中国科学院生态环境研究中心机构知识库
Advanced  
RCEES OpenIR  > 环境化学与生态毒理学国家重点实验室  > 学位论文
题名: 卤代酚类化合物在高级氧化过程中产生化学发光的结构-效应关系及其分子机制
作者: 高慧颖
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 朱本占
关键词: 化学发光,卤代酚类化合物,Fenton试剂,卤代醌,卤代半醌自由基 ; Chemiluminescence ; Halogenated phenols ; Fenton reageant ; Halogenated quinones ; Halogenated semiquinone radicals
其他题名: Structure-Activity Relationship and Molecular Mechanism of Chemiluminescence Generated by Halogenated Phenolic Compounds during Advanced Oxidation Processes
学位专业: 环境科学
中文摘要:       卤代芳烃类化合物是一类在环境中分布极其广泛,且对生物体具有强致癌性的化合物,近年来引起了人们的极大关注。近期我们研究发现,多卤代芳烃类有机物的降解中间体和致癌代谢产物——卤代醌类化合物如四氯苯醌能与H2O2通过不依赖于金属离子的途径发生两步反应产生羟基自由基(OH)和独特的内源性的二次化学发光(CL),且该二次CL与四氯苯醌/H2O2体系产生两次OH有很好的相关性。由于四氯苯醌是五氯酚(PCP)的主要代谢和降解产物,因此我们有理由推测PCP可能也会在OH产生体系中产生CL;若如此,那么是否所有的氯代酚类化合物都能产生这种依赖于OH的CL?具有相似结构的所有19种氯代酚类同系物(CPs)产生的CL是否有一定的规律性,分子机制为何?此外,作为一种简单有效且灵敏的分析检测手段,这种新型的依赖于OH的CL分析方法能否检测其它卤代芳烃类污染物,能否用于实际环境样品的定性和定量分析?本论文将对上述问题进行系统研究。本研究可能具有重要的环境学与生物学意义,为今后深入研究这些具有强烈肝毒性、肾毒性和致癌性的有毒污染物降解和检测提供理论及实践的指导依据。
1. 五氯酚和2,3,5,6-四氯酚在Fenton体系中产生化学发光的可能分子机制
      研究结果正如预期,所有19种氯代酚(CPs)都能在Fenton体系中产生明显的CL。我们以产生CL最强的两个CPs,即PCP和2,3,5,6-四氯酚(2,3,5,6-TeCP)为代表进行了详细研究。结果表明,PCP和2,3,5,6-TeCP不仅能够在Fenton体系中,而且在其它具有氧化还原活性的金属离子介导的类Fenton体系中也能产生明显的CL,且同样依赖于OH。通过联合运用高效液相色谱、质谱和离子色谱等检测方法对降解产生的中间体和终产物进行定性定量分析,发现二者生成的主要中间体和终产物为:初始羟基化中间体四氯氢醌、四氯苯醌和四氯儿茶酚/3,4,6-三氯儿茶酚;二级羟基化中间体三氯-羟基-1,4-苯醌以及三级羟基化中间体2,5-二氯-3,6-二羟基-1,4-苯醌;终产物为开环的小分子酸类化合物以及氯离子。进而发现,在这些中间体和终产物中只有氯代醌类中间体才会在Fenton体系中产生CL。利用ESR和UV-Vis两种方法同时成功检测到了体系中产生的半醌自由基四氯半醌自由基(TCSQ),同时发现TCSQ的生成与CL的产生存在很好的相关性。基于上述研究,我们提出了PCP/2,3,5,6-TeCP)和Fenton体系产生CL的分子机制,并深入探讨了CL与体系中生成的氯代醌类中间体以及TCSQ的直接相关性。
2. 多氯代酚在Fenton体系中产生化学发光的结构-效应关系
      本研究首次建立了CPs结构与CL之间的结构-效应关系,具体如下:1)总体而言,随着酚环上氯原子取代数目的增加,CPs产生的CL总量增加;2)对具有相同氯原子取代数目的CPs同分异构体而言,2-/3-/5-位氯代的CPs产生的CL较强,而4-/6-位氯代的CPs产生的CL较弱。通过对高氯代CPs/Fenton体系中生成的氯代醌类中间体(氯代氢醌CHQs、氯代苯醌CBQs和氯代儿茶酚CCs)的定量分析,以及对CBQs/CCs在Fenton体系中的CL变化趋势的研究,发现CBQs的生成对产生CL起主导作用。通过直接ESR法和UV-Vis法观察到CSQs的生成也与CL之间存在良好的相关性。在此基础上,我们提出了CPs/Fenton体系产生CL的详细分子机制。同时开展了CPs对明亮发光杆菌的毒性实验研究,建立了CPs的毒性与其结构之间的结构-效应关系。研究表明,CPs的CL、毒性和降解速率三者之间存在密切的联系。
3. 其它常见卤代芳香族化合物在Fenton体系中产生化学发光的机理及应用
      其它卤代的酚类化合物(XPs)/Fenton体系也能产生明显的CL。在高浓度反应比例条件(1:300:3)下,XPs(包括五卤酚(PXP)、2,4,6-三卤酚(2,4,6-TXP)和一卤酚(XP))产生CL的顺序为:氟代酚 > 氯代酚 > 溴代酚 > 碘代酚。XPs产生CL的机制与CPs类似,同样是与其在反应过程中卤代醌型中间体及卤代半醌自由基的生成密切相关的。其它常见的卤代芳香族化合物(XAr),如2,4-二氯苯氧乙酸(2,4-D)、2,4,5-三氯苯氧乙酸(2,4,5-T)、五氯苯(PCB)和六氯苯(HCB)等,也都能在Fenton体系中产生CL,但相对较弱。更多的XAr甚至是实际环境样品亦能在Fenton体系中产生CL。在此基础上,发展了一种用于检测XAr的快速、简便的CL分析方法。
英文摘要:       Halogenated aromatic compounds (XAr) are a class of widely distributed chemicals which have been used as pesticides, disinfectants, personal care agents, flame retardants and pharmaceuticals. The ubiquitous nature coupled with their carcinogenicity has raised public concern on the potential risks to both human health and ecosystem. We have shown recently that an unprecedented two-step chemiluminescence (CL) can be produced by H2O2 and tetrachloro-1,4-benzoquinone (TCBQ), one of the genotoxic and carcinogenic quinoid metabolites and degradation intermediates of the wood preservative pentachlorophenol (PCP). The two-step CL emission was found to be well-correlated to and directly dependent on its two-step metal-independent production of intrinsic hydroxyl radicals (OH). However, it is still not clear: (i) whether CL can be produced by PCP and Fenton reagent, in the absence of a fluorescent agent; and if so, (ii) can other chlorinated phenols (CPs) also produce CL with Fenton system or other OH-generating systems; (iii) are there any structure-activity correlations (SAR) between CL production and the chemical structure for all 19 CPs congeners; (iv) what is the underlying molecular mechanism for the SAR; (v) is the new OH-dependent CL production also a general phenomenon for other halogenated phenols, or the more general XAr. Therefore, in the present study, we plan to address the above questions. These studies should have broad biological and environmental implications for future research on polyhalogenated quinones and their phenol precursors, which are known to cause acute hepatoxicity, nephrotoxicity and carcinogenesis.
