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本文采用滴涂法制备了还原氧化石墨烯/Nafion溶液修饰玻碳电极(rGO/Nafion/GCE),用电化学聚合法将L-半胱氨酸(L-Cys)聚合在rGO/Nafion/GCE表面,得到Poly-L-Cys/rGO/Nafion/GCE。采用伏安法研究了芦丁在该修饰电极上的电化学行为及其影响因素。结果表明,L-Cys的电聚合圈数对修饰电极的电化学性能具有一定的影响。在最优条件下,芦丁的峰电流与其浓度在2.0×10~(-8)~1.0×10~(-5) mol/L内呈现好的线性关系,检出限(S/N=3)为1.0×10~(-8) mol/L。 相似文献
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为了提高电化学检测NADH的分析性能,制备了硫堇/Nafion/石墨烯修饰的玻碳电极(GCE),利用Nifion的强离子交换能力将硫堇修饰在电极表面,形成硫堇/Nafion/石墨烯复合电极.与裸玻碳电极相比,在NADH的反应中观察到了电位明显降低和电流响应显著增大.证实了硫堇/Nafion/石墨烯复合电极对NADH有协同的电催化能力.为构造有效地检测NADH的电化学传感器提供一个良好的应用平台. 相似文献
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使用多壁碳纳米管(MWCNTs)和Nafion溶液制备了多壁碳纳米管-Nafion膜修饰的铂电极。运用扫描电子显微镜(SEM)对多壁碳纳米管、Nafion膜、多壁碳纳米管-DMF膜和多壁碳纳米管-Nafion膜进行了形貌表征。通过电化学系统研究了铁氰化钾在多壁碳纳米管-Nafion膜修饰电极、多壁碳纳米管-DMF修饰电极以及未修饰铂电极的表面电化学行为。结果显示,多壁碳纳米管-Nafion膜修饰的电极对铁氰化钾有显著的电化学增强作用,于0.185 V处形成了一个尖锐的还原特征峰,比未修饰的铂电极还原峰增强近8.7倍;在0.231 V处形成了一个较强的氧化特征峰,比未修饰的铂电极氧化峰增强近2.7倍。由于多壁碳纳米管的比表面积大,利用其与Nafion修饰的电极能增强电子传输效率,使测定的峰电流增大,从而提高灵敏度,有助于检测低浓度物质。进一步研究发现,铁氰化钾在未修饰的铂电极表面反应为可逆反应,而在MWCNTsNafion膜修饰后的电极表面反应为不可逆反应。 相似文献
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《化学研究与应用》2015,(11)
本文采用电化学性能独特的联吡啶钌(Ru(bpy)32+)、氮掺杂石墨烯(NG)和Nafion膜构建了一种新型的盐酸异丙嗪电化学传感器。采用红外光谱和扫描电子显微镜对氮掺杂石墨烯的形貌进行了表征。在Nafion膜中添加导电性好、比表面积大的氮掺杂石墨烯可以增加电子传递速度并且可以防止联吡啶钌扩散到Nafion膜的非电活性区域而增加电极使用寿命。在p H 7.0的磷酸盐缓冲溶液中,盐酸异丙嗪在Ru(bpy)32+/NG/Nafion修饰电极上的循环伏安曲线表明,与单一的裸玻碳电极、Ru(bpy)32+/Nafion修饰电极以及NG/Nafion修饰电极相比,该修饰电极使盐酸异丙嗪得氧化峰电流显著增加,而峰电位明显负移,表明采用Ru(bpy)32+/NG/Nafion膜制备的复合修饰电极对盐酸异丙嗪呈现出较强的电化学催化作用。优化实验条件后,发现在1.0×10-6mol·L-1~1.0×10-4mol·L-1.浓度范围内,盐酸异丙嗪的氧化峰电流与其浓度呈良好的线性关系,检测限为3.6×10-7mol·L-1。而且该电极的重现性、稳定性和选择性良好,采用标准加入法可成功用于商业盐酸异丙嗪注射液中盐酸异丙嗪的测定。 相似文献
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电化学氧化增强金属钴卟啉的自组装研究 总被引:1,自引:0,他引:1
应用电化学方法将钴(Ⅱ)卟啉氧化成钴(Ⅲ)卟啉以增强它与4-巯基吡啶(MP)自组装膜的轴向配位作用,从而快速制备了有序钴卟啉自组装修饰电极CoTMPP/MP/Au(E).电化学石英晶体微天平(EQCM)测试证实电化学氧化对钴卟啉膜生长过程的增强作用.Ram an光谱及修饰电极电催化还原氧研究显示,该修饰电极与经过长时间浸渍法得到的CoTMPP/MP/Au(I)修饰电极具有完全相似的有序结构和性质.与直接将钴卟啉吸附在电极表面的CoTMPP/Au修饰电极相比,以巯基吡啶为桥键得到的钴卟啉修饰电极具有更好的电催化活性和稳定性. 相似文献
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Nafion修饰碳纤维微电极在抗坏血酸共存下选择性测定去甲肾上腺素 总被引:1,自引:0,他引:1
制备了碳纤维微电极,将洁净的碳纤维微电极浸入Nafion溶液中,采用电沉积的方法制得Nafion修饰碳纤维微电极。采用循环伏安法(CV)、差分脉冲伏安法(DPV)研究了去甲肾上腺素(NE)和抗坏血酸(AA)在电极上的电化学行为。结果表明:在最优条件下制备的Nafion修饰电极能完全屏蔽AA的电化学响应,而对NE仍表现出良好的电化学响应。修饰电极能在1.0 mmol/L AA的共存下选择性地测定NE,采用DPV进行检测,NE的氧化峰电流与其浓度在1.0×10~(-6)~1.0×10~(-4)mol/L范围内呈良好的线性关系,相关系数(r~2)为0.991 2,检出限(S/N=3)为8.6×10~(-7)mol/L。利用该方法测定了模拟样品中NE的含量,平均加标回收率为101.6%。该电极的重现性和稳定性良好,且具有良好的灵敏度和选择性,有望用于复杂生物环境中NE浓度的检测。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
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. 相似文献
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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. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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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%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
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. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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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. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献