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381.
The compound (Hql)2[Fe2(cit)2(H2O)2]·4H2O (1) [ql = quinoline, cit4– = C(O–)(CO–
2)(CH2CO–
2)2], prepared by reacting ferric nitrate, sodium citrate and quinoline in a molar ratio of 1:1:1 in aqueous solution, was characterized by density measurements, elementary analysis, i.r., X-ray crystallography and magnetic measurements. The X-ray crystallography results reveal that the molecule (1) consists of a binuclear iron(III) citrate anionic complex [Fe2(cit)2(H2O)2]2– and two protonated quinolines [Hql]+. The anionic complex has a centro-symmetric structure, in which two Fe3+ ions are bridged by two 2-alkoxo groups of the two deprotonated citrate ligands. The other coordination sites of the two slightly distorted octahedra are completed by all the carboxylate groups of the two cit4– ligands in a monodentate mode, and two coordinated water molecules. Magnetic measurements indicate that the two Fe3+ ions are antiferromagnetically coupled below 200 K. A least-squares fit of variable-temperature (1.5–291 K) molar susceptibility data to a dimer model gave the coupling constant J/k = –6.35(7) K and Landé factor g = 2.052(9), where the spin-only Heisenberg–Dirac–van Vleck Hamiltonian is expressed as H = –2J
S
1
S
2. 相似文献
382.
A facile approach to chiral dihydroquinazolinone derivatives has been described via biomimetic asymmetric reduction of quinazolinones with chiral and regenerable NAD(P)H models. The utility of this method was demonstrated by a concise synthesis of the bromodomain protein divalent inhibitor. 相似文献
383.
LIU Xiang LIU Yu-Jie ZHANG Qian-Feng 《结构化学》2005,24(7)
1 INTRODUCTION There is continuing interest in the assembly of molecular capsules based on concomitant formation of multiple hydrogen bonds between smaller mole- cular components[1]. A particularly attractive buil- ding block is calix[4]resorcinarenes with eight pen- dant hydroxyl functional groups[2]. In a crystal engi- neering design strategy for molecular self-assembly, cocrystallization of C-methylcalix[4]resorcinarenes with nitrogen-donor molecules such as pyridines in the presence … 相似文献
384.
IntroductionTheincreasingcommercialvalueoftransitionmetalcomplexesofxanthateshasarousedconsiderableinterestintheirchemistry .Whiletheiranalyticalapplicationsarewellknown ,1theyarenowfindingextensiveuseinvulcan izationofrubber ,frothfloatationprocessforconcentrationofsulphideores ,asantioxidants ,lubricants ,2 ,3andhavebeenfoundtopossessfungicidalandinsecticidalactivi ties .4 Recently ,molecularrecognitionbetweenhostandguestmolecules ,inclusionphenomenaandnoncovalentmolecularinteractionarefunda… 相似文献
385.
高效液相色谱-串联质谱法结合多糖衍生物手性固定相拆分氰戊菊酯 总被引:1,自引:0,他引:1
建立了以多糖衍生物为手性固定相的高效液相色谱-串联质谱(HPLC-MS/MS)直接拆分氰戊菊酯对映体的方法。在反相液相色谱条件下,考察了手性固定相的种类、流动相组成、柱温、流速对氰戊菊酯4个立体异构体分离的影响。同时,利用热力学方法对氰戊菊酯的立体异构体与固定相之间的色谱保留和分离的热力学机理进行了探讨。结果表明:采用Lux Cellulose-3(纤维素-三(4-甲基苯甲酸酯))手性色谱柱,在以流动相为乙腈-水(5 mmol/L甲酸铵)=(55:45,V:V)流速0.4 mL/min,柱温30℃的条件下,可在14 mins内实现氰戊菊酯4个立体异构体的基线分离。拓展了HPLC-MS/MS在菊酯类手性农药对映体分离及检测上的应用。 相似文献
386.
New microporous particles with large pore size (mean pore diameter of 820 nm) are successfully prepared from a mixture of cellulose and konjac glucomannan (RC-KGM3) in 1.5 M NaOH-0.65 M thiourea aqueous solution by coagulating with 5 weight percentage (wt%) CaCl(2), and then 2 wt% HCl aqueous solution. A preparative size-exclusion chromatographic (SEC) column packed with the gel particles is used for the fractionation of a dextran in water. The exclusion limit and fractionation range of the stationary phase are molecular masses of 125 yen 104 g/mol and 5.6 yen 104 to 125 yen 104 g/mol, respectively. The dextran [dextran 50, weight-average molecular mass (M(w)) = 40.1 yen 104 g/mol, polydispersity index (d) = 3.5] is fractionated by the preparative SEC column to obtain six fractions, and four of them are refractionated twice by the same preparative SEC column. The refractionated samples F-3-3 and F-4-3 are characterized by analytical SEC combined with laser light scattering and light scattering to obtain M(w) of 91.8 and 61.9 yen 104 g/mol, as well as d of 1.3 and 1.4, respectively. The results indicate that the fractions having narrow molecular mass distribution are satisfactorily prepared with the SEC column. The described SEC column can be successfully used to fractionate polymers in aqueous solution. 相似文献
387.
添加剂铜和银离子对MnO2催化燃烧CH4的影响 总被引:2,自引:1,他引:2
催化燃烧法,由于起燃温度低、去除率高、适用氧浓度范围大、无二次污染、燃烧缓和等,是国内外治理有机废气时,回收利用能量最有效的方法之一[1].但目前用于该过程的催化剂中均含有来源有限、价格昂贵的贵金属铂或钯[2].因此,寻找来源丰富、价格低廉、性能相当... 相似文献
388.
3-苯氧甲基-6-(2,4-二氟苯基)-7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪的合成与晶体结构研究 总被引:2,自引:0,他引:2
由苯氧乙酸出发,经多步反应,制得3-苯氧甲基-4-氨基-5-巯基-1,2, 4-三唑,它与2-氯-2',4'-二氟苯乙酮进行环化反应,生成3-苯氧甲基-6-( 2,4-二氟苯基)-7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪,通过元素分析、红外 光谱、核磁共振氢谱与碳谱、质谱进行表征,并利用单晶X射线衍射法测定其结构 。晶体属单斜晶系、P2_(1/c)空间群,a = 1.339(3) nm, b = 1.4683(4) nm, c = 0.8606(2) nm, β = 108.49(2)°, Z = 4, F(000) = 736, R_1 = 0.0509。还 对均三唑并噻二唑两类稠杂环的晶体结构作了比较。 相似文献
389.
The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step. 相似文献
390.
Chuanguang Qin 《Tetrahedron letters》2004,45(1):217-220
Total synthesis of decapeptide antibiotics streptocidins A-D from Streptomyces sp. Tü 6071 was accomplished for the first time by solid-phase peptide synthesis followed by traceless cyclization of the activated linear precursors, without protection of nucleophilic side chain. Synthetic products were equally active as the natural products isolated from the bacterial source and found to possess similar bacterial selectivity as other members in the amphipathic antimicrobial cyclic decapeptide family. 相似文献