EXCITED STATE DYNAMICS OF TRANSITION METAL PORPHYRINS

过渡金属卟啉的激发态动力学

• 批准号: 2177527
• 负责人: DEWEY HOLTEN
• 金额: $ 12.08万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-26 至 1997-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2177527
• 关键词: charge coupled device camera; charge transfer complex; chemical models; chemical structure function; dimer; dipole moment; electric field; electron transport; electronic spectra; emission spectrometry; fluorescence; fluorescence spectrometry; free radicals; hemoprotein; intermolecular interaction; laser spectrometry; metalloporphyrins; molecular asymmetry; molecular energy level; optics; phosphorescence; photosynthetic reaction centers; quinones; tetrapyrroles; time resolved data

the long-term objective of this grant is to elucidate the relationships between structure, electronic properties, and dynamics of tetrapyrroles. These relationships are crucial for the functioning of porphyrins and related molecules in numerous biological systems but are difficult to explore in vivo. However, the functionally-important properties of tetrapyrroles and the diagnostic spectroscopic characteristics of the associated transient states can be systematically examined through time- resolved and steady state spectroscopic studies of simple tetrapyrrole systems in vitro. This proposal focuses on three areas of fundamental importance to the study of the heme proteins and the bacterial photosynthetic reaction center. First, the composition of the electronic states and the associated optical properties and relaxation dynamics of supermolecules consisting of two tetra-pyrroles held in van der Waals contact will be explored. The special properties of strongly-coupled porphyrin dimers such as the bacteriochlorophyll dimer of the reaction center will be investigated using a series of symmetric and asymmetric porphyrin sandwich complexes that differ incrementally in the distance between the macrocycles. Second, the manifestations of excess vibrational energy and the rates and mechanisms of vibrational relaxation in porphyrinic systems will be addressed through ultrafast and steady state optical studies of a series of tetrapyrrole complexes in the condensed and gas phase. It is becoming increasingly clear that vibrational excitation and dynamics widely affect time-resolved spectroscopic measurements of heme proteins and the reaction center and also may be functionally important for the latter. Finally, the proposed research will address the excited state optical properties and relaxation dynamics of tetrapyrrole pi-cation and pi-anion radicals. This is an essentially unexplored area that warrants serious attention considering that porphyrin ionic intermediates are intimate to the function of numerous tetrapyrrole-protein complexes. These important issues will be addressed using femtosecond and slower transient absorption spectroscopy and steady state optical techniques. Collectively, the work will help elucidate the properties of tetrapyrroles that underpin their diverse biological functions.

这笔赠款的长期目标是阐明关系 在结构，电子特性和四吡咯的动力学之间。 这些关系对于卟啉的功能至关重要 许多生物系统中的相关分子，但很难 在体内探索。 但是， 四吡咯和诊断光谱特征 可以通过时间系统地检查相关的瞬态状态 简单四吡咯的解决方案和稳态光谱研究 体外系统。 该提案重点是基本的三个领域 对血红素蛋白和细菌的研究重要性 光合反应中心。 首先，电子的组成 状态和相关的光学特性和放松动力学 超分子由范德华（Van der Waals）组成的两个四吡咯 将探索联系人。 强耦合的特殊特性 卟啉二聚体，例如反应的细菌氯粘合二聚体 将使用一系列对称和不对称的中心研究中心 卟啉三明治络合物在距离上逐渐差异 在大环之间。 其次，多余的表现 振动能以及振动松弛的速率和机制 在卟啉系统中，将通过超快和稳定来解决 一系列四吡咯络合物的状态光学研究 凝结和气相。 越来越清楚 振动激发和动态广泛影响时间分辨 血红素蛋白和反应中心的光谱测量以及 对于后者，也可能在功能上很重要。 最后，提议 研究将解决激发的状态光学特性和放松 四吡俄Pi-cation和pi-anion自由基的动力学。 这是一个 本质上是未开发的区域，值得关注的是 卟啉离子中间体对 许多四吡咯蛋白复合物。 这些重要的问题将是 使用飞秒和较慢的瞬态吸收光谱探测 和稳态光学技术。 总的来说，这项工作将有所帮助 阐明四吡咯的特性，这些特性支撑了它们的多样性 生物功能。