EXCITED STATED DYNAMICS OF TRANSITION METAL PORPHYRINS

过渡金属卟啉的激发态动力学

• 批准号: 3286093
• 负责人: DEWEY HOLTEN
• 金额: $ 10.79万
• 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 1993-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3286093
• 关键词: charge transfer complex; chemical kinetics; chromium; cobalt; electronic spectra; heavy metals; iron; lanthanum; ligands; manganese; metalloporphyrins; molecular energy level; nickel; photochemistry; photosynthesis; photosystem; protein reconstitution; ruthenium; spectrometry; temperature

Metalloporphyrins serve as the active sites in numerous proteins that carry out important biological functions. Examples of these systems include hemoglobin (ligand binding and release). cytochromes (electron transport), photosynthetic reaction centers (charge separation), and catalase, peroxidases, and cytochrome P450 (redox and catalytic chemistry). A crucial long-standing issue is how the molecular architecture of the porphyrin and its immediate protein environment influences function. The key link between chemical composition and physical structure, on the one hand, and reaction dynamics and function, on the other hand, is the electronic structure of the metalloporphyrin. The relationships between physical structure, electronic structure, and transient state behavior are difficult to study in vivo. A major goal of our research is to investigate these relationships through time- resolved absorption studies of metalloporphyrin excited state and transient state dynamics in vitro. To this end, femtosecond and slower time scale transient absorption studies are proposed in four major areas: 1) mechanisms of radiationless deactivation of nonluminescent porphyrins, 2) mechanisms of photodissociation and photoassociation of ligands from transition metal porphyrins, 3) photophysics of porphyrin dimer sandwich complexes, and 4) excited state dynamics of porphyrin cations and anions. The underlying objectives in each area include the elucidation of the most important contributors to the electronic and vibrational factors that control the energies, rates of formation and decay, and reaction channels of the ring (Pe, Pi*) excited states, metal ring (d, Pi*) and (Pi, d) charge transfer (CT) excited states, and metal (d,d) excited states. The photophysical and photochemical behavior will be investigated for simple systems encompassing well- chosen variations in the metal ion and its oxidation state, axial ligands, porphyrin macrocycle, solvent, and temperature. The proposed studies will not only increase our understanding of metalloporphyrin transient state dynamics in vivo and in vitro, but also address issues of importance in other areas of chemistry and molecular physics, such as excited state relaxation processes and electron transfer mechanisms.

金属磷脂充当许多蛋白质中的活性位点 执行重要的生物学功能。 这些例子 系统包括血红蛋白（配体结合和释放）。 细胞色素（电子传输），光合反应中心 （电荷分离）和过氧化氢酶，过氧化物酶和细胞色素P450 （氧化还原和催化化学）。 至关重要的长期问题是 卟啉的分子结构及其直接的结构如何 蛋白质环境会影响功能。 关键链接 一方面，化学成分和物理结构， 另一方面，反应动态和功能是 金属卟啉的电子结构。 关系 在物理结构，电子结构和瞬态之间 状态行为很难在体内研究。 我们的主要目标 研究是通过时间调查这些关系 - 金属核蛋白激发态和 体外瞬态状态动力学。 为此，飞秒和 在四个 主要领域：1）无辐射失活的机制 非发光卟啉，2）光解离的机制和 过渡金属卟啉的配体的光相结合，3） 卟啉二聚体三明治络合物的光体物理和4）激发 卟啉阳离子和阴离子的状态动力学。 基础 每个区域中的目标包括最多的阐明 电子和振动因子的重要贡献者 控制能量，形成和衰减的速率，以及 环（PE，pi*）激发态，金属环的反应通道 （d，pi*）和（pi，d）电荷转移（CT）激发态和金属 （d，d）激发状态。 光学和光化学 将对涵盖良好系统的简单系统进行研究 金属离子及其氧化状态的选择变化，轴向 配体，卟啉大环，溶剂和温度。 这 拟议的研究不仅会增加我们对 在体内和体外的金属核磷脂瞬态态动力学，但 还解决了化学其他领域的重要性问题 分子物理学，例如激发态放松过程和 电子传输机制。