Synthesis, characterization and antibacterial studies of macrocyclic schiff base derived from malonic acid and o-phenylenediamine and its Cd (II), Co (II), Cu (II), Ni (II), and Zn (II) comlplexes

Abstract

The condensation of Malonic acid with o-phenylenediamine have yielded the Schiff Base 7,16-dihydrodibenzo[1,4,8,11]tetraazacyclotetradecine-6,8,15,17-tetraol (89.39%). Its metal (II) complexes were prepared from the chloride salts of Cd²⁺, Co²⁺, Cu²⁺, Ni²⁺ and Zn²⁺. Solubility, melting/decomposition temperature, FT-IR, molar conductance and magnetic moments were used to determine the ligands and its complexes. The FT-IR result indicates a band at 1633cm^-1 which corresponds to azomethine and confirms the formation of the ligand. There was a bathochromic shift in the peak to 1607cm^-1, 1596cm^-1, 1611cm^-1, 1573cm^-1 and 1566cm^-1 in the spectra of Cd²⁺, Co²⁺, Cu²⁺, Ni²⁺ and Zn²⁺ complexes respectively which is attributed to the binding of the nitrogen of azomethine to the metal ions. The compounds were tested for their antibacterial activity against Staphylococcus aureus and Escherichia coli using agar cup-plate method. The ligand and its complexes were found to be active against both Staphylococcus aureus and Escherichia coli. The Ni (II) complex displayed an enhanced activity with the highest zone of inhibition (45mm).

Keywords: Synthesis, Characterization, Ligand, Complexes, Antibacterial