 1. Possible molecular mechanism of OH-dependent chemiluminescence production by pentachlorophenol/2,3,5,6-tetrachlorophenol and Fenton reagent
      As expected, we found that intrinsic CL could be produced by all 19 CPs congeners and Fenton reagent. To further investigate the underlying molecular mechanism, PCP and 2,3,5,6-TeCP, the two CPs with the strongest CL emission, were chosen as two model CPs for more systematic studies. We found that CL could be markedly produced not only in the classic Fenton system, but also in the other redox-active metal-mediated Fenton-like systems. Meanwhile, the CL emission was also directly dependent on OH formation. Hydroxylated chloroquinone intermediates including the mono-hydroxylation (tetrachlorohydroquinone (TCHQ), TCBQ and tetrachlorocatechol/3,4,6-trichlorocatechol (TCC/3,4,6-TrCC)), di-hydroxylation trichlorohydroxy-1,4-benzoquinone (TrCBQ-OH), tri-hydroxylation 2,5-dichloro- 3,6-dihydroxy-1,4-benzoquonine (DDBQ); and ring-opened compounds were also identified as degradation intermediates and final products. Further studies showed that only chlorinated quinoid intermediates (such as TCHQ, TCBQ, TCC, TrCBQ-OH and DDBQ) could produce CL in Fenton system. Interestingly, the radical intermediate tetrachlorosemiquinone (TCSQ) were detected in this system by both direct electron spin resonance (ESR) and UV-visible (UV-Vis) methods, and a good correlation was observed between the yield of TCSQ and CL emission. Based on these results, an OH-dependent mechanism for CL generation which was directly correlated with the formation of chlorinated quinoid intermediates and semiquinone radicals in PCP/2,3,5,6-TeCP and Fenton system was proposed.
2. Structure-activity relationship (SAR) of chemiluminescence production from the degradation of highly chlorinated phenols by Fenton system
      SAR between the chemical structures and the CL generation was observed: (i) in general, the CL intensity increases with increasing number of Cl-substitution; (ii) among the CPs isomers, CPs with position-2, -3 or -5 Cl-substitution exhibit stronger CL, while those with position-4 or -6 Cl-substitution produce relatively weaker CL. We found that the CL intensity of CPs is dependent primarily on the yield of the highly chlorinated 1,4-benzoquinones (CBQs), and there is also a good correlation between CL production and the formation of the chlorinated semiquinone radicals (CSQs). A detailed molecular mechanism was proposed for OH-dependent CL production by CPs/Fenton system.
Further, we found there are some good correlations between CL production and the toxicity/degradation rate of CPs, which might be helpful for predicting potential toxicity and degradation rate of CPs.
3. Chemiluminescence production from the degradation of other halogenated aromatic compounds by Fenton system and the potential implications
      In addition to CPs, other halogenated phenols (XPs) can also produce CL in Fenton system. Under the high ratios of XPs/H2O2/Fe2+-EDTA (such as 1:300:3), the order of CL production by XPs (including pentahalophenols (PXP), 2,4,6-trihalophenols (2,4,6-TXP) and monohalophenols (XP)) was found to be: fluorophenols (FPs) > CPs > bromophenols (BrPs) > iodophenols (IPs). We further found that other XAr, such as 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), pentachlorobenzene (PCB) and hexachlorobenzene (HCB), could also produce CL in Fenton system, although they are much weaker than CPs with the same chlorine atom under the same experimental conditions. These results demonstrated that the CL emission of XAr was related not only to the types and number of halo-substitution, but also closely to -OH group on the benzene ring. Moreover, CL could also be generated from real environmental samples in Fenton system, and the CL-based method could be used to evaluate potential XAr contamination in real environmental samples. Therefore, our findings should have potential environmental implications.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36791
Appears in Collections:环境化学与生态毒理学国家重点实验室_学位论文

