Go toArchive
Browse byFacets
Bookbag ( 0 )
'Crown Ethers' in keywords
Results  14 Items
Sorted by   
Section
Publication Year
2001 (1)
1999 (2)
1998 (2)
1997 (1)
1995 (1)
1991 (1)
1987 (1)
1983 (1)
1982 (1)
1981 (2)
1Author    Markus Ströbele, H.-Jtirgen MeyerRequires cookie*
 Title    Synthesen  
 Abstract    , Kristallstrukturen und magnetische Eigenschaften von [Li(12-Krone-4)2][Li(12-Krone-4)(OH2)]2[Nb6Cl18], [Li(15-Krone-5)2(OH2)]3[Nb6Cl18] und [(18-Krone-6)2(0 2H5)]3[Nb6Cl18] Syntheses, Crystal Structures and Magnetic Behaviour of [Li(12-crown-4)2 ] [Li(12-crown-4)OH2 ]2 [Nb6Cl x8], [Li(15-crown-5)2(OH2)]3[Nb6C l18], and [(18-crown-6)2(0 2H5)]3[Nb6C l18] The title compounds were prepared through reactions of Li2Nb6Cl16 with the corresponding crown ethers in acetone. All three compounds were obtained as dark brown crystals. Their structures were solved with the means of single-crystal X-ray diffraction. [Li(12-crown-4),][Li(12-crown-4)(OHi)]2 [Nb6Cl 18]: space group P 2 ,In, Z =2, a = 1320.4(1), b = 1879.1(1), c = 1321.7(1) pm, ß = 92.515(6)°, P, = 0.0297 (I>2a(I)). The crystal structure contains Li+ sandwiched by two 12-crown-4-ethers plus Li+ coordinated by one 12-crown-4-ether and one water molecule. [Li(15-crown-5)2(OH2)]3[Nb6C l|8]: space group R3, Z = 3, a = b = 2081.7(1), c = 1991.7(1) pm, R\ = 0.0395 (/ > 2<r(/)). In the crystal structure Li+ and one water molecule are sandwiched by two 15-crown-5-ethers. [(18-crown-6)2(0 2H5)]3[Nb6Cl18]: space group P i, Z = 1 ,a = 1405.1(1),/?= 1461.1(2), c = 1492.2(2) pm; a = 98.80(1)°, ß = 98.15(1)°, 7 = 97.41(1)°, P, = 0.0538 (/ > 2a(I)). H5 0 2+ was found in the structure refinement sandwiched between two 18-crown-6-ethers. All compounds reported contain [Nb6Cl18] clusters with Nb-Nb distances between 299 and 301 pm. The paramagnetic behaviour expected for [Nb6C l|8]3~ in all three compounds was confirmed by magnetic measurements. 
  Reference    Z. Naturforsch. 56b, 1025—1034 (2001); eingegangen am 5. Juli 2001 
  Published    2001 
  Keywords    Niobium Cluster, Chloride, Crown Ether 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-1025.pdf 
 Identifier    ZNB-2001-56b-1025 
 Volume    56 
2Author    T. Platzner, J. K. ThomasRequires cookie*
 Title    Fluorescence and Proton Nuclear Magnetic Resonance Studies of Thallous Ions - Crown Ether Complexes in Organic Solvents  
 Abstract    The complexing of thallous ions (T1+), with the crown ether dibenzo 18 crown-6 poly-ether (DB) has been studied by NMR, fluorescence, and pulse radiolysis techniques. NMR data show a strong interaction of the T1+ ions with the aromatic moieties. This is also illustrated by a static quenching of the aromatic fluorescence by Tl + . The rates of reactions of T1+ with hydrated electrons eaq~ and pyrene excited singlet states are decreases on complexing the ion by the crown ether. 
