RUI: Photophysics of Small-Molecule and Polymeric Fullerene-Transition Metal Organometallic Supramolecular Systems

RUI：小分子和聚合物富勒烯-过渡金属有机金属超分子体系的光物理学大分子、超分子和纳米化学计划支持北肯塔基大学的Keith A.Walters教授合成富勒烯和过渡金属的有机金属体系及其光谱行为。相对简单的Diels-Alder反应允许这些分子的官能化，并提供了将富勒烯结合到pi共轭配体结构中并最终与各种过渡金属(如Re和Ru)形成络合物的机会。对后续系统的光谱分析表明，存在多个激发态和衰变路径。斯塔克吸收光谱被用来确认电荷转移正在发生。在这项工作中，研究人员将继续进行这些研究，目标有几个：1)研究其他反应方法以提高反应的产率，包括使用微波辅助反应；2)在类似系统中探索其他多芳香族部分(如冠烯和冠烯)，以更好地了解有机亚基在观察到的光物理中的作用；3)修饰过渡金属和富勒烯之间的键，以可能增加它们的激发态相互作用；以及4)将努力扩展到小分子以外，制备包含取代的富勒烯构筑块和过渡金属发色团的聚(苯乙炔)型聚合物。这项研究将扩展有机金属超分子化学领域的知识，并为各种分子器件的应用提供新的结构，例如在太阳能转换方面。在过去的二十年里，人们对用于能量转换(例如太阳能电池)和电荷传输(例如分子线)的分子器件的设计产生了浓厚的兴趣。这种方法已经从纯有机聚合物体系发展到利用过渡金属生色团来调整有机聚合物的有机金属体系，需要大量的重新设计来改变体系的S性质。沃尔特斯的研究小组对这些系统感兴趣已经有一段时间了，他们探索了光激励下的合成挑战和系统特性。这项工作的中心是本科生研究人员开发的方法，即在富勒烯上附加一个简单的化学手柄。将这些修饰的富勒烯和过渡金属结合在一起的有机金属系统在光激发后表现出复杂的行为，这表明电荷确实在分子的各个部分之间移动，这是所需的分子器件中的必要成分。展望未来，这项研究试图进一步了解这些分子如何与光相互作用。所获得的知识还将应用于聚合物系统的创建，这是在所需的新分子装置中使用这些材料的一个重要的进化步骤。此外，本科生研究人员将与其他系教师和北肯塔基大学的化学学生团体合作开展外联活动，通过演讲和其他演示来宣传替代能源和纳米材料的重要性。

RUI: Photophysics of Small-Molecule and Polymer Fullerene-Transition Metal Organometallic Supramolecular SystemsThe Macromolecular, Supramolecular, and Nanochemistry Program supports Professor Keith A. Walters of Northern Kentucky University for the synthesis and spectroscopic behavior of organometallic systems that combine fullerenes and transition metals. Relatively simple Diels-Alder reactions have allowed for the functionalization of these molecules and provided an opportunity to incorporate fullerene into pi-conjugated ligand structures and ultimately to form complexes with various transition metals (e.g., Rhenium and Ruthenium). Spectroscopic analysis of the ensuing systems indicates the presence of multiple excited states and decay pathways. Stark absorption spectroscopy is being used to confirm that charge transfer is taking place. In this work, the researchers will continue these investigations with several goals: 1) to investigate other reaction methodologies to improve the yields of the reactions, including the use of microwave-assisted reactions; 2) to explore other polyaromatic moieties (e.g., coronene and corannulene) in analogous systems to better understand the role of the organic subunit in the observed photophysics; 3) to modify the linkages between the transition metal and fullerene to possibly increase their excited state interaction; and 4) to expand efforts beyond small molecules and prepare poly(phenylene-ethynylene)-type polymers containing the substituted fullerene building blocks and transition metal chromophores. The research will expand knowledge in the field of organometallic supramolecular chemistry and provide new structures for use in various molecular device applications, for example in solar energy conversion. Over the past two decades, there has been keen interest in the design of molecular devices for use in energy conversion (e.g., solar cells) and charge transport (e.g., molecular wires). This approach has evolved from purely organic polymeric systems, which require considerable redesign to modify the system?s properties, to organometallic systems that utilize transition metal chromophores to tune the organic polymer. The Walters research group has been interested in these systems for some time, where both the synthetic challenges and system characteristics upon light excitation are explored. This work is centered upon methods developed by undergraduate researchers that attach a simple chemical handles to fullerene. Organometallic systems bringing together these modified fullerenes and transition metals have exhibited complex behavior following light excitation that suggests charge does move between portions of the molecule, a necessary component in the desired molecular devices. Moving forward, this research seeks to further understand how these molecules interact with light. The acquired knowledge will also be applied in the creation of polymeric systems, an essential evolutionary step in the use of these materials in the desired new molecular devices. In addition, undergraduate researchers will work with other department instructors and with the chemistry student group at Northern Kentucky University in their outreach activities to advance the importance of alternative energy and nanoscale materials through presentations and other demonstrations.