Files in This Item:
File Name/ File Size Content Type Version Access License
高慧颖--卤代酚类化合物在高级氧化过程中产生化学发光的结构-效应关系及其分子机制.pdf(10768KB)学位论文--限制开放 联系获取全文

Recommended Citation:
高慧颖. 卤代酚类化合物在高级氧化过程中产生化学发光的结构-效应关系及其分子机制[D]. 北京. 中国科学院研究生院. 2016.
Service
Recommend this item
Sava as my favorate item
Show this item's statistics
Export Endnote File
Google Scholar
Similar articles in Google Scholar
[高慧颖]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[高慧颖]‘s Articles
Related Copyright Policies
Null
Social Bookmarking
Add to CiteULike Add to Connotea Add to Del.icio.us Add to Digg Add to Reddit
所有评论 (0)
暂无评论
 
评注功能仅针对注册用户开放,请您登录
您对该条目有什么异议,请填写以下表单,管理员会尽快联系您。
内 容:
Email:  *
单位:
验证码:   刷新
您在IR的使用过程中有什么好的想法或者建议可以反馈给我们。
标 题:
 *
内 容:
Email:  *
验证码:   刷新

Items in IR are protected by copyright, with all rights reserved, unless otherwise indicated.

 

 

Valid XHTML 1.0!
Copyright © 2007-2017  中国科学院生态环境研究中心 - Feedback
Powered by CSpace