以茜素兰S为电化学探针测定DNA的研究

在pH 4.5的0.2 mol/L Britton-Robinson(B-R)缓冲溶液中,茜素兰S(ABS)于-0.51 V(vs.SCE)产生一个灵敏的线性扫描二阶导数极谱还原峰。当在上述溶液中加入DNA后,茜素兰S在-0.51 V处还原峰的峰电流降低并且峰电位正移,说明两者之间可以通过嵌插作用而结合。结合反应的发生使溶液中游离的茜素兰S浓度降低,相应的还原峰电流降低。实验优化了结合反应条件和电化学测定条件。在最佳条件下,峰电流的降低值同DNA的浓度在1.0~60.0 mg/L范围内呈线性关系,线性回归方程为△ip″(nA)=18.13c(mg/L)-7.61(n=9,r=0.998)。方法应用于合成样品中DNA的测定,结果令人满意。     

藏红T作为电化学探针线扫极谱法测定透明质酸

在pH 1.5的B ritton-Rob inson(B-R)缓冲溶液中,藏红T(ST)在-0.35 V(vs.SCE)处有一个灵敏的线性扫描二阶导数极谱还原波。当加入一定量的透明质酸(HA)后,由于此条件下ST带正电荷,而HA带负电荷,两者之间通过静电力作用形成一种生物超分子复合物,导致溶液中游离的ST的浓度降低,相应的还原峰电流降低。实验优化了结合反应条件和电化学测定条件。在最佳条件下,还原峰电流的降低值与HA的浓度在3.0~100.0 mg/L范围内呈线性关系,线性回归方程为Δip(″nA/s-2)=27.23 15.18C(mg/L)(n=14,r=0.996),本方法成功应用于HA模拟样品的测定。     

钍试剂线扫极谱分析法测定蛋白质的研究

在0.2 mol/L pH 3.0的Britton-Robinson(B-R)缓冲溶液中,钍试剂于-0.49 V(vs.SCE)产生一个灵敏的线性扫描二阶导数极谱还原峰。当在上述溶液中加入人血清白蛋白(HSA)后,钍试剂在-0.49 V处的峰电流降低,而峰电位基本没有变化,这是由于HSA与钍试剂会发生结合反应,使溶液中游离的钍试剂浓度降低,相应的还原峰电流也降低。对结合反应条件和电化学测定条件进行了优化。在最佳条件下,峰电流的降低值同HSA的浓度在1.0~12.0 mg/L范围内呈线性关系。将本法应用于人血清样品的测定所得结果同考马斯亮蓝G-250光度法一致。此方法还可应用于牛血清白蛋白、卵清白蛋白等蛋白质的测定。     

纳米纤维在辣椒粉中苏丹红Ⅱ测定中的应用

建立了以静电纺丝聚苯乙烯纳米纤维作固相微萃取载体富集辣椒粉中苏丹红Ⅱ,线性扫描极谱测定的新方法。苏丹红Ⅱ在硼砂-NaOH缓冲溶液(pH11.5)体系中,用线性扫描极谱法测定,在Ep=-0.93V处产生了一个灵敏的还原峰。峰电流(ip)与苏丹红Ⅱ浓度在2×10-2～2×10-1mg/L范围内呈线性关系,相关系数r=0.9947,检出限为3×10-3mg/L。此法用于辣椒粉中苏丹红Ⅱ的检测,回收率在78.0%～85.7%。     

酸性铬蓝K-蛋白质结合反应体系的极谱分析

酸性铬蓝K(ACBK)在pH3.0Britton Robinson(B R)缓冲溶液中,于-0.41V(vs.SCE)产生一个灵敏的线性扫描二阶导数极谱峰。当在上述溶液中加入人血清白蛋白(HSA)后,由于HSA带正电,而ACBK带负电,两者之间主要通过静电引力形成一种超分子复合物,该复合物无电化学活性,使ACBK在溶液中的游离浓度降低,相应其在-0.41V处的极谱峰电流降低。优化了结合反应的条件和电化学测定条件。在最佳条件下,峰电流的降低值与HSA的加入量在3.0～20.0mg·L-1范围内呈线性关系,应用于人血清样品的测定,试验结果同考马斯亮蓝光度法一致。     

