A Potentiometric Investigation of Complex Formation between Some Metal Ions and Biologically Active Quinazoline-4-3(H)-one Schiff’s Base

The proton dissociation constant of the ligand and the stability of the complexes of Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Cu(II), Ba(II), Mg(II), Mn(II), Th(IV), and UO2(II) ions with 2-phenyl-3-(2'- hydroxy-5'-benzylidine)-quinazoline-4-(3H)-one [PBQ] were determined potentiometrically at $30 \pm 0.1 ^\circ C$ and ionic strengths of 0.025, 0.05, 0.10, 0.15 and 0.20 M $NaNO_3$ in a 60:40 (v/v) ethanol-water medium. The pro-ton–ligand and metal–ligand stability constants of the complexes were determined pH metrically by the Calvin–Bjerrum titration technique. The order of stability constants obeys the Irving–Rossotti rule. The negative values of $\Delta G ^ \circ$ suggest that the reactions are spontaneous

Synthesis, spectral characterization and biological activity of benzofuran Schiff bases with Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes

New Schiff bases have been synthesized from benzofuran-2-carbohydrazide and benzaldehyde,[BPMC] or 3,4-dimethoxybenzaldehyde, [BDMeOPMC]; complexes of the type $MLX_2$,where M=Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), L=BPMC or BDMeOPMC and X = Cl, have been prepared. Structures have been elucidated on the basis of elemental analysis, conductance measurements, magnetic properties, spectral studies i.e., $^1H$ NMR, electronic, ESR and IR studies show that the Schiff bases are bidentate through the azomethine nitrogen and oxygen of the carbonyl. We propose tentative structures for all of these complexes. The antifungal and antibacterial activities of the ligands and their metal complexes have been screened against fungi Aspergillus niger and Aspergillus fumigatus and against bacteria Escherichia coli and S. aurious

Synthesis and spectroscopic characterization of metal complexes with naphthofuran-2-carbohydrazide Schiff's base

Two Schiff-base ligands (I) naphthofuro-[phenylmethine] carbohydrazone [NPMC] and (II) naphthofruo-[3,4-dimethoxyphenylmethine]carbohydrazone [NDMeOPMC] were prepared by reaction between naphthofuran-2-carbohydrazone and benzaldehyde or 3,4-dihydroxybenzaldehyde, respectively. Both ligands are bidentate by coordinating through carboxy oxygen and azomethine nitrogen atoms. Complexes of the type $MLX_n$ were obtained. where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), $UO_2(II)$ and Th(IV), L = [NPMC] or [NDMeOPMC] and X = $Cl_2$ for Co(II), Cu(II), Ni(II), Zn(II), Cd(II) and Hg(II) complexes, X = $NO_3$, n = 2 for $UO_2(II)$ complexes and X = $NO_3$, n = 4 for Th(IV) complexes. All the complexes and ligands were characterized IR, electronic, $^1H$ NMR, ESR, conductance data and magnetic susceptibility measurements

1,3-Bis(4-methoxyphenyl)thiourea

In the crystal structure of the title compound, C_1_5H_1_6N_2O_2S, the The C=S group lies on a mirror plane. The molecules are packed in a centrosymmetric manner through intermolecular $N-H\cdot\cdot\cdot{S}$ hydrogen bonds