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

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。国际研究奖学金项目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。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Anne M. Poduska博士与位于印度班加罗尔的印度科学研究所的Eluvathingal D. Jemmis博士开展为期24个月的研究。几十年来，研究人员一直试图理解这种现象。和消失?二价铅和其他重跃迁后元素的孤对立体化学活性。由于其对多种因素的敏感性，如配体的立体结构和碱度，铅？S孤对活性很难预测，因此抑制了解决铅毒性问题的努力，无论是设计特定的生物螯合剂还是从污染的土壤和水中去除铅。对孤对活性的全面化学理解可以从含铅化合物的研究中发展出来，其中配体特征系统地变化，并仔细监测孤对活性的变化。由Nordell等人、Cui等人和Shi等人合成的二维Pb（II）聚合物为系统研究提供了机会：当Cl与铅结合时，孤对具有立体化学活性，但当Br或I结合时则没有。PI和宿主采用了一种理论方法，将高密度泛函理论计算与定性的、半经验的扩展h<s:1> ckel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）活性与六卤铅中的活性联系起来。在获得博士后奖学金期间，PI还将在喀拉拉邦新成立的印度科学教育与研究所（Indian Institute of science Education and Research）的本科机构教授化学和科学传播课程。此外，她将参加卡纳塔克邦Rajya Vijnana Parishat非政府组织的科学推广活动，在印度科学院出版的教育期刊《共振》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推广合作关系。

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.