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2001 (1)
1994 (1)
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    J.-Ch Buhl, C. Mundus, J. Löns, W. HoffmannRequires cookie*
 Title    On the Enclathration of N aB(O H )4 in the /J-Cages of Sodalite: Crystallization Kinetics and Crystal Structure  
 Abstract    The hydrothermal formation of sodium hydroxyborate enclathrated sodalite synthesized from an initial ternary mixture of mullite, cristobalite and corundum has been investigated. Depending on temperature and pressure the compound Na7-5[AlSi04]6[B(0H)4]1.5 • 2 H 20 could be synthesized in form of polycrystalline powder as well as in form of single crystals. The kinetics of the sodalite growth could be determined at 423 K and 473 K. 29Si-and 27A1 MAS NMR was shown to be the preferred method to describe the conversion into sodalite quantitatively. Evidence for the first formation of polycrystalline sodalite has been found after the total dissolution of mullite and cristobalite. Single crystal X-ray diffraction data were used for the structure determination and refinement. The position and orientation of the hydroxyborate anions within the sodalite's /J-cages could only be found in the course of a "rigid body" refinement with constraints for the B(OH)4 tetrahedron. The boron atoms are located in an off-centre position within the sodalite cages. One out of the four oxygen atoms of the hydroxyborate group is positioned near the centre of a face of the sodium tetrahedron, whereas the three remaining oxygen atoms are near to the middle of its edges. 
  Reference    Z. Naturforsch. 49a, 1171—1178 (1994); received September 26 1994 
  Published    1994 
  Keywords    Sodalite solid solution, Crystallization kinetics, IR-spectroscopy, MAS NMR, Structure refinement 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-1171.pdf 
 Identifier    ZNA-1994-49a-1171 
 Volume    49