A new macrocyclic Schiff-base ligand, L, was synthesized by condensation reaction of 1,4-bis(2-formylphenyl) homopiperazine and 1,3-diaminopropane in acetonitrile. The Schiff-base ligand was characterized by using elemental analyses, IR, and mass spectroscopic techniques. Four new Ni(II), Cu(II), Co(II) and Zn(II) complexes of ligand, [NiLCl]ClO4, [CuLCl](ClO4), [CoLCl]ClO4 and [ZnLCl]ClO4 were prepared and characterized by elemental analyses and IR spectroscopy. X-ray crystal structure of [ZnLCl]ClO4 showed that the complex contains Zn(II) in a distorted square pyramidal geometry with a N4Cl core. In addition, structural parameters, vibration frequencies, frontier molecular orbitals (FMOs), UV bands and biological activity ranking of mentioned complexes are investigated as theoretically for all complexes. Computational studies of the relevant complexes are performed with the aid of density functional theory (DFT). (C) 2015 Elsevier B.V. All rights reserved.