司帕沙星的吸附伏安特性及其应用

在0.2mol·L-1 KH2PO4-K2HPO4(pH6.80)底液中,司帕沙星(sparfloxacin,简称SPFX)在汞电极上有一线性扫描还原峰,峰电位Vp= -1.40V(vsAg/AgCl),该峰具有明显的吸附性 ;吸附粒子为SPFX中性分子,测得SPFX在汞电极上的饱和吸附量Гs =5.08×10-11 mol·cm-2,每个SPFX分子所占电极面积为3.27nm2,SPFX在汞电极上的吸附符合Langmuir吸附等温式 ;测得吸附系数 β=1.04×106,25℃时的吸附自由能ΔGФ= -34.33kJ·mol -1,电极反应电子数n=2,不可逆体系动力学参量αnα=1.54,表面电极反应速率常量ks=0.29s -1 ;建立了吸附溶出伏安法测定SPFX的最佳条件,方法的检出限为2.0×10 -8mol·L -1。     

利凡诺的吸附溶出伏安法研究

在NH~3-NH~4Cl底液中,利凡诺(RIL)在汞电极上有一线性扫描还原峰,E~P~C=-1.42V(vs.饱和Ag/AgCl电极).该峰具有明显的吸附性.当RIL浓度较小,扫描速度较快,搅拌富集时间较长时,电极反应完全为吸附态的RIL的还原所控制.吸附粒子为RIL中的二氨基乙氧基丫啶中性分子.测得RIL在汞电极上的饱和吸附量为4.0×10^- ^1^0mol·cm^-^2,每个RIL分子所占电极面积为0.42nm^2,电子转移数n为2, 不可逆吸附的转移系数α为0.71.探讨了RIL在汞电极上还原的机理. 并建立了吸附溶出伏安法测定RIL的最佳条件,最低检测限为1.0×10^-^9mol·dm^-^3     

尼莫地平的吸附伏安行为

在NH_3-NH_4Cl底液中,尼莫地平(nimodipine,NMD)在汞电极上有一线性扫描还原峰,峰电位E_(pc)=-0.62V(vs.Ag/AgCl).该峰具有明显的吸附性,吸附粒子为NMD中性分子.测得NMD在汞电极上的饱和吸附量为1.49 ×10~(-10)mol/cm~2,每个NMD分子所占电极面积为1.11nm~2,NMD在悬汞电极上的吸附符合Frumkin等温式.测得吸附系数β=4.32×10~5,吸附因素γ=0.46;吸附自由能△G°=-32.14kJ/mol;电子转移数n=4;不可逆吸附的动力学参数αn_α为1.10.探讨了NMD在汞电极上的还原机理,并建立了吸附溶出伏安法测定NMD的最佳条件,检测限为1.0×10~(-9)mol/L.     

阿西美辛的吸附伏安特性

在乙酸 -乙酸钠 ( p H 4.2 0 )底液中 ,阿西美辛 ( ACE)在汞电极上有一线性扫描还原峰 ,峰电位 Epc=- 1 .1 8V( vs.Ag/Ag Cl) ,该峰具有明显的吸附性。吸附粒子为 ACE中性分子 ,测得 ACE在汞电极上的饱和吸附量为 1 .1 9× 1 0 - 10 mol/cm2 ,每个 ACE分子所占电极面积为 1 .43nm2 ,ACE在悬汞电极上的吸附符合 Frumkin等温式。测得吸附系数β =1 .2 9× 1 0 6 ,吸引因素γ =1 .0 4 ,电子转移数 n为 2 ,不可逆吸附的电子转移系数α为 0 .86,表面电极反应速率常数 ks=0 .32 /s。建立了吸附伏安法测定 ACE的最佳条件 ,检出限为 1 .0× 1 0 - 9mol/L     

氟哌啶的吸附溶出伏安法研究

在NH~3-NH~4Cl底液中, 氟哌啶(Dro)在汞电极上有一线性扫描还原峰。E~p~c=-1.46V(vs.饱和Ag/AgCl电极)。该峰具有明显的吸附性。当Dro浓度较小, 扫描速度较快, 搅拌富集时间较长时, 电极反应完全为吸附态的Dro的还原所控制。吸附粒子为Dro中性分子。测得Dro在汞电极上的饱和吸附量为1.12x10^-^1^0mol.cm^-^2, 每个Dro分子所占电极面积为1.48nm^2, 不可逆吸附的转移系数α为0.58。并建立了吸附溶出伏安法测定Dro的最佳条件, 最低检测限为1.0x10^-^9mol.dm^-^3。     

