- Studies on biologically potent tetraazamacrocyclic complexes of bivalent tin
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Fourteen- to eighteen-membered tetraamide macrocyclic ligands N4L1-N4L4 have been prepared by the condensation of 1,2-diaminoethane or 1,3-diaminopropane with malonic or succinic acid in the presence of condensing reagents dicyclohexylcarbodiimide and 4-dimethylaminopyridine. On reduction, these macrocyclic ligands give a new series of tetraazamacrocycles MacL1-MacL4 which form complexes with tin(II) chloride. The ligands and their complexes were characterized by elemental analyses, molecular weight determinations, infrared and 1H NMR spectral studies. The hexacoordinated state for tin has been confirmed by spectral studies. An octahedral geometry for these complexes has been proposed as the binding sites are the nitrogen atoms of the macrocycles. On the basis of the chemical composition the representation of the complexes as [Sn(MacLn)Cl2] (n = 1-4) has been established. The ligands and their complexes also have been screened for their antifungal and antibacterial activities and the findings have been reported and explained.
- Chaudhary, Ashu,Singh
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p. 615 - 626
(2007/10/03)
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- Studies on the interaction of iron(II), nickel(II), copper(II) and zinc(II) with tetraazamacrocycles
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The condensation of aliphatic diamines H2N(CH2)nNH2 (n = 2-3) with dicarboxylic acid HOOC - (CH2)n - COOH (n=1-2) in the presence of dicyclohexyl-carbodiimide and 4-(dimethylamino)pyridine results in new types of 14-18 membered tetraamide macrocyclic ligands 1a-1d. These compounds on reduction with LiAlH4 yield a series of tetraazamacrocycles 2a-2d which form complexes with Fe(II), Ni(II), Cu(II) and Zn(II). The ligands and their complexes have been characterized by elemental analyses, mass, IR, 1H NMR, UV/Vis, EPR spectroscopic, molar conductance and magnetic moment data. An octahedral geometry around the metal ion is suggested for [M2aCl2][M2dCl2], where M = Fe(II) and Ni(II) while a square-planar and a tetrahedral geometry is proposed for [M2a]Cl2-[M2d]Cl2 for M = Cu(II) and Zn(II).
- Shakir, Mohammad,Varkey, Saji P.,Nasman, Omar S. M.
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p. 671 - 676
(2007/10/03)
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- Triflamides for protection and cyclization of tetraamines to tetraazamacrocycles
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A facile two-step synthesis of tetraazamacrocycles is reported starting from trifluoromethanesulfonyl derivatives of linear tetraamines. After cyclization, the macrocycle was deprotected using sodium in liquid ammonia.
- Panetta,Yaouanc,Handel
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p. 5505 - 5508
(2007/10/02)
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