噻吩甲酰三氟丙酮的电化学性质及应用

在 0 .5mol/LHCl和 0 .2g/L的明胶溶液中 ,利用线性扫描极谱法测定噻吩甲酰三氟丙酮 (简称TTA) ,发现有一还原峰 ,其峰电位是 - 1 .0 0V (vs.SCE)。峰电流与TTA浓度在 2 .5× 1 0 - 5mol/L～ 2 .0× 1 0 - 3mol/L之间存在线性关系 (r=0 .9986) ,检测下限为 1 .0× 1 0 - 5mol/L。利用单扫描极谱法和循环伏安法对极谱峰的电化学性质进行了研究     

甲氧氯普胺的测定及与牛血清白蛋白相互作用的研究

建立了多壁碳纳米管糊电极测定盐酸甲氧氯普胺(MCPM)的电化学分析方法,研究了MCPM与牛血清白蛋白(BSA)相互作用的电化学行为。在pH2.2的Britton-Robinson(B-R)缓冲溶液中,MCPM在1.084V处出现一灵敏的氧化峰。电化学测定MCPM的线性范围为0.17～10.3mg/L,检出限为0.03 mg/L。对5.18mg/L的MCPM进行11次平行测定,相对标准偏差为2.4%。当BSA加入到MCPM溶液中,MCPM的氧化峰电流明显降低。其降低值(ΔIp)与BSA的浓度在5.00×10-7～1.67×10-5mol/L范围内呈良好线性关系,检出限为2.0×10-7mol/L。MCPM与BSA相互作用的结合常数为1.05×105L/mol。     

阿替洛尔的电化学行为及与牛血清白蛋白的相互作用

建立了石墨烯修饰玻碳电极测定阿替洛尔的电化学分析新方法。采用电化学方法结合紫外、荧光光谱分析,研究了阿替洛尔(ATN)与牛血清白蛋白(BSA)的相互作用。实验发现,在pH 10.0的Na2CO3-NaHCO3缓冲溶液中,ATN在0.78 V处有一灵敏的氧化峰,氧化峰电流Ip与ATN的浓度在4.8～30.0μmol/L范围内呈良好的线性关系(r=0.9926,n=11),方法检出限为3μmol/L。当BSA加入ATN溶液后,ATN氧化峰电流降低,氧化峰电流的降低值ΔIp与BSA的浓度在2.6～31.0μmol/L范围内呈良好线性关系。紫外光谱表明ATN的加入使BSA的吸收峰发生蓝移。荧光光谱表明,ATN对BSA的内源荧光有显著的猝灭作用,猝灭机制为静态猝灭。     

甲基紫与肝素钠结合反应的电化学研究及分析应用

应用电化学分析法研究了在pH 1.5的酸性反应条件下肝素钠与甲基紫的结合反应. 甲基紫在滴汞电极上有一个不可逆的还原峰, 峰电位为－0.58 V (vs. SCE), 加入肝素钠后峰电位发生正移且峰电流下降, 利用电化学方法对电极反应过程进行了研究, 结果发现两者结合后生成了一种电化学活性的复合物, 导致溶液的电化学参数发生了变化, 求解出结合比为1∶3, 结合常数为2.47×10¹⁴, 对结合反应条件和电化学检测条件进行了优化, 在最佳条件下峰电流的降低同肝素钠的浓度在0.2～4.0 mg/L范围内呈线性关系, 线性回归方程为∆I_p″ (nA)＝－724.9＋1741.4c (mg/L) (n＝11, γ＝0.994), 检测限为0.072 mg/L. 将本方法应用于肝素钠样品的测定, 结果令人满意. 对常见干扰物质的影响进行了考察, 表明本方法具有较好的选择性.     

茜素黄R与蛋白质相互作用的线性扫描极谱法研究及分析应用

以电化学方法研究了在pH3.2的Britton Robinson(B R)缓冲溶液中茜素黄R与蛋白质的相互作用。茜素黄R在-0.43V(vs.SCE)有一个良好的极谱还原峰,加入人血清白蛋白(HSA)后,其峰电位不变而峰电流下降,利用峰电流的下降可以测定蛋白质。优化了结合反应条件和电化学测定条件,在最佳条件下,峰电流降低值同HSA的质量浓度在4.0～40.0mg L范围内呈线性关系,其线性方程为ΔI″p(nA)=-5.48 72.28ρ(mg L),r=0.993。将该方法应用于人血清样品的测定,结果与经典的考马斯亮蓝G 250光度法一致,回收率在97%～103%之间。此方法还可应用于牛血清白蛋白、牛血红蛋白、卵清白蛋白等蛋白质的测定。     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.