RUI: Photoisomerization Potential of Molecular Switches on Surfaces

西华盛顿大学(WWU)的安德烈亚斯·里曼教授得到了化学系大分子、超分子和纳米化学(MSN)计划的支持，以研究螺吡喃分子开关的行为。分子开关是一种可以在两种或两种以上稳定状态之间来回摆动的分子。在每种状态下，分子都有独特的形状、结构以及电子和光学性质。分子对外界刺激，如光，会从一种状态转换到另一种状态。其目标是控制开关机制，并创建由功能分子开关组成的表面结构。分子开关是电子设备中分子电子学的重要组成部分。WWU的本科生是这个项目不可或缺的一部分，并为他们未来的科研或工业提供相关经验。此外，Riemann教授还参与了通过“指南针2校园”的推广活动，这是西华盛顿大学的一项倡议，旨在通过激发学生对研究的兴趣并为他们提供接受高等教育的途径，提高传统上代表性较低背景的学生的科学素养。本研究的目的是研究能够在足够大的截面上进行光异构化过程的分子/底物组合，使其适合于在分子电子学中的进一步应用。所研究的体系是沉积在贵金属衬底和石墨上的螺吡喃/花青异构体。单个分子可以被激发以改变其构型的薄膜分子被创造出来。利用各种实验表面科学技术，如STM、LEED和XPS，以及包括密度泛函和分子力学计算在内的计算化学方法，研究了这些分子的构象行为和光异构化过程的控制。该项目分三个阶段进行：1)分析不同温度和底物覆盖物下各种螺吡喃分子的吸附行为；2)使用光和热来触发和监测异构化转换；3)使用计算化学来模拟螺吡喃分子的吸附行为。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Professor Andreas Riemann of Western Washington University (WWU) is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to investigate the behavior of spiropyran molecular switches. A molecular switch is a molecule that can swing back and forth between two or more stable states. In each state, the molecule has a distinctive shape, structure, and electronic and optical properties. The molecules switch from one state to another in response to external stimuli, such as light. The goal is to control the switching mechanism and create surface structures consisting of functional molecular switches. Molecular switches are important components of molecular electronics used in electronic devices. Undergraduate students at WWU are an integral part of this project and are given relevant experiences for their futures in scientific research or in industry. Additionally, Professor Riemann is involved in outreach through "Compass 2 Campus," a Western Washington University initiative to increase science literacy of students from traditionally underrepresented backgrounds, by stimulating their interest in research and providing them with pathways to higher education. The goal of this research is to study molecule/substrate combinations which are able to undergo a photoisomerization process with a large enough cross-section to make it suitable for further application in molecular electronics. The systems under investigation are spiropyran/merocyanine isomers deposited on noble metal substrates and graphite. Thin molecular films where individual molecules can be excited to switch their configuration are created. Conformational behavior of these molecules and control of the photoisomerization process are investigated using a variety of experimental surface science techniques such as STM, LEED and XPS as well as computational chemistry methods including DFT and Molecular Mechanics calculations. The project is conducted in three stages: 1) the analysis of adsorption behavior of various spiropyran-based molecules at various temperatures and substrate coverages; 2) the use of light and heat to trigger and monitor isomerization switching; and 3) the use of computational chemistry to simulate the adsorption behavior of spiropyran-based isomers.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.