CAS: Spectroscopy and Reactivity of Isolated Metal-oxo Complexes

CAS：分离金属氧配合物的光谱学和反应性

• 批准号: 1954268
• 负责人: Etienne Garand
• 金额: $ 42万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1954268&HistoricalAwards=false
• 关键词: CAS; Spectroscopy; Reactivity; Isolated; Metal

With this grant, the Chemical Structure, Dynamics, and Mechanisms-B program is supporting the research of Professor Etienne Garand at the University of Wisconsin-Madison. The project focuses on improving the efficiency of fundamental processes involved in the conversion of solar energy into chemical fuels. Artificial photosynthesis is a promising option for the storage of solar energy. The water oxidation process is key to artificial photosynthesis, it includes the splitting water (H2O) into oxygen (O2) and protons (H+). The research challenge in water splitting resides in lowering its substantial extra energy needed to perform this reaction. To reduce this energy, a large number of catalysts have been reported. The search for catalysts underscores the need for understanding the catalytic water oxidation itself, such that rational catalyst design can be applied. This research project utilizes a combination of tools - mass spectrometry and laser spectroscopy - to probe critical catalytic complexes which are intermediates in the water oxidation reaction. The results from these studies clarify the structures and reactivity of these reactive complexes and provide stringent benchmarks for computational chemistry methods, which can then be used to design future catalysts. In addition, this research project benefits a diverse and competitive STEM workforce by providing mentorship, high-level training and career development for students. The project will support the team's participation in three programs aimed at increasing diversity in STEM; namely, the ACS Bridge to the doctorate which aims at increasing the pool of competitive underrepresented students applying to graduate program; CHOPS which provides an opportunity for students to visit the chemistry department and learn about the graduate program, and CATALYST which provides individual mentoring and support to targeted first-year graduate students.This research project addresses the mechanism for water oxidation using solar energy. A critical step in this mechanism involves nucleophilic attack of a water molecule on a metal-oxo species and the formation of an O-O bond. Building on methodology developed with earlier NSF support, the experimental approach is based on sequential cryogenic ion traps for the controlled manipulation and characterization of ions and clusters. This provides the capabilities to generate highly reactive intermediates and directly probe their structure and reactivity. Precise chemical structure characterizations of the complexes are obtained via cryogenic ion predissociation spectroscopy. This project: 1) Characterizes the electronic structure and spin state of metal-oxo complexes and their relationship with the nature of the metal center and the influence of the ligands; 2) Explores the intrinsic reactivity and interactions between metal-oxo complexes and water molecules, with particular focus on the propensity to form O-O bond and its relationship to the electronic structure of the M=O group; and 3) Defines the role of bases and an extended water solvent network in inducing structural changes and interactions that promote and facilitate the critical O-O formation step. This research promotes the development of a diverse and competitive workforce by providing training and career development at the graduate level.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.

有了这笔资金，化学结构、动力学和机理b项目将支持威斯康星大学麦迪逊分校的Etienne Garand教授的研究。该项目的重点是提高将太阳能转化为化学燃料的基本过程的效率。人工光合作用是太阳能储存的一个很有前途的选择。水氧化过程是人工光合作用的关键，它包括将水（H2O）分解成氧（O2）和质子（H+）。水裂解的研究挑战在于降低进行该反应所需的大量额外能量。为了降低这种能量，已经报道了大量的催化剂。对催化剂的研究强调了理解催化水氧化本身的必要性，这样才能应用合理的催化剂设计。本研究项目结合使用质谱法和激光光谱法来探测水氧化反应中作为中间体的关键催化配合物。这些研究的结果阐明了这些反应性复合物的结构和反应性，并为计算化学方法提供了严格的基准，然后可用于设计未来的催化剂。此外，该研究项目通过为学生提供指导、高水平培训和职业发展，使多元化和有竞争力的STEM劳动力受益。该项目将支持该团队参与三个旨在增加STEM多样性的项目；即，ACS通往博士学位的桥梁，旨在增加申请研究生课程的竞争不足的学生的数量；为学生提供参观化学系和了解研究生课程的机会，以及为目标一年级研究生提供个人指导和支持的CATALYST。本课题研究利用太阳能氧化水的机理。该机制的关键步骤包括水分子对金属氧的亲核攻击和O-O键的形成。在早期NSF支持下开发的方法的基础上，实验方法基于顺序低温离子阱，用于控制离子和簇的操作和表征。这提供了生成高反应性中间体并直接探测其结构和反应性的能力。配合物的精确化学结构表征是通过低温离子预解光谱。本项目：1)表征金属-氧配合物的电子结构和自旋态及其与金属中心性质的关系以及配体的影响；2)探索金属-氧配合物与水分子之间的内在反应性和相互作用，特别关注O-O键的形成倾向及其与M=O基团电子结构的关系；3)定义了碱和扩展的水溶剂网络在诱导结构变化和相互作用中的作用，这些变化和相互作用促进和促进了O-O的关键形成步骤。该研究通过提供研究生水平的培训和职业发展，促进了多元化和有竞争力的劳动力队伍的发展。该奖项反映了美国国家科学基金会的法定使命，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。

项目成果

Spectroscopy and Theoretical Modeling of Tetracene Anion Resonances

并四苯阴离子共振的光谱学和理论模型

• DOI: 10.1021/acs.jpclett.2c02931
• 发表时间: 2022
• 期刊: The Journal of Physical Chemistry Letters
• 作者: Sagan, Cole R.;Anstöter, Cate S.;Thodika, Mushir;Wilson, Kenneth D.;Matsika, Spiridoula;Garand, Etienne
• 通讯作者: Garand, Etienne

Tandem Mass-Selective Cryogenic Digital Ion Traps for Enhanced Cluster Formation

• DOI: 10.1021/acs.jpca.3c04706
• 发表时间: 2023-09-01
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY A
• 影响因子: 2.9
• 作者: Roesch，Gina C.;Garand，Etienne
• 通讯作者: Garand，Etienne