point obtained, and were 1.1 and 13.8 ng/mL, respectively; the Cmax values for the estrone metabolite, E1-d4, were 1.1 and 43.2 ng/mL, respectively. The area-under-the-plasma-time curve (AUC(0-2 h)) values were determined to be 0.65 and 2.90 ng. h/mL for E2-d4 and 0.77 and 6.74 ng. h/mL for E1-d4, respectively, at 1 and 3 mg/kg. The mean brain-to-plasma ratio for E1-d4 and E2-d4 after P.O. administration of E2-d4 to the OVX mice at 1 and 3 mg/kg indicated that both E1-d4 and E2-d4 were present in the brain as well as in the circulation.     

Electrochemical fabrication of metal/organic/metal junctions for molecular electronics and sensing applications

A simple electrochemical approach was used for fabricating electrode/metal nanowire/(molecule or polymer)/electrode junctions for sensing or molecular electronics applications. The procedure for fabricating these molecule-based devices involves electropolymerization of phenol or chemisorption of alkanethiols on one set of electrodes (E1) and electrodeposition of Ag metal nano/microwires on a second electrode (E2) which is ～5 μm away from E1. Under appropriate deposition conditions, Ag nanowires grow from E2 and cross over to E1, forming a E1/(molecule or polymer)/Ag nanowire (NW)/E2 junction. The junction resistance was controlled by (1) electrodepositing polyphenol of varied densities on E1 and (2) assembling alkanethiols of different chain lengths on E1. Ag NWs at high resistance E1/polyphenol/Ag NW/E2 junctions functionalized with Pd monolayer protected clusters (MPCs) responded fast and reversibly to H(2) concentrations as low as 0.11% in a nitrogen carrier gas by a resistance decrease, likely due to volume expansion of the Pd nanoparticles, demonstrating the use of these electrochemically fabricated junctions for gas sensing applications.     

Metabolism of Ecdysteroids During the Embryogenesis of Manduca Sexta

Abstract

The combination of ion suppression, reverse phase high pressure liquid chromatography (IS-RPHPLC) and radioimmunoassay (RIA) employing two relatively non-specific, complimentary antisera was used to identify and quantify ecdysteroids of divergent polarities during embryogenesis of the tobacco hornworm, Manduca sexta. Newly layed eggs (0–1 hr) contained high levels (>30 μg/g) of a maternally derived, polar conjugate of 26-hydroxy-ecdysone (26E) but less than 0.6 and 0.2 μg/g of the polar conjugates of ecdysone (E) and 20-hydroxyecdysone (20E), respectively. The only free ecdysteroid detected was 26E (0.4 μg/g). Between 4 and 12 hr after oviposition, marked deconjugation activity occurred as titers of free 26E increased to 14 μg/g while levels of conjugated 26E fell to 19 μg/g. By this time there were only negligible levels of free E (less than 0.1 μg/g). After 12 hr, the deconjugation of the maternal polar 26E-26-phosphate conjugate slowed and levels of free 26E fell as it was metabolized. At 24 hr, low titers of free 20,26-dihydroxyecdysone (20,26E, 0.4 μg/g) and a β-D-glucose conjugate of 26E (0.8 μg/g) were detected, presumably formed by embryonic 20-monooxygenase and uridine diphospho-α-D-glucose (UDPG) glucosyltransferase activities, respectively. About the time of the deposition of the first larval cuticle (66–72 hr), these 26E metabolites reached high concentrations, (5 μg/g free 20,26E and 7 μg/g 26E-glucose conjugate) while free 26E fell to 2 μg/g. In newly hatched larvae, the 26E-glucose conjugate was the major detectable ecdysteroid. At no time during embryogenesis did the concentrations of free E and 20E exceed 0.5 μg/g and 0.3 μg/g, respectively.     

Novel synthesis of alkenes via triethylborane-induced free-radical reactions of alkyl iodides and beta-nitrostyrenes

Reactions of (E)-beta-nitrostyrenes 1 and triethylborane 2 or tricyclohexylborane 4 in THF solution at room temperature in the presence of oxygen in the air as radical initiator generate high yields of trans-alkenes (E)-3 or (E)-5. Medium to high yields of different (E)-alkenes (E)-5, 7, 10, 12, and 14 also can be prepared when 1 reacts with different radicals, prepared from secondary alkyl iodides 6 and 8 or tertiary alkyl iodides 9, 11, and 13, in the presence of 2 and air as radical initiator. The generation of the only product (E)-alkenes can be explained by the generation of the benzylic radical A and/or B as the intermediate only and the mechanism is similar to Scheme 1. Both (E)- and (Z)-16a-c are generated when (E)- and (Z)-15a-c are used to react with adamantyl radical under similar conditions. Only (Z)-16d was observed when either (E)- or (Z)-15d was used to react with adamantyl radical. The generation of the (E)- and/or (Z)-alkenes can be explained by the free rotation of the A and/or B to generate A' and/or B' and vice versa, and the mechanism is proposed to be a free-radical reaction via NO2/alkyl substitution and is shown as Scheme 2.     

