Synthesis and fluorescence properties of Tb(III) complex with a novel β-diketone ligand as well as spectroscopic studies on the interaction between Tb(III) complex and bovine serum albumin

A novel aromatic β-diketone ligand, 4-isopropyl-2,6-bisbenzoylactyl pyridine (L), and its corresponding Tb(III) complex Tb2(L)3·5H2O were synthesised in this paper. The ligand was characterized by FT-IR and 1H NMR. The complex was characterized with elemental analysis and FT-IR. The investigation of fluorescence property of the complex showed that the Tb(III) ion could be sensitized efficiently by the ligand. Furthermore, the interaction of Tb2(L)3·5H2O with bovine serum albumin (BSA) has been investigated by fluorescence quenching spectra, UV–vis absorbance and synchronous fluorescence spectra. The fluorescence quenching mechanism of BSA by Tb2(L)3·5H2O was analyzed. The binding constants, binding site number and the corresponding thermodynamic parameters at different temperatures were calculated. The results indicated that the Van der Waals and hydrogen bond interactions were the predominant intermolecular forces in stabilizing the complex. Moreover, the effect of Tb2(L)3·5H2O on the conformation of BSA was analyzed according to synchronous fluorescence.