Synthesis and characterization of 18-to 22-membered tetraazamacrocycles and their tin complexes

Abstract

The tetraamide macrocyclic ligands L¹-L⁴ have been prepared by the condensation of 1,2-diaminoethane or 1,3-diaminopropane with glutaric acid or adipic acid in the presence of condensing reagents dicyclohexylcarbodiimide and 4-dimethylaminopyridine. On reduction, these macrocyclic ligands give tetraazamacrocyclcs L⁵-L⁸, which form complexes with tin(II) chloride. The ligands and their complexes have been 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. The formulation of the complexes

[Sn(Lⁿ)Cl₂] has been established on the basis of chemical composition. The ligands and their complexes have also been screened for their antimicrobial activities.