Quantitative Structure-Activity Relationship (QSAR) models, based on molecular descriptors, derived from molecular structures, have been used for the prediction for computed the Hepatic Cancer Cell lines HepG2 of flavonoids substituted. QSAR model including some molecular descriptors, regression quality indicates that these descriptors provide valuable information and have significant role in the assessment of the cytotoxicity of compounds under study. Four QSAR equations, for the prediction of cytotoxicity, have been drawn up by using the multiple regression technique, (Eqs 1-4) with the values of R 2 ranged from 0.767-0.797, Q 2 ranged from 0.765-0.796 and the values of S ranged from 7.051-7.391, while the values of F ranged from 9.328-10.354. The results have shown excellent model by Eq 4. with high R 2 ,F and minimum S by using eight parameters [Gm, nO, nH, nCIC, nBM, nAB, D.M and Ku], and have found and indicated that these parameters have significant role in determining the properties of cytotoxicity. This result encourages the application of QSAR to a wider selection of compounds properties.

Based on vanillin and diamine compounds (ortho phenylene diamine, meta phenylene diamine, 3,4- diamine toluene), derivation of two new Schiff base ligands (L1 and L2) was done, after which synthesis and treatment with Co (II) chloride was performed at a metal-to-ligand ratio of 1:1 to get two new complexes, i.e. [CoL3(H2O)2]Cl2 and [CoL1(H2O)2]Cl2. These complexes and ligands were characterized by employing NMR, IR, atomic absorption, UV visible absorption, molecular weight determination, molar conductance, and magnetic measurement techniques. As per the data, the ligands were found to be bidentate ligands that were linked to two azomethine nitrogen sites. It was suggested that these complexes were paramagnetic electrolyte compounds that possessed coordination number four. Screening of the ligands and metal complexes was done to assess their antimicrobial activities against gram-negative and gram-positive bacteria, which was found to show biological activity. Calculations using quantum chemistry were done to examine the molecule geometry. The investigation includes several quantum chemical characteristics derived from frontier molecular orbitals. Keywords: Schiff bases, transition metal complexes, vanillin, diamine aromatic compounds, antibacterial activity, DFT study.