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1Author    Edmund Kwiatkowski, Krystyna Kozubek, Zbigniew PepliǹskiRequires cookie*
 Title    Complexation of Tertiary Amides by Phenols in Carbon Tetrachloride Solutions  
 Abstract    Formation constants for 1 : 1 complexes of N,N-dialkylamides and N-acetylmorpholine with chloro-and nitrophenols have been determined spectrophotometrically in carbon tetrachloride solutions at 20 °C. Enthalpies of reaction for 14 systems have been obtained calorimetrically. Dipole moments of N,N-di(n-butyl)acetamide, N,N-di(isobutyl)acet-amide and N-acetylmorpholine have been determined. 
  Reference    Z. Naturforsch. 33b, 230—236 (1978); received November 15 1977 
  Published    1978 
  Keywords    Molecular Complexes, Tertiary Amides, Phenols 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0230.pdf 
 Identifier    ZNB-1978-33b-0230 
 Volume    33 
2Author    M. M. Aly, A. M. ShalabyRequires cookie*
 Title    The Isolation and Characterization of Molecular Complexes Produced from the Reaction of Nitrophenols with Divalent Metal Oxinates  
 Abstract    The reaction of nitrophenols (picric acid, 2,6-dinitrophenol, and 2,4-dinitrophenol) with divalent metal oxinate (metal = Cu, Co, Ni, Mn, and Zn) produced a type of molecular complex, which comprises two molecules of the metal oxinate and one molecule of the nitrophenol. In the case of the Mg complex the ratio is 1:1. A definite charge-transfer band is detected for the Co(II) complex. A hydrogen bonding system 0I...H+...02 is suggested. This includes the proton of the nitrophenol and two oxygen atoms; each is related to a coordinated oxinate of two different metal oxinate molecules. Analytical and spectral evidence are in accordance with the tentatively suggested formulations. 
  Reference    Z. Naturforsch. 34b, 230—234 (1979); received July 31 1978 
  Published    1979 
  Keywords    Nitrophenols, Divalent Metal Oxinates, Molecular Complexes 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0230.pdf 
 Identifier    ZNB-1979-34b-0230 
 Volume    34 
3Author    Wolfgang KaimRequires cookie*
 Title    Zur Reaktion aromatischer Phosphanderivate mit Elektronen, III [1, 2] Phosphan-Borane, -Alane und -Gallane On the Reaction of Aromatic Phosphane Derivatives with Electrons, III [1, 2] Phosphane-Boranes, -Alanes, and -Gallanes  
 Abstract    The 1:2 molecular complexes formed from l,4-phenylenebis(dimethylphosphane) and boranes, trialkyl-aluminum and -gallium have been reduced by potassium in THF in the presence of a K + -complexing crown ether. The bis(borane) complex anion radicals proved to be quite persistent, whereas corresponding aluminum radical complexes could only be observed below 240 K. The bis(trimethylgallium) complex gave gallium metal on reduction with potassium. An ESR spectro-scopic comparison with the anion radicals of the free ligand, of corresponding chalcogenides, imines and phosphonium salts demonstrates negligible effects of P-complexation on the JI spin distribution but high sensitivity of the 31 P coupling constant towards coordination of electrophiles at the basic P(III) centers. 
  Reference    (Z. Naturforsch. 40b, 61—66 [1985]; eingegangen am 1. Oktober 1984) 
  Published    1985 
  Keywords    Molecular Complexes, Reduction, Anion Radicals, ESR Spectra 
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 TEI-XML for    default:Reihe_B/40/ZNB-1985-40b-0061.pdf 
 Identifier    ZNB-1985-40b-0061 
 Volume    40 
4Author    Kai-Udo Sewe, Roland ReichRequires cookie*
 Title    The Effect of Molecular Polarization on the Electrochromism of Carotenoids * II. Lutein-Chlorophyll Complexes: The Origin of the Field-Indicating Absorption-Change at 520 nm in the Membranes of Photosynthesis  
 Abstract    Electrochromic spectra of monolayers of carotenoids (lutein and ß -carotene) in contact with monolayers of chlorophylls and of pheophytin a are measured in thin capacitors. A specific inter­ action of one of the OH-groups of lutein with the Mg-atom of chlorophyll is found. The formation of this oriented complex accounts for the fact that a part of the electrochromic absorption-change of lutein depends linearly on the electric field strength, whereas for lutein alone only a smaller, quadratic electrochromism is found. In the preparation with chlorophyll a, the maximum of this linear electrochromism is located at shorter wavelengths (512 nm) than in the preparation with chlorophyll b (517 nm). The permanent field that has been postulated in photosynthetic membranes (to explain the linear dependence of the field-indicating absorption-changes of the carotenoids) may also be at­ tributed to such a complex formation with chlorophylls. Especially, the field-indicating absorption-change at 520 nm can now be attributed mainly to a lutein-chlorophyll b complex. The absorption-change at 520 nm, calculated according to this model from the present experiments in vitro, is of the same order of magnitude as observed in vivo. Furthermore, this model agrees with the hitherto unexplained observation that in chlorophyll-b-lacking mutants the absorption-change at 520 nm is smaller than in normal plants, and the maximum is located at shorter wavelengths. Besites, it is concluded that lutein is mainly located in the regions of photosystem II. The contributions of the other carotenoids (especially of neoxanthin) to the spectrum of the field-indicating absorption-changes are also discussed. From the above model, some conclusions are drawn on the asymmetrical arrangement of the different pigments in the membrane of photosynthesis: The bulk chlorophyll molecules that serve as complex partners for the carotenoids should be located near to the inner surface of the thylakoid membrane, and the carotenoids attached to these chlorophylls should be located more to the out­ side. The phytol chain of a chlorophyll molecule should form an acute angle with the plane of the porphyrin ring. 
  Reference    (Z. Naturforsch. 32c, 161—171 [1977]; received January 20 1977) 
  Published    1977 
  Keywords    Electrochromism, Carotenoids, Molecular Complexes, Biological Membranes, Photosynthesis 
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 TEI-XML for    default:Reihe_C/32/ZNC-1977-32c-0161.pdf 
 Identifier    ZNC-1977-32c-0161 
 Volume    32 
5Author    Ming-Ta Sung, JohnA. ParkerRequires cookie*
 Title    Molecular Complexes between Methoxyamphetamines and Riboflavin Derivatives  
 Abstract    Molecular complexes in the ratio 1:1 were formed in aqueous solution between various methoxy-substituted phenylisopropylamine (amphetamine) hydrochloride or oxalate salts and riboflavin deri­ vatives (flavin mononucleotide and flavin adenine dinucleotide). The association constants for these complexes were determined by the fluorescence quenching method as well as by the absorption method. The nature of the complex formation may be due to charge-transfer, electron-transfer, electrostatic and hydrophobic forces. The steric effect also plays an important role in the complex formation. The absorption wavelength and association constant of the complexes are correlated with the published biological activities of the methoxyamphetamines. 
  Reference    (Z. Naturforsch. 29c, 122 [1974]; received September 5/November 11 1973) 
  Published    1974 
  Keywords    Riboflavin Derivatives, Association Constant, Hallucinogenic Activity, Molecular Complexes, Methoxyamphetamines 
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 TEI-XML for    default:Reihe_C/29/ZNC-1974-29c-0122.pdf 
 Identifier    ZNC-1974-29c-0122 
 Volume    29