Synthesis and characterization of polymer eight-coordinate (enH2)[YIII(pdta)(H2O)]2·10H2O as well as the interaction of [YIII(pdta)(H2O)]22− with BSA

The eight-coordinate (enH2)[YIII(pdta)(H2O)]2·10H2O (en = ethylenediamine and H4pdta = 1,3-propylenediamine-N,N,N′,N′-tetraacetic acid) was synthesized, meanwhile its molecular and crystal structures were determined by single-crystal X-ray diffraction technology. The interaction between [YIII(pdta)(H2O)]22− and bovine serum albumin (BSA) was investigated by UV-vis and fluorescence spectra. The results indicate that [YIII(pdta)(H2O)]22− quenched effectively the intrinsic fluorescence of BSA via a static quenching process with the binding constant (Ka) of the order of 104. Meanwhile, the binding and damaging sites to BSA molecules were also estimated by synchronous fluorescence. Results indicate that the hydrophobic environments around Trp and Tyr residues were all slightly changed. The thermodynamic parameters (ΔG = −25.20 kJ mol−1, ΔH = −26.57 kJ mol−1 and ΔS = −4.58 J mol−1 K−1) showed that the reaction was spontaneous and exothermic. What is more, both ΔH and ΔS were negative values indicated that hydrogen bond and Van der Waals forces were the predominant intermolecular forces between [YIII(pdta)(H2O)]22− and BSA.