Excited-State Proton Transfer in Chemistry and Biology

阐明超快反应的机理需要在光激发时被激活的分子。 对于光诱导的电子转移，这样的分子是容易获得的。 对于光诱导质子转移，需要在激发态下变成强酸（光酸）的分子。 虽然分子重排产生永久性酸，即，光酸产生剂在平版印刷工业中是重要的，但是作为瞬时酸的分子更难以捉摸。该计划旨在开发此类分子-该领域各种研究人员的普遍兴趣-并且在使用理论有机化学和有机合成的原理来提供此类试剂方面是独一无二的。 在这个过程中，该小组正在生产酸性接近强无机酸的光酸。 最近，这些方法已经扩展到生物学中的光酸，利用绿色荧光蛋白（GFP）的独特机制，其通过中继机制表现出质子转移级联。 通过将GFP拆开并重新组装，该小组正在阐明这种革命性蛋白质的物理学细节，并将其应用于许多相关系统。 除了继续这些研究之外，他们还建议将这些原理应用于GFP发色团的开发，剥离其保护性蛋白质桶，以及一类新的传感器，该传感器使用荧光开关和质子转移来在传感过程中提供两个变量。他们进一步建议继续研究新的光酸，揭示离子对动力学的细节和非对映选择性对酸解离的影响。 研究范围广泛，包括超临界介质和分子射流。拟议活动的智力价值在于设计和合成新的“超级”光酸，验证超快质子转移的分子细节模型，以及将这些模型用于生物学中的质子转移。 拟议活动的更广泛影响包括为光谱学家和光生物学家的更大社区开发新的光谱和机械工具，通过在会议和文献中传播这些结果来转让这种技术和知识基础，与一些实验室的科学家合作，以及培养一批精通有机合成，光谱学，机械化学和合作研究。托尔伯特将访问10所历史悠久的黑人大学的赠款的第一年，以比较他们在建设本科生化学研究生院的努力，并与他在克拉克亚特兰大大学的经验进行比较，以提高他在招聘非洲裔美国人克拉克亚特兰大的有效性。

Elucidating the mechanism of ultrafast reactions requires molecules which are activated upon photoexcitation. For photoinduced electron transfer, such molecules are readily available. For photoinduced proton transfer, molecules are required which become strong acids (photoacids) in the excited state. Although molecules which rearrange to generate permanent acids, i.e., photoacid generators, are important in the lithographic industry, molecules which are transient acids are more elusive. This program has sought to develop such molecules--of general interest to a variety of investigators in the field--and is unique in using the principles of theoretical organic chemistry and organic synthesis to provide such reagents. The group, in the process, is producing photoacids with acidities approaching that of strong mineral acids. More recently, these methods have been extended to photoacids in biology, taking advantage of the unique mechanism of the green fluorescent protein (GFP), which exhibits a proton transfer cascade through a relay mechanism. By taking GFP apart and putting it back together, the group is elucidating the details of the photophysics of this revolutionary protein and applying them to a number of related systems. In addition to continuing these studies, they propose to apply these principles to the development of GFP chromophores, stripped of their protective protein barrel,and to a new category of sensors which use both fluorescence off-on switching and proton transfer to give two variables in the sensing process. They further propose to continue studies on new photoacids which reveal details of ion-pair dynamics and effects of diastereoselectivity on acid dissociation. A wide array of objects including supercritical media and molecular jets will be studied.The intellectual merit of the proposed activity lies in the design and synthesis of new "super" photoacids, the validation of models for the molecular details of ultrafast proton transfer, and the use of those models in proton transfer in biology. The broader impacts of the proposed activity encompass the development of new spectroscopic and mechanistic tools for the larger community of spectroscopists and photobiologists, the transfer of this technology and knowledge base through dissemination of these results at conferences and the literature, the collaboration with scientists in a number of laboratories, and the development of a set of future scientists skilled in organic synthesis, spectroscopy, mechanistic chemistry, and collaborative research. As part of this effort, Prof. Tolbert will visit 10 historically black universities the first year of the grant to compare their efforts in building undergraduates for graduate school in chemistry and compare those with his experience at Clark Atlanta University in order to improve his effectiveness in recruitment of African-Americans to Clark Atlanta.