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A new PVC membrane electrode for the triiodide ion based on a charge-transfer complex of iodine with 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane as a membrane carrier was prepared. The electrode exhibits a Nernstian response for triiodide ions over a wide concentration range (1.0 x 10(-1)-1.0 x 10(-5) M) with a slope of 59.3 +/- 0.9 mV decade(-1) and a detection limit of 6.3 x 10(-6) M. It has a response time of 30 s and can be used for at least 3 months without any divergence in the potential. The potentiometric response is independent of the pH, in the pH range 1.6 - 10.0. The proposed electrode has shown very high selectivity for the triiodide ion over a wide variety of other anions. This electrode was successfully applied as an indicator electrode in the potentiometric titration of ascorbic acid and hydroquinone from pharmaceutical preparations as well as ascorbic acid in orange juice and dissolved O2 in tap water. 相似文献
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1,4,10,13-Tetrathia-7,16-diazacyclooctadecane (ATCO) and its binary extraction system containing lauric acid were studied extensively as extractants of lanthanide (M(3+)=La(3+), Ce(3+), Pr(3+), Nd(3+), Sm(3+), Eu(3+) and Gd(3+)) in 1,2-dichloroethane solution. The percentage extraction of Ce(3+) and Eu(3+) by ATCO were only measured to be less than 5% during a pH range 5.5-7.0 in NCS(-), ClO(4)(-) and PF(6)(-) mediums respectively, which indicates that ATCO alone has very low extractability to lanthanide, due to the bad fit of metal ions in its cavity. However, when lauric acid was added to the ATCO organic phase, because of forming rare earth adduct, the percentage extraction for lanthanide until Gd(3+) was enhanced in the binary system in comparison with that did not adopt the lauric acid within the pH range 6-7. The extraction species and extraction equilibrium constants logK(ex) were found to be CeLA(3)3HA, -8.5, EuLA(3)HA, -6.7, and GdLA(2)NO(3)2HA, -1.8, respectively. The separation factor between Eu(3+) and Ce(3+) was found to be 2.5, however, poor selectivity for lanthanide was observed. From Gd(3+) to Er(3+) and Lu(3+), the synergistic effect of the binary extraction system decreases with increasing atomic number. For gadolinium, the synergistic effect becomes much weaker than that of Ce(3+) and Eu(3+), no synergistic effect existed for erbium and lutetium. Thermodynamic data for synergistic solvent extraction are also reported in this paper. The order of organic phase stability constants of the extraction species is Sm (5.8)>Pr (5.7)>Eu (5.6)>Ce (5.3)>La (5.2)>Gd (2.8). 相似文献
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作为系统研究大环硫氮杂冠醚结构的一部分, 合成了1,4,10,13-四硫-7,16-二氮杂环十八冠醚的硝酸盐[H2(C12H26N2S4)(NO3)2]1和镍配合物[Ni(C12H26N2S4)Cl2·4H2O]2,并测定和计算了它们的晶体结构和电子结构。化合物1属单斜晶系, 空间群P21/c,a=7.936(5), b=8.866(7), c=14.756(5)埃, β=95.33(4)°, V=1033.7埃^3, Z=2,Do=1.45g·cm^-^3, μ=43.7cm^-^1, F(000)=480, 最终偏离因子R=0.059, Rw=0.059。化合物2属三斜晶系, 空间群p1, a=6.941(4), b=9.862(3), c=16.507(3)埃,α=98.78(2), β=95.52(3), γ=93.48(3)°, V=1108.3埃^3, Z=2, Dc=1.58g·cm^-^3,μ=14.9cm^-^1, F=(000)=556; 最终偏离因子R=0.060, Rw=0.065。晶体结构测定结果表明: 化合物1与自由配体L相比较, N原子的构型变化最大, 在氯化镍配合物2中, 四硫二氮大环发生严重扭曲, 其中四个S和两个N原子在Ni原子周围形成八面体配位, Ni-N距离从2.109到2.140埃, Ni-S距离从2.370到2.435埃。同时, 量化计算结果说明, S、N原子与Ni^2^+本位时均为电子授体, 且S对Ni^2^+的授电子能力, 似略大于N原子。 相似文献
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Synthesis and Crystal Structure of the Copper Complex of 7,16-Bis(2-hyd roxy-5-met hylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane 总被引:1,自引:0,他引:1
A lariat crown ether ligand 7,16-bis (2-hydroxy-5-methylbenzyl)- 1,4,10,13-tetraoxa-7,16-diazacyclooctadeeane (L1) has been prepared via one-pot Mannich reaction. Its copper(Ⅱ) complex Cu-L1 was synthesized and characterized by elemental analysis, IR and UV-visible spectroscopy. The crystal structure of the complex has been determined by X-ray diffraction analysis. The result shows that the copper(Ⅱ) ion is six-coordinated by two nitrogen and four oxygen atoms, two from the crown ether and the other two from the deprotonated phenolate anions, forming an elongated octahedral complex. Electrochemical study indicates that the complex undergoes reversible reduction in DMF solution. 相似文献
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《Polyhedron》2003,22(25-26):3249-3253
Reaction of the crown ether ligand H2L (H2L=7,16-bis (5-t-butyl-2-hydroxybenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) with Cu(Ac)2 and Cu(NO3)2 affords complexes 1 and 2, respectively, which are characterized by elemental analysis, IR and UV–Visible spectroscopy and X-ray diffraction. Both crystal structure analysis and spectroscopy study unexpectedly showed that the two side-arm p-tert-butylphenols of the original crown ether are converted to nitro p-tert-butylphenols in complex 2. In each complex the copper (II) ion is coordinated to two nitrogen and four oxygen atoms, two from the crown ether ring and other two from the deprotonated phenolate groups, which define an elongated octahedron. Electrochemical studies indicate that the two complexes undergo irreversible reduction in DMF solution. 相似文献
