Biological activity and spectral, magnetic and thermal studies of newer transition metal complexes of hydrazone derived from Dihydralazine and 2-formyl carvacrol

In the present work, we report a new series of cobalt(II), copper(II), zinc(II), manganese(II), and iron(II) complexes of hydrazone (H₂L) ligand synthesized from well-known drug molecule Dihydralazine and a 2-formyl derivative of naturally occurring monoterpenoid (carvacrol) by environment friendly method. The hydrazone behaves as a dibasic hexadentate ligand and dinuclear metal complexes with the general composition [M₂L(Cl)m(H₂O)]n (M = Co(II), Cu(II), Zn(II), Mn(II), and Fe(II); m = 1–2 and n = 0–4) were obtained by reaction of hydrazone (H₂L) and metal salts (MCl₂) in the presence of methanol as solvent. The nature of bonding and the stereochemistry of the desired complexes have been presumed from ESI–MS, FTIR, UV–Vis, elemental analyses, TGA, molar conductivity and magnetic susceptibility measurements. The results revealed that the ligand (H₂L) forms coordination bonds with central metal ions through nitrogens of phthalazine as well as azomethine (–C = N–) groups and phenolic oxygen atoms. The hydrazone base ligand (H₂L), and its metal complexes were evaluated for their in vitro anticancer activity against breast cancer cell line (MDA-MB-231). The anticancer screening results revealed that the compounds H₂L, 1, 3, and 5 have good activity.