  Reference    Z. Naturforsch. 33b, 614—618 (1978); received December 12 1977/March 13 1978 
  Published    1978 
  Keywords    Photochemistry, Fluorescence, Crown Ethers, Biology 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0614.pdf 
 Identifier    ZNB-1978-33b-0614 
 Volume    33 
3Author    M. Schnock+, P. BöttcherRequires cookie*
 Title    Darstellung und Kristallstruktur von [Cs4(Dibenzo-18-Krone-6)3](S6)2-2CH3CN Synthesis and Crystal Structure of [Cs4(Dibenzo-18-Krone-6)3](S6)2 * 2 CH3CN  
 Abstract    [Cs4(dibenzo-18-crown-6)3](S6)2-2CH3CN has been prepared from dibenzo-18-crown-6, Cs2C 0 3 and suifur in acetonitrile saturated with H 2S. The title compound crystallizes in space group P I (lattice dimensions: a = 10,507(7)Ä, b = 11,504(6) A, c = 17,792(9) A, a = 97,86(4)°, ß = 105,86(4)°, y = 101,48(5)°) with one formula unit. The crystallographic units are built of stacks of three crown ether molecules and two hexasulfide chains with the cations located between them. The conformation of the hexasulfide chains is all-cis. 
  Reference    Z. Naturforsch. 50b, 721—724 (1995); eingegangen am 15. Septem ber 1994 
  Published    1995 
  Keywords    Cesium, Crown Ether, Polysulfide, Crystal Structure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/50/ZNB-1995-50b-0721.pdf 
 Identifier    ZNB-1995-50b-0721 
 Volume    50 
4Author    Z. NaturforschRequires cookie*
 Title    U ntersuchungen an Polyhalogeniden, X X X IX  
 Abstract    [1] [(H 30)(1 8 -K r o n e -6)]I7, eine Struktur-Neubestim m ung Studies on Polyhalides, X X X IX [1] S tructure R efinem ent of [(H 30)(1 8 -cro w n -6)]I7 Sawsan A bd El K halika, M ervat El Essaw ia, Ingo D om brow skih, K arl-Friedrich T ebbeb * The structure analysis of the compound [(H30)(18-Krone-6)]I7 has been repeated. The al­ ready known structure could now be described with improved precision. The unique polyiodide chain i [ (I _'2I2) I2] may be derived from the regu­ lar three dimensional iodide-iodine lattice c»[U 3I2] by separation. 
  Reference    Z. Naturforsch. 54b, 136—139 (1999); eingegangen am 6. Oktober 1998 
  Published    1999 
  Keywords    Polyhalogenide, Heptaiodide, Crown Ether, Oxonium Compound, Crystal Structure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0136_n.pdf 
 Identifier    ZNB-1999-54b-0136_n 
 Volume    54 
5Author    VictorA. Trusha, KonstantinV. Domasevitcha, VladimirM. Amirkhanov2, Joachim SielerbRequires cookie*
 Title    Structure of Tl(18-cr0wn-6){Cl3C C (0)N P (0)(0C H 3)2}: Coordination of the Ionic Multidentate Weakens the Interaction of the Metal Atom with the Crown Ether  
 Abstract    The thallium(I) dimethyl-N-trichloroacetylamidophosphate complex with a 18-crown-6 of the composition Tl(18-crown-6){L} (L = {Cl3CC(0)NP(0)(0 CH3)2}_) has been prepared and characterized by means of IR spectroscopy and X-ray diffraction (orthorhombic, space group P2,2,2, with a = 8.660(1), b = 11.557(2), c =26.296(3) A, Z = 4, V = 2631.8(6) Ä3; R\ = 0.0285 and wR2 = 0.0558 for 4314 unique reflections). It was shown that (L~) is coordinatedoto the central atom in a bidentate manner via oxygen atoms of phosphoryl [Tl-O(l) 2.678(4) A] and carbonyl groups [Tl-0(2) 3.012(6) A], The Tl(18-crown-6)+ moiety adopts a typical "sunrise" coordination with the metal atom laying 1.134(2) A above the mean plane of the oxygen atoms of the macrocycle. This deviation is the highest value of the structurally examined Tl(18-crown-6)+ complexes. The Tl-O (etheric) separations are in the range 2.913(4) -3.198(5) A (av. 3.030(6) A). 
  Reference    Z. Naturforsch. 54b, 451—455 (1999); received September 29 1998 
  Published    1999 
  Keywords    Thallium(I), Crown Ethers, Carbacylamidophosphates, X-Ray Data 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0451.pdf 
 Identifier    ZNB-1999-54b-0451 
 Volume    54 
6Author    Gabriela WeberRequires cookie*
 Title    The Structure of a 2:1 Host Guest Complex between p-Nitroaniline and 18-Crown-6  
 Abstract    The crown and two nitroaniline molecules are linked by four N-H • • • O interactions leaving the cyclic ether in a strain free conformation of approximate Ü3d symmetry. Partial disorder of one O atom facilitates one more H bond but induces considerable conformational strain in the ligand. 
