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Non-Statisticality, Selectivity and Phase Space Structure in Organic Reactions

有机反应中的非统计性、选择性和相空间结构

基本信息

批准号：
EP/K000489/1
负责人：
Steve Wiggins
金额：
$ 47.55万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FK000489%2F1
关键词：
Non Statisticality Selectivity Phase Space

项目摘要

The proposed research is submitted under the NSF/EPSRC Chemistry Proposals 2011 call for proposals. Our US collaborator is Professor Gregory S. Ezra of the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York. This work is a theoretical and computational exploration of nonstatistical dynamics in organic reactions, motivated by recent experiments, and its relation to phase space structure in classical Hamiltonian models for polyatomic molecules. The overall aim of the research is the development of a phase space approach to understanding and ultimately predicting nonstatistical dynamics in thermal reactions of organic molecules. Such reactions have been the focus of much recent experimental and theoretical work, which has convincingly demonstrated that, for a growing number of cases, standard transition state theory approaches for prediction of rates, product ratios, stereospecificity and isotope effects fail completely. The proposed research will apply the significant recent theoretical and computational advances in applied dynamical systems theory (e.g., normal form theory) to study reaction dynamics and phase space structure in multimode molecules, and to probe the dynamical origins of nonstatistical behavior. The gap time formalism for unimolecular rates will be used to provide novel diagnostics for nonstatistical behavior.These methods will be applied to a investigate a number of representative cases: branching ratios in systems exhibiting reaction path bifurcation; stereospecificity in nominally pericyclic reactions involving diradical intermediates; nonstatisticality and dynamic matching in reactions occuring on shallow potential walls. The influence of bath modes will be studied and, ultimately, the nature of quantum effects for such systems will be explored.Control of selectivity is arguably the most important problem that synthetic chemists face. Understanding the factors that control selectivity is of essential importance to the chemical enterprise, and the proposed work begins to develop the fundamental mathematical framework that will be necessary to make non-empirical reaction design a reality. It is anticipated that the work will provide a rigorous dynamical foundation for the ongoing paradigm shift in the interpretation of organic reaction mechanisms, and so have considerable impact beyond the field of theoretical chemistry.Annual exchanges of postdocs between collaborating institutions will ensure that the coworkers involved in the project will receive a broad interdisciplinary education in a wide range of research methodologies. There will in particular be fruitful cross-fertilization between the subfields of chemical dynamics, dynamical systems, and the study of organic reaction mechanisms, as required for a new generation of researchers in chemistry.This project is a unique collaborative effort spanning the fields of physical organic chemistry, theoretical reaction dynamics and applied dynamicalsystems theory. It addresses problems of reactivity and selectivity in organic reactions that are of immense practical and theoretical importance, while exploiting state-of-the-art methodology and concepts from the theory of Hamiltonian dynamics. The synergy provided by such a collaborative effort is essential for full progress to be made in understanding this important class of problems in reaction dynamics. The PIs bring a combination ofdifferent backgrounds and strengths whose application to the proposed problems in physical organic chemistry is, as far as we know, unprecedented. The complementary skills and expertise of the three PIs will form a well-balanced ``tripod'' of capabilities for attacking these problems.

拟议的研究是根据 NSF/EPSRC 2011 年化学提案征集提案提交的。我们的美国合作者是纽约州伊萨卡康奈尔大学化学与化学生物学系的 Gregory S. Ezra 教授。这项工作是对有机反应中非统计动力学的理论和计算探索，受到最近实验的推动，及其与多原子分子经典哈密顿模型中相空间结构的关系。该研究的总体目标是开发相空间方法来理解并最终预测有机分子热反应中的非统计动力学。此类反应一直是最近许多实验和理论工作的焦点，这些工作令人信服地证明，在越来越多的情况下，用于预测速率、产物比率、立体特异性和同位素效应的标准过渡态理论方法完全失败。拟议的研究将应用应用动力系统理论（例如范式理论）中最新的重大理论和计算进展来研究多模分子的反应动力学和相空间结构，并探讨非统计行为的动力学起源。单分子速率的间隙时间形式将用于为非统计行为提供新颖的诊断。这些方法将应用于研究许多代表性案例：表现出反应路径分叉的系统中的支化比；涉及双自由基中间体的名义周环反应的立体特异性；浅势壁上发生的反应的非统计性和动态匹配。我们将研究浴模式的影响，并最终探索此类系统的量子效应的本质。选择性的控制可以说是合成化学家面临的最重要的问题。了解控制选择性的因素对于化工企业至关重要，并且拟议的工作开始开发使非经验反应设计成为现实所必需的基本数学框架。预计这项工作将为有机反应机制解释中正在进行的范式转变提供严格的动力基础，从而在理论化学领域之外产生相当大的影响。合作机构之间每年的博士后交流将确保参与该项目的同事在广泛的研究方法中接受广泛的跨学科教育。根据新一代化学研究人员的要求，化学动力学、动力系统和有机反应机制研究等子领域之间将特别产生富有成效的交叉融合。该项目是跨越物理有机化学、理论反应动力学和应用动力系统理论领域的独特合作成果。它解决了有机反应中具有巨大实践和理论重要性的反应性和选择性问题，同时利用了哈密顿动力学理论中最先进的方法和概念。这种协作努力所提供的协同作用对于理解反应动力学中这一类重要问题的全面进展至关重要。据我们所知，这些 PI 汇集了不同的背景和优势，在物理有机化学提出的问题上的应用是前所未有的。三位 PI 的互补技能和专业知识将形成解决这些问题的均衡能力“三足鼎立”。