Pendant Photochromic Switches Enabling Fluxional Macromolecular Pi-Electronics

在化学系大分子、超分子和纳米化学项目的支持下，约翰霍普金斯大学的John D. Tovar和Arthur E. Bragg正在研究由光吸收驱动的具有流动电子结构的pi共轭构建块如何调节有机电子材料的性质。从高速晶体管到光伏电池，再到低阻抗神经电极涂层，各种各样的pi共轭有机分子和聚合物材料目前正在被研究作为尖端应用的活性成分。本研究将包括系统合成几种可光开关的单体、低聚物和聚合物。然后将利用计算模型来检查引入这些构建块的化学变化如何影响它们形成的有机材料的整体特性。最后，先进的光谱和电测量技术将用于实时了解电子和分子结构的变化。这种系统的研究有可能产生基础知识，从而导致从高速晶体管到能量存储等尖端应用的改进。本研究的跨学科性质将为本科生和研究生提供强有力的培训和专业发展机会。通过参与巴尔的摩市城市高中的高中化学教育，将有助于提高妇女和未被充分代表的少数民族在高级学位课程中的参与度。有机电子系统将影响当代能源和电气科学的许多领域，在大面积照明、能源存储和生物医学等领域不断创新。该项目将重点发展pi共轭大分子体系和含有刺激响应光致变色单元的聚合物。重点将放在理解如何通过电环反应改变共轭途径可以影响光电过程。该研究策略将利用噻吩和其他单体单元合成一套新的响应pi系统，并研究有机电子材料中离域途径的可调性。合成将辅以光谱研究，使用稳态、超快和其他时间分辨技术，以及计算建模。与此研究相关的一般方法可能导致实现不同基态组成的高度极化电子结构的新策略，而不是更常见的特定能级带隙工程方法。从长远来看，概述的概念有潜力转化为特定应用的材料设计，例如具有外部可控共轭通路的可激发开关晶体管。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。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, John D. Tovar and Arthur E. Bragg of Johns Hopkins University are investigating how pi-conjugated building blocks with fluxional electronic structures driven by light absorption can tune the properties of organic electronic materials. A wide variety of pi-conjugated organic molecular and polymeric materials are currently being studied as active components for cutting-edge applications ranging from high-speed transistors to photovoltaic cells to low impedance neural electrode coatings. This research will involve the systematic synthesis of several photoswitchable fluxional monomers, oligomers, and polymers. Computational modeling will then be utilized to examine how chemical changes introduced into these building blocks affect the overall properties of the organic materials from which they are formed. Finally, advanced spectroscopic and electrical measurement techniques will be used to understand changes in electronic and molecular structures in real time. Such systematic investigations have the potential to generate fundamental knowledge that could lead to improvements in cutting-edge applications ranging from high-speed transistors to energy storage. The interdisciplinary nature of this research will provide strong training and professional development opportunities for undergraduate and graduate students. The outreach efforts through involvement with high-school chemistry education in urban Baltimore high schools will help increase participation of women and underrepresented minorities in advanced degree programs.Organic electronics systems stand to impact many areas of contemporary energy and electrical science, with innovations on the horizon in fields such as large-area lighting, energy storage, and biomedicine. This project will focus on the development of pi-conjugated macromolecular systems and polymers containing stimuli-responsive photochromic units. Strong emphasis will be placed on understanding how conjugation pathway alteration via electrocyclic reactions can impact optoelectronic processes. The research strategy will utilize thienothiophene and other monomer units to synthesize a new set of responsive pi-systems and investigate the tunability of delocalization pathways within organic electronic materials. The syntheses will be complemented by spectroscopic studies using steady-state, ultrafast and other time-resolved techniques, as well as computational modeling. The general approaches associated with this research could lead to new strategies to achieve highly polarizable electronic structures of varied ground state composition, as opposed to the more common approach of bandgap engineering of specific energy levels. The outlined concepts have the potential, in the longer term, to be transitioned into application-specific materials designs such as stimuli-switchable transistors with externally controllable conjugation pathways.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.