  Reference    Z. Naturforsch. 36b, 896—897 (1981); received May 6 1981 
  Published    1981 
  Keywords    Neutral Complexes, Crown Ethers, H Bonds, X-ray 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0896_n.pdf 
 Identifier    ZNB-1981-36b-0896_n 
 Volume    36 
7Author    Gabriela WeberRequires cookie*
 Title    A 1:1 Host-Guest Complex between ('18-crown-6') and m-Nitroaniline: Mere Stoicheiometry or a Genuine 1:1 Adduct ?  
 Abstract    The stoicheiometrically 1:1 adduct of 1,4,7,10,13,16-hexaoxa-cyclooctadecane with m-nitroaniline, C18H30N2O8, Mr = 402.45, crystallises from toluene in red-orange prisms, (probable) space group Pi, a = 801.8(3), b = 920.4(3), c = 1403.3(4) pm, a = 80.40(4), ß = 79.79(4), y = 85.95(3)°, V = 1.07910 nm 3 , Z = 2, dcaic. = 1.238 Mgm~ 3 . Structure refinement converged at R = 0.060 (Rw = 0.002) for 2915 diffractometer data. 
  Reference    Z. Naturforsch. 37b, 1250—1254 (1982); received March 22 1982 
  Published    1982 
  Keywords    Crown Ether, m-Nitroaniline, H Bridges, X-ray 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-1250.pdf 
 Identifier    ZNB-1982-37b-1250 
 Volume    37 
8Author    FranzL. Dickert, Walter GumbrechtRequires cookie*
 Title    Komplexbildung und Ligandenfluktuation im System Co (II) / [18] Krone-6 Complex Formation and Ligand Fluctuation in the System Co(II)/[18]crown-6  
 Abstract    The ligand properties of [18]crown-6 towards Co(II) ions were studied by iH and 13 C NMR spectroscopy in nitromethane and nitromethane/methanol. The complexes [Co([18]crown-6)] ++ and mer-[Co([18]crown-6)(CH30H)3] ++ which were detected in solu-tion show ligand fluctuations on the NMR time scale. For the mixed complex a crown ether rotation occurs. Additionally, a synchronous process between the movement of the macrocyclic ligand and the dissociation reaction of methanol from the metal ion is observed. 
  Reference    Z. Naturforsch. 38b, 934—937 (1983); eingegangen am 28. März/27. April 1983 
  Published    1983 
  Keywords    Crown Ether, Complex Formation, Ligand Fluctuation, NMR Spectroscopy 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0934.pdf 
 Identifier    ZNB-1983-38b-0934 
 Volume    38 
9Author    FranzL. Dickert, MichaelW. VonendRequires cookie*
 Title    Konkurrierende Koordination von Kronenethern, Perchloratanionen und Lösungsmittelmolekülen am Co(II)-Ion — Eine Leitfähigkeits-und NMR-Studie in Nitromethan Anions and Solvent Molecules at Co(II)-Ions — A Conductivity and NMR Study on Nitromethane  
 Abstract    The 1:1 complexes between Co(II) and the crown ethers dibenzo[24]crown-8, dibenzo[18]-crown-6 and [18]crown-6 show a molar conductivity in nitromethane which indicates coordination of even Perchlorate anions. The substitution of this anion by solvent molecules can be monitored by conductometric titrations. This procedure reveals that dibenzo[24]crown-8 and [18]crown-6 is a potent five dentate ligand whereas dibenzo[18]crown-6 strongly coordinates only via three donor atoms. The mixed complexes with crown ether and methanol show strong outer-sphere associa-tion with the Perchlorate anions, which can be confirmed by investigations with [15]crown-5 complexes. 
