EXCITED STATE DYNAMICS OF TRANSITION METAL PORPHYRINS

过渡金属卟啉的激发态动力学

• 批准号: 6179695
• 负责人: DEWEY HOLTEN
• 金额: $ 15.62万
• 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 2003-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6179695
• 关键词: chemical models; chemical structure function; chlorophyll; cofactor; conformation; dimer; dipole moment; electron transport; electronic spectra; emission spectrometry; fluorescence; fluorescence spectrometry; hemoprotein; intermolecular interaction; laser spectrometry; metalloporphyrins; molecular energy level; molecular orbital; optics; photochemistry; photosynthetic reaction centers; tetrapyrroles; time resolved data

DESCRIPTION: The goal of this research is to understand the relationships among molecular structure, electron properties, and ground and excited state reactivity and relaxation dynamics of porphyrins and related ring systems. These relationships are central to the mechanisms of the diverse biological functions of tetrapyrrole chromophores, but are often difficult to investigate in detail in vivo. Therefore, research on the biological systems must be complemented by the study of tetrapyrroles in vitro. Time-resolved and steady state optical studies of model complexes are proposed to delineate functional properties of porphyrinic cofactors in biological systems such as the heme proteins and photosynthetic reaction center. Specific Aim 1 is to elucidate the electronic properties and excited state relaxation and electron transfer mechanisms of closely-spaced porphyrin dimers. Several tetrapyrrole dimers will be studied to probe key characteristics of biological complexes such as the bacteriochlorophyll special pair of the reaction center. The proposed studies will explore the effects of electronic asymmetry on the nature and relaxation kinetics of the lowest excited states, the role of the pi-overlap pattern in defining photophysical properties, and electron transfer involving strongly-coupled porphyrin dimers. Specific Aim 2 is to elucidate how nonplanar macrocycle distortions modulate the static and transient electronic properties of tetrapyrrole. Nonplanar distortions of the tetrapyrrole cofactors are widely observed in the protein complexes. Work from the PI s lab has shown that such distortions have dramatic effects on ground and excited state properties. Studies of electronic relaxation rates and pathways, photoinduced conformational excursions, and transient ligand binding/release and other properties will be extended to porphyrins with varying modes of nonplanar distotion (saddle, ruffle, dome, wave), chlorins (chlorophyll models), and iron porphyrins (heme models). Complementary ultrafast time resolved vibrational studies will give direct structural information. There have been few such studies for planar porphyrins and none for the nonplanar complexes. The combined studies will provide fundamental insights into the functional and spectroscopic properties of tetrapyrrole cofactors in vivo.

描述：本研究的目的是了解 在分子结构、电子性质、基态和激发态之间 卟啉和相关环系统的反应性和弛豫动力学。 这些关系是生物多样性机制的核心。 四吡咯发色团的功能，但往往难以 在体内进行了详细研究。 因此，研究生物 系统必须通过体外研究四吡咯来补充。 时间分辨和稳态光学研究的模型配合物是 提出描绘卟啉辅因子的功能特性， 生物系统，如血红素蛋白和光合反应 中心 具体目标1是阐明电子性质和 激发态弛豫和电子转移机制 卟啉二聚体。 几个四吡咯二聚体将被研究，以探测关键 细菌叶绿素等生物复合物的特征 反应中心的特殊对。 拟议的研究将探讨 电子不对称性的性质和弛豫动力学的影响， 最低激发态，π重叠模式在定义 电子物理性质和电子转移涉及强耦合 卟啉二聚体。 具体目标2是阐明非平面大环 失真调制的静态和瞬态电子性能 四吡咯。 四吡咯辅因子的非平面畸变是 在蛋白质复合物中广泛观察到。 私家侦探实验室的工作表明 这种扭曲会对基态和激发态产生巨大的影响 特性. 电子弛豫速率和途径的研究， 光诱导构象偏移和瞬时配体结合/释放 和其他性质将扩展到卟啉与不同的模式， 非平面畸变（鞍形、皱褶形、圆顶形、波浪形），叶绿素（叶绿素 模型）和铁卟啉（血红素模型）。 互补超快时间 解析的振动研究将给出直接的结构信息。 那里 对平面卟啉的这类研究很少，而对非平面卟啉的这类研究则没有 配合物 这些综合研究将为以下方面提供基本见解： 四吡咯辅因子在体内的功能和光谱性质。