Photoactivation of Stable Bonds for Chemical Conversions

用于化学转化的稳定键的光活化

• 批准号: 2243724
• 负责人: Daniel Nocera
• 金额: $ 70万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2243724&HistoricalAwards=false
• 关键词: Photoactivation; Stable; Bonds; Chemical; Conversions

With the support of the Chemical Catalysis Program in the Division of Chemistry, Professor Daniel G. Nocera of Harvard University is studying the generation of highly energetic species that are both critical to storing energy in the form of fuels and relevant to the development of new synthetic methods for drug discovery. The light-driven rearrangement of bonds with low energy content to ones of high energy content lies at the heart of converting renewable energy to fuels and of efficiently harnessing it to drive catalytic processes. Accordingly, the funded research focuses on facilitating bond rearrangements at the metal center of a molecular complex with solar light or solar electricity as an energy input. A variety of modern analytical techniques will be deployed to understand the fundamental principles underpinning how the metal complexes of interest mediate light- and electro-driven bond rearrangements. The findings from this work are anticipated to provide the tools and knowledge necessary for the discovery of new sustainable chemical processes for the manufacture of fuels and other materials of relevance to society. Beyond the benefits of the basic science being pursued, which are expected to contribute to the economic competitiveness of the US, the broader impacts of the award are augmented by educational and outreach activities performed by Professor Nocera and his team of coworkers. The research program introduces a talented and diverse pool of students at Harvard to forefront problems in chemistry and provides a mechanism to educate these young people with the broad technical skill set needed for them to contribute to critical problems in their future independent scientific careers. In the realm of outreach, Professor Nocera continues to raise public awareness of the role that chemistry, and science in general, can play in addressing challenges in energy and catalysis through his many contributions across a variety of platforms including national news, TV, radio programs, movies, and other broadcast media. The Nocera laboratory has a successful track record of broadening the participation of individuals belonging to groups underrepresented in science and the plan is to continue this effort to build excellence through diversity in the team.Through an interplay of spectroscopic and synthetic studies, the funded research focuses on the creation of new reagents, reactions, and processes for the generation of high energy species via the activation of stable bonds by transition metal complexes in excited states. Three lines of inquiry are being pursued: (1) photoactivation of metal-halide bonds within sculpted secondary coordination spheres with the goal of enhancing the selectivity of C-H bond activation by halogen radicals; (2) generation of super-reducing/-oxidizing closed-shell photoreagents from radical intermediates [such closed-shell species derived from radicals can greatly expand the redox window of photoredox reagents, thus allowing for the development of new methods based on the generation of highly reactive intermediates], and; (3) expansion of the types of super-reducing/-oxidizing reagents that are accessible by exploiting the oxidizing holes (in the valence band) and the reducing electrons (of the conduction band) of semiconductor photocatalysts. Among the impactful transformations that are anticipated to emerge from this work are perfluoromethylations and perfluoroalkylations, as well as efficient new processes for the decomposition of environmentally harmful perfluorocarboxylic acids. In all photoconversion reactions (1)-(3), an intriguing possibility also of interest is to introduce photoelectrochemical methods to allow a closed catalytic cycle to be achieved as well as the use of solar light. The photoelectrochemical approach opens a potential pathway to sustainable chemical manufacturing using photoredox methods which are otherwise limited in their range of applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在化学系化学催化项目的支持下，丹尼尔G.哈佛大学的Nocera正在研究高能物种的产生，这些物种对于以燃料形式储存能量至关重要，并且与药物发现的新合成方法的开发有关。光驱动的低能量含量的键到高能量含量的键的重排是将可再生能源转化为燃料和有效地利用它来驱动催化过程的核心。因此，资助的研究重点是促进分子复合物金属中心的键重排，太阳光或太阳能电作为能量输入。将部署各种现代分析技术，以了解感兴趣的金属络合物如何介导光和电驱动的键重排的基本原理。这项工作的结果预计将提供必要的工具和知识，以发现新的可持续化学工艺，用于制造燃料和其他与社会有关的材料。除了正在追求的基础科学的好处，预计将有助于美国的经济竞争力，该奖项的更广泛的影响是由教授Nocera和他的同事团队进行的教育和推广活动增强。该研究计划在哈佛引入了一个有才华的和多样化的学生池，以解决化学前沿问题，并提供了一种机制，以教育这些年轻人所需的广泛的技术技能，使他们能够在未来的独立科学生涯中为关键问题做出贡献。在外联领域，教授Nocera继续提高公众对化学和科学的作用的认识，一般来说，可以通过他在各种平台，包括国家新闻，电视，广播节目，电影和其他广播媒体的许多贡献，在解决能源和催化的挑战。Nocera实验室在扩大属于科学中代表性不足的群体的个人参与方面有着成功的记录，该计划将继续努力，通过团队的多样性来建立卓越。通过光谱和合成研究的相互作用，资助的研究重点是创造新的试剂，反应，以及通过由处于激发态的过渡金属络合物活化稳定键来产生高能物质的方法。研究方向有三：（1）光活化二次配位球内的金属-卤素键，目的是提高卤素自由基活化C-H键的选择性;（2）从自由基中间体产生超还原/氧化闭壳光试剂[这种衍生自自由基的闭壳物质可以极大地扩展光氧化还原试剂的氧化还原窗口，从而允许开发基于产生高活性中间体的新方法]，和（3）通过利用半导体光催化剂的氧化空穴（在价带中）和还原电子（在导带中）可获得的超还原/氧化试剂的类型的扩展。预计这项工作将产生的有影响力的转变包括全氟甲基化和全氟烷基化，以及分解对环境有害的全氟羧酸的有效新工艺。在所有的光转化反应（1）-（3）中，一个令人感兴趣的有趣的可能性是引入光电化学方法以允许实现封闭的催化循环以及使用太阳光。光电化学方法为使用光氧化还原方法的可持续化学制造开辟了一条潜在的途径，否则这些方法的应用范围有限。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。