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991.
Separation of the dyes methyl violet, methylene blue, and congo red from aqueous solutions by paper capillary permeation adsorption method was studied using paper. Nearly 100% of the investigated dyes could be separated under the optimum conditions. The effect of pH on the separation efficiency was studied in particular. At pH 5–9, 1.3–11, and 7–11, the maximum separation was achieved for methyl violet, methylene blue and congo red, respectively. The effects of dye concentration and some foreign ions on the separatability were examined. Moreover, the selective separation of some dyes was attempted by elution with chemical reagents. 相似文献
992.
993.
ThecombinationofstrippingvoltammetrywithUPDcanleadtotheimprovementofsensitivity ,selectivi tyandreversibilityforelectroanalyticalpurposeandavoidtheuseoftoxicmercuryastheworkelectrode1andthenanalyticalapplicationshavebeendescribed .2 4 Inthiswork ,wedevelo… 相似文献
994.
The substitution of Mo(III) for Cr(III) in metal-cyanide clusters is demonstrated as an effective means of increasing the strength of the magnetic exchange coupling and introducing magnetic anisotropy. Synthesis of the octahedral complex [(Me(3)tacn)Mo(CN)(3)] (Me(3)tacn = N,N',N"-trimethyl-1,4,7-triazacyclononane) is accomplished with the addition of precisely 3 equiv of LiCN to a solution of [(Me(3)tacn)Mo(CF(3)SO(3))(3)] in DMF. An excess of LiCN prompts formation of a seven-coordinate complex, [(Me(3)tacn)Mo(CN)(4)](1)(-), whereas less LiCN produces multinuclear species such as [(Me(3)tacn)(2)Mo(2)(CN)(5)](1+). In close parallel to reactions previously performed with [(Me(3)tacn)Cr(CN)(3)], assembly reactions between [(Me(3)tacn)Mo(CN)(3)] and [Ni(H(2)O)(6)](2+) or [(cyclam)Ni(H(2)O)(2)](2+) (cyclam = 1,4,8,11-tetraazacyclotetradecane) afford face-centered cubic [(Me(3)tacn)(8)Mo(8)Ni(6)(CN)(24)](12+) and linear [(Me(3)tacn)(2)(cyclam)NiMo(2)(CN)(6)](2+) clusters, respectively. Generation of the former involves a thermally induced cyanide linkage isomerization, which rapidly leads to a low-spin form of the cluster containing diamagnetic Ni(II) centers. The cyclic voltammagram of this species in DMF reveals a sequence of six successive reduction waves spaced approximately 130 mV apart, suggesting class II mixed-valence behavior upon reduction. The magnetic properties of the aforementioned linear cluster are consistent with the expected ferromagnetic coupling and an S = 4 ground state, but otherwise vary slightly with the specific conformation adopted (as influenced by the packing of associated counteranions and solvate molecules in the crystal). Magnetization data indicate an axial zero-field splitting parameter with a magnitude falling in the range [D] = 0.44-0.72 cm(-1), and fits to the magnetic susceptibility data yield exchange coupling constants in the range J = 17.0-17.6 cm(-1). These values represent significant increases over those displayed by the analogous Cr(III)-containing cluster. When perchlorate is used as a counteranion, [(Me(3)tacn)(2)(cyclam)NiMo(2)(CN)(6)](2+) crystallizes from water in a dimeric form with pairs of the linear clusters directly linked via hydrogen bonding. In this case, fitting the magnetic susceptibility data requires use of two coupling constants: one intramolecular with J = 14.9 cm(-1) and another intermolecular with J' = -1.9 cm(-1). Reacting [(Me(3)tacn)Mo(CN)(3)] with a large excess of [(cyclam)Ni(H(2)O)(2)](2+) produces a [(Me(3)tacn)(2)(cyclam)(3)(H(2)O)(2)Ni(3)Mo(2)(CN)(6)](6+) cluster possessing a zigzag structure that is a simple extension of the linear cluster geometry. Its magnetic behavior is consistent with weaker ferromagnetic coupling and an S = 6 ground state. Similar reactions employing an equimolar ratio of reactants afford related one-dimensional chains of formula [(Me(3)tacn)(cyclam)NiMo(CN)(3)](2+). Once again, the ensuing structure depends on the associated counteranions, and the magnetic behavior indicates ferromagnetic coupling. It is hoped that substitutions of the type exemplified here will be of utility in the design of new single-molecule magnets. 相似文献
995.
Highly ordered mesoporous silica can be regenerated from a mesoporous carbon CMK-3 that is a negative replica of mesoporous silica SBA-15, indicating reversible replication between carbon and inorganic materials. 相似文献
996.
