The Role of Transition Metals in Formation of Environmentally Persistent Free Radicals

CTS-0625548奖摘要标题：过渡金属在环境持久性自由基形成中的作用本研究将研究常见过渡金属在环境持久性自由基(PFR)的形成和稳定中的作用，这些自由基一直与有害的健康影响有关。PI以前的研究已经清楚地表明，当被取代的有机分子与含铜(II)O的颗粒表面反应时，燃烧系统可以产生PFRs，例如被发现为燃烧生成的颗粒物。自由基与金属的配位使其不受大气氧化的影响。电子顺磁共振(EPR)研究表明，这些自由基在大气条件下不变地存在长达24小时，并以某种改变的形式无限期地存在。与生物医学研究人员的合作研究表明，这些自由基粒子系统在暴露的组织中诱导氧化应激，导致DNA损伤以及肺和心血管功能障碍。空气中的细颗粒物(PM2.5)和燃烧产生的颗粒物样本也观察到了类似的结果，这表明这些自由基可能至少对PM2.5报告的部分健康影响负责。铜、铁和钒似乎是最有利于诱导PFRs形成的金属。我们将用EPR，X-射线和FTIR光谱技术和实验室制备的替代粒子研究各种分子前驱体的自由基形成和稳定，就像以前研究铜(II)O一样，从头算方法将被用来计算模型自由基-粒子体系的反应能、电荷分布和EPR谱。基质分离EPR将被用来产生相关自由基的光谱标准，以帮助在更复杂的环境中识别PFR。溶剂萃取和GC-MS分析将被用来确定全氟芳烃是可提取的还是在提取过程中被转化为分子物种。广泛的影响：燃烧产生的颗粒中通常不知道燃烧产生的颗粒含有全氟芳烃。除了持久性自由基对健康的影响外，自由基可能是许多污染物形成的关键中间体，包括多氯二苯并对二恶英和多氯呋喃(PCDD/F)。该项目旨在提供关键信息，以便研究界能够进一步探讨持久性自由基在特定条件下和特定应用下的影响。除了研究生的参与，还指定了一名本科生研究人员作为REU项目进行提取和化学分析任务，这将导致编写本科生研究论文。

CTS-0625548 Award AbstractTitle: The Role of Transition Metals in Formation of Environmentally Persistent Free RadicalsThis research will study the role of common transition metals in the formation and stabilization of environmentally persistent free radicals (PFRs) that have been linked to adverse health impacts. Previous research by the PI has clearly demonstrated that combustion systems can generate PFRs when substituted organic molecules react on the surface of Cu(II)O-containing particles such as are found as combustion-generated particulate matter. Co-ordination of the radical with the metal stabilizes it against atmospheric oxidation. Electron paramagnetic resonance (EPR) studies indicate that these radicals exist unchanged under atmospheric conditions for up to 24 hours and persistent indefinitely in a somewhat altered form. Collaborative studies with biomedical researchers have demonstrated that these radical-particle systems induce oxidative stress in exposed tissues that lead to DNA damage as well as pulmonary and cardiovascular dysfunction. Similar results were observed for airborne fine particulate matter (PM2.5) and samples of combustion-generated particulate matter, suggesting that these radicals may be responsible for at least some of the reported health impacts of PM2.5. Copper, iron, and vanadium appear to be the most favorable metals for inducing formation of PFRs. Radical formation and stabilization from various molecular precursors will be studied using EPR, X-ray, and FTIR spectroscopic techniques and laboratory-prepared surrogate particles in the manner successfully used in the previous study of Cu(II)O. Ab initio methods will be used to calculate reaction energies, charge distributions, and EPR spectra of model radical-particle systems. Matrix isolation EPR will be used to generate standards of spectra of relevant radicals to assist in identification of PFRs in a more complex environment. Solvent extraction and GC-MS analysis will be used to determine whether PFRs are extractable or if they are converted to molecular species during the extraction process.Broader Impacts: It is not generally known within the combustion community that combustion generated particles contain PFRs. In addition to the health impacts of persistent radicals, radicals may be key intermediates in the formation of many pollutants including polychlorinated dibenzo-p-dioxins and polychlorinated furans (PCDD/F). This project is designed to provide key information so that the research community can further explore the impacts of persistent radicals under specific conditions and for specific applications. In addition to graduate student involvement, an undergraduate researcher has been identified to conduct the extraction and chemical analysis task as a REU project that will result in the preparation of an undergraduate research thesis.