  Reference    (Z. Naturforsch. 42b, 42—46 [1987]; eingegangen am 15. August/17. Oktober 1986) 
  Published    1987 
  Keywords    Crown Ether, Complex Formation Ionic Conductivity, NMR Spectra 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-0042.pdf 
 Identifier    ZNB-1987-42b-0042 
 Volume    42 
10Author    Antje Albert, D. Ietrich, M. OotzRequires cookie*
 Title    Formation and Crystal Structures of the Hydrates of 18-Crown-6 [1]  
 Abstract    The melting diagram of the system 18-crown-6/water has been set up and the existence of four binary hydrates confirmed. Crystal structures have been determined for three of these, in addition to that for the hexahydrate already published. The hydrates are monoclinic, a tetrahydrate (previously reported as a 4.5-hydrate) with space group P2|/c and Z = 2 formula units per unit cell, an octahydrate with I2/a and Z = 4, and a dodecahydrate with P2i/n and Z= 2. In each structure the crown ether molecule has the (pseudo) D.^ conformation common for many of its complexes, and is immediately hydrogen-bonded by a group of four water molecules in a similar, characteristic pattern. In the tetrahydrate, with one of the waters disordered, the total connectivity is that of a 1D chain, while the overall structures of the octa-and dodecahydrate are 3D networks. Four of the six independent water molecules in the dodecahydrate are linked with each other into a rare 2D ice-like layer. 
  Reference    Z. Naturforsch. 52b, 615—619 (1997); received January 15 1997 
  Published    1997 
  Keywords    Crown Ether, Crystal Structure, Hydrate, Hydrogen Bonding, Melting Diagram 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-0615.pdf 
 Identifier    ZNB-1997-52b-0615 
 Volume    52 
11Author    Antje Albert, Dietrich MootzRequires cookie*
 Title    8-Krone-6 und kleine Carbonsäuren. Bildung und Struktur binärer Addukte mit Ameisen-und Essigsäure sowie ternärer mit Essigsäure und Wasser 18-Crown-6 and Small Carboxylic Acids. Formation and Structure of Binary Adducts with Formic and Acetic Acid, as well as Ternary Ones with Acetic Acid and Water  
 Abstract    The melting diagrams of the binary systems 18-crown-6/formic acid and 18-crown-6/acetic acid have been set up and the crystal structures of the adducts 18C6 • 2 HCOOH (1, space group P 2 !/c with Z = 2 formula units per unit cell) and 18C6 • 2 CH 3COOH (2, C2/m, Z = 2) determined. Furthermore three ternary phases, 18C6 • CH3COOH • H20 (3, P2!/c, Z = 4) and dimorphic 18C6 • 2 C H 3COOH • 4 H 20 (high temperature form 4, P2,/n, Z = 2; low temperature form 5, P2|/n, Z = 2) have been characterized in the same way. In each structure the crown ether molecule has the (pseudo) D3d conformation common for many of its complexes. Various aspects of the intermolecular hydrogen bonding are described. 
  Reference    Z. Naturforsch. 53b, 242—248 (1998); eingegangen am 29. Oktober 1997 
  Published    1998 
  Keywords    Acetic Acid, Crown Ether, Formic Acid, Hydrate, Melting Diagram 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0242.pdf 
 Identifier    ZNB-1998-53b-0242 
 Volume    53 
12Author    Dirk Steinbom, Olaf Gravenhorst, Henrik Junicke, FrankW. HeinemannRequires cookie*
 Title    Synthese und Charakterisierung von kronenetherstabilisierten Platin(IV)- Komplexen mit Aminosäureliganden Synthesis and Characterization of Amino Acid Complexes of Platinum(IV) Stabilized by Crown Ethers  
 Abstract    Crown ether complexed pentachloro(aqua)platinic acid, (H30)[PtCl5(H20)]-2(18-cr-6) • 6H20 (1) reacts with glycine, L-alanine, and DL-2-aminobutyric acid to give ds-[PtCl4(0-glyH)(H20)](1 8 -cr-6)H 20 (4a)1 and ds-[PtCl4(0-amacH)(H2O)](18-cr-6) (amacH = alaH 4b, abuH 4c), respectively, as well as (amacH2)2[PtCl6]-2(18-cr-6) (amacH = glyH 5a, alaH 5b, abuH 5c). The crown ether complexed hexachloroplatinic acid, (H30) 2[PtCl6]-2(18-cr-6) (2), reacts with glycine to afford (glyH2)[PtCl4(yV,0-gly)]-2(18-cr-6)1.25H20 (6). The structures of 4b and 6 were determined by X-ray diffraction. The alanine ligand in 4b is a zwitterion that is coordinated to platinum by one oxygen atom of the carboxylate group only. The other oxygen atom is engaged in a strong hydrogen bond to the ds-coordinated aqua ligand. The glycinato ligand in 6 is /V,(9-coordinated at platinum forming an anion [PtCl4(/V,0-gly)]_ . The other oxygen atom of the carboxylate group is involved in a strong hydrogen bridge to the cation (glyH2)+. In both complexes hydrogen bridges are formed between the -N+H3 and -NH2 groups of the amino acid ligands and the oxygen atoms of the crown ether molecules. 1 Abbreviations: amacH = amino acid, glyH = glycine, alaH = L-alanine, abuH = DL-2-amino-butyric acid. 
