Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2‐(2,4‐dichlorobenzamido)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide ( LH ₃ ) have been synthesized and characterized using various physico‐chemical, spectroscopic and single crystal X‐ray diffraction techniques. Structural studies of [Co( LH )( LH ₂ )]·H₂O ( 4 ) revealed the presence of both amido and imidol tautomeric forms of LH ₃ , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni( LH )(H₂O)]·H₂O ( 5 ) and [Cu( LH )(H₂O)]·H₂O ( 6 ) are isomorphous structures and crystallize in the monoclinic P2₁/c space group. The crystal structures of 4 , 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C‐H···π and π···π interactions. Complexes along with the ligand ( LH ₃ ) were screened for their in vivo anti‐inflammatory activity (carrageenan‐induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti‐inflammatory and antioxidant potential.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of tridentate di‐tert‐butylphenylhydrazone: Synthesis,characterization, X‐ray crystal structures,Hirshfeld surface analysis,molecular docking and in vivo anti‐inflammatory activity

A new hydrazone (LH₂) derived from the condensation of 2‐(4‐fluorobenzamido)benzohydrazide with 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde was used to synthesize Co(III), Ni(II) and Cu(II) complexes. These were characterized using various physicochemical, thermal, spectroscopic and single‐crystal X‐ray diffraction techniques. All the complexes crystallize in a monoclinic crystal system with P2₁/n space group and Z = 4. Structural studies of [Co(L)(LH)]?H₂O indicate the presence of both amido and imidol tautomeric forms of the ligand, resulting in a distorted octahedral geometry around the Co(III) ion. On the other hand, in the [Ni(L)(DMF)] and [Cu(L)(H₂O)] complexes, the ligand coordinates to the metal through imidol form resulting in distorted square planar geometry, in which the fourth position is occupied by the oxygen of coordinated DMF in [Ni(L)(DMF)] and by a water molecule in [Cu(L)(H₂O)]. Hirshfeld surface calculations were performed to explore hydrogen bonding and C―H???π interactions. Molecular docking studies were carried out to study the interaction between the synthesized compounds and proteins (cyclooxygenase‐2 and 5‐lipoxygenase). The complexes along with the parent ligand were screened for their in vivo anti‐inflammatory activity, using the carrageenan‐induced rat paw oedema method. The complexes show significant anti‐inflammatory potencies.     

Synthesis,structural characterization and biological evaluation of mononuclear transition metal complexes of zwitterionic dehydroacetic acid N‐aroylhydrazone ligand

Synthesis and characterization of mononuclear transition metal complexes viz., Co(II), Ni(II), Cu(II) and Zn(II) with a newly designed ligand, (E)‐2‐benzamido‐N'‐(1‐(2‐hydroxy‐6‐methyl‐4‐oxo‐4H‐pyran‐3‐yl) ethylidene) benzohydrazide ( H ₂ L ) are reported. Molecular structures of H ₂ L , Ni(II) and Cu(II) complexes were determined by single‐crystal X‐ray diffraction studies. The structures were stabilized by various intra/inter‐molecular H‐bonding, C‐H···π and π···π stacking interactions. H ₂ L exists in zwitterionic form and acts in a monoanionic manner. Ligand/metal ratio was 2:1 for cobalt, nickel and zinc, whereas 1:1 for the copper complex. Co(II), Ni(II) and Zn(II) complexes display distorted octahedral geometry, while the Cu(II) complex shows distorted square pyramidal geometry around the metal ion. Hirshfeld surface analysis and 2D fingerprint plots revealed that H ₂ L and its complexes were supported mainly by H?H, O?H and C?H intermolecular interactions. The synthesized compounds were screened for in vitro anti‐inflammatory activity by gelatin zymography and the activity was comparable with tetracycline. Their cleavage behavior towards calf thymus DNA has been studied using agarose gel electrophoresis method. H ₂ L and Cu(II) complex were selected by National Cancer Institute (NCI) for in vitro single dose testing in the full NCI 60 cell lines panel assay. Finally, molecular docking simulation effectively proves the binding of all the synthesized compounds at cyclooxygenase‐2 (COX‐2) active sites.     

Transition metal complexes of a hydrazone derived from hydralazine hydrochloride and 3,5-di-tert-butylsalicylaldehyde

Mononuclear Co(III), Ni(II) and Cu(II) coordination compounds of (E)-1-(3,5-di-tert-butyl-2-hydroxybenzylidene)-2-(phthalazin-1-yl)hydrazine (LH) were prepared and characterized by physicochemical and spectroscopic methods. The metal-to-ligand ratio was found to be 1:2 in [Co(L)₂]Cl·2H₂O (1) and [Ni(L)₂]·2H₂O (2), while it is 1:1 in [Cu(L)Cl]·2CH₃OH (3). The X-ray crystal structures of LH and complex 1 is are reported. LH shows monobasic behavior, coordinating through NNO donor atoms. The complexes were investigated for their antimicrobial properties. Complexes 1 and 3 show excellent antibacterial and antifungal activities, respectively.