Multi-Excited-State Phosphorescent Molecules With Photoinduced Structural Changes

在这个由化学学部化学结构、动力学与机制B项目资助的项目中，佛罗里达a&m大学-佛罗里达州立大学工程学院化学与生物医学工程系的Biwu Ma教授正在开发和研究一类具有有趣光物理性质的新型磷光金属配合物。本研究的目标是获得对这些具有可控势能面（PES）和光致结构变化（PSC）的分子的激发态动力学和动力学的基本理解，这些分子具有从分子电子学，太阳能转换装置到发光二极管等各个领域的潜在应用。该研究包含了分子设计、合成、结构表征、光谱学、计算和器件等多学科元素，非常适合新一代科学家的综合教育。该研究小组在培养各级科学家方面有着丰富的历史，包括本科生和来自代表性不足群体的科学家。涉及K-12学生的外展活动也是该项目的一部分。光致结构变化（PSC）可以导致多个激发态的形成。然而，精确控制PSC以在平衡状态下产生多个激发态是具有挑战性的。该小组开发了一类吡甲酸桥接铂双核配合物，由于PSC在平衡状态下具有多个激发态。为了进一步研究这类有趣的分子，利用超快时间分辨发射光谱和瞬态吸收光谱来获得光学交易和结构变化过程的基本认识，以及分子形状和电子结构对这些分子的激发态动力学和动力学的影响。此外，合成了具有可调谐PES和PSC的新型多激发态光活性分子，利用其独特的将光子能量转化为势能触发具有不同光学和电子性质的结构重排的能力，可以开发一种新型的分子光敏器件。

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Biwu Ma of the Department of Chemical and Biomedical Engineering at Florida A&M University - Florida State University College of Engineering is developing and studying a new class of phosphorescent metal complexes with interesting photophysical properties. The goal of this research is to gain fundamental understanding of the excited state dynamics and kinetics of these molecules with controlled potential energy surfaces (PES) and photoinduced structural changes (PSC), which have potential applications in various areas, ranging from molecular electronics, solar energy conversion devices, to light emitting diodes. The research contains multidisciplinary elements of molecular design, synthesis, structural characterization, spectroscopy, computation, and device, which is well suited for an integrated education of new generation scientists. The research group has a rich history of training scientists at all levels, including undergraduates and those from underrepresented groups. Outreach activities involving K-12 students are also a part of this project. Photoinduced structural changes (PSC) can lead to the formation of multiple excited states. However, precise control of PSC to create multiple excited states in equilibrium is challenging. The group developed a class of pyrazolate bridged platinum binuclear complexes that possesses multiple excited states in equilibrium as a result of PSC. To further the study of this class of interesting molecules, ultrafast time-resolved emission spectroscopy and transient absorption spectroscopy are utilized to gain fundamental understanding of the optical transactions and structural change processes, and the effects of molecular shape and electronic structure on the excited state dynamics and kinetics of these molecules. In addition, new multi-excited-state photoactive molecules with tunable PES and PSC are synthesized, with which a new type of molecular photosensing devices can be developed, considering their unique capability of converting photonic energy to potential energy to trigger structural rearrangements with distinct optical and electronic properties.