Temperature investigations of E/Z isomers in ketimines based of p-dibenzoylobenzene with aniline and 2,6-dimethylaniline by infrared spectroscopy

The reaction of aniline with p-dibenzoylobenzene (K1) can lead to Z/Z, Z/E and E/E isomers however the only Z/Z and E/E were formed. At room temperature these isomers may be separated, thus the corresponding FTIR spectra could be recorded. The observed bands were assigned and temperature investigations were lead to monitor the structural changes during heating Z and E forms of K1 from 20 to 240 degrees C. FTIR spectroscopy showed that the bigger changes of the Z form was observed with an increase of temperature. Similar experience was lead with the ketimine synthesized from 2,6-dimethylaniline and p-dibenzoylobenzene (K2) investigated as a mixture of isomers.     

Determination of fluoroquinolone residues in animal tissues using Escherichia coli as indicator organism

Three strains of Escherichia coli (ATCC 128, 10536, and 25922) and one strain of Bacillus subtilis (ATCC 3491) were compared as indicator microorganisms in microbial inhibition tests for their ability to detect fluoroquinolone residues. E. coli strains 128 and 10536 were most susceptible to fluoroquinolone residues, with detection limits of 35-50 micrograms/kg for enrofloxacin. Of the 2 strains, E. coli 10536 was slightly less susceptible. Ciprofloxacin was detected consistently by E. coli 128 at 30 micrograms/kg. Other fluoroquinolone drugs of veterinary interest detected by E. coli 128 were sarafloxacin and difloxacin at 100-250 micrograms/kg concentration. E. coli 25922 yielded 100% sensitivity in detection of enrofloxacin only at the 250 micrograms/kg concentration, and ciprofloxacin and sarafloxacin at 200 micrograms/kg. B. subtilis detected only enrofloxacin 100% of the time at 250 micrograms/kg. The E. coli strains tested were insensitive to other antibacterials commonly used in animals, with the exception of ceftiofur which was detected by E. coli 128 and 10536 at 500 micrograms/kg. The B. subtilis strain was not effective in detecting the fluoroquinolone drugs, whereas the E. coli strains were selective for the fluoroquinolones. E. coli 128 was 100% effective in detecting enrofloxacin and ciprofloxacin in spiked diaphragm homogenate samples at 50 micrograms/kg. Of the microorganisms tested, E. coli strain ATCC 128 was highly suitable as an indicator microorganism in a microbial inhibition assay for selective detection of fluoroquinolone antibacterial residues in animal tissues.     

以烟草花叶病毒为半抗原载体的活体免疫反应

以烟草花叶病毒的赖氨酸突变体(TMV-EPMK)为半抗原载体,利用“点击化学”反应,将半抗原小分子雌三醇(E3)经由两个不同亲/疏水性的连接臂修饰在TMV-EPMK上,成功制备了TMV-EPMK/E3完全抗原。 通过免疫实验发现,以亲水性连接臂制备的TMV-EPMK/E3偶联体可在小鼠体内诱导更高水平的E3特异性免疫反应,所产生的IgG抗体的滴度达21800。 该结果表明,以烟草花叶病毒为载体制备的完全抗原,其免疫原性受连接臂性质的影响,亲水性的连接臂更有利于抗体反应的发生。     

An ellipsometry-based Alzheimer plaque mimic: Effect of beta-amyloid, lipoprotein identity and apolipoprotein E isoform

Ca2+-induced deposition of low-density lipoprotein (LDL), intermediate-density lipoprotein (IDL), and high-density lipoprotein (HDL) at proteoheparan sulfate-modified surfaces was investigated as a function of beta-amyloid (Abeta) presence and apolipoprotein E isoform. Presence of beta-amyloid resulted in an increased deposition, as did the E4/E4 isoform compared to the corresponding E3/E3 isoform. The results are compatible with findings reported in literature on plaque formation in Alzheimer's disease, and suggest that, although simplistic, the present model system may have some potential in biosensor studies of Alzheimer plaque formation.