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1Author    Akinobu Sasane, Hisanori Shinohara, Yoshihiro Mori, Yoshio Kume, Tetsuo Asaji, Daiyu NakamuraRequires cookie*
 Title    A Temperature Dependence Study of 35 C1 Nuclear Quadrupole Resonance Frequencies in Some Hexachloroplatinate(IV) Hexahydrates  
 Abstract    The temperature dependence of 35 C1 NQR frequencies was investigated in various hexachloro-platinate(IV) hexahydrates containing the following divalent ions as counter cations: Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Ba(II). All of the compounds except the Cu(II) and Ba(II) salts yield a single 35 C1 NQR line at all temperatures studied. For the Mn(II), Cu(II), and Ba(II) salts, the NQR frequencies are considerably shifted by deuteration. For the deuterated Mn(II) salt, two 35 C1 NQR lines were observed whose relative peak-height intensities vary in dependence on the history of the thermal treatment of the sample. The very broad higher frequency line could be observed for a sample which had been at 77 K or below. It could not be observed for a sample which was cooled slowly to room temperature after it had been heated up to ca. 420 K. A structural phase transition was located at 135. 6 and 129. 4 K for the Cu(II) salt and its deuterated analog, respectively. The frequency shift by deuteration is discussed in relation to the strength of O-H ... CI type hydrogen bonds. 
  Reference    Z. Naturforsch. 42a, 611—616 (1987); received February 171987 
  Published    1987 
  Keywords    Magnetic resonance (NQR), hydrogen bonding, phase transition 
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 TEI-XML for    default:Reihe_A/42/ZNA-1987-42a-0611.pdf 
 Identifier    ZNA-1987-42a-0611 
 Volume    42 
2Author    Haruo Niki, Ryokan Igei, Takuya Higa, Masao Hashimoto, Takahiro IsonoRequires cookie*
 Title    Lattice Imperfections and Relaxation of Cl NQR in Chloral Iso-Butylhemiacetal  
 Abstract    The temperature dependence of the S/N ratios of three 35 C1 NQR lines (v l5 v 2 , v 3) in chloral iso-butylhemiacetal shows interesting features in the range 77-300 K. 35 C1 T y indicates that above 220 K reorientation of CC1 3 is excited, and this results in a gradual decrease in S/N. The activation energy calculated from 35 C1 NQR T l results is 30 kJ mol -1 for v x and v 2 but 25 kJ mol -1 for v 3 . The difference seems to be attributable to the motion of H in the OH group. A minimum of 35 C1 NQR T 2 is found around 180 K but 35 C1 T\ shows no anomaly. 35 C1 T 2 determines the S/N ratios in the range between 130-220 K. The line broadening below 130 K is attributable to an inhomo-geneity of the electric field gradient at resonant nuclei produced by lattice defects. 
  Reference    Z. Naturforsch. 45a, 481—484 (1990); received August 26 1989 
  Published    1990 
  Keywords    NQR, Lattice imperfections, Magnetic relaxation, Hydrogen bonding 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0481.pdf 
 Identifier    ZNA-1990-45a-0481 
 Volume    45 
3Author    M. Wichmann, M. StockhausenRequires cookie*
 Title      
 Abstract    Relaxation spectra have been measured at 20°C for mono-, di-and triethanolamine in the pure liquid state and in a 0.6 mole fraction mixture with 1,4-dioxane. The general resemblance to the dielectric behaviour of alcohols and aminoalcohols shows that relaxation is governed by association effects. In this regard, several features point to significantly differing behaviour of the mono compound in comparison with both di-and triethanol­ amine. 
  Reference    Z. Naturforsch. 56a, 603—604 (2001); received June 18 2001 
  Published    2001 
  Keywords    Association, Dielectric Spectroscopy, Hydrogen Bonding, Liquids 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0603_n.pdf 
 Identifier    ZNA-2001-56a-0603_n 
 Volume    56 
4Author    Swathi Pisupati, P. A. Kumar, V.G K M PisipatiRequires cookie*
 Title    Induced Smectic-G Phase through Intermolecular Hydrogen Bonding Part IX: Comparative Thermal and Phase Behaviour Studies on Two Distinct Structural Isomers Possessing Linear and Bow Shapes  
 Abstract    Two novel intermolecular hydrogen bonding mesogenic series comprising two distinct structural iso­ mers nABA:R:nABA and «ABA:H:«ABA (where R = resorcinol; H = hydroquinone; nABA = p-n-al-kyloxybenzoic acid with the alkyl carbon number varying from propyl-to decyl-and dodecyl-) have been synthesized using resorcinol and hydroquinone as central bent and linear cores, respectively. The thermal and phase behaviour of these complexes is studied by thermal microscopy and differential scan­ ning calorimetry. The IR spectral data confirm the formation of intermolecular hydrogen bonding between the OH group of the non-mesogen and -COOH group of the nABA moiety. Thermal studies reveal the existence of new phases: smectic-A and smectic-G. Comparative phase transition studies sug­ gest that these isomers exhibit a different trend of mesomorphism. 