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El-Nemma EM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(13):3181-3185
The molecular complexation reaction between iodine and the interesting mixed oxygen-nitrogen cyclic base N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DBTODAOD) has been studied spectrophotometrically in CH2Cl2, CHCl3, and CCl4. The results of photometric titrations and elemental analysis show that the DBTODAOD base:iodine ratio is 1:4 forming the heptaiodide complex [(DBTODAOD)I]+.I7-. The heptaiodide ion (I7-) is described as I3-(2I2) confirmed by the observation of its characteristic strong absorptions around 365 and 295 nm. In addition, the far infrared spectrum of the solid complex shows the three vibrations of I3- unit at 142, 104, and 62 cm(-1) assigned to nuas(I-I), nus(I-I) and delta(I-3), respectively, while the Raman spectrum shows the corresponding bands at 147 and 108 cm(-1) beside two other bands at 181 and 214 cm(-1) related to the vibration of the I2 unit and the first overtone of nus(I-I) of I3-, respectively. The structure of the formed heptaiodide complex was further supported by thermal gravimetric analysis measurements. Group theoretical analysis indicate that the triiodide unit (I3-) in I7- may be non-linear with C2v symmetry. 相似文献
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《Journal of Molecular Structure》2002,602(1-3):141-146
A lariat crown ether compound 7,16-bis(2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane has been prepared via one-pot Mannich reaction. A copper(II) complex with the ligand 7,16-bis(2-hydroxy-5-methyl-3-nitrobenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane was unexpectedly synthesized and characterized by elemental analysis, IR and UV spectra. The crystal structure of the complex has been determined by X-ray diffraction. Both crystal structure analysis and spectroscopy study indicated that the side-arm phenols of lariat crown ether are nitrated while complexing with Cu(NO3)2. Structure shows that the copper(II) ion is coordinated to two nitrogen and four oxygen atoms, two from the crown ether and other two from the deprotonated phenolate groups. The coordination polyhedron is a distorted octahedron. 相似文献
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Polyaniline (PANI) chemically coated on polyvinylchloride (PVC) membrane based on a neutral carrier 7,16-didecyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (Kryptofix 22 DD) as the active component has been developed for determination of pH values ranging from pH 0.1–1. Effect of experimental parameters such as membrane composition, nature and amount of plasticizer, lipophilic additives and thickness of PANI film on the potential response of the pH electrode was investigated. The electrode has an apparent Nernstian response slope of 54.5 ± 0.4 mV/pH (at 20°C). The equilibrium water content of the electrode was determined in pure water and NaCl solution (I = 0.1 mol/kg). The electrode had low electric resistance, good potential stability and reproducibility (±1.5 mV, n = 10). It had a rapid potential response to changes of pH (15 s). The excellent performance in terms of linearity, stability and fast response makes this device suitable for pH measurements in highly acidic media. 相似文献
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Teleb SM Gaballa AS Elmosallamy MA Nour el-M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2708-2712
The interaction of the mixed oxygen-nitrogen cyclic base, N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DD18C6) with pi-acceptors such as picric acid (HPA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been studied spectrophotometrically in chloroform at 25 degrees C. The results obtained indicate the formation of 1:4 charge-transfer complexes with the general formula (DD18C6)(acceptor)4. The electronic and infrared spectra of charge-transfer complexes along with the (1)H NMR spectra were recorded and discussed. Based on the data obtained, the complexes were formulated as [(DD18C6H2)(HPA)2](PA)2 and [(DD18C6H2)(DDQ)2](DDQH)2. A general mechanism explaining the formation of the DDQ complex has been suggested. 相似文献
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Sergey N Adamovich Anna N Mirskova Rudolf G Mirskov Uwe Schilde 《Chemistry Central journal》2011,5(1):23
The title compound was prepared by the reaction of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane with 4-chloro-2-methyl-phenoxyacetic
acid in a ratio of 1:2. The structure has been proved by the data of elemental analysis, IR spectroscopy, NMR (1H, 13C) technique and by X-ray diffraction analysis. Intermolecular hydrogen bonds between the azonium protons and oxygen atoms
of the carboxylate groups were found. Immunoactive properties of the title compound have been screened. The compound has the
ability to suppress spontaneous and Con A-stimulated cell proliferation in vitro and therefore can be considered as immunodepressant. 相似文献