Pendant Photochromic Switches Enabling Fluxional Macromolecular Pi-Electronics

有了这个奖项，在化学系的大分子，超分子和纳米化学计划是资助教授约翰D。托瓦尔和亚瑟E.为了了解具有由光吸收驱动的流动电子结构的π共轭结构单元如何调节有机电子材料的性质，约翰霍普金斯大学化学系的布拉格博士进行了研究。 有机电子学可以影响当代能源和电气科学的许多领域，在大面积照明、储能甚至生物医学等领域都有创新。 这些材料本质上是长链塑料样分子，但具有通过称为π键的特殊键赋予的不寻常的电子特性。 π键与单键的交替使得分子或聚合物在这些键变化时能够导电。 在这项研究中，研究人员首先为具有不同电子性质的聚合物构建分子积木。 利用计算建模系统地研究引入到构建块中的化学变化如何影响它们形成的聚合物的整体性质。 先进的光谱和电学测量技术用于了解电子和分子结构的变化在真实的时间。 这种系统性的研究产生的知识可能会导致从高速晶体管到能量存储等尖端应用的重大改进。 与该项目相关的学生将接触跨学科研究，并准备成为下一代跨学科科学家的领导者。 针对城市巴尔的摩高中的学生和代表性不足的少数群体的教育和外展活动为更广泛的社区参与提供了额外的创造性机会。这项工作的重点是探索有机电子材料衍生自复杂的芳香族结构作为组成部分的光开关共轭聚合物。 该研究计划涉及由各种外部刺激触发的光可切换流动单体单元的合成以及对低聚物和聚合物类似物的扩展，计算建模以了解这些化学变化如何影响电子特性，以及使用稳态和超快或其他时间分辨技术的光谱查询来捕获电子和分子结构的变化。 一般的研究方法主要是关注新的策略，以实现高度极化的聚合物电子结构，而不是特定的带隙工程的能级。从该项目中阐明的想法可以过渡到许多类型的应用特定的材料设计，例如刺激开关晶体管，从而可以从外部控制共轭途径。该奖项反映了NSF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。

With this award, the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry is funding Professors John D. Tovar and Arthur E. Bragg of the Department of Chemistry at Johns Hopkins University to understand how pi-conjugated building blocks with fluxional electronic structures driven by light absorption can tune the properties of organic electronic materials. Organic electronics can impact many areas of contemporary energy and electrical science, with innovations on the horizon in fields such as large-area lighting, energy storage, and even biomedicine. These materials are essentially long chain plastic-like molecules but with unusual electronic properties imparted through special bonds called pi-bonds. The alternation of pi-bonds with single bonds enables the molecules or polymers to conduct electricity when these bonds are varied. In this research, the investigators first construct molecular building blocks for the polymers with different electronic properties. Computational modelling is utilized to systematically investigate how chemical changes introduced into the building blocks affect the overall properties of the polymers from which they are formed. Advanced spectroscopic and electrical measurement techniques are used to understand changes in electronic and molecular structures in real time. Such systematic investigations generate knowledge that could lead to significant improvements in cutting-edge applications ranging from high-speed transistors to energy storage. Students associated with this project are exposed to interdisciplinary research and prepared to be leaders in the next generation of interdisciplinary scientists. Education and outreach activities targeting students and underrepresented minority groups in urban Baltimore high schools provide additional creative opportunities for broader community involvement.This work is focused on the exploration of organic electronic materials derived from complex aromatic structures as components of photoswitchable conjugated polymers. The research plan involves the synthesis of photoswitchable fluxional monomer units triggered by various external stimuli and extensions to oligomeric and polymeric analogues, computational modeling to understand how these chemical changes impact electronic properties, and spectroscopic interrogations using steady-state and ultrafast or other time-resolved techniques to capture changes in electronic and molecular structure. The general research approach is primarily concerned with new strategies to achieve highly polarizable polymer electronic structures as opposed to particular bandgap engineering of energy levels. The ideas elucidated from this project could be transitioned to many types of application-specific materials designs such as stimuli-switchable transistors whereby conjugation pathways can be controlled externally.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.