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1Author    M. Srinivasulu, P.V V Satyanarayana, P. A. Kumar3, V.G K M PisipatiaRequires cookie*
 Title    Induced Smectic-G Phase through Intermolecular Hydrogen Bonding Part VIII: Phase and Crystallization Behaviours of 2-(p-/i-heptyloxybenzyIidene imino)-5-chIoro-pyridine: p-n-alkoxybenzoic acid (HICP:n ABA) Complexes  
 Abstract    New intermolecular H-bonded liquid crystalline complexes, viz., 2-(p-n-heptyloxybenzylidene imi-no)-5-chloro-pyridine:p-/z-alkoxybenzoic acid; (HICP:nABA) (where n denotes the alkoxy carbon num­ bers 3 to 10 and 12) exhibiting smectic-F (n = 12) and smectic-G phases have been synthesized and char­ acterized by Thermal Microscopy and Differential Scanning Calorimetry (DSC). Detailed IR (solid and solution states) analysis confirms the existence of intermolecular H-bonding between the pyridyl nitro­ gen and the COOH group of the p-n-alkoxybenzoic acid moiety. The phase behaviour of the series is discussed in the light of reported data on free p-n-alkoxybenzoic acids. The crystallization kinetics of a representative complex, using the DSC technique, is discussed. The mechanism of the crystal growth of the new crystalline smectic-G phase is computed with the Avrami equation. 
  Reference    Z. Naturforsch. 56a, 685—691 (2001); received June 27 2001 
  Published    2001 
  Keywords    H-bonding, HICP:nABA, Crystallization Kinetics, Avrami Parameters 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0685.pdf 
 Identifier    ZNA-2001-56a-0685 
 Volume    56 
2Author    JohnN. Phillips, WendyK. BanhamRequires cookie*
 Title    Hydrogen Bonding of Cyanoacrylates with the D 1 Peptide  
 Abstract    Representatives o f two structural types o f cyanoacrylate PS II inhibitors have been studied in respect to their p/ 50 values and qualitative rate o f binding with wild type and S 2 6 4 G mutant thylakoids isolated from Brassica napus. Both are potent inhibitors o f photosynthetic electron transport and both show a large discrimination between wild type and mutant thylakoids under equilibrium conditions. However one, an N-m ethylanilino cyanoacrylate, has an initial rapid reaction with both wild type and mutant thylakoids, but continues to react slowly with the wild type species until equilibrium is reached, while the other, a benzylamino cyanoacry­ late, equilibrates rapidly with both species as does the classical PS II inhibitor, atrazine. These differences in kinetic behaviour have been interpreted in terms o f different H-bond interac­ tions with the serine-264 hydroxyl group. It is suggested that the slow binding reaction is due to the N -m ethylanilino com pound interacting as an H-bond acceptor with the serine-264 hy­ droxyl hydrogen thus disrupting an intramolecular ser-264-his-252 H-bond within the D 1 peptide. Rapid equilibration on the other hand, has been attributed to the benzylam ino deriva­ tive acting as an H-bond donor to the serine-264 hydroxyl oxygen and strengthening the 2 6 4 -2 5 2 H -bond by conjugation. It is proposed that atrazine and other classical PS II inhibi­ tors act in this way and that this may explain their ability to inhibit trypsin degradation o f the D 1 peptide, if the 2 6 4 -2 5 2 intramolecular H-bond plays an important role in stabilizing the peptide conform ation. It is also speculated that photodegradation may be related to the ability o f Q b~ to act as an H-bond acceptor and disrupt the 2 6 4 -2 5 2 H-bond. 
  Reference    Z. Naturforsch. 48c, 132 (1993); received N ovem ber 16 1992 
  Published    1993 
  Keywords    Brassica napus, Cyanoacrylates, D 1 Peptide, H -Bonding, Photodegradation 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0132.pdf 
 Identifier    ZNC-1993-48c-0132 
 Volume    48 
3Author    Hirom Itsu Terao, TsutomuO., Kichiro Koto, Shi-Qi, AlarichW. Eiss2Requires cookie*
 Title    81 Br NQR and Crystal Structure of Ethylammonium Tribromomercurate(II), CHgCHjNI-^HgBrg  
 Abstract    The 81Br NQR triplet spectrum of (CH3 CH2 NH)®(HgBr3)e was measured in the range 77 K to near the m.p. (99~106°C). decreases strongly with increasing temperature, exhibiting 136.784 MHz at 77 K and 128.129 MHz at 298 K. v2 decreases from 82.060 MHz at 77 K to 76.322 MHz at 298 K. v3 increases with temperature, showing v3 = 81.292 MHz at 77 K and 84.903 MHz at 298 K. Replacement of the ammonium hydrogens by deuterium produces a negative shift of Vj and positive ones of v2 and v3 at high temperatures. These shifts change with temperature from | — 0| up to |~ 2 0 0 | kHz. The crystal structure of the title compound was determined at room temperature: P 21/m, Z = 2, a = 1021.6(8) pm, b = 643.0(6) pm, c = 691.8(6) pm, ß = 96.96 (4)°. The coordination of the mercury atom by the bromines is trigonal bipyramidal; by formation of bridges Hg • • ■ Br • • ■ Hg by one of the three bromines (Br(2)) of the planar HgBr® ions a double chain of trigonal bipyramids is formed, running along the b-axis of the crystal. B r 1' and Br(3) are single bonded to Hg. The hydrogen bonds N -H • • • Br(1 and N -H • ■ • Br(' (twice), connect the H g-B r chains to planes lying parallel to the be plane at x = 0. The relations between the Br-NQR spectrum and the structure are discussed. 
