U.S.-Greece Dissertation Enhancement: Mössbauer Spectroscopic Studies of Redox-Active Fe4O4-Cubanes

NSF-0827841美国-希腊学位论文增强：氧化还原活性Fe4O4 Cubanes的穆斯堡尔光谱研究本项目将派遣波多黎各大学里奥皮德拉斯分校的学生Dalice M.Piñero到希腊雅典NCSR？Demokritos材料科学研究所进行为期两个月的57Fe穆斯堡尔光谱实验，作为她关于低聚核吡唑铁络合物博士论文工作的一部分。皮涅罗夫人将与扬尼斯·萨纳基斯博士合作，扬尼斯·萨纳基斯博士是拉斐尔·拉蒂斯博士的积极合作者，皮涅罗·S夫人是波多黎各大学的论文导师。该项目建议使用穆斯堡尔光谱学来研究[Fe8O4(4-R-PZ)12X4]0/n-(R=H，Cl，BrMe，Ph；X=Cl-，Br3-，SCN-，N3-)核心中含有氧化还原活性的Fe4O4-立方烷；在这些体系中，从[FeIII8]到[FeIII4FeII4]，有五个氧化态是电化学可及的。穆斯堡尔谱可以区分存在于这些八核络合物中的两个结构不同的铁中心，以及氧化态之间的区别。最近有人提出，蛋白质的电子转移部位可能存在Fe4O4立方烷。本项目所取得的成果将(1)有助于建立光谱指纹？数据库将用于识别自然界中的这些基序，(2)将用于研究它们的电子状态关于混合价态的局域/非局域性质，以及(3)通过施加外部磁场，将探测通过全铁化合物的氧化还原修饰访问的每个氧化态的磁性状态。该项目的学术价值包括对一种罕见的、逐步氧化还原修饰的多铁团簇进行系统研究。少数族裔学生在该项目期间将获得的国际经验以及当地没有的技术培训构成了该项目更广泛的影响。

NSF-0827841U.S.-Greece Dissertation Enhancement: Mössbauer Spectroscopic Studies of Redox-Active Fe4O4 Cubanes ABSTRACTThis project will send Dalice M. Piñero, a student from the University of Puerto Rico at Río Piedras, to the Institute of Materials Science, NCSR ?Demokritos?, Athens, Greece, for two one-month periods to conduct 57Fe Mössbauer Spectroscopy experiments as part of her doctoral dissertation work on oligonuclear iron pyrazolato complexes. Mrs. Piñero will work with Dr. Yiannis Sanakis, an active collaborator of Dr. Raphael Raptis, the PI on this award and Mrs. Piñero?s Thesis advisor at the University of Puerto Rico. The project proposes the use Mössbauer spectroscopy to study the redox-active Fe4O4-cubane contained within the core of [Fe8O4(4-R-pz)12X4]0/n- (R = H, Cl, Br, Me, Ph; X= Cl-, Br-, SCN-, N3-) over a range of redox-modified oxidation states; five oxidation states are electrochemically accessible in these systems, from [FeIII8] to [FeIII4FeII4]. Mössbauer spectroscopy allows the differentiation between the two structurally distinct Fe-sites present in these octanuclear complexes, as well as the differentiation between oxidation states. The possible existence of Fe4O4 cubanes at the electron transfer sites of proteins has been suggested resently. Results obtained in this project will (1) contribute to the creation of a spectroscopic ?fingerprint? data bank to be used for recognition of these motifs in Nature, (2) will serve to study their electronic states with regard to localized/delocalized nature of mixed valence states, and (3) by the application of external magnetic fields, will probe the magnetic states at each oxidation state, accessed by redox modification of the all-ferric compounds. The Intellectual Merit of the project consists of the systematic study of a rare, stepwise redox-modified multi-iron cluster. The international experience to be gained by an under-represented minority student during this project and the training in techniques not available locally constitute the Broader Impacts of this project.