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891.
A novel copper selective sensor 2 based on hydrazide and salicylaldehyde has been designed and prepared. Sensor 2 behaves a single selectivity and sensitivity in the recognition for Cu2+ over other metal ions such as Fe3+, Hg2+, Ag+, Ca2+, Zn2+, Pb2+, Cd2+, Ni2+, Co2+, Cr3+ and Mg2+ in DMSO. The distinct color change and the rapid changement of fluorescence emission provide naked‐eyes detection for Cu2+. The UV‐vis data indicate that 1:2 stoichiometry complex is formed by sensor 2 and Cu2+. The association constant Ks was 3.51×104 mol?1·L. The detection limitation of Cu2+ with the sensor 2 was 2.2×10?7 mol·L?1. The sensing of Cu2+ by this sensor was found to be reversible, with the Cu2+‐induced color being lost upon addition of EDTA. 相似文献
892.
Four new star‐shaped π‐conjugated oligomers ( TPA‐CZ3 , TPA‐TPA3 , TPA‐PTZ3 and TPA‐BT3 ) with triphenylamine as a core and different electron‐donating ability groups, carbazole, triphenylamine, phenothiazine and bithiophene, as peripheral units have been designed and synthesized via the Heck reaction. These oligomers show good solubility in common organic solvents. Their photophysical, electrochemical, electronic structure and charge transfer properties between these star‐shaped π‐conjugated oligomers and N,N′‐bis(1‐ethylpropyl)‐3,4:9,10‐perylene bis(tetracarboxyl diimide) (EP‐PDI) have been investigated by UV‐vis absorption spectra, photoluminescence (PL) spectra, cyclic voltammetry (CV) measurement, theoretical calculations and fluorescence quenching. The results show that the absorptions and fluorescences of TPA‐CZ3 , TPA‐TPA3 and TPA‐PTZ3 are red shifted with the electron‐donating ability of the peripheral unit increasing from carbazole to triphenylamine and phenothiazine. In addition, although the bithiophene group has a weaker electron‐donating ability than carbazole, triphenylamine and phenothiazine, the absorption and fluorescence of TPA‐BT3 have a red shift than those of TPA‐CZ3 , TPA‐TPA3 and TPA‐PTZ3 because TPA‐BT3 has a longer conjugation length than TPA‐CZ3 , TPA‐TPA3 and TPA‐PTZ3 . The triphenylamine core and the peripheral units can constitute a large conjugated structure. The fluorescence quenching properties indicate that efficient charge transfer can happen between the star‐shaped oligomers and EP‐PDI. 相似文献
893.
The energies, geometries and harmonic vibrational frequencies of 1:1 5‐hydroxytryptamine‐water (5‐HT‐H2O) complexes are studied at the MP2/6‐311++G(d,p) level. Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM) analyses and the localized molecular orbital energy decomposition analysis (LMO‐EDA) were performed to explore the nature of the hydrogen‐bonding interactions in these complexes. Various types of hydrogen bonds (H‐bonds) are formed in these 5‐HT‐H2O complexes. The intermolecular C4H55‐HT···Ow H‐bond in HTW3 is strengthened due to the cooperativity, whereas no such cooperativity is found in the other 5‐HT‐H2O complexes. H‐bond in which nitrogen atom of amino in 5‐HT acted as proton donors was stronger than other H‐bonds. Our researches show that the hydrogen bonding interaction plays a vital role on the relative stabilities of 5‐HT‐H2O complexes. 相似文献
894.
茚三酮衍生高效毛细管电泳法测定纯奶中的甘氨酸含量 总被引:1,自引:0,他引:1
建立了茚三酮衍生高效毛细管电泳法测定纯奶中甘氨酸含量的方法,该法可选择性测定甘氨酸含量。使用氯化镁为蛋白沉淀剂,沉淀效果较好,研究了甘氨酸–茚三酮聚合物衍生条件,确定最佳实验条件为:未涂层弹性石英毛细管柱(60 cm×75μm,有效长度49 cm),分离缓冲溶液为3.5 mmol磷酸二氢钾–8.2 mmol磷酸氢二钠(pH 6.8),检测波长为570 nm,电泳电压为25 kV,进样压力为25 kPa,进样时间为3 s,电泳温度为室温。甘氨酸的线性范围为2.00~200.00μg/mL,检出限为0.14μg/mL,线性相关系数不小于0.999。甘氨酸的加标回收率为88.7%~107.2%,测定结果的相对标准偏差为2.9%~4.2%(n=6)。该法简便、快速、准确,可用于测定纯奶中甘氨酸含量。 相似文献
895.
