Mononuclear late first row transition metal complexes of ONO donor hydrazone ligand: Synthesis, characterization, crystallographic insight, in vivo and in vitro antiinflammator activity

Air and moisture stable coordination compounds of late first row transition metal ions, viz., Co(II), Ni(II), Cu(II) and Zn(II) with a newly designed ligand, (E)-2-amino-N'-(1-(2-hydroxy-6- methyl-4-oxo-4H-pyran-3-yl)ethylidene)benzohydrazide (H2L) were prepared and extensively characterized using various spectro-analytical techniques. The ligand acts both in mono as well as doubly deprotonated manner. The ligand to metal stoichiometry was found to be 1:2 in case of complexes using chloride salts, whereas 1:1 in case of copper (II) complex using its acetate salt. The molecular structures of H2L, nickel and copper complexes were unambiguously determined by single-crystal X-ray diffraction studies reveal that H2L exists in a zwitterionic form while copper complex has copper centre in a distorted square planar environment. On the other hand, cobalt, nickel and zinc complexes display distorted octahedral coordination around the metal ion. In case of [Ni(HL)2].H2O, intramolecular C-H···π stacking interaction were observed between the centroid of five membered chelate ring and phenyl proton C(5)-H(5) and intermolecular CH ···π stacking interaction between the centroid of phenyl ring, dehydroacetic acid (DHA) ring and phenyl protons. The [Cu(L)DMF] complex is stabilized by intramolecular hydrogen bonding N(1)H···N(2) and by intermolecular hydrogen bonding N(1)H···O(4). Intermolecular interactions were investigated by Hirshfeld surfaces. Further, H2L and its metal complexes were screened for their in vivo and in vitro anti-inflammatory activities. The activity of the ligand has enhanced on coordination with transition metals. The tested compounds have shown excellent activity, which is almost equipotent to the standard used in the study

Synthesis, characterization and photophysical studies of zinc(II) complexes derived from a hydralazine hydrazone

In the present study, we report two novel mononuclear zinc(II) complexes (1 and 2) obtained by reacting (E)-1-(phenyl(pyridin-2-yl)methylene)-2-(phthalazin-1-yl)hydrazine (L) with ZnCl2 and Zn(NO3)(2)center dot 6H(2)O respectively. Photophysical properties of the compounds were studied in both solution and solid phase. The fluorescence absolute quantum yield of the complexes in solution varies in the order 1 (0.01) < 2 (0.030), on the other hand in the solid state it varies in the order 2(0.034) < 1(0.69). Quenching of fluorescence intensity of 2 in the solid-state has been attributed to intense and extensive non-covalent interactions present in the crystal structure. Theoretical calculations, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were also performed to support the experimental findings. (C) 2017 Elsevier B.V. All rights reserved