  Reference    Z. Naturforsch. 53b, 581—586 (1998); eingegangen am 16. Januar 1998 
  Published    1998 
  Keywords    Platinum(IV) Complexes, Crown Ethers, Amino Acids, Crystal Structure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0581.pdf 
 Identifier    ZNB-1998-53b-0581 
 Volume    53 
13Author    R. Hilgenfeld, W. SaengerRequires cookie*
 Title    Stabilization of a Host-Guest Type Complex by Bifurcated Hydrogen Bonds : 18-crown-6 * (2,4-Dinitrophenylhydrazine)2 a  
 Abstract    The X-ray structure of the 1:2 host-guest complex between 1,4,7,10,13,16-hexaoxa-cyclooctadecane (18-crown-6) and 2,4-dinitrophenylhydrazine is reported. Crystallo-graphy data are: space group P2i/c, a = 8.557(2), b = 16.745(6), c = 12.387(4) Ä, ß = 117.08(13)°, Z = 2, Dm = 1.37 g • cm" 3 , Dc = 1.387 g • cm-3 , m.p. 414 K (decomp.). The present B is 0.11 for 1733 diffractometer data. In the complex, the two 2,4-dinitrophenylhydrazine molecules are located "above" and "below" the plane of the hexaether and related by an inversion centre. They interact with the macrocyclic host via N-H---0 hydrogen bonds, two of which are bifurcated. All the ether oxygens of the crown serve as hydrogen bond acceptors. 
  Reference    Z. Naturforsch. 36b, 242—247 (1981); received October 28 1980 
  Published    1981 
  Keywords    Crown Ether, Dinitrophenylhydrazine Complex, Bifurcated Hydrogen Bonds, X-ray 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0242.pdf 
 Identifier    ZNB-1981-36b-0242 
 Volume    36 
14Author    S. C. Sabat, V. Vijayavergiya, B. C. Tripathy, PrasannaM. OhantyRequires cookie*
 Title    Inhibitory Effect of Crown Compound on Photoelectron Transport Activity of Beet Spinach Thylakoid Membranes  
 Abstract    The effect o f K-picrate-18-crown-6 (crown) on the photoelectron transport activity o f beet spinach thylakoid membranes was investigated. A ddition o f micromolar concentration o f crown to thylakoid preparation inhibited p-benzoquinone, chloride-indophenol, methyl violo-gen supported Hill activities maximally by 75 per cent in a concentration dependent manner. However, the photosystem I catalyzed reaction remained insensitive to crown suggesting that crown specifically inhibits photosystem II electron transport. Addition o f exogenous electron donors like hydroxylamine or diphenylcarbazide failed to restore the crown induced inhibition o f photosystem II electron transport and lowering o f steady state chlorophyll a fluorescence yield. These observations suggest that crown also inhibits photosystem II catalyzed electron transport after the donation sites o f these exogenous donors. Washing o f the crown pre-treat-ed thylakoids with isolation buffer, relieved the crown inhibited electron transport activity, indicating that this inhibition is reversible. Furthermore, in hydroxylamine washed thylakoids which are devoid o f 0 2 evolution capacity, the hydroxylamine induced increase in chlorophyll a fluorescence o f variable yield was quenched by the addition o f crown. These observations suggest that crown affects the oxygen evolution and inhibits at a site close to photosystem II reaction centres. 
  Reference    Z. Naturforsch. 46c, 87 (1991); received August 14 1990 
  Published    1991 
  Keywords    Crown-Ether, Electron Transport, Photosystem II, Thylakoids, Beet Spinach ( Beta vulgaris) 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0087.pdf 
 Identifier    ZNC-1991-46c-0087 
 Volume    46