Lipophilic counterion effect on aggregation and adsorption behavior of quaternary ammonium surfactants

The obvious different aggregation and adsorption behavior of six newly quaternary ammonium surfactants with different lipophilic counterions has been discoverd by measurements of equilibrium and dynamic surface tension, fluorescence and conductivity. Interestingly, the critical micelle concentration (CMC) and its surface tension γ_CMC decrease with the increasing counterion chain length. However, three methods have confirmed that an exception of CMC increases slightly from C₁₆NC₁ to C₁₆NC₂. According to experimental results, a balanced mechanism between hydrophobicity and electrostatic of counterion is proposed. Besides, the dynamic surface tension results show the diffusion coefficient increases with the increasing counterion length both at a short time (D_t?→?0) and long time (D_t?→?∞), which indicates a faster adsorption process. Unlike the inorganic counterion, the diffusion coefficient decreases with the increase of hydrophobic chain length. This is attributed to the strong electrostatic interactions between counterions and cationic headgroups.     

一个富路易斯碱位配合物的合成、结构及对痕量Ag+的荧光检测

通过溶剂热方法合成了一个由氢键拓展的携带路易斯碱位的三维超分子配位聚合物：{[Cd（HTZ-IP）（HPYTZ）（H₂O）₂]·5H₂O}_n（HTZ-H₂IP=5-（5-四氮唑基）间苯二甲酸;HPYTZ=3,5-（4-吡啶基）-1,2,4-三唑]。X射线单晶衍射结果表明,中心镉离子由含氮杂环羧酸配体和富氮辅助配体连接成"有悬挂手臂"的一维链,而链间则凭借配位水和2个配体的氢键作用拓展成三维超分子化合物。有趣的是配合物存在大量裸露的未配位的N原子,此N原子具有路易斯碱性质,能与路易斯酸性质的Ag⁺有效结合,从而引起配合物的荧光猝灭。该性质能在无色溶液中有效检测10^-4~10^-6 mol·L^-1范围内的痕量Ag⁺离子。     

新型含苯硼酸和喹啉的囊泡荧光多糖传感器的制备

利用合成的含有识别基团苯硼酸和荧光读出基团喹啉的新型双亲化合物对硼酸苯甲基-8-十六烷氧基溴化喹啉(BHQB)在水中自组织成囊泡,囊泡的相变温度为52.4℃;当向囊泡体系加糖时,BHQB囊泡中的喹啉生色基在508nm的荧光峰强度急剧减弱,425nm处荧光逐渐增强.荧光强度变化可能归于所形成的硼酸酯改变了双亲化合物中硼原子的杂化轨道形式,进一步引起了整个分子内部的电子云排布所致.BHQB囊泡与糖的相互作用而导致体系荧光强度变化,并且这种变化的幅度与加入糖的种类和量均有关.因此体系有可能应用于检测生物物质如糖的化学传感器.     

Concise synthesis of the oxapentacyclic core of cortistatin A

A concise synthetic approach for constructing the oxapentacyclic framework of cortistatin A is described. The synthesis features a furan-oxyallyl [4 + 3] cycloaddition and double-intramolecular aldol reactions. In addition, an interesting core structure was obtained in 11 steps from furan by using our method.     

18β-甘草次酸A环开环衍生物的合成及抗肿瘤活性

采用化学方法在18β-甘草次酸A环上进行结构修饰,合成了一系列新颖的A环具有不同官能团的开环衍生物.初步研究了它们对人体肝癌细胞HepG-2的体外细胞毒活性,结果表明,羟基的数目和位置对抑制HepG-2细胞增殖起着重要的作用.     