The electrochemical behavior of dopamine (DA) at a MWNTs-modified glassy carbon electrode was investigated by cyclic voltammetry (CV), square wave voltammetry (SWV). The MWNTs modified electrode exhibited marked promotion of the electrochemical reaction of DA in different environments. Under optimum conditions, the peak currents of SWV of DA were increased linearly with incremental concentration of DA in the range from 5 × 10?7 to 1 × 10?5 mol L?1. The limit of detection is 3 × 10?7 mol L?1. 相似文献
896.
897.
二芳基碘鎓盐属于有机高价碘化合物,具有无毒、反应条件温和以及良好的选择性等优点,在有机合成中具有重要地位,受到广大化学工作者的关注。近年来,利用二芳基碘鎓盐在金属催化下进行的芳基化反应为一些难以合成的杂环化合物的合成提供了简便、高效的方法;同时,二芳基碘鎓盐在无催化剂下进行的芳基化反应,为C—C偶联反应开辟了新的绿色合成路线。本文综述了近年来二芳基碘鎓盐在有机合成中促进芳基化反应的最新进展,着重介绍了利用二芳基碘鎓盐作为芳基化试剂与有机金属试剂、烯烃和炔烃类以及杂环化合物进行芳基化反应的研究;总结了二芳基碘鎓盐与杂环化合物反应中钯催化和铜催化下芳基化反应的机理,最后对二芳基碘鎓盐在今后有机合成中的应用作出了展望。 相似文献
898.
Ling Guo 《Journal of Cluster Science》2013,24(2):575-589
The growth behavior of (GaAl) n (n = 1–12) and the chemisorptions of hydrogen on the ground state geometries have been studied with the three-parameter hybrid generalized gradient approximation due to Becke-Lee–Yang–Parr (B3LYP). The dissociation energy, the second-order energy differences, and the HOMO–LUMO gaps indicate that the magic numbers of the calculated (GaAl) n clusters are n = 4 and 6. To my knowledge, this is the first time that a systematic study of chemisorptions of hydrogen on gallium aluminum clusters. The onefold top site of aluminum atom is identified to be the most favorable chemisorptions site for one hydrogen chemisorptions on most (GaAl) n clusters. In general, dissociative chemisorptions of a hydrogen molecule on a top site of aluminum atom is found common for all sizes clusters considered here except for (GaAl) n (n = 1–3) clusters. The stability of the (GaAl) n H m complexes shows that both large second-order difference and large fragmentation energies for (GaAl)10H2 and (GaAl)11H2 make these species behaving like magic clusters. 相似文献
899.
Yun-Yun Tang Hou-Yu Wang Lu Chen Si Li Chen-Gang Guo Hui-Zhi Fan Cheng-Xi Cao Liu-Yin Fan 《Analytical and bioanalytical chemistry》2013,405(26):8587-8595
We developed a novel polyacrylamide gel electrophoresis (PAGE) method to stack and separate human hemoglobins (Hbs) based on the concept of moving reaction boundary (MRB). This differs from the classic isotachophoresis (ITP)-based stacking PAGE in the aspect of buffer composition, including the electrode buffer (pH 8.62 Tris–Gly), sample buffer (pH 6.78 Tris–Gly), and separation buffer (pH 8.52 Tris–Gly). In the MRB-PAGE system, a transient MRB was formed between alkaline electrode buffer and acidic sample buffer, being designed to move toward the anode. Hbs carried partial positive charges in the sample buffer due to its pH below pI values of Hbs, resulting in electromigrating to the cathode. Hbs would carry negative charges quickly when migrated into the alkaline electrode buffer and be transported to the anode until meeting the sample buffer again. Thus, Hbs were stacked within a MRB until the transient MRB reached the separation buffer and then separated by zone electrophoresis with molecular sieve effect of the gel. The experimental results demonstrated that there were three clear and sharp protein zones of Hbs (HbA1c, HbA0, and HbA2) in MRB-PAGE, in contrast to only one protein zone (HbA0) in ITP-PAGE for large-volume loading (≥15 μl), indicating high stacking efficiency, separation resolution, and good sensitivity of MRB-PAGE. In addition, MRB-PAGE was performed in a conventional slab PAGE device, requiring no special device. Thus, it could be widely used in separation and analysis of diluted protein in a standard laboratory. Figure
Diagram of MRB-induced stacking in a slab PAGE. (A) arrangement of separation buffer (pH 8.01–9.55 Tris–Gly), sample buffer (pH 6.37–7.22 Tris–Gly), and electrode buffer (pH 8.21–9.05 Tris–Gly); (B) initial MRB formed between electrode and sample buffers for stacking of low-content Hbs in sample buffer under electric field; (C) MRB moving toward the anode and partly stacking of Hbs within the MRB; (D) quasi-complete stacking of Hbs via MRB closing to the separating gel; (E) separation of Hbs in a zone electrophoresis mode 相似文献
900.