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921.
922.
Chi Won Kim Jungmin Ahn Sung Min Kim Tae Hwan Noh Ok-Sang Jung 《Transition Metal Chemistry》2011,36(5):545-551
Type studies on competitive polyatomic anion versus acetonitrile coordination in the self-assembly of a series of [Ag2(X)
m
(bip)(NCCH3)
n
](X)2−m
(X− = NO3
−, CF3SO3
−, ClO4
−, BF4
−, and PF6
−; m = 0, 2; n = 0, 2, 4; bip = 1,4-bis(2-isonicotinoyloxyethyl)piperazine) were carried out. Each bip spacer acts as an N4 tetradentate ligand and is linked to four silver(I) centers through two pyridine and two piperazine moieties, producing a
double strand consisting of two 20-membered ring units. The coordinating environment around the silver(I) center is subtly
determined by the competition of the polyatomic anions with acetonitrile, that is, by the Ag···NCCH3 versus Ag···X interactions. The coordinating ability of acetonitrile is inversely proportional to the order of the coordination
ability of the Hoffmeister series of polyatomic anions, NO3
− ≫ CF3SO3
− > ClO4
− > BF4
− ≫ PF6
−. 相似文献
923.
Four novel transitional metal complexes with 3-(4-pyridly)-4-phenyl-5-sulfhydryl- 1,2,4- triazole (HL1) and 3-(3-pyridly)-4-phenyl-5-sulfhydryl-l,2,4-triazole (HLz) were synthesized and characterized by elemental analysis, IR and X-ray diffraction. Complexes 1, 3 and 4 have two-dimensional (2-D) neutral rhombohedral grid with a (4, 4) topology. In 1, 3 and 4, all the metal ions are six-coordinated to four nitrogen atoms of four distinct ligands and two O atoms from water molecules. Complex 2 has tetranuclear CuaCI4 units which are interconnected by four desulfuri- zation ligands (L1-S) via Cu-N bonds to form a 2-D layer with (4,4) topology. 相似文献
924.
Fangting Chi Xiaolin Wang Jie Xiong Sheng Hu 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(3):1331-1340
PVA functionalized with vinylphosphonic acid was prepared as a new adsorbent for uranyl (VI) adsorption from aqueous solutions. The vinylphosphonic acid was cografted onto PVA fibers by preirradiation grafting technique. The adsorbent were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The adsorbent was observed to possess a fibrous structure and was bonded with phosphonic acid groups successfully. The adsorbent was used for the adsorption of low levels uranyl (VI) ions from aqueous solutions. The influence of analytical parameters including pH, adsorption time, amount of adsorbent, metal ion concentration, and temperature were investigated on the recovery of uranyl (VI) ion in aqueous solution. The maximum adsorption capacity (32.1 mg g?1) and fast equilibrium time (30 min) were achieved at pH of 4.5 at room temperature. Thermodynamic parameters (ΔH° = 2.695 kJ mol?1; ΔS° = 31.15 J mol?1 K?1; ΔG° = ?6.748 kJ mol?1) show the adsorption of an exothermic process and spontaneous nature, respectively. The possible coordination mechanism was illustrated. Adsorption and desorption coexist in aqueous solutions and then the system becomes equilibrium. 相似文献
925.
用于流化床燃烧脱硫的石灰石的反应活性评价和测试研究 总被引:4,自引:1,他引:4
对用于燃煤流化床燃烧脱硫的脱硫剂石灰石的反应活性进行了研究,提出了易于进行数学处理的石灰石硫盐化模型,得出了评价石灰石反应活性的两个指标-最大转化率和反应速率常数。研究方法除采用了传统的热天平法和鼓泡流化床外,还根据循环流化床燃烧技术的特点,发展了提出了湍流床法和石英棉法,并进行了不同试验条件下的实验研究,对不同反应活性温度技术进行了试验比较。 相似文献
926.
Assume X is a normed space,every x * ∈ S(X*) can reach its norm at some point in B(X),and Y is a β-normed space.If there is a quotient space of Y which is asymptotically isometric to l β,then L(X,Y) contains an asymptotically isometric copy of l β.Some sufficient conditions are given under which L(X,Y) fails to have the fixed point property for nonexpansive mappings on closed bounded β-convex subsets of L(X,Y). 相似文献
927.
Let be a cycle of order 4. Write for the maximum number of edges in a balanced 3‐partite graph whose vertex set consists of three parts, each has vertices that have no subgraph isomorphic to . In this paper, we show that , where and is a prime number. Note that from Tait and Timmons's works. Since for every integer , one can find a prime such that , we obtain that . 相似文献
928.
929.
930.