  Reference    Z. Naturforsch. 49a, 202—208 (1994); received August 16 1993 
  Published    1994 
  Keywords    Mercury(II) Bromide Complex, Crystal Structure, 81Br NQR, * H -2D isotope effect, H-bonding 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0202.pdf 
 Identifier    ZNA-1994-49a-0202 
 Volume    49 
4Author    A. Ishikawa, A. Sasane, Y. Hirakawa, Y. MoriRequires cookie*
 Title    Motion of Water Molecules and Hydrogen Bonds in Zinc Hexachlorostannate (IV) Hexahydrate as Studied by *H NMR and 35 C1 NQR  
 Abstract    The *H NMR spin-lattice relaxation time 7\, 35 C1 NQR frequency VQ, and 35 C1 NQR spin-lattice relaxation time 7\ Q of [Zn(H 2 0) 6 ] [SnCl 6 ] (zinc hexachlorostannate(IV) hexahydrate) have been measured at temperatures between 77 and 350 K. The NQR spin echo signal with Vq— 15.689 MHz at 77 K showed a positive temperature coefficient attributable to O-H-Cl type H-bonds in the crystal. v Q at 77 K is strongly correlated with the electronegativity Xm of the metal M in the series of stannates [M(H 2 0) 6 ] [SnCl 6 ] (M = Mg, Ca, Mn, Co, Ni, Zn). A 7\ minimum observed for the Zn salt is ascribed to 180° flips of water molecules with an activation energy of 20 kJ mol -1 . The motion is influenced by repulsive forces among the water molecules within a cation rather than by attractive forces between the H-bonded H and CI atoms. 7\q proved to be mainly governed by lattice vibrations, weakly modulated by the fluctuating electric field gradient caused by the 180° flip motions. 
  Reference    Z. Naturforsch. 51a, 693—697 (1996); received October 10 1995 
  Published    1996 
  Keywords    'H NMR spin-lattice relaxation, 35 C1 NQR frequency, 35 C1 NQR spin-lattice relaxation, H-bonding, Electronegativity 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0693.pdf 
 Identifier    ZNA-1996-51a-0693 
 Volume    51 
5Author    Hiromitsu Terao, Tsutomu Okuda, Aya Minami, Takashi Matsumoto, Yoshio TakedaRequires cookie*
 Title    Br and l27 I NQR Studies of (CH 3 NH 3 ) 2 HgBr 4 and (CH 3 NH 3 ) 2 HgI 4  
 Abstract    The 81 Br and 127 I NQR frequencies in (CH 3 NH 3) 2 HgBr 4 and (CH 3 NH 3) 2 HgI 4 , respectively, have been recorded from above 77 K to around room temperature. The resonance lines exist in a wide range of frequencies. An unusual temperature dependence of the resonance frequencies has been observed. Small 1 H-2 D isotope effects have been observed between (CH 3 ND 3) 2 HgBr 4 and (CH 3 NH 3) 2 HgBr 4 . Both negative and positive frequency differences between the deuterated and the nondeuterated compound have been observed at 77 K. The relatively large asymmetry parameters in the iodine compound decrease with increasing temperature, indicating the existence of H-bonds. The present results are interpreted qualitatively by considering the effects of H-bonding, N-H • • • X, between the halogen atoms and the CH 3 NH 3 ions which may undergo large molecular motions. It is suggested that not only frequency-lowering but also frequency-rising effects may be produced, depending on the direction of the H-bond, i.e., the angle between the Hg-X bond and the X • • • H bond. 
  Reference    Z. Naturforsch. 47a, 99—105 (1992); received October 8 1991 
  Published    1992 
  Keywords    81 Br NQR, 127 I NQR, Anomalous temperature dependence, r H-2 D isotope effect, H-bonding, Motions of CH 3 NH+ 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0099.pdf 
 Identifier    ZNA-1992-47a-0099 
 Volume    47