乙醇酸与铀酰的配位化学研究  

Coordination Chemistry of Glycolic Acid and Uranyl

作　　者：曾德丽 柳倩 杨琪 李佳乐 浦曈凯 杨素亮[1] 田国新[1,2] ZENG Deli;LIU Qian;YANG Qi;LI Jiale;PU Tongkai;YANG Suliang;TIAN Guoxin(China Institute of Atomic Energy,Beijing 102413,China;Tsinghua University,Beijng 100084,China)

机构地区：[1]中国原子能科学研究院,北京102413 [2]清华大学,北京100084

出　　处：《原子能科学技术》2025年第3期532-539,共8页Atomic Energy Science and Technology

摘　　要：乙醇酸(α-羟基乙酸,HA)是一种简单的水溶性羧酸配体,可通过羧基氧原子和羟基氧原子与金属离子配位。本文通过电位滴定、吸收光谱和拉曼光谱技术研究了乙醇酸与铀酰在水溶液中的配位化学。结果表明,在pH<5的水溶液中,乙醇酸与铀酰可形成5种不同的配合物。采用电位滴定和吸收光谱技术测定了配合物的稳定常数,并获得了它们的摩尔吸收光谱。通过拉曼光谱推测了配合物中乙醇酸的配位模式:配合物(UO_(2)A)+和UO_(2)A_(2)中乙醇酸根通过1个羧基氧原子和羟基氧原子与铀酰形成五元环螯合结构;配合物(UO_(2)A_(3))^(-)中2个配体以五元环配位,第3个配体通过羧基的2个氧原子以四元环配位;配合物(UO_(2)A_(3))^(-)中以五元环配位的2个乙醇酸根羟基上的氢原子依次发生解离,生成配合物(UO_(2)A3H-1)2-和(UO_(2)A_(3)H-2)^(3-)。Glycolic acid(α-hydroxyacetic acid,HA)is a simple,water-soluble carboxylic acid ligand commonly found in the environment.It can coordinate with metal ions through both its carboxyl and hydroxyl oxygen atoms.The complexation of uranyl ions with HA has been investigated using potentiometry,absorption spectroscopy and Raman spectroscopy.Five complex species were identified:(UO_(2)A)+,UO_(2)A_(2),(UO_(2)A_(3))^(-),(UO_(2)A_(3)H-1)2-and(UO_(2)A_(3)H-2)3-.Their stability constants were determined through potentiometric and absorption spectroscopic methods,and the coordination modes of HA were elucidated using Raman spectroscopy in aqueous solutions with pH<5.For the first three species(UO_(2)A)+,UO_(2)A_(2)and(UO_(2)A_(3))^(-),the stability constants measured by potentiometry are 2.36±0.09,4.02±0.01 and 5.33±0.27 respectively,which are consistent with the results that calculated from absorption spectroscopy and previous reports.The latter two species,(UO_(2)A_(3)H-1)2-and(UO_(2)A_(3)H-2)3-,are reported here for the first time,with stability constants determined by potentiometry as 1.66±0.05 and-3.11±0.06,respectively.The molar absorption spectra of the five complexes were obtained using absorption spectroscopy.The spectra of the first three species are quite similar,while the characteristic peaks of uranyl in the latter two species are nearly absent.This indicates that the dissociation of hydrogen atoms from the hydroxyl groups of glycolic acid significantly affects the uranyl absorption spectra.Raman spectroscopy was used to infer the coordination modes of glycolic acid in the complexes.The Raman shift peaks for UO^(2+)_(2),(UO_(2)A)+,UO_(2)A_(2)and(UO_(2)A_(3))^(-)were found at 869,858.7,848.4,and 843.3 cm-1,respectively.According to the empirical relationship between the Raman shift of the uranyl group and ligand ability(i.e.a larger Raman shift corresponds to a stronger ligand ability),in the(UO_(2)A)+and UO_(2)A_(2),glycolate forms a five-membered ring chelate with uranyl through both a carboxyl and a hydrox

关 键 词：乙醇酸 铀酰 配合物组成和结构 电位滴定 吸收光谱 拉曼光谱 

分 类 号：TL99[核科学技术—核技术及应用] O65[理学—分析化学]