Synthesis, spectral studies, thermal decomposition kinetics, reactivity and antibacterial activity of some lanthanide(III) nitrate complexes of 2-(N-indole-2-one) amino-3-carboxyethyl -4,5,6,7-tetrahydrobenzo[b] thiophene

Abstract

Complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Dy(III), Yb(III) and Lu(III) with 2-(N-indole-2-one)amino-3-carboxyethyl- 4,5,6,7-tetrahydrobenzo[b]thiophene formed by the condensation of isatin and 2-amino-3-carboxyethyl -4,5,6,7-tetrahydrobenzo[b]thiophene have been synthesized and characterized on the basis of elemental analysis, molar conductance measurements, magnetic susceptibility data and UV-vis, IR and NMR spectral studies. The spectral data reveal that the ligand acts as neutral tridentate coordinating to the metal ion through the azomethine nitrogen, ester carbonyl and carbonyl oxygen of the isatin moiety. Coordination number nine has been proposed for the complexes. The XRD pattern of the lanthanum(III) complex shows that the metal complex possesses tetragonal crystal lattice. The lanthanum(III) complex undergoes facile transesterification reaction when refluxed in methanol for a long period. Studies on antibacterial activity show that the complexes are more potent bactericides than the ligand.