International Research Fellowship Program: Changing Ligands, Changing Lone Pair Stereochemical Activity: A Theoretical Study of a Divalent Lead Coordination Polymer

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。国际研究奖学金计划使美国科学家和工程师能够在国外进行9至24个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持Anne M.Poduska博士与印度班加罗尔印度科学研究所的Eluvathingal D.Jemmis博士合作的为期24个月的研究奖学金。几十年来，研究人员一直试图了解二价铅和其他重过渡后元素中孤立的立体化学活动的出现和消失。由于其对配体空间和碱性等多种因素的敏感性，铅-S孤对的活性很难预测，因此阻碍了解决铅毒性问题的努力，无论是涉及设计特定的生物螯合剂还是从受污染的土壤和水中去除铅。对含铅化合物的研究可以发展出对孤对活性的全面化学理解，在含铅化合物中，配体特征是系统地变化的，并仔细监测由此产生的孤对活性的变化。由Nordell等人、Cui等人和Shih等人合成的二维铅(II)聚合物为系统研究提供了机会：当氯与铅结合时，孤子对具有立体化学活性，而当溴或碘结合时则不是。PI和HOST采用了一种理论方法，将高密度泛函理论计算与定性的半经验扩展Hück el分子轨道计算相结合，以确定孤对的位置和组成，并将这些二维聚合物中的孤对(In)活性与六卤化铅中的活性联系起来。在博士后奖学金期间，国际和平研究所还将在喀拉拉邦新成立的印度科学教育与研究所这一本科生机构教授化学和科学交流课程。此外，她将与卡纳塔克邦Rajya Vijnana Parishat非政府组织一起参加科学外联活动，在印度科学院出版的教育期刊《共鸣》上发表文章，并与印度研究人员和教育工作者建立长期的科学和外联合作关系。

0852893PoduskaThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Anne M. Poduska to work with Dr. Eluvathingal D. Jemmis at the Indian Institute of Science in Bangalore, India.For decades, researchers have sought to understand the appearance?and disappearance?of lone pair stereochemical activity in divalent lead and other heavy, post-transition elements. Due to its sensitivity to a variety of factors such as ligand sterics and basicity, the lead?s lone pair activity is difficult to predict, thus inhibiting efforts to solve issues of lead toxicity, whether it involves designing specific biological chelating agents or removing lead from contaminated soil and water. A comprehensive chemical understanding of lone pair activity can evolve from studies of lead-containing compounds in which ligand characteristics are systematically varied and the resulting changes in lone pair activity carefully monitored. A two-dimensional Pb(II) polymer, synthesized by Nordell et al., Cui et al., and Shi et al., presents an opportunity for a systematic study: the lone pair is stereochemically active when Cl is bound to lead, but not when Br or I are. The PI and host are employing a theoretical approach, combining high-level density functional theory calculations with qualitative, semi-empirical extended Hückel molecular orbital calculations, to identify lone pair location and composition, and to connect the lone pair (in)activity in these two-dimensional polymers with that seen in the lead hexahalides. During this post-doctoral fellowship, the PI will also teach chemistry and a science communication course at an undergraduate institution, the newly established Indian Institute of Science Education and Research in Kerala. Moreover, she will participate in science outreach activities with the Karnataka Rajya Vijnana Parishat NGO, publish articles in Resonance, an educational journal produced by the Indian Academy of Sciences, and establish long-term science and outreach collaborations with Indian researchers and educators.