Lanthanum(Ⅲ) sorption studies on poly[dibenzo-18-crown-6] and its separation from uranium(Ⅵ) and thorium(Ⅳ) in L-valine medium

The sorption study of La(Ⅲ) was carried out on poly[dibenzo-18-crown-6] and L-valine medium. The quantitative adsorption of La(Ⅲ) was found at 1×10-2 to 1×10-5 mol/L L-valine. The various eluting agents were found efficient eluents for La(Ⅲ). The capacity of crown polymer for La(Ⅲ) was found to be 0.43 ±0.01 mmol/g. The tolerance limit of various cations and anions for La(Ⅲ) was determined. La(Ⅲ) was quantitatively separated from other metal ions in binary as well as multicomponent mixtures. The study was extended to sequential separation of La(Ⅲ), U(VI) and Th(IV). The good separation yields were obtained and had good reproducibility (±2%). The method incorporated the determination of La(Ⅲ) in real sample. The method was simple, rapid and selective.

Synergistic Effect in Mixed Capillary Gas Chromatographic Stationap Phases Containing Heptakis(2,3,6-tri-o-pentyl)-β-cyclodextrin and Dibenzo-18-crown-6

used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．

Chromatographic separation of Be（Ⅱ） from Mg（Ⅱ）, Ca（Ⅱ）, Sr（Ⅱ） and Ba（Ⅱ） using poly[dibenzo-18-crown-6] and L-arginine

A simple and selective method for the separation of Be（Ⅱ） was developed using poly[dibenzo-18-crown-6] as a stationary phase in column chromatography. The study was carried out in L-arginine medium. 1.0-8.0 M HCl and CH3COOH, 0.5-8.0 M HBr, HClO4 and H2SO4, 0.2-1.0 M EDTA and 0.02-0.12 M ammonium oxalate were found to be an efficient eluents for Be（Ⅱ）. The capacity of polymer was 0.554-0.01 mmol/g of crown polymer. The tolerance limit of various cations and anions were reported. Be（Ⅱ） was quantitatively separated from Mg（Ⅱ）, Ca（Ⅱ）, Sr（Ⅱ） and Ba（Ⅱ）. The selective separation of Be（Ⅱ） was possible from multicomponent mixtures. The method was extended to determine Be（Ⅱ） from geological samples. Method was simple, rapid and selective having good reproducibility （approximately4-2%）.

4,4′-二胺甲基联苯搭桥的二苯并-18-冠-6环状二聚体的合成

在高度稀释条件下 ,二酰氯 (1)与二氨基二苯并 18 冠 6 (2 )反应 ,以高收率生成大环二酰胺 (3) ,3在甲苯溶剂中用SMEAH[二 (2 甲氧乙氧基 )二氢化钠铝 ]还原得到目标化合物——— 4,4′ 二胺甲基联苯搭桥的二苯并 18 冠 6环状二聚体 (4 ) .在吡啶溶剂中 4与 [6 0 ]富勒烯有弱的π 电子给体 -受体相互作用 .

Structure of 〔Na(DB18C6) (CH_3OH)〕_2W_6O_(19)·(DB18C6)·(CH_3OH)

Complex [(DB18C6 ) (CH3OH )]2W6O19. (DB18C6 ) - (CH3OH),Mr=2630. 43, monoclinic, space group P21/c, a=18. 699 (5), b= 19. 568 (4), c=22. 785(5) A, β= 112. 91(2)°, V=7679(7) A, Z=4, D.=2- 275 g/cm3, F(000)= 4992, p= 92. 52 cm-1. The final R=0. 035 and Rw =0. 041 for 5689 observed reflections (I>3σ(I) ). The complex contains one hexatungstate anion and two sodiumcations. Each Na cation is inlaid in the cavity of one dibenzo-18-crown-6 (DB18C6)with six Na-O coordination bonds. In addition, it linked to O atom of CH3OH fromone side of DB18C6 and bonded to one of the terminal O atoms in hexatungstate anionfrom the other side. The two DB18C6 connected with hexatungstate symmetrically bythe long-distance interaction through the O- Na -O bonds with Na- O distances of2. 28(1)~2- 37(1 ) A W-O distances are 1. 68(2) ~2. 34(2) A. C-O distancesin methanol coordinated with cation are 1. 38 (4 ) ~ 1- 41 (4) A.

Crystal Structure of Dimer Complex of 〔K (dndb)(H_2O)(NCS)〕_2

The title complex [K (dndb ) (H2O) (NCS ) ], (dndb = trans-dinitro-dibenzo-- 18 -- crown -- 6 -- ether ) crystallied in triclinic system, space group Pl wit h unit celldimensions a= 7. 844 (4), b= 11. 979(8), c= 14. 436(11) A; a= 75. 62(6), β=80. 15(5), γ= 71. 94(5)°, M.= 1131. 39, V= 1243(2) A3, Z= l, F(000) = 588, D.= 1. 511 g/cm3, μ= 10. 5 cm-l (MoKa). The final R= 0. 045 for 2740 observed reflections (I＞3σ). The title complex molecule is a dimer complex and the potassium(I) ionis nine--coordinated, being bonded to one NCS-- anion, one H2O molecule, six oxygenatoms of a crown ether ligand and an oxygen atom of a nitro of another crown ether ligand. The potassium(I) ion and the nine atoms bonded with it are all in two planeswhich are approximately vertical with each other. The trans--dinitro-- dibenzo-- 18 -- crown6 is a heptadentate ligand.

Synthesis and Crystal Structure of the Copper Complex of 7,16-Bis(2-hydroxy-5-methylbenzyl)-1,4,10,13- tetraoxa-7,16-diazacyclooctadecane

A lariat crown ether ligand 7,16-bis (2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (L1) has been prepared via one-pot Mannich reaction. Its copper(II) complex Cu-L1 was synthesized and charac-terized by elemental analysis, IR and UV-visible spectroscopy. The crystal structure of the complex has been deter-mined 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.