蒿甲醚在单壁碳纳米管修饰电极上的电催化还原

研制了单壁碳纳米管(SWCNTs)修饰玻碳电极。用交流阻抗谱法(EIS)和扫描电镜(SEM)研究了电极膜性能,应用循环伏安法(CV)、计时库仑法(CC)、计时电流法(CA)研究了蒿甲醚在修饰电极上的电化学行为。结果表明,SWCNTs修饰电极对蒿甲醚的还原有良好的电催化活性,其还原反应为双电子过程,电极反应的扩散系数及速率常数分别为6·67×10-4cm2·s-1及8·54×10-2mol·L-1·s-1。在优化实验条件下,还原峰的峰电位位于-0·85V,其峰电流与蒿甲醚浓度在6·71×10-7~2·45×10-4mol·L-1范围内呈良好线性,检出限达4·02×10-7mol·L-1,相对标准偏差(n=10)为4·2%,可用于蒿甲醚样品的含量测定。     

对氟-γ-(4-二苯甲基哌嗪-l)-丁酰苯的吸附伏安行为的研究

在NH_(3-)NH_4Cl底液中,对氟-γ-(4-二苯甲基哌嗪-1)-丁酰苯(FDB)在汞电极上有一线性扫描还原峰.E_(pc)=-1.43V(vs.饱和Ag/AgCl电极)。该峰具有明显的吸附性.当FDB浓度较小,扫描较快,搅拌富集时间较长时,电极反应完全为吸附态的FDB的还原所控制。吸附粒子为FDB中性分子.测得FDB在汞电极上的饱和吸附量为7.04×10~(-11)mol/cm~2。每个FDB分子所占电极面积为2.34 nm~2,不可逆吸附的转移系数α为0.64.并建立了吸附伏安法测定FDB的最佳条件.当富集时间为300s时,最低检测限可达5.0×10~(-10)mol/L.     

杯[4]芳烃化学修饰玻碳电极对多巴胺的测定

研究了多巴胺在杯[4]芳烃化学修饰玻碳电极上的电化学行为,建立了一种直接测定多巴胺的电化学方法.在0.1 mol·L-1KH2PO4-Na2HPO4(pH 7.4)底液中,开路搅拌富集300 s后,多巴胺在+0.158 V(vs SCE)处产生1个灵敏的准可逆氧化峰,电极反应主要受扩散控制,氧化峰电流Ip与多巴胺浓度在1.0×10-6 ～5.0×10-4 mol·L-1范围内呈现良好的线性关系,检出限达7.0×10-7 mol·L-1.同一支电极连续10次测定1.0×10-4 mol·L-1的多巴胺溶液,相对标准偏差为2.6%.该法用于盐酸多巴胺针剂中多巴胺含量的测定,结果令人满意.     

对乙酰氨基酚在活化玻碳电极上的电化学行为及测定

应用循环伏安法,研究了对乙酰氨基酚(PCT)在活化玻碳电极上的电化学行为.在pH=4.00的HAc-NaAc缓冲溶液中,PCT的CV扫描于0.54 V左右出现一对明显的氧化-还原峰.电极反应为2电子、2质子的受吸附控制的准可逆过程.其氧化峰电流与PCT浓度在8.00×10-6~2.00×10-4mol.L-1范围内呈良好的线性关系,相关系数r=-0.99918;检出限为6.34×10-6mol.L-1.用于药物样品PCT的含量测定,结果满意.     

司帕沙星在单壁碳纳米管修饰电极上的电化学行为及其测定

运用循环伏安法和线性扫描伏安法研究了司帕沙星在单壁碳纳米管修饰电极上的电化学行为,提出了一种简便、准确、灵敏的检测药物司帕沙星的电化学分析方法.在pH 6.0的0.1 mol·L-1Na2HPO4-NaH2PO4缓冲溶液中,司帕沙星在单壁碳纳米管修饰电极上于1.06 V电位处有一峰形很好的氧化峰.在最佳的试验条件下,该氧化峰电流与司帕沙星的浓度分别在1.1×10-6～2.2×10-5mol·L-1和2.7×10-5～1.6×10-4mol·L-1范围内呈线性关系.在开路富集30 s的条件下测得方法的检出限(3S/N)为5.0×10-7mol·L-1.电极上的吸着物质经循环伏安扫描即可除去,从而使电极活性恢复,在SPFX浓度为4.0X10-5mol·L-1的浓度水平下用同一电极连续测定10次,求得相对标准偏差为5.1%,取片剂样品按提出方法分析,测定值与标示值相符.在此基础上用标准加入法作回收试验,测得回收率在97.6%～105.7%之间.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.