Excited state dynamics of shape-shifting molecules

响应于光而改变形状（异构化）的分子在许多光控技术应用中是必不可少的，包括光学存储寄存器、先进材料和能够在微观水平上执行特定任务的纳米技术分子机器。除了它们的技术应用外，形状改变的“光开关”分子具有广泛的生物学重要性，包括在视觉，细菌中的向光性和光合作用以及离子通道开关中的作用。这些光开关分子的形状变化特性源于两种或更多种不同的异构体的存在，这些异构体可以在暴露于不同颜色的光之后切换。每种异构体都可能具有独特的性质，包括分子体积、颜色、溶解度和电导率。提高我们对光开关的光化机制细节（即所谓的激发态动力学）的分子水平理解，对于合理设计改进的衍生物至关重要。由于光电开关广泛应用于日常生活，因此利用这一知识变得越来越重要，需要新的光谱方法来提供更高的选择性和信息含量。特别是，光谱工具包必须有能力独立地探测与每个异构体相关的激发态动力学，这总是发生在超快飞秒（0.0000000000001秒）的时间尺度，也有能力将分支转换为多个光开关形式或降解途径。使用常规的分析或物理化学技术通常难以或不可能验证每种异构体的固有光开关性质，特别是当存在几种异构体、快速相互转化和强烈的环境影响时。该研究计划将开发新的真空仪器和方法来帮助解决这些缺陷，并将重点应用该工具包来表征在光电子学和生物技术分子光学控制中重要的两类分子光开关。基于我们从多个世界领先实验室获得的独特专业知识，该研究计划将在英国建立长期研究基础设施，允许研究形状选择的分子及其超快的形状变化动力学。仪器和方法将提供一种独特的新方法，并提供任何其他单一研究小组都不可能实现的最终功能。

Molecules that change shape (isomerise) in response to light are essential in numerous light-controlled technological applications including optical memory registers, advanced materials and nanotechnological molecular machines capable of performing specific tasks at the microscopic level. In addition to their technological applications, shape-changing 'photoswitch' molecules have widespread biological importance, including roles in vision, phototropism and photosynthesis in bacteria, and ion channel switches. The shape-shifting properties of these photoswitch molecules stems from the existence of two or more distinct isomers that can be toggled following exposure to different colours of light. Each isomer may have unique properties, including molecular volume, colour, solubility, and conductivity.Improving our molecular-level understanding of the actinic mechanistic details of photoswitching - the so-called excited state dynamics - is critical for the rational design of improved derivatives. Harnessing this knowledge is becoming increasingly important due to the widespread adoption of photoswitches into everyday life, requiring new spectroscopic methodologies that offer increased selectivity and information content. In particular, the spectroscopic toolkit must have the capacity to independently probe the excited state dynamics associated with each isomer, which invariably occurs over the ultrafast femtosecond (0.000000000000001 second) timescale, and also the capacity to characterise branching to multiple photoswitch forms or degradation pathways. It is often difficult or impossible to characterise the inherent photoswitching properties of each isomer using conventional analytical or physical chemistry techniques, particularly when there are several isomers, rapid interconversion and strong environmental influences. This research program will develop new vacuum-based instrumentation and methodology to help address these deficiencies and will focus on applying the toolkit to characterising two classes of molecular photoswitches important in optoelectronics and optical control of biotechnological molecules.Building on our unique expertise gained from multiple world-leading laboratories, this research program will establish long-term research infrastructure in the UK, permitting study of shape-selected molecules and their ultrafast shape-shifting dynamics. The instrumentation and methodology will provide a distinctive new approach and offer end capabilities that are not possible by any other single research group.