Synthesis and characterization of lanthanoid complexes with 3, 3′-[(4-bromophenyl)methylene]bis (4-hydroxy-2h-1-benzopyrane-2-one)

Complexes of coumarin derivate 3, 3'-[(4-bromophenyl) methylene] bis-(4-hydroxy-2H-1-benzopyrane-2-one), with some lanthanoid ions Ln(III) = La(III), Nd(III), Eu(III), Gd(III), and Tb(III) were synthesized. The complexes obtained were characterized by means of elemental analysis, IR spectroscopy, UV-Vis spectroscopy, fluorescence spectroscopy and microscopy. The spectral data of the synthesized complexes were interpreted on the basis of comparison with the spectra of the free ligand in order to determine the mode of coordination in the complexes. Results from the IR spectra suggested that the coordination is through the carbonyl oxygen atom as well as through the deprotonated hydroxyl group. The complexes possess optical properties shown by their absorption in the UV/Vis region. The excitation and emission spectra of Tb(III) complex were taken in solid state. The lifetime of the excited state was measured.