Synthesis and characterization of terbium(III) complexes with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one)

• Complexes of Tb(III) with 4-hydroxy-bis-coumarin derivative are synthesized.
• The optimized geometries of the ligand and the complexes are obtained.
• Triplet state of the mono-deprotonated ligand is determined.

Complexes of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) are synthesized by using a solution of tetraethylammonium hydroxide, [(C2H5)4N]OH, in water as deprotonating base. Elemental analysis, IR- and fluorescence spectroscopy are used to characterize the samples obtained. The complexes have good fluorescent properties and show the characteristic emission bands of the Tb(III) ion. The triplet state of the mono-deprotonated ligand H2L− was determined. The optimised geometries of the ligand and the complexes were obtained by means of molecular modelling with first principles (DFT) methods.

Optimised geometries of the complexes TbL10-1 (left), TbL10-2 (centre), TbL10-3 (right) revealing the depletion and growing inhomogeneity of the coordination environment. Colour code: Tb – cyan; O – red; C – grey; H – white; N – blue.Figure optionsDownload as PowerPoint slide