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111.
Aparna Sil & Ashwini K. Srivastava 《Supramolecular chemistry》2013,25(5):343-351
Complexation of Cu(II), Zn(II), Ni(II), Co(II), Pb(II), Cd(II), Cr(III) and Fe(III) ions with 15-crown-5, benzo-15-crown-5, 18-crown-6, dibenzo-18-crown-6, dicyclohexano-18-crown-6, dibenzo-24-crown-8, 5,6,14,15-dibenzo-1,4-dioxa-8,12-diazacyclopentadeca-5,14-diene, 1,4,10-trioxa-7,13-diazacyclopentadecane and cyclam has been investigated in 75% (v/v) DMF+water using the silver(I) ion as an auxiliary cation at 0.05?M ionic strength adjusted with tetrabutylammonium perchlorate (TBAP) by competitive potentiometry. Stability constant values obtained for the metal ion–aza macrocyclic complexes are higher than those for the oxa crowns. Shifts in the peak potential and reduction in the peak current in the differential pulse polarography (DPP) method were also used to determine the stability constants of some of the metal ions with aza and tosylated-aza macrocycles using TBAP as supporting electrolyte in 75% (v/v) DMF+water and 90% (v/v) DMSO+water media. Stability constant values determined both by shifts in the potential and by reduction in the peak current were found to be in good agreement with each other. 相似文献
112.
The Mitsunobu cyclization of p-t-butylthiacalix[4]arene with glycols was expanded to oligoethylene glycol analogues composed of O, S and N atoms in the chain. In this way a number of 1,3-thiacalix[4]monocrowns have been synthesized, offering simple and general access to a large variety of crowned thiacalixarenes. The binding properties of some ligands towards transition metal cations have been studied by 1H NMR, UV/Vis spectroscopic and potentiometric methods. 相似文献
113.
Jean-Pierre Dutasta Brigitte Bibal Jean-Paul Declercq Beatrice Dubessy Jean-Christophe Mulatier Bernard Tinant 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1485-1488
The recent results in the chemistry of cavitands have proved that they are very efficient molecular receptors and potential precursors of molecular devices. In this context, we have investigated the synthesis and binding properties of phosphorylated cavitands. The stereoselective synthesis and the structural studies of the new compounds showed that these bowl-shaped molecules possess a well defined aromatic cavity surrounded by four phosphoryl groups (P=O or P=S). They are very efficient ligands for metal and organic cations. They are able to encapsulate cationic species by cooperative effect of the preorganized aromatic cavity and the four phosphorylated groups. Moreover, the upper and lower rim functionalitics can lead to the formation of molecular capsules and supramolecular assemblies whose properties and structures have been investigated by X-ray diffraction and NMR studies in solution. 相似文献
114.
以乙二胺四乙酸(EDTA)为配位剂,采用溶胶凝胶和溶剂热法相结合的方法合成了Li2MnSiO4/C纳米复合正极材料。经过EDTA配位的锂锰硅前驱体在氩气中经过700℃煅烧后,产生为颗粒尺寸约为50nm的Li2MnSiO4/C纳米复合粉体。在0.1C=33mA·g-1进行充放电测试时,其首次充电和放电比容量分别为223和140mAh·g-1,第5次循环放电比容量仍为138mAh·g-1;电流密度升至0.2C=66mA·g-1时,在第20次循环的放电比容量仍可稳定在80mAh·g-1左右。这些结果表明,EDTA的配位作用可抑制杂相的形成,这种分散性相对较好的纳米复合粉体Li2MnSiO4正极材料表现出提高的循环稳定性。 相似文献
115.
The novel calixarene-linked discotic triphenylene 5a and 5b were synthesized in good yields via click chemistry. Structural and conformational characterization of new compounds had been achieved by NMR, MS, and elemental analysis. Their liquid crystalline behaviors before and after complexation were studied by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction. The neat compounds 5a and 5b showed mesophase but the complexes of 5a and 5b with metallic salts exhibited no liquid crystal behaviors. 相似文献
116.
