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1Author    F. Burak, J. Tyrzyk, Z. PolackiRequires cookie*
 Abstract    Time resolved em ission spectra and the luminescence decay of 2,5-diphenyloxasole in dioxane-water mixtures disclose an im portant influence o f water on the observed luminescence. We suppose that this is caused by structural changes of the solution connected with its water content. 
  Reference    Z. Naturforsch. 49a, 964 (1994); received July 16 1994 
  Published    1994 
  Keywords    Luminescence, Excimers, TRES, Em ission spectra, Solution structure 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0964.pdf 
 Identifier    ZNA-1994-49a-0964 
 Volume    49 
2Author    Roland Krebs, Dietmar Schomburg, Reinhard SchmutzlerRequires cookie*
 Title    Pentakoordiniertes Silicium: Intramolekulare Koordination bei O-Fluorsilylderivaten von N.N-disubstituierten Aminoethanolen bzw. N-fluorsilylsubstituierten Derivaten des Trimethylethylendiamins Penta-co-ordinate Silicon: Intramolecular Coordination of O-Fluorosilyl Derivatives of N.N-Disubstituted Aminoethanols and of N-Fluorosilyl Substituted Derivatives of Trimethylethylenediamine  
 Abstract    Tetrafluorosilane and phenyltrifluorosilane react with the O-trimethylsilyl derivatives of N.N-disubstituted aminoethanols and with the N-trimethylsilyl derivative of N.N.N'-trimethylethylene diamine to give the corresponding monosubstituted fluorosilyl compounds in which, on the basis of 19 F NMR spectroscopic studies, intramolecular N —Si bonding raises the coordination number of silicon from four to five (i.e. A 4 Si —> A 5 Si). The low temperature 19 F NMR data suggest a trigonal-bipyramidal configuration at A 5 Si with an axial N —Si coordinate bond. 
  Reference    Z. Naturforsch. 40b, 282—287 (1985); eingegangen am 25. Juni/10. September 1984 
  Published    1985 
  Keywords    Penta-Coordinate Silicon, Solution Structure, 19 F NMR Spectra 
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 TEI-XML for    default:Reihe_B/40/ZNB-1985-40b-0282.pdf 
 Identifier    ZNB-1985-40b-0282 
 Volume    40 
3Author    BernhardG. Ollasa, S. Bernd, Peiser1, H. Artm, Ut Stahp, Jürgen Sieglenb, Joachim StrählebRequires cookie*
 Title    Electrochemistry of Oxygenation Catalysts, Part 6* Electrosynthesis, Structure, Analytical and Electrochemical Properties of Monomeric [Coin(salen)(DMF)2]+ X' Salts (X = PF6, C104)  
 Abstract    Electrochemistry [CoH1(salen)(DMF)2]+ X" salts [X = PF6, C104; salen = bis(salicyliden)ethylendiiminato; DMF = dimethylformamide] have been synthesized by electrochemical and chemical (air) oxidation of Co"(salen). Their monomeric structure with two DMF molecules in the axial positions in both the solid state and DMF solution is shown by X-ray crystal structure analysis, thermal analysis, mass spectroscopy, and 'H and l3C NMR spectroscopy. The electrochemical reduction of the [Coni(salen)(DMF)2]+ cation is investigated by cyclic voltammetry and com­ pared to the oxidation of the neutral CoH(salen). The redox reaction connecting the cobalt(II) and the cobalt(III) species appears to be a quasi-reversible electron transfer. These properties make the [Co1 1 (salen)(DMF)2]+ X-salts starting materials for the analysis of the interaction of basic substrates with cobalt(III) species in the context of the biomimetic oxygenation reactions catalyzed by such complexes. 
  Reference    Z. Naturforsch. 51b, 388—398 (1996); received September 4. 1995 
  Published    1996 
  Keywords    Cobalt Complexes, Oxygenation Catalysts, Crystal Structure, Solution Structure 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-0388.pdf 
 Identifier    ZNB-1996-51b-0388 
 Volume    51 
4Author    Joachim Granzin, W. Olfram Saenger, Ryszard Stolarski, David ShugarRequires cookie*
 Title    Solid State and Solution Structures of an Adenine Analogue of the Antiviral Acyclonucleoside 9-(l,3-Dihydroxy-2-propoxymethyl)guanine  
 Abstract    The title com pound, 9-(l,3-dihydroxy-2-propoxym ethyl)adenine (D H P-A de), an analogue o f the antiviral acyclonucleoside 9-(l,3-dihydroxy-2-propoxym ethyl)guanine (D H P G), crys­ tallizes in the m onoclinic space group P 2,, with unit cell dimensions o f a = 10.848(4), b = 8.765(3), c = 11.432(4) A, ß = 102.14(3)°, with two independent molecules in the asymmetric unit. The crystal structure o f D H P-A de was determined and compared with that for D H PG . The solution conform ations o f both acyclonucleosides were also determined with the aid o f 'H and 13C N M R spectroscopy. In the solid state the acyclic chain may adopt a "folded" form, i.e. gauche about the C (l) —O (l') bond (as in D H P-A de), or an "extended" form (as in D H PG), results which corre­ spond to the rotations about this bond in solution. A general discussion is presented o f the conform ations o f the acyclic chains o f various acyclonucleosides, from the antiviral 9-(2-hydroxyethoxymethyl)guanine (Acyclovir, ACV) through to 2',3'-^co-nucleosides, both in the solid state and in solution, and the relevance o f these to biological activities. 
