CAREER: Time-Resolved Multi-Pulse Spectroscopy of Solvated Aza-Aromatics

职业：溶剂化氮杂芳烃的时间分辨多脉冲光谱

• 批准号: 1846480
• 负责人: Cody Schlenker
• 金额: $ 68.5万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1846480&HistoricalAwards=false
• 关键词: CAREER; Time; Resolved; Multi; Pulse

Molecules that can absorb light and use the energy to drive chemical reactions are potentially interesting for new technologies in energy storage, water treatment, and industrial chemical production. However, understanding and controlling these processes is challenging because energy is generally expended quickly but stored slowly. For example, filming a speeding bullet (energy flow) poses different challenges than filming a flower growing (energy storage). In this project, funded by the Chemical Structure Dynamics and Mechanisms (CSDM-A) program of the Chemistry Division, Professor Cody W. Schlenker of the University of Washington (UW) is using advanced laser techniques to provide fundamental understanding of how light absorption drives chemical reactions, two processes with rates as different as the velocity of a speeding bullet and the growth of a flower. The scientific knowledge gleaned from this project has the potential to improve sunlight-to-fuel conversions, solar water decontamination, and possibly even new avenues for light-driven industrial chemical production. Professor Schlenker's Research-Integrated Science Education (RISE) Program focusses on helping to equip low-income and potential first-generation college students with the tools needed to apply to college, succeed in STEM majors, and enter the STEM workforce. The group integrates research and education to develop new peer-generated science tutorials presented by students from the most ethnically and culturally diverse public high-schools in Washington State (e.g. Chief Sealth High School in Southern West Seattle through a partnership with the UW's Math & Science Upward Bound program). One example product of the RISE Program: Step-by-step, peer-led-learning video science experiments are distributed freely on a RISE-dedicated YouTube channel. The research group also leverages existing UW resources, for example, through a partnership with the UW Clean Energy Institute. Organic photochemistry may lay the conceptual groundwork for new research in the field of solar water splitting. Cheap and scalable solar hydrogen could positively impact energy and food sustainability, since ammonia fertilizer production is resource intensive.The scientific objective of this project is to understand the role of inter-molecular excited states in the photochemistry of hydrogen-bonded molecular complexes. This research is focused particularly on understanding how nitrogen-containing molecules known as azaarenes photochemically react by removing hydrogen atoms from water and alcohols. To achieve this goal, the research team uses spectroscopic and electrochemical signals associated with transient, photogenerated, excited-states and free radicals. The population of these species are monitored as a function of the temporal delay between an initial ultrafast visible laser pulse (pump) and a subsequent infrared pulse (push) using transient absorption, photoluminescence, and electrical current detection. This approach is notable because it has the potential to extract ultrafast time information from the relative yields of much slower chemical reactions. Azaarenes play critical roles in photosynthetic assemblies, DNA photo-protection, photo-stabilization of industrial pigments, and they are common chromophores in renewable energy research focused on proton-coupled electron transfer (PCET). In these capacities, azaarenes can hydrogen-bond with hydroxyl groups. These hydrogen bonding interactions often alter the chromophore's photophysics and photochemical reactivity in seemingly unintuitive ways. The critical mechanistic links between the branching ratio among ultrafast photophysical pathways and the much slower subsequent photochemical reactions of azaarene molecules may constitute a step forward. Broader impacts of this work include potential societal benefits resulting from clarifying whether inter-molecular electronic excited-states that arise from hydrogen bonding interactions serve as a chemical gateway to photon-initiated reactions. Additionally, this project provides training opportunities for graduate and undergraduate students, integrating research concepts into public engagement activities for science outreach.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.

