Mn(Ⅱ)与EHPG结合的光谱研究

Spectroscopic Study on the Binding of Mn(Ⅱ) to EHPG

在pH7.4,0.05mol·L-1N-2-羟乙基哌嗪-N’-2-乙磺酸(Hepes)及室温条件下,用荧光光谱和紫外吸收差光谱进行了Mn(Ⅱ)与N,N’-乙烯-二[2-(2-羟基苯基)甘氨酸](EHPG)相互作用的研究。结果表明,Mn(Ⅱ)对EHPG荧光的猝灭为静态猝灭,Mn(Ⅱ)与EHPG形成1∶1的配合物,条件解离常数KD为1.43×10-5。紫外吸收差光谱表明,随着Mn(Ⅱ)的不断滴加其紫外差光谱在238和291nm处吸收峰逐渐增强。经计算配合物的ε238nm为(1.31±0.02)×104cm-1.mol-1·L,条件解离常数KD为(1.36±0.21)×10-5。与荧光光谱结果一致且均表明Mn(Ⅱ)与EHPG结合比较弱。

Under the conditions of 0.05 mol · L^-1 Hepes buffer at room temperature and pH 7. 4, the interaction of ethylene-N, N＇-bis（o-hydioxyphenylglycine） （EHPG） and Mn（ Ⅱ ） was investigated by both fluorescence and UV difference spectra. Results showed that the molar ratio of the complex is 1 ： 1. With the addition of manganese ions, the fluorescence peak of EHPG at 310 nm decreased, while the peaks of UV absorptivity at 238 and 291 nm increased. The molar absorptivity of Mn（ II ） to EHPG at 238 nm is （1.31±0. 02） × 10^4 cm^-1 · mol^-1· L. The disassociation constant for Mn-EHPG was determined to be （1.36± 0. 21） × 10^-5. It can be concluded that the binding of Mn（ Ⅱ ） to EHPG is not a strongly binding reaction.