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Thawatchai Tuntulani Praput Thavornyutikarn Sirilux Poompradub Nongnuj Jaiboon Vithaya Ruangpornvisuti Narongsak Chaichit Zouhair Asfari Jacques Vicens 《Tetrahedron》2002,58(52):10277-10285
Tripodal aza crown ether calix[4]arenes, 5a, 5b, 6a and 6b, have been synthesized. The structure of protonated 5a was elucidated by X-ray crystallography to be a self-threaded rotaxane. Complexation studies of 5a and 5b towards anions using Na+ as countercation were carried out by 1H NMR titration in dimethylsulfoxide-d6 and the mixture of chloroform-d and methanol-d4, respectively. Ligands 5a and 5b were able to form 1:1 complexes with Br−, I− and NO3− and the complexation stability varied as follows: NO3−>I−>Br−. The effect of countercation on anion complexation was also investigated. The results showed that the association constants of 5a towards Br− in the presence of various cations varied as K+>Bu4N+>Na+. The enhancement in anion complexation ability of 5a may result from the rearrangement of the tripodal ammonium unit in the presence of K+. The neutral forms, 6a and 6b, were able to form complexes with transition metal ions such as Co2+, Ni2+, Cu2+ and Zn2+. The stability of the complexes followed the sequence: Ni2+2+Cu2+Zn2+. Compounds 6a and 6b may, therefore, potentially be used as either transition metal ion or anion receptors that can be controlled by pH of the solution. 相似文献
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This paper presents a new route to the synthesis of UV-curable poly(dimethylsiloxane) dimethacrylate (PDMSDMA). PDMSDMA was essentially prepared by modification of poly(dimethylsiloxane), bis(3-aminopropyl) terminated (PDMS-NH2) with methacrylic anhydride (MAA). The synthesized products were cured under UV in the presence of camphorquinone (CQ) used as a photoinitiator. The chemical structure of PDMSDMA samples was analyzed by FT-IR and 1H-NMR spectroscopy. The 1H-NMR spectrum of PDMSDMA revealed new peaks at 3.20 ppm, corresponding to methylene protons in CH2 NH , and 5.25 and 5.65 ppm, corresponding to vinylic protons in NH CO CCH3CH2. The chemical structure of the cured products and the degree of curing were determined by solid state 13C CP/MAS NMR and FT-IR (Micro-ATR) spectroscopy. Various parameters, such as concentration of methacrylic anhydride, amount of camphorquinone, and curing time, were studied. 相似文献
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The hydrolysis of aryltellurium trihalides to aryltellurium oxide halides in neutral aqueous media is considered to proceed in a stepwise manner in which the first stage involves the formation of a monomeric species. In alkaline media the initially isolated hydrolysis product analyses as (p-EtOC6H4)TeO(OH) and on treatment with dilute acid, affords the known (p-EtOC6H4TeO)2O.The infrared spectra are assigned in the low frequency region for the compounds RTe(O)X (X = halogen), RTeO(OH) and (RTeO)2O. It is argued that the probable coordination number for tellurium in RTe(O)X is four, and that a ring structure is likely. The preparation of the salts(C5H5NH+)(RTeCl4?) is reported and the anions are considered to have square-based pyramidal structures of approximately C4v symmetry. The reaction of (C5H5NH+)(PhTeCl4?) with acetone affords Ph(CH3COCH2)TeCl2. 相似文献
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