  Reference    Z. Naturforsch. 56a, 692—696 (2001); received July 4 2001 
  Published    2001 
  Keywords    Hydrogen Bonding, Thermal, Phase Behaviour, rtABA:R:rcABA, nABA:H:rcABA 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0692.pdf 
 Identifier    ZNA-2001-56a-0692 
 Volume    56 
5Author    M. Weisser, W. WeyrichRequires cookie*
 Title    The Electronic Structure of Hydrogen Bonding in a-Oxalic Acid Dihydrate  
 Abstract    Compton spectra of a-oxalic acid dihydrate single-crystal slices and powder samples were mea-sured in a helium atmosphere using 59.537 keV 241 Am radiation. In the anisotropic case, the scattering vector was oriented parallel to the shortest hydrogen bond, in the direction of the C = O bond, parallel to the C — O bond and perpendicular to the (a, c)-plane. The comparison of theoretical reciprocal form factors, calculated with a local density-approximation (LDA) method for an a-(COOH) 2 • 2H 2 0 cluster in triple-zeta basis-set quality, with the experimental data has demon-strated that there is a considerable influence of intermolecular interactions on the electronic struc-ture. Further calculations including the intermolecular interactions of the first coordination sphere by symmetrical orthogonalisation of the LDA wave functions clearly improved the agreement of experiment and theory. A theoretical analysis of the reciprocal form factor B a (s) in the direction of the three different hydrogen bonds of a-oxalic acid dihydrate on the basis of the cluster calculations has shown that in the region above s = 1.9 Ä all these bonds are dominated by electrostatic attrac-tion and exchange repulsion of the donor and the acceptor system. 
  Reference    Z. Naturforsch. 48a, 315—324 (1993); received January 28 1993 
  Published    1993 
  Keywords    a-Oxalic acid dihydrate, Compton spectroscopy, Hydrogen bonding, Reciprocal form factor, Density functional calculations 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0315.pdf 
 Identifier    ZNA-1993-48a-0315 
 Volume    48 
6Author    G. Gowri, Tina Briere, Sudha Srinivas, Hwa-Suck Cho, T. P. Das, M. Frank, W. Kreische, K.V S Rama RaoRequires cookie*
 Title    Theory of Nuclear Quadrupole Interactions in Solid Fluoromethanes with Implanted l9 F* Nuclei. Coupling of HF* and Host Molecule  
 Abstract    The Quadrupole Coupling Constant e 2 qQ and Asymmetry Parameter rj of fluorine for fluorine-substitute methane compounds are calculated using the Hartree-Fock Roothaan procedure. Our results are compared with experimental data from measurements by the Time Differential Perturbed Angular Distribution (TDPAD) technique using excited 19 F* (spin 5/2) nuclei. The theoretical e 2 qQ's for the 19 F* nuclei in the fluoromethanes are in good agreement with experimental results. For CH 2 F 2 and CHC1F 2 molecules, where finite rj are expected from symmetry considerations, our results for ri are small, 0.12 and 0.05 respectively, in agreement with experimental observation. Besides the F* coupling constants associated with the C-F bonds in fluoromethanes, additional interesting NQI parameters, close to those in solid hydrogen fluoride, are observed in the TDPAD measurements. It is demonstrated through investigations of the total energies and electric field gradients that these additional NQI parameters for the fluoromethanes can be explained by a HF* molecule hydrogen-bonded through the hydrogen to a fluorine atom in the host molecular systems. This complexing of an ionic molecule to the host molecules in organic solids containing strongly electronegative atoms is expected to be a general feature in both implantation and conventional techniques. 
  Reference    Z. Naturforsch. 51a, 565—571 (1996); received March 8 1996 
  Published    1996 
  Keywords    Nuclear Quadrupole Interaction, 19 F* (nuclear excited state), Fluoromethane, Hartree-Fock Calculation, Hydrogen Bonding 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0565.pdf 
 Identifier    ZNA-1996-51a-0565 
 Volume    51