EHPG与铝(Ⅲ)结合的光谱研究

The Spectroscopic Studies on the Binding of Al(Ⅲ) to EHPG

在 pH 7 4 ,0 1mol·L- 1 N 2 羟乙基哌嗪 N′ 2 乙磺酸 (Hepes)及室温条件下 ,使用紫外吸收差光谱和荧光光谱进行了铝 (Ⅲ )对N ,N′ 乙烯 二 [2 (2 羟基苯基 )苷氨酸 ](EHPG)的滴定。结果表明铝 (Ⅲ )与EH PG形成 1∶1的配合物。铝 (Ⅲ )与EHPG结合后其紫外差光谱在 2 35和 2 91nm处出现吸收峰 ;配合物在 2 35nm的摩尔吸光系数是 1 2 7× 10 4 cm- 1 ·mol- 1 ·L ;条件稳定常数是lgK =14 2 0± 0 0 3;铝 (Ⅲ )对EHPG的荧光猝灭是由于EHPG的酚羟基质子解离并与铝 (Ⅲ )配合而引起的。

Interaction of ethylene N,N′ bis(o hydioxyphenylglycine) (EHPG) with Al 3+ has been investigated by both UV difference and fluorescent spectra.Both results show that the molar ration of the complex is most likely 1∶1.Aluminum binding produces peaks at 235 and 291 nm.The molar absorptivity of aluminum ions to EHPG at 235 nm is 1 27×10 4 cm -1 ·mol -1 ·L.The conditional stability constant for Al 3+ binding to EHPG is determined to be lg K =14 20±0 03 in 0 1 mol·L -1 Hepes buffer at room temperature,pH 7 4 by UV difference spectra.At the same condition,the fluorescent intensity of EHPG at 310 nm has been monitored.In result,the fluorescent intensity of EHPG at 310 nm is decreased with the addition of Al 3+ .Then the quench of the fluorescent intensity is ascribed to deprotonated phenolic groups coordinated to aluminum ions.