Redox and Excited State Properties of Oligothiophene-Bearing Ru(II) Photodrugs

在化学结构、动力学和机理-B (CSDM-B) 项目的支持下，德克萨斯大学阿灵顿分校的 Sherri McFarland 教授将探究分子构象、电离性和分子间相互作用如何影响光敏剂的行为，特别是含低聚噻吩的钌化合物。光敏剂是利用光能促进所需的物理过程或化学转化的化合物。此类分子在太阳能转化、化学催化以及光医学等领域具有实用性。该项目重点研究一种光敏剂类，该类光敏剂在癌症治疗方面显示出前景，并且可能遵循一种独特的多模式作用，将光催化和分子间光化学反应与单线态氧敏化相结合。该项目将利用配位化学加上光物理和电化学技术来探索异构、团聚和限制以及环境对这些途径的作用。拟议的工作将培训研究生和本科生进行化学、生物学、物理学和工程学的高度多学科研究。这种合成、无机光物理和光谱学以及电化学方面的多方面培训将有助于培养未来的科学技术人才。更广泛的影响目标旨在提高科学素养和解决研究中的教育公平问题。 McFarland 团队特别专注于解决本科生研究中的教育公平问题，并通过为本科 STEM 学生提供基于课程的研究体验 (CURE) 来提高科学素养，从而利用具有社会影响力的从实验室到临床的项目。该项目旨在为未来的领导者提供科学传播技能，并让他们接触创业精神，因为这涉及到将科学发现从实验室推向社会。根据该奖项，Sherri McFarland 教授和她的团队将研究含有低聚噻吩的 Ru(II) 配合物的氧化还原和激发态特性，这些化合物作为光敏剂在从太阳能转换到光医学等领域具有重要的应用。咪唑并[4,5-f][1,10]菲咯啉（IP）配体附加到足够链长n的低聚噻吩（nT）上，采用具有显着配体内电荷转移（ILCT）特征的平面化最低能量三重态。低聚噻吩具有氧化还原活性，相邻的 IP 基团可以实现质子耦合电子转移 (PCET)，以促进 3ILCT 态的催化光氧化还原反应。这些电荷分离的激发态也可能发生化学二聚并产生单线态氧。该项目旨在为这些系统在简单溶剂和复杂生物环境中开发光物理模型。每个系统都将从分子结构、氧化还原化学和光物理学的角度进行研究，并对光疗机制产生长期影响。 UTA 团队将合成并表征寡聚噻吩附加的 Ru(II) 配合物 [Ru(LL)2(IP-nT)]2 ，以探讨各种因素对所提出的 PCET 促进途径的影响：电离态、激发态构象、三重态能量和特征以及双分子过程。合成、光谱和电化学技术将用于测试具有 CT 特征和可电离基团的 nT 三联体对于多模式作用的重要性，并探讨基于电离、构象和异构等因素如何影响生物界面上的激发态动力学。 该项目旨在从长远来看推动配位化学、光化学和光物理学领域的发展，并最终推动光医学领域的发展。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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 support from the Chemical Structure, Dynamics, and Mechanism-B (CSDM-B) program, Professor Sherri McFarland at the University of Texas, Arlington will interrogate how molecular conformation, ionizability, and intermolecular interactions influence the behavior of photosensitizers, particularly oligothiophene-containing ruthenium compounds. Photosensitizers are compounds that harness the light energy to facilitate a desirable physical process or chemical transformation. Such molecules have utility in fields spanning solar energy conversion to chemical catalysis, and also photomedicine. This project focuses on a photosensitizer class that shows promise for cancer therapy and may follow a unique type of multimodal action that combines photocatalysis and intermolecular photochemical reactions with singlet oxygen sensitization. The project will use the tools of coordination chemistry plus photophysical and electrochemical techniques to explore the roles of isomerism, agglomeration and confinement, and environment on these pathways. The proposed work will train graduate students and undergraduates in highly multidisciplinary research at the nexus of chemistry, biology, physics, and engineering. This multifaceted training in synthesis, inorganic photophysics and spectroscopy, and electrochemistry will help to prepare the future workforce in science and technology. The broader impact objectives are aimed at improving scientific literacy and addressing educational equity in research. The McFarland team is particularly focused on addressing educational equity issues in undergraduate research and improving scientific literacy using bench-to-bedside projects with societal impact through curriculum-based research experiences (CUREs) for undergraduate STEM students. The project aims to equip tomorrow’s leaders with skills in science communication and expose them to entrepreneurship as it relates to bringing scientific discoveries from the laboratory to society.Under this award, Professor Sherri McFarland and her team will examine the redox and excited state properties of oligothiophene-containing Ru(II) complexes, compounds that have important applications as photosensitizers in fields ranging from solar energy conversion to photomedicine. Imidazo[4,5-f][1,10]phenanthroline (IP) ligands appended to oligothiophenes (nT) of sufficient chain length n adopt planarized lowest-energy triplet states that are of significant intraligand charge transfer (ILCT) character. Oligothiophenes are redox active, and the neighboring IP group may enable proton coupled electron transfer (PCET) to facilitate catalytic photoredox reactions from the 3ILCT states. These charge-separated excited states may also undergo chemical dimerization and generate singlet oxygen. The project aims to develop a photophysical model for these systems in simple solvents and in complex biological environments. Each system will be studied from the point of view of molecular structure, redox chemistry and photophysics, with longer term implications for phototherapy mechanisms. The UTA team will synthesize and characterize oligothiophene-appended Ru(II) complexes, [Ru(LL)2(IP-nT)]2+, to probe the effects of various factors on the proposed PCET-facilitated pathways: ionization state, excited state conformation, triplet energy and character, and bimolecular processes. Synthetic, spectroscopic, and electrochemical techniques will be used to test the importance of nT-based triplets with CT character and ionizable groups for multimodal action and probe how the excited state dynamics are influenced at biological interfaces based on factors such as ionization, conformation, and isomerism. This project aims to advance the fields of coordination chemistry, photochemistry and photophysics, and ultimately photomedicine, in the longer term.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.