Synthesis, characterization, thermal degradation and urease inhibitory studies of the new hydrazide based Schiff base ligand 2-(2-hydroxyphenyl)-3-{[(E)-(2-hydroxyphenyl)methylidene]amino}-2,3-dihydroquinazolin-4(1H)-one

The novel Schiff base ligand 2-(2-hydroxyphenyl)-3-{[(E)-(2-hydroxyphenyl)methylidene]amino}- 2,3-dihydroquinazolin-4(1H)-one (H-HHAQ) derived from 2-aminobenzhydrazide was synthesized and characterized by elemental analyses, ES+-MS, 1H and C-13{H-1}-NMR, and IR studies. The characterization of the ligand was further confirmed by single crystal analysis. The Schiff base ligand was complexed with metal ions like Co(II), Ni(II), Cu(II) and Zn(II) to obtain the bis-octahedral complexes. The ligand and its metal complexes were also studied for their urease inhibitory activities. All the tested compounds show medium to moderate activities for the enzyme, whereas the copper based complex was found to be much more active against urease with an IC50 = 0.3 +/- 0.1 mu M +/- SEM, which is even more potent than the standard thiourea. The IC50 of the cobalt complex was 43.4 +/- 1.2 mu M +/- SEM, whereas that of the nickel complex was 294.2 +/- 5.0 mu M +/- SEM. The ligand H-HHAQ and the zinc complex were inactive against the tested enzyme.