%A WANG Jin-ling;BI He-ping;YANG Bin-sheng* %T Determination on Conditional Equilibrium Constants of the Complexes of Gd(Ⅲ) and Yb(Ⅲ) with HBED by UV Difference Spectra %0 Journal Article %D 2005 %J SPECTROSCOPY AND SPECTRAL ANALYSIS %R %P 89-91 %V 25 %N 01 %U {https://www.gpxygpfx.com/CN/abstract/article_3558.shtml} %8 2005-01-26 %X In 0.01 mol·L-1 Hepes, pH 7.4 and at room temperature the binding of HBED with Gd(Ⅲ) or Yb(Ⅲ) was monitored by UV difference spectrum. The results show that the molar ratio of the complexes is most likely 1∶1. Gd-HBED or Yb-HBED complex produced peaks at 237 nm and 291 nm. The molar absorptivities of Gd-HBED and Yb-HBED at 237 nm are ΔεGd= (22.52±0.20)×103 cm-1·mol-1·L, ΔεYb=(27.15±0.11)×103 cm-1·mol-1·L, respectively. The conditional equilibrium constants for the complexes were measured to be lgKGd-HBED=13.56±0.28 and lgKYb-HBED=16.06±0.03. A linear free energy relationship for the complexes of Yb(Ⅲ) and Gd(Ⅲ) has been established by using equilibrium data on 18 complexes. The HBED binding constants for Yb(Ⅲ) and Gd (Ⅲ) are in agreement with the linear free energy relationship.