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101.
The synthesis of four new oxo‐centered Fe clusters ( 1 a – c , 2 ) of the form [FeIII3(μ3‐O)(CH2=CHCOO)6] with acrylate as the bridging ligand gives rise to potentially intrinsically chiral oxo‐centered {M3} trimers that show a tendency to spontaneously resolve upon crystallization. For instance, 1 a , [FeIII3(μ3‐O)(CH2=CHCOO)6‐(H2O)3]+, crystallizes in the chiral space group P31 as a chloride salt. Crystallization of 1 b , [Fe3(μ3‐O)(C2H3CO2)6(H2O)3]NO3?4.5H2O, from aqueous solution followed by recrystallization from acetonitrile also gives rise to spontaneous resolution to yield the homochiral salt [Fe3(μ3‐O)(C2H3CO2)6‐(H2O)3]NO3?CH3CN of 1 c (space group P212121). Furthermore, the reaction of 1 a with hexamolybdate in acetonitrile gives the helical coordination polymer {[(Fe3(μ3‐O)L6(H2O))(MoO4)‐(Fe3(μ3‐O)L6(H2O)2)]?2CH3CN?H2O}∞ 2 (L: H2C?CHCOO), which crystallizes in the space group P21. The nature of the ligand geometry allows the formation of atropisomers in both the discrete ( 1 a – c ) and linked {Fe3} clusters ( 2 ), which is described along with a magnetic analysis of 1 a and 2 . 相似文献
102.
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104.
Wu J Huang J Xiao Q Zhang S Xiao Z Li Q Long L Huang L 《Magnetic resonance in chemistry : MRC》2004,42(7):659-662
Ten phenylethanoid glycosides, including two new ones, isolated from the aerial parts of the mangrove plant Acanthus ilicifolius were identified. The first complete assignments of the 1H and 13C NMR chemical shifts for these glycosides were achieved by means of 2D NMR techniques, including 1H-1H COSY, TOCSY, HSQC and HMBC spectra. 相似文献
105.
106.
The adsorption equilibrium isotherms of three aromatic sulfonic acid compounds, 2-naphthalenesulfonic acid, p-toluenesulfonic acid and p-chlorobenzenesulfonic acid, from aqueous solutions by macroporous weak base anion exchanger within the temperature range of 293 K-313 K were obtained. Several isotherm equations were correlated with the equilibrium data, and the experimental data was found to fit the three-parameter Redlich-Peterson equation best within the entire range of concentrations. The study showed that the hydrophobicity of solute has distinct influence on adsorption capacity of the anion exchanger for the aromatic sulfonic acid. Moreover, estimations of the isosteric enthalpy, free energy,and entropy change of adsorption were also reported. The positive isosteric enthalpy and entropy change for adsorption indicate an endothermic and entropy driven process in the present study. 相似文献
107.
Yang LI Yu ZHANG Xiao Long WANG Zhi HUANG Xiao Ping CAOState Key Laboratory of Applied Organic Chemistry College of Chemistry Chemical Engineering Lanzhou University Lanzhou 《中国化学快报》2004,(6)
A convenient and rapid approach for the synthesis of piperamide alkaloids la ~ h by the recently developed one-flask Ramberg-Backlund reaction was described. The synthesis of 1e was reported for the first time. 相似文献
108.
水中痕量酚的富集和紫外分光光度测定法的研究 总被引:2,自引:0,他引:2
本文研究了用微型树脂柱快速富集,分离,紫外分光光度测定水中痕量酚的方法。结果表明,以GDX-502为吸附剂,水样pH为1~3并含0.2mol/L氯化钠,以每分种15~20ml的速度通过吸附柱,以热的1%氢氧化钠水溶液为淋洗剂时,在291nm处测定苯酚的回收率为89~98%。此外探讨了干扰物的消除方法。吸附柱对苯酚的富集倍数达300倍,最低检测限为0.001ppm。方法精密度为0.3(%),相对标准偏差为3.18%。本法对实际水样进行了测定。结果满意。 相似文献
109.
Mei Hong Fu Zhu Ju Wang Hong Jun Yang Mayila Maimai Jing Fang Li Ying Tang Lan Yang 《中国化学快报》2007,18(4):415-417
A new C21-steroidal glycoside with two known compounds were isolated from the root of Cynanchum Stauntonii.Based on thespectral analysis,including MS,1H NMR,13C NMR,DEPT,1H-1H COSY,13C-1H COSY,HMQC and HMBC,their chemicalstructures were determinated as glaucogenin-C 3-O-a-L-cymaropyranosyl-(1→4)-b-D-digitoxopyranosyl-(1→4)-β-D-canaropyranoside(1),stigmasterol(2)and ursolic acid(3). 相似文献
110.