肌红蛋白在氧化镍纳米粒子中的固定及新型生物传感器的制备

研究了在氧化镍纳米粒子改性石墨电极(GE)上肌红蛋白(Mb)的直接电化学行为, 并制备了新型H2O2 传感器.在0.1 mol/L 磷酸盐缓冲溶液(PBS, pH 7.0)中, 肌红蛋白有稳定而明确的氧化还原峰,电子转移速率常数为6.48/s;式量电位为-0.34 V(vs·SCE), 表面覆盖量8.06×10-10 mol/cm2.二甲亚砜(DMSO)的存在对加速肌红蛋白分子与电极之间的电子传递起了重要作用.光谱分析表明: 固定在Mb/NiO/DMSO膜中肌红蛋白能保持其生物活性,对H2O2有电催化活性,电催化响应与H2O2浓度呈线性关系,线性范围为0.8～24 μmol/L;检出限为0.039 μmol/L. 对H2O2的表观米氏常数为0.21 mmol/L, 灵敏度为417 mA cm2 L/mol, 呈现出高亲和性.     

有机化合物的氧化溴化研究进展

综述了几类在氧化剂存在下的羰基α位、芳环、烯烃双键、烷基苯苄位及烷烃上的氧化溴化反应。氧化溴化体系主要有Br-/H2O2和Br-/BrO3-体系。总结了不同反应条件对反应收率的影响,并展望了该领域的研究前景。     

急性子中总皂苷的含量测定

采用香草醛-冰醋酸-高氯酸显色法,以齐墩果酸为对照,分光光度法测定急性子中总皂苷的含量.经显色后,齐墩果酸在541nm处有最大吸收,并在7.327-25.64μg/mL范围内吸光度与齐墩果酸量呈良好线性关系(r=0.9996),方法平均回收率为98.7％(n=6),RSD为0.51％.该方法简便、准确、灵敏,可以快速测...     

红色荧光粉NazCa1-x-2y-zBiyMoO4∶Eu3+x+y发光研究

采用高温固相法制备系列红色荧光粉Naz Ca1-x-2y-zBiyMoO4 ∶ Eu3+x+y (y,z=0,x=0.24,0.26,0.30,0.34,0.38; x=0.30,y=0.01,0.02,0.03,0.04,0.05,0.06,0.07,z=0; x=0.30,y=0.04,z=0.38).用X射线粉末衍射(XRD)法测试了所制样品晶相结构.采用荧光光谱仪对样品的发光性能进行了表征,结果表明:当Eu3+单掺杂量浓度x=0.30时,荧光粉(Ca0.70 MoO4∶Eu3+0.30)的发光强度最强;当Eu3+-Bi3+共掺杂量浓度y=0.03时,电荷迁移带(CTB)强度达到最强,而对于Eu3+特征发射峰,当共掺杂浓度y＜0.03时,位于393 nm处的激发峰强度比464 nm强,共掺浓度y＞0.03时,464 nm峰比393 nm峰强,共掺浓度为y=0.04时,393和464 nm处两峰位置强度都达到最强.作为电荷补尝剂的Na2 CO3掺入上述荧光粉中后,荧光粉激发和发射强度明显地增强.结果表明,通过调节Bi3+ /Eu3+掺杂比例可以改变位于近紫外光393 nm和蓝光区464 nm处激发光相对强度.     

Short,enantioselective, gram-scale synthesis of (−)-zephyranthine

A reasonable synthesis design by strategically integrating functional group manipulation into the ring system construction resulted in a short, enantioselective, gram-scale total synthesis of (−)-zephyranthine. The concise route includes a catalytic Michael/Michael cascade for the asymmetric synthesis of a penta-substituted cyclohexane with three contiguous stereogenic centers, a remarkable 8-step one-pot operation to easily assemble the zephyranthine tetracyclic skeleton, the regioselective construction of a double bond in the C ring and an asymmetric dihydroxylation. This synthesis is also flexible and paves a potential path to a variety of cyclohexylamine-fused tricyclic or polycyclic alkaloids.

A reasonable synthesis design by strategically integrating functional group manipulation into the ring system construction resulted in a short, enantioselective, gram-scale total synthesis of (−)-zephyranthine.