Jun-Hui Xue Xiao-Hui Hua Li-Min Yang Wei-Hong Li Yi-Zhuang Xu Guo-Zhong Zhao Gao-Hui Zhang Ke-Xin Liu Jia-Er Chen Jin-Guang Wua 《中国化学快报》2014,25(6):887-891
The novel coordination structures of europium and terbium chloride-picolinamide complexes (EuCl3-(C6H6N2O)2.5H2O, Eu-pa and TbCl3.(C6H6N2O)2.5H2O, Tb-pa) are reported. The crystal structures in the solid state are characterized by X-ray single crystal diffraction, FTIR, Raman, FIR, THz and luminescence spectroscopy. In the crystal structures, the pyridyl nitrogen and carbonyl oxygen atoms in picolinamide are coordinated to the metal ions to form a five-membered ring structure. The experimental results indicate the similar coordination structures of Eu and Tb-pa complexes and the changes of hydrogen bonds and conformation provide models for the coordination structures of the ligands induced by complexation. The results of lanthanide ions with ligands having amide groups. 相似文献
117.
The derivatized cyclotetrachromotropylene host forms complexes of 1:1 host to guest stoichiometry with tetraalkylammonium cations and amino acids whereas complexes of 1:2 host to guest stoichiometry are formed with mono and diprotonated amines in an aqueous solution. Both electrostatic and hydrophobic interactions are involved in the complexation. 相似文献
118.
Eu(3+)在HAc-NaAc(pH4.6)溶液中与五碳醛糖有弱的络合作用,用循环伏安法和微分脉冲极谱可以观察到D-核糖,D-阿拉伯糖,D-木糖对Eu(3+)还原波形的络合影响,使还原和氧化过程变得较为可逆,其中D-核糖最为明显,而来苏糖无影响.Eu(3+)与氨基酸在相同实验条件下有络合作用,且在汞电极上有吸附现象,因此分别加入L-苯丙氨酸、L-组氨酸和L-蛋氨酸等,进一步改善了Eu(3+)的波形而接近于可逆氧化-还原过程,其中以Eu(3+)-D-核糖-L-苯丙氨酸最明确。绘出了在电极表面形成三元络合物的示意图。 相似文献
119.
M. Zafer Köylü Nadir Demirel F. Doganel Polat Ali Yιlmaz Halil Hoşgören Metin Balci 《Journal of inclusion phenomena and macrocyclic chemistry》2005,52(1-2):51-54
The complexation of the crown ethers with Na+ ion was studied. 1H-NMR chemical shifts are discussed in terms of structural modification as well as also binding studies with UV–vis spectra
were included.
This revised version was published online in July 2005 with a corrected issue number.
An erratum to this article is available at . 相似文献
120.
Keqiang Dmg Qingfei Wang Zhenbm Jia Na Tian Ning Wang Ruting Tong Xinkui Wang Huibo Shao 《中国化学会会志》2002,49(2):185-190
In this paper, Schiffbases were investigated using cyclic voltammetry (CV) and impedance electrochemical spectroscopy (EIS) techniques by means of self‐assembled monolayers for the first time, where a 0.1 M KCl solution and the redox couple of Fe(CN)63?/Fe(CN)64?were used as the electrolyte and probing‐pin, respectively. The monolayers formed by the employed Schiff base were proved to be relatively stable, and its electrochemical response in the studied system with different pH values was also de scribed clearly with CV and EIS plots. The results show that the monolayer of Schiff bases could exist in the solution with pH value from 2 to 10. In the EIS measurement in the concentration range from 10?5 M to 5× 10?4 M, a nearly linear relation ship between the charge transfer resistance (Rct) and the logarithm concentration of Cu2+was observed, suggesting that Cu2+ could be titrated with the EIS method quasi‐quantitatively. The phenomenon agreed with the former report very well. Using the self‐assembled monolayers to study Schiff bases with the electrochemical method is the major contribution of our work. 相似文献