CAREER: Optically-Controlled Phase Transition of Organic Molecules via Molecular Switching

光响应分子已成为一种光学控制固态材料各种性能的新工具。对固态材料的光学、热、相和机械性能的可逆控制使涉及光存储、能量存储和机械响应的应用成为可能。然而，对固体中光诱导的分子转变以及这种转变如何导致相变的基本理解目前还缺乏。该CAREER研究项目由材料研究部固态与材料化学项目和化学部化学结构、动力学与机制B项目共同支持，拓宽了凝聚态环境中光分子相互作用的知识，并将其转化为对国家能源安全具有巨大影响的太阳能热能储存的理解。该项目有助于研究分子开关，相变行为和可再生太阳能存储的各个领域的进步。此外，它还解决了改善布兰迪斯大学和当地社区中代表性不足的少数族裔参与STEM的关键领域。积极招募来自弱势群体的本科生，并对他们进行有机材料化学方面的培训，并与当地一所高中合作，建立了西班牙语-英语双语科学活动，以促进学生对化学和可再生能源技术的兴趣。技术概述：本研究项目开发了通过光学刺激在固体和液体之间进行可逆相变的有机材料。首席研究员和她的研究小组设计并合成了新的有机功能材料，利用光开关的光诱导构象和极性变化来控制大块材料的相位。探索了各种光致变色核心结构和官能团，从而对结构-性质关系有了深入的了解。研究了新的功能化策略，描述了极性、位阻、分子对称和氟相互作用对凝聚态光开关和随后的相变的影响。通过这项工作，揭示了拥挤环境中的分子开关动力学，并开发了改变分子开关运动部分周围构象自由的策略。此外，相变材料的热参数测量被用作表征工具，以了解凝聚态中分子间相互作用的类型和程度。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。

NON-TECHNICAL SUMMARYLight-responsive molecules have emerged as a new tool to optically control various properties of solid-state materials. Reversible control over the optical, thermal, phase, and mechanical properties of solid-state materials enables applications that involve optical storage, energy storage, and mechanical response. The fundamental understanding of the optically-induced molecular transformation in solids and how such transformation results in phase change, however, is currently lacking. This CAREER research project, jointly supported by the Solid State and Materials Chemistry program in the Division of Materials Research and the Chemical Structure, Dynamics, and Mechanisms B program in the Division of Chemistry, broadens the knowledge on light-molecule interactions in a condensed environment, which is translated to understand solar thermal energy storage that has a tremendous impact on the energy security of the nation. The project contributes to the advancement of various fields studying molecular switching, phase transition behaviors, and renewable solar energy storage. Additionally, it addresses critical areas for improving underrepresented minority engagement in STEM at Brandeis University and in the local community. Undergraduate students from underrepresented groups are actively recruited and trained in organic materials chemistry, and Spanish-English bilingual science events are established in partnership with a local high school to promote the interests of students in chemistry and renewable energy technologies.TECHNICAL SUMMARYWith this research project organic materials that are optically stimulated to undergo reversible phase transitions between solid and liquid are developed. The principal investigator and her research group design and synthesize new organic functional materials that harness the optically-induced conformational and polarity change of photoswitches to control the phase of bulk materials. Various photochromic core structures and functional groups are explored to yield a deep understanding of the structure-property relationship. New functionalization strategies that delineate the effect of the polarity, steric hindrance, molecular symmetry, and fluorous interactions on the condense-phase photoswitching and consequent phase transitions are investigated. Through this work, molecular switching dynamics in a crowded environment are unraveled, and strategies to alter the conformational freedom around the moving parts of molecular switches are developed. Additionally, measurements of thermal parameters of phase transition materials are used as a characterization tool to understand the types and degree of intermolecular interactions in condensed phases.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.