New multidentate ligands 1,4,7,9,12-pentaaza-10,11-dioxo-8,9,12,13-bis-(1_,3_-dioxo- 6,6-diethyl-2_-hydropyrimidine)-trideca-7,13-diene, (L1) and 1,4,7,9,13-pentaaza-10,12- dioxo-8,9,13,14-bis-(1_,3_-dioxo-6,6-diethyl-2_-hydropyrimidine)-tetradeca-7,14-diene (L2) have been prepared by the reaction of 5,5-diethylbarbituric acid, diethylenetriamine, diethyl oxalate and 5,5-diethylbarbituric acid, diethylenetriamine, diethyl malonate. Their coordination properties with the first row of transition metal ions have been explored. The macrocyclic complexes were characterized by elemental analysis, IR, 1H NMR, UV-visible spectroscopy, magnetic moment measurements and molar conductance measurements. The electronic spectra and magnetic moment measurements are discussed with respect to assignment of square planar and tetrahedral structure except chromium(III), iron(III) ions. The chromium(III) and iron(III) complexes are considered to be octahedral. Molar conductance measurements suggest that the complexes of divalent metal ions are 1:1 electrolytes, while the trivalent metal ions are nonelectrolytes. The compounds have been tested against gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Escherichia coli. The results show that all the compounds inhibit the growth of bacteria.