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2001 (1)
1995 (1)
1Author    TeresaE. Krai, Janina Kuczera, Stanislaw Przestalski, TeresaE. KraiRequires cookie*
 Title    Organometallics and Quaternary Ammonium Salts Affect Calcium Ion Desorption from Lecithin Liposome Membranes  
 Abstract    The objective of the present work was to compare the effects of groups o f tin and lead organometallic com pounds and their mixtures with amphiphilic quaternary ammonium salts (Q A S) on the process of calcium ion desorption from lecithin liposom e membranes, as de­ pendent on the properties of the hydrophilic and hydrophobic parts o f QAS. In the investiga­ tions the method of radioactive labels was applied. Synergism and antagonism in the action of both groups o f compounds were found. The effectiveness o f the cooperation depended more on chain length o f Q A S compounds than on the size and polarity of their hydrophobic parts. The most effective of all compounds studied was a the mixture of benzyldimethylam-monium chloride in a mixture with tripropyltin. Since the rate of calcium desorption proved to be a good measure o f efficacy of biologically active surfactants, it seem s that the conclu­ sions reached in this paper may be useful for choosing compounds which are able to decon­ taminate the environm ent polluted with heavy metals. 
  Reference    Z. Naturforsch. 56c, 395 (2001); received September 7 2000/January 26 2001 
  Published    2001 
  Keywords    Organometallics, Quaternary Ammonium Salts, Cooperative Effect 
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 TEI-XML for    default:Reihe_C/56/ZNC-2001-56c-0395.pdf 
 Identifier    ZNC-2001-56c-0395 
 Volume    56 
2Author    C. P., R. S. Tu D, Wolfgang Baumann, Yuri Oprunenko, Harald GüntherRequires cookie*
 Abstract    y n a m ic B e h a v io u r o f T e tra m e th y le th y le n e D ia m in e (T M E D A) L ig a n d s in S o lid O r g a n o lith iu m C o m p o u n d s : A V a r ia b le T e m p e r a tu r e 13C a n d 15N Dedicated to Professor Dr. W . Müller-Warmuth on the occasion of his 65th birthday The dynamic behaviour of tetramethylethylene diamine (TMEDA) ligands in three organometallic complexes, dimeric phenyllithium, [Li(tmeda)/*-Ph]2 (1), lithium cyclopentadienide, [Li(tmeda)]C5H5 (2), and dilithium naphthalendiide, trans-[Li(tmeda)]2C10H8 (3), has been studied by CP/MAS 13C and 15N as well as 7Li MAS NMR spectroscopy of powdered samples. Two dynamic processes with free activation enthalpies of 40 and 68 kJ mol-1, respectively, were detected for 1. The first one can be assigned to ring inversion of the five-membered Li-TMEDA rings, while the second is caused by a complete rotation of the TMEDA ligands or a ring inversion of the central four-membered C-Li-C-Li metallacycle. Fast rotation of the ligands on the NMR time scale was found for 2, while 3 shows 180° ring flips of the Li-TMEDA groups, which are characterized by an energy barrier AG" (317) of 64 kJ mol-1. 
  Reference    Z. Naturforsch. 50a, 429—438 (1995); received November 8 1994 
  Published    1995 
  Keywords    CP/MAS NMR, 13C-NMR, 15N-NMR, 7Li NMR, dynamic processes, organometallics 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0429.pdf 
 Identifier    ZNA-1995-50a-0429 
 Volume    50