Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/21090
Title: Template synthesis of 1-(8'-amino-α-naphthyl)-4-(8 '-amino-α-naphthylanline)- 1-azabuta-1,3-diene, a tetraaza half-cyclised ligand, and characterisation of its copper(II) complexes
Authors: Lewis, Nita A
Tocher, Derek A
Patra, Goutam K
Naskar, Jnan P
Datta, Dipankar
Issue Date: Apr-2000
Publisher: NISCAIR-CSIR, India
Abstract: Reaction of 1,1,3,3-tetramethoxypropane with 1,8-diaminonaphthalene in presence of a nickel(II) template in aqueous medium generates the free acyclic ligand 1-(8'-amino-α-naphthyl)-4-(8'-amino-α-naphthylamine)-1-azabuta-1,3-diene (LH; H: dissociable proton) as a 1.5 hydrate. The ligand undergoes acid dissociation in non-aqueous solvents which is reflected in its 13C NMR spectrum in deuteriated dimethyl sulphexide (DMSO). Its pKa value determined in DMSO from conductivity data is 5.18. With copper(II) perchlorate, LH forms air sensitive complexes of type CuL(ClO4).3H2O and CuL(ClO4).DMF (DMF: dimethylformamide). In both the complexes, the perchlorate anion is weakly bound to the metal as revealed by their conductivity in DMF suggesting a CuN4O2+ chromophore. Their EPR spectra in DMF-toluene glass at 77 K are almost identical and have rhombic features (3>, 2.40; 2>, 2.08; 1>, 2.01; <A3>, 137×10-4 cm-1; <A2>, 18×10-4 cm-1) indicating that the coordination sphere around the copper ion is of distorted square-pyramidal type. ZINDO calculations show that the CuL+ fragment has a butterfly like shape with the naphthalene fragments spanning like two wings and the metal in the N4 plane. In cyclic voltammetric experiments in DMF at a platinum electrode, the complexes show a quasireversible two-electron ligand oxidation with an E1/2 of 0.12V vs saturated calomel electrode (SCE) and a irreversible metal oxidation process at a low potential (< 0.5 V vs SCE).
Page(s): 400-406
URI: http://hdl.handle.net/123456789/21090
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.39A(04) [April 2000]

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