Design Synthesis and Insilico Study of Some 8 Hydroxyquinoline Based Multidentate Chelators

Abstract

The present research of the dissertation describes the design, synthesis and complexation behaviour of three new 8-hydroxyquinoline-based tripodal ligands with some trivalent Metal ions. The three novel newlinetripodal multidentate chelators developed are: (TACH2OX, L1), (TACH2COX, L2), and (TREN2OX, L3) have been characterized. newline newlineThe resulting tripods have been characterized by melting point, elemental analysis, FT- IR, NMR ( 1H and 13C), electrospray mass spectrometry and Density Functional Theory study. The solution thermodynamic stability of these ligands was studied and determined by potentiometric, and UV-Visible spectrophotometric titration methods. To evaluate the acid-base properties, protonation constants of these synthesized ligands were evaluated. Six protonation constants were obtained with formation constants ranging 1.22-9.91, 1.35-10.34 and 1.50 -9.86 for L1, L2 and L3 respectively. newline newlineThe photophysical studies of these ligands by absorption and emission spectrophotometry reveal that the pH- dependent properties arise due to the formation of protonated quinolinium and deprotonated quinolinate forms of the 8-HQ moiety, respectively. This renders these compounds the special OFF-ON-OFF type of pH-dependent fluorescent sensors. Complexation in solution, thermodynamic and photophysical properties of the ligands with trivalent transition metal ion (Fe3+), two with main group metal ions (Al3+ and Ga3+) and five lanthanide ions (La3+, Eu3+, Gd3+, Tb3+ and Lu3+) are described. newline newlineThe present work also explores the theoretical investigations carried out to predict the structure, electronic properties and binding efficiency of the ligands and their corresponding metal complexes using density functional theory (DFT) along with the comparative studies with the experimental results. newline