能够吸收光并利用能量驱动化学反应的分子对于能源储存、水处理和工业化学品生产的新技术来说可能很有趣。然而，理解和控制这些过程是具有挑战性的，因为能量通常消耗得快，储存得慢。例如，拍摄一颗高速飞行的子弹（能量流）与拍摄一朵生长的花（能量储存）面临不同的挑战。在这个由化学部化学结构动力学和机制（CSDM-A）项目资助的项目中，华盛顿大学（UW）的Cody W. Schlenker教授正在使用先进的激光技术来提供对光吸收如何驱动化学反应的基本理解，这两个过程的速度与高速子弹的速度和花朵的生长速度一样不同。从这个项目中收集到的科学知识有可能改善阳光到燃料的转换，太阳能水的净化，甚至可能为光驱动的工业化学生产开辟新的途径。Schlenker教授的研究综合科学教育（RISE）项目侧重于帮助低收入和潜在的第一代大学生掌握申请大学、在STEM专业取得成功并进入STEM劳动力市场所需的工具。该小组将研究和教育结合起来，开发新的同行生成的科学教程，由来自华盛顿州种族和文化最多样化的公立高中的学生讲授（例如，西雅图西南部的首席Sealth高中与华盛顿大学的数学和科学向上发展项目合作）。RISE项目的一个例子是：一步一步、由同行领导的科学实验视频在RISE专用的YouTube频道上免费发布。该研究小组还利用现有的华盛顿大学资源，例如，通过与华盛顿大学清洁能源研究所的合作。有机光化学可以为太阳能水分解领域的新研究奠定概念基础。廉价和可扩展的太阳能氢可以对能源和粮食的可持续性产生积极影响，因为氨肥生产是资源密集型的。该项目的科学目标是了解分子间激发态在氢键分子配合物光化学中的作用。这项研究的重点是了解氮氮分子是如何通过从水和醇中去除氢原子而发生光化学反应的。为了实现这一目标，研究小组使用了与瞬态、光生态、激发态和自由基相关的光谱和电化学信号。利用瞬态吸收、光致发光和电流检测来监测这些物种的种群，作为初始超快可见激光脉冲（泵）和随后的红外脉冲（推）之间的时间延迟的函数。这种方法是值得注意的，因为它有可能从慢得多的化学反应的相对产量中提取超快的时间信息。氮杂芳烃在光合作用、DNA光保护、工业色素的光稳定等方面发挥着重要作用，是质子耦合电子转移（PCET）等可再生能源研究中常见的发色团。在这些能力下，氮扎芳烃可以与羟基形成氢键。这些氢键相互作用经常以看似不直观的方式改变发色团的光物理和光化学反应性。超快光物理途径之间的分支比例与随后azaarene分子的慢得多的光化学反应之间的关键机制联系可能构成了一个进步。这项工作更广泛的影响包括潜在的社会效益，因为它澄清了由氢键相互作用产生的分子间电子激发态是否可以作为光子引发反应的化学通道。此外，本项目为研究生和本科生提供培训机会，将研究理念融入科学推广的公众参与活动中。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

Barrierless Heptazine-Driven Excited State Proton-Coupled Electron Transfer: Implications for Controlling Photochemistry of Carbon Nitrides and Aza-Arenes

• DOI: 10.1021/acs.jpcc.9b08842
• 发表时间: 2019-11
• 期刊: Journal of Physical Chemistry C
• 影响因子: 3.7
• 作者: Emily J Rabe;Kathryn L Corp;Xiang Huang;Johannes Ehrmaier;Ryan G. Flores;Sabrina L Estes;A. Sobolewski;W. Domcke;Cody W. Schlenker

Control of Excited-State Proton-Coupled Electron Transfer by Ultrafast Pump-Push-Probe Spectroscopy in Heptazine-Phenol Complexes: Implications for Photochemical Water Oxidation

• DOI: 10.1021/acs.jpcc.0c00415
• 发表时间: 2020-04-30
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY C
• 影响因子: 3.7
• 作者: Corp, Kathryn L.;Rabe, Emily J.;Schlenker, Cody W.
• 通讯作者: Schlenker, Cody W.

Intermolecular Hydrogen Bonding Tunes Vibronic Coupling in Heptazine Complexes

分子间氢键调节七嗪配合物中的电子振动耦合

• DOI: 10.1021/acs.jpcb.0c07719
• 发表时间: 2020
• 期刊: The Journal of Physical Chemistry B
• 作者: Rabe, Emily J.;Goldwyn, Harrison J.;Hwang, Doyk;Masiello, David J.;Schlenker, Cody W.
• 通讯作者: Schlenker, Cody W.

Molecular Design of Heptazine-Based Photocatalysts: Effect of Substituents on Photocatalytic Efficiency and Photostability

• DOI: 10.1021/acs.jpca.0c00488
• 发表时间: 2020-05-14
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY A
• 影响因子: 2.9
• 作者: Ehrmaier, Johannes;Huang, Xiang;Domcke, Wolfgang
• 通讯作者: Domcke, Wolfgang