TEMPLATE SYNTHESIS AND CHARACTERIZATION OF LANTHANIDE(III) COMPLEXES OF 21-MEMBERED UNSYMMETRICAL PENTAAZA MACROCYCLIC SCHIFF BASES BEARING PENDANT ARM. IDENTICAL FRAME WORK: PART II

摘要

A series of discrete mononuclear lanthanide(III) complexes of H₂L₁ [Ln(H₂L₁)(NO₃)₂]NO₃.nH₂O (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Y; n = 1 for Ce; n = 2 for La, Sm, Gd and Y; n = 3 for Pr, Nd, Eu, and Tb) have been prepared by the condensation of Schiff-bases with the precursor compounds namely, 2,6-diformyl-4-methylphenol, 1,5-diamino-3-azamethypentane and 4,5-dimethyl-1,2-phenylenediamine. All the mononuclear complexes have been prepared in situ by the step-wise condensation from the precursor compounds. The phenolate oxygen atom of the nucleating ligand behaves as a bridging group between the metal. The complexes have been characterized by elemental analysis, IR, UV-Visible, ESI mass spectra and magnetic studies. The yield of these complexes increases from lighter lanthanides to heavier lanthanides. The fluorescence studies were carried out for europium and terbium complexes. The results of elemental analysis of the complexes are in good agreement with the theoretical values. The complexes are soluble in methanol, chloroform, DMF, DMSO, and CH₃CN. Conductivity studies reveal that all the complexes are 1:1 electrolytes.