Designing Bright and Fast Fluorophores with Large Stokes' Shifts Based on Superradiant Molecular J-Aggregates

在美国国家科学基金会化学系大分子、超分子和纳米化学项目的支持下，麻省理工学院的蒙吉·g·巴文迪教授和他的团队将研究和利用分子相互作用的基本特性，开发出在几百皮秒的短时间内产生高效光爆发的材料。能够快速有效地发光的材料具有广泛的应用，包括深空光通信，高速智能发光二极管（led）和量子信息技术。受自然光收集系统的复杂性和精致效率的启发，该团队将探索如何通过将分子排列在纳米和微尺度的j聚集体中来改善分子的光学特性。除了这项研究之外，该团队还将努力通过为代表性不足的少数民族和妇女提供机会，使科学更具包容性，以帮助发展她们的科学潜力并赋予弱势社区权力。特别是，该团队将参加麻省理工学院的ACCESS计划，该计划为学生提供课程和研究机会，以帮助弥合从本科到研究生过渡的差距。该团队还将利用针对K-12学生的补充课程来传达进行科学研究的兴奋感。该项目旨在了解激子行为、稳定性和相互作用分子j聚集体耦合的基本特性，以开发寿命短、约为数百皮秒、具有大斯托克斯位移和高量子产率的材料。传统的荧光团用于各种领域，并被优化为高量子产率、大斯托克斯位移和良好的吸收截面。然而，它们在需要短响应时间的系统中的应用受到了限制，因为它们固有的长寿命通常在纳秒范围内。偶联分子j聚集体有可能满足对快速、明亮发色团的需求。该团队将研究结构变化和环境影响如何改变分子聚集体的激子行为，以及什么动力学在聚集体之间的相互作用中起作用。首先，该团队将研究纳米管光收集聚集体的基质效应和结构变化，以及通过在硅壳中封装而固化的影响。其次，该团队将研究分子聚集体中非辐射损失途径的起源以及减轻它们的潜在方法。第三，研究小组将研究稳定的纳米管聚集体之间的耦合，以了解超分子荧光团之间能量转移的关键动力学。这项研究有可能导致对限制j聚集体的激子行为和相互作用的性质的基本理解。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 NSF division of Chemistry, Professor Moungi G. Bawendi and his team at the Massachusetts Institute of Technology will study and harness fundamental properties of molecular interactions to develop materials that generate efficient bursts of light in short timescales that are on the order of a few hundred picoseconds. Materials that can emit light quickly and efficiently have a wide range of applications, including deep-space optical communication, high-speed smart light-emitting diodes (LEDs), and quantum information technologies. Inspired by the complexity and exquisite efficiency of natural light harvesting systems, the team will explore how the optical properties of molecules can be improved by arranging them in nano- and microscale clusters called J-aggregates. In addition to this research, the team will work to make science more inclusive by providing opportunities to under-represented minorities and women in order to help develop their scientific potential and empower disadvantaged communities. In particular, the team will take part in the MIT ACCESS program that provides classes and research opportunities to students to help bridge the gap in transitioning from undergraduate to graduate school. The team will also utilize complementary programs aimed at K-12 students to convey the excitement of conducting scientific research.This project aims to gain understanding of fundamental properties that underlie excitonic behavior, stability, and coupling in interacting molecular J-aggregates to develop materials with short lifetimes that are on the order of hundreds of picoseconds and that feature large Stokes shifts and high quantum yields. Traditional fluorophores are used in a variety of fields and have been optimized for high quantum yield, large Stokes shift, and favorable absorption cross-section. However, their application in systems that require a short response time have been limited due to their inherently long lifetimes that are typically in the nanosecond range. Coupled molecular J-aggregates have the potential to fill the need for fast, bright chromophores. The team will investigate how structural changes and environmental effects alter the excitonic behavior of molecular aggregates, and what dynamics play a role in interactions between aggregates. First, the team will study matrix effects and structural changes in nanotubular light harvesting aggregates, as well as the impact of rigidification through encapsulation in a silica shell. Second, the team will investigate origins of non-radiative loss pathways in molecular aggregates and potential ways to mitigate them. Third, the team will look at the coupling between stabilized nanotubular aggregates to understand the key dynamics involved in energy transfer between supramolecular fluorophores. This research has the potential to lead to a fundamental understanding of the properties that limit excitonic behavior and interactions of J-aggregates.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.