基于多吡啶铁/钴配合物的雌激素非自由基型氧化降解机理

Environmental estrogens (EEs) are a kind of important endocrine disruptors. As EEs are low concentration, high toxic and difficult to degrade, they have been global concern. Though oxidative process based on free radical •OH could mineralize or degrade EEs fast, the degradation efficiency is still low due to low selectivity of •OH attack. In order to solve this problem, non-free-radical oxidation process to degrade estrogens based on iron/cobalt polypyridyl complexes is proposed. This method is based on metal-organic catalysis in which metal center is the active species. Through changing coordination environment of metal, the ability of oxidation of metal center will be adjusted and the selectivity will be enhanced. In this project, various iron and cobalt polypyridyl complexes are used as catalysts, H2O2 is used as oxidant and 17β-estradiol, 17α-estradiol and estriol are used as model substrates. Firstly, through characterizing and detecting products by electrochemical or spectum/chromatograph/mass methods, relationship of coordination environment with degradation efficiency of substrates is discussed and oxidized pathway and kinetic parameters are clearly resolved. Secondly, mechanism of estrogen degradation by iron or cobalt polypyridyl complexes is proposed using isotope labeling and mechanism probe method. Thirdly, homogeneous-heterogeneous hybrid systems are built to further increase the stability of complexes. The outcomes of this project will help develop the non-free-radical oxidation methods to degrade pollutants in environmental.

环境雌激素是一类重要的内分泌干扰素，其浓度低、毒性高、降解难，受到全世界广泛关注。传统的基于羟基自由基（•OH）的氧化过程，虽能快速矿化或降解环境雌激素，但选择性差，降解效率低。因此，本项目提出“基于多吡啶铁/钴配合物的雌激素非自由基型氧化降解方法”，该方法基于有机金属配合物催化，利用中心金属为活性物质，通过中心金属配位环境的改变来调控配合物的氧还能力及降解过程的选择性，可望克服传统自由基氧化技术的选择性差的技术难题。项目以多吡啶铁/钴配合物为催化剂，过氧化氢为氧化剂，17β-雌二醇、17α-雌二醇、雌三醇为模型底物，借助电化学、光谱/色谱/质谱、同位素标记、机理探针等手段，探讨配位环境与底物降解的关系，解析底物的降解途径及动力学参数，揭示多吡啶铁/钴配合物降解雌激素的机理过程，构建均相-异相体系以提高反应稳定性，为发展基于有机金属配合物的非自由基型氧化降解技术提供理论依据。

本项目以环境雌激素为目标底物，过氧化氢（H2O2）/过硫酸盐（PMS）为氧化剂，高稳定的桥连的十四烷基铁配合物（Fe-cyclam）为催化剂，围绕非自由基型的污染物降解过程，研究Fe-cyclam对氧化剂的活化过程及目标污染物的降解效应及机制。研究成果包括：（1）构建了Fe-cyclam/H2O2体系，证明了该体系能快速降解罗丹明B、酸性红88、酸性橙Ⅱ、活性红24、中性红等多种染料，并对偶氮类染料有较高的选择性。（2）证明了Fe-cylam/H2O2体系能够选择催化降解多种环境雌激素。该体系对17β-雌二醇、17α-雌二醇、雌三醇具有较高的选择性。淬灭实验、机制探针证明17β-雌二醇的降解为非自由基主导的过程。EPR光谱捕捉到高活性的FeV=O物质。Fe-cyclam/H2O2展现了高稳定性、宽pH适用性及对靶向污染物的选择性。（3）构建了以高价铁氧活性物质为主导的异相Fe-C催化体系，证明FeC体系可以活化PMS，有效降解双酚A。该体系的活性物质为FeV(O)、单线态氧、羟基自由基、硫酸盐自由基等。其中单线态氧为主要活性物质。该体系有良好的稳定性。本项目揭示了十四烷基铁配合物活化H2O2及PMS去除水体环境雌激素的机理过程，为发展非自由基型氧化降解技术提供理论依据，为水体中微污染物的去除提供技术支撑。项目合成了Fe-cyclam及磁性Fe-C材料，发表SCI论文3篇，培养硕士1名。