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1Author    Prasad Durga, Devesh Ojha, V.G K M Kumar, PisipatiRequires cookie*
 Title    Smectogenic Behaviour of 70.6 at it's Phase Transition Temperature: A Computational Analysis Reprint request to  
 Abstract    A computational analysis has been carried out to determine the configurational preference of a pair of Ar-(4-n-heptyloxybenzylidine)-4-hexylaniline (70.6) molecules with respect to translatory and orien­ tational motions. The CNDO/2 method has been employed to evaluate the net atomic charge and atom­ ic dipole components at each atomic centre of the molecule. The configurational energy has been com­ puted using the modified Rayleigh-Schrödinger perturbation method. The obtained energies were used to calculate the probability of each configuration at phase transition temperature, using Maxwell-Boltz-mann's formula. The flexibility of various configurations has been studied in terms o f variations of the probability due to small departures from the most probable configuration. The results are discussed in the light of experimental as well as other theoretical observations. The smectogenic character of the molecule has been correlated with the parameters introduced in this paper. 
  Reference    Z. Naturforsch. 56a, 873—878 (2001); received October 12 2001 
  Published    2001 
  Keywords    706, CNDO/2 Method, Quantum Chemistry, Computer Simulation 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0873.pdf 
 Identifier    ZNA-2001-56a-0873 
 Volume    56 
2Author    RobertA. ShawRequires cookie*
 Title    The Reactions of Halogenocyclophosphazenes with Nitrogenous Bases  
 Abstract    The reactions of hexachlorocyclotriphosphazatriene, N3P3CI6, and to a lesser extent octachlorocyclotetraphosphazatetraene, N4P4CI8, and other halogenocyclophosphazenes with primary, secondary, and tertiary amines, are described. The effect on the substitution pattern of variables such as the structure of the amine, nature of the reaction solvent, etc., are discussed in some detail. Attention is drawn to the importance of steric effects. Isomerisation reactions are referred to. The physical properties of aminocyclophosphazenes and aminohalogenocyclophos-phazenes are discussed in some detail. These include basicity studies, X H and 31 P NMR and 35 C1 NQR studies, Faraday effect measurements, etc. Attempts are made to correlate the above properties with X-ray crystallographic studies and quantum chemical calculations. The distinction between ground state and perturbed state properties is emphasised. Synthesis, structure, and properties of phosphazenylcyclophosphazenes and related com-pounds are described and a novel conformational behaviour is discussed and rationalised. 
  Reference    (Z. Naturforsch. 31b, 641—667 [1976]; received October 20 1975) 
  Published    1976 
  Keywords    Halogenocyclophosphazenes, Substitution Patterns, Nitrogenous Bases, Quantum Chemistry, Conformational Analysis 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0641.pdf 
 Identifier    ZNB-1976-31b-0641 
 Volume    31 
3Author    Hans Sohr, Günter Hanschmann, Hermann UtschikRequires cookie*
 Title    Thermoanalytische, IR-spektroskopische und quantenchemische Untersuchungen an Kristallmodifikationen des Trichlorphons Thermo-analytical, IR-spectroscopical and Quantum-chemical Investigations on Crystal Modifications of Trichlorphone  
 Abstract    Several modifications of trichlorphone can be prepared by recrystallizing the raw substance from various solvents under special conditions. One of these modifications is obviously an optical isomer. The different thermo-analytical behavior of the modifications is probably due to the relative content of distinct dimer species. This interpretation is supported by quantum-chemical calculations and by analysis of infrared spectra. Die phosphor-organische Verbindung 2.2.2-Tri-chlor-1 -hydroxyethyl-dimethyl-phosphonat (Tri-chlorphon, Metrifonat) ist ein seit etwa 30 Jahren bekanntes Insektizid [1], das auch als Arzneimittel für die Behandlung von Schistosomiasis eingesetzt wird [2]. Diese im folgenden als Trichlorphon be-zeichnete Substanz hat nach Schräder [3] einen Schmelzpunkt von 356-357 K. In den meisten Fäl-len hegen jedoch die von verschiedenen Autoren angegebenen Schmelzpunkte um 348-351 K. Bei der Reinigung von Trichlorphonproben durch Umkristallisieren stellten wir fest, daß man je nach den gewählten Bedingungen mehrere Kristallfor-men erhält, deren Schmelzpunkte zwischen 343 und 383 K variieren. Über die Erscheinung der Polymorphie beim Tri-chlorphon sind uns aus der Literatur keine Hinweise bekannt. Das Ziel unserer Untersuchungen war es deshalb, mit Hilfe strukturanalytischer Methoden eine Erklärung für die beobachteten Schmelzpunkts-differenzen zu finden. Von den bisher publizierten physikochemischen Eigenschaften der Substanz sind neben den zahl-reichen Schmelzpunkten hauptsächlich die optische Aktivität und die Bimolekularität als Ausgangs-punkt für eine Strukturanalyse von Bedeutung. Brienne und Jacques [4] gelang die präparative Dar-stellung einer optisch aktiven Form (Drehung [a] 
  Reference    Z. Naturforsch. 38b, 819—824 (1983); eingegangen am 29. November 1982/11. März 1983 
  Published    1983 
  Keywords    Differential Thermal Analysis, IR Spectra, Quantum Chemistry, Polymorphism, Trichlorphone 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0819.pdf 
 Identifier    ZNB-1983-38b-0819 
 Volume    38