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

nsf - 0827841美国。该项目将为波多黎各大学（Río Piedras）的学生Dalice M. Piñero提交给NCSR材料科学研究所。Demokritos吗?她在希腊雅典进行了两个为期一个月的57Fe Mössbauer光谱实验，这是她关于寡核铁吡唑啉配合物的博士论文的一部分。Piñero女士将与Yiannis Sanakis博士合作，他是该奖项的PI Raphael Raptis博士的积极合作者，Piñero？他是波多黎各大学的论文指导老师。该项目提出利用Mössbauer光谱技术研究[Fe8O4(4-R-pz)12X4]0/n- （R = H, Cl, Br, Me, Ph； X= Cl-, Br-, SCN-, N3-）在一系列氧化还原修饰氧化态下的氧化还原活性Fe4O4-cubane；从[FeIII8]到[FeIII4FeII4]，在这些体系中有五种电化学氧化态。Mössbauer光谱可以区分这些八核配合物中存在的两种结构不同的铁位点，以及氧化态之间的区分。Fe4O4 cubanes可能存在于蛋白质的电子转移位点。本项目获得的结果将(1)有助于建立光谱指纹图谱。数据库将用于识别自然中的这些基序，(2)将用于研究混合价态的局域/非局域性质的电子态，(3)通过外部磁场的应用，将探测每个氧化态的磁态，通过对全铁化合物的氧化还原改性获得。该项目的智力优势在于系统地研究了一种罕见的、逐步氧化还原修饰的多铁簇。在这个项目中，少数民族学生获得的国际经验以及当地无法获得的技术培训构成了这个项目的更广泛影响。

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.