Wen‐Bin Pan Li‐Mei Wei Li‐Lan Wei Chin‐Chung Wu Fang‐Rong Chang Yang‐Chang Wu 《中国化学会会志》2005,52(3):581-588
Oxidation of a series of phenols with cerium(IV) ammonium nitrate (CAN) in acetonitrile under mild conditions yields the mixture of corresponding nitrophenols. In the cases of methylphenols and hydroxy ‐carboxylic acids, the steric effect may reduce the nitration reaction. Compounds 3a and 4b showed selective activities to Hep 3B and Hep G2 cancer cell lines, respectively. Compound 2c showed selective activities to Hep G2 and MDA‐MB‐231 cancer cell lines. Furthermore, compound 10b showed selective activities to Hep G2, Hep 3B, MCF‐7 and MDA‐MB‐231 cancer cell lines. 相似文献
997.
998.
AIBN/SmCl3/乳酸体系催化甲基丙烯酸甲酯的反向原子转移自由基聚合 总被引:5,自引:0,他引:5
利用稀土金属化合物三氯化钐(SmCl3)和二氯化钐(SmCl2)之间的单电子转移反应,以AIBN/SmCl3/乳酸作为反向原子转移自由基聚合(ReverseATRP)的催化体系,成功地实现了甲基丙烯酸甲酯(MMA)的反向ATRP,并考察了温度、溶剂和组分比对聚合反应的影响.MMA在该体系中的聚合反应是一级反应,所得PMMA的分子量与单体转化率成正比,聚合物的分子量分布较窄(Mw/Mn<1.5),具有活性聚合的特征. 相似文献
999.
Yi Long Zhu Li-Na Ding Bin Cheng Peng Liao Dai-Zheng Zhai Yu-Ping Yan Shi-Ping Jiang Zong-Hui 《Transition Metal Chemistry》2004,29(2):200-204
Two novel complexes, [Cu(HL)2(H2O)]2(OH)2(ClO4)2·1.5H2O (1) and [Cu(HL)2]Cl2·4H2O (2), have been prepared by reacting copper salts with the 4-amino-3-ethyl-1,2,4-triazole-5-thione (HL) ligand in neutral solution and in HCl (6 mol L–1) medium, respectively. They were characterized by FT-IR and u.v.–vis. spectra, and the structures were determined by single crystal X-ray diffraction techniques. In both complexes, the triazole ligand chelated the metal ions through the amine and thione substituents on the five-membered ring. Complex (1) has a square-pyramidal copper(II) ion coordinated by two triazole ligands and one water molecule. Unlike (1), the Cu2+ ion in (2) displays its characteristic Jahn–Teller distortion with the distance of the Cl– anions to metal ion further away than that of the triazole ligands. The most intriguing structural features of the title complexes are that the HL ligands chelate copper(II) ions through the N(1) and S(1) atoms, in a cis mode in (1) and a trans mode in (2). In both cases, self-assembled crystals, by supramolecular contacts simultaneously, form two multi-dimensional frameworks. 相似文献
1000.
Yeh‐Long Chen Po‐Hsu Chen Chao‐Ho Chung Kuang‐Chieh Li Haw‐Yaun Jeng Cherng‐Chyi Tzeng 《Helvetica chimica acta》2003,86(3):778-786
2‐(Aryloxymethyl)‐5‐benzyloxy‐1‐methyl‐1H‐pyridin‐4‐ones 8a – 8g , 2‐(aryloxymethyl)‐5‐hydroxy‐4H‐pyran‐4‐ones 9a – 9g , and 2‐(aryloxymethyl)‐5‐hydroxy‐1‐methyl‐1H‐pyridin‐4‐ones 10a – 10g were prepared from the known 5‐benzyloxy‐2‐(hydroxymethyl)pyran‐4‐one ( 3 ) in a good overall yield. These compounds were evaluated in vitro against a three‐cell lines panel consisting of MCF7 (breast), NCI‐H460 (lung), and SF‐268 (CNS), and the active compounds passed on for evaluation in the full panel of 60 human tumor cell lines derived from nine cancer cell types. The results indicated that 5‐hydroxy derivatives are more favorable than their corresponding 5‐benzyloxy precursors ( 10a – 10g vs. 8a – 8g ), and 1‐methyl‐1H‐pyridin‐4‐ones are more favorable than their corresponding pyran‐4(1H)‐ones ( 10a – 10g vs. 9a – 9g ). Among these three types of compounds, 2‐(aryloxymethyl)‐5‐hydroxy‐1‐methyl‐1H‐pyridin‐4‐ones 10a – 10g were the most cytotoxic; they inhibited the growth of almost all the cancer cells tested. On the contrary, compound 8a (a mean GI50=27.8 μM ), 8b (38.5), 8d (11.0), and 8e (30.5) are especially active against the growth of SK‐MEL‐5 (a melanoma cancer cell) with a GI50 of <0.01, 5.65, 0.55, and 0.03 μM , respectively (cf. Table 2). 相似文献