  Reference    Z. Naturforsch. 45c, 915 (1990); received December 21 1989/April 27 1990 
  Published    1990 
  Keywords    Antiviral Acyclonucleoside, Solid State, Solution Structures 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0915.pdf 
 Identifier    ZNC-1990-45c-0915 
 Volume    45 
5Author    Toshiyuki Takamuku, Mikito Ihara, Toshio Yamaguchi, Hisanobu WakitaRequires cookie*
 Title    Raman Spectroscopic and X-ray Diffraction Studies on Concentrated Aqueous Zinc (II) Bromide Solution at High Temperatures  
 Abstract    Raman and X-ray scattering experiments have been performed on an aqueous zinc (II) bromide solution with molar ratio [H20]/[ZnBr2] = 10 at 25 to 140 °C. The intensity of the totally symmetric Zn-Br stretching vibration (v^ for the dibromozinc(II) complex increased with increasing temper-ature while that for the tetrabromo complex decreased. A broad band assigned to the symmetric Zn-O stretching vibration (vj for the aqua zinc (I I) ion decreased in intensity with increasing temperature. The X-ray diffraction data revealed that the average number of the Zn-Br interactions within the zinc (II) bromo complexes does not change with temperature, whereas the number of Br • • • Br nonbonding interactions within the complexes decreases from 1.8 at 25 °C to 1.5 at 100 °C. From both Raman and X-ray data it is concluded that with increasing temperature the dibromo species is favored, whereas the tetrabromo and aqua zinc(II) species are unstable in the solution. The analysis of the X-ray diffraction data has shown that the mean Zn-Br bond length within the zinc (II) bromo complexes shortens gradually with increasing temperature, accompanied with an increase in the interligand Br • • • Br distance. This finding suggests that the Br-Zn-Br bond angle increases with decreasing Zn-Br distance for the lower zinc(II) bromo complexes. The equilibrium shift of the zinc (II) bromo complexes with temperature is discussed on the basis of ion-ion, ion-water, and water-water interactions. 
  Reference    Z. Naturforsch. 47a, 485—492 (1992); received November 27 1991 
  Published    1992 
  Keywords    Raman spectroscopy, X-ray diffraction, Zinc(II)bromide, High temperature, Solution structure 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0485.pdf 
 Identifier    ZNA-1992-47a-0485 
 Volume    47 
6Author    P. M. Abuja, I. PilzRequires cookie*
 Title    Investigation of Ribulose-1,5-bisphosphate Carboxylase-Oxygenase from Tobacco by Small Angle X-Ray Scattering: A Structural Model for the Enzyme in Solution  
 Abstract    The quaternary structure of ribulose-l,5-bisphosphate carboxylase/oxygenase from tobacco (Nicotiana tabacum) was investigated in solution by means of small angle X-ray scattering. The most important molecular parameters as the radius of gyration (Rg) and the maximum diameter (Dmax) were determined. Both the active and the inactive form of the enzyme were measured at 5 °C and at 20 °C. A more distinct difference in size could be detected between the inactive forms at these two temperatures (Rg = 4.80 nm (5 °C) and 4.68 nm (20 °C)) than between the active forms (Rg = 4.73 nm and 4.69 nm). The maximum diameters were determined to be 13.1 nm for the inactive form at 5 °C and 12.8 nm for the other forms. A model is proposed consisting of eight large and eight small subunits arranged in the way that seems to be typical for this enzyme in higher plants. 
  Reference    Z. Naturforsch. 43c, 373—376 (1988); received December 21 1987/February 15 1988 
  Published    1988 
  Keywords    Small-Angle X-Ray Scattering, Solution Structure, Ribulose-l, 5-bisphosphate Carboxylase/ Oxygenase, Conformational Change, Temperature Effect 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0373.pdf 
 Identifier    ZNC-1988-43c-0373 
 Volume    43