EXCITED STATE DYNAMICS OF TRANSITION METAL PORPHYRINS

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 卟啉及其相关环系的反应性和松弛动力学。 这些关系是生物多样性机制的核心。 四吡咯发色团的功能，但通常很难 在体内进行详细的研究。因此，对生物多样性的研究 系统必须得到体外四吡咯研究的补充。 对模型化合物的时间分辨和稳态光学性质进行了研究 建议用来描述卟啉辅因子的功能性质 生物系统，如血红素蛋白和光合作用反应 中间。具体目标1是阐明电子性质和 近间距分子的激发态弛豫和电子转移机制 卟啉二聚体。将研究几种四吡咯二聚体来探测密钥 细菌-叶绿素等生物复合体的特性 反应中心的特殊配对。建议的研究将探讨 电子不对称性对电子的性质和弛豫动力学的影响 最低激发态，圆周率重叠图案在定义 涉及强耦合的光物理性质和电子转移 卟啉二聚体。具体目标2是阐明非平面大循环是如何 扭曲调制静态和瞬变的电子性质 四吡咯。四吡咯辅助因子的非平面扭曲为 广泛存在于蛋白质复合体中。派S实验室的研究表明 这种扭曲对基态和激发态有很大的影响 属性。电子弛豫速率和电子路径的研究， 光诱导构象漂移和瞬时配体结合/释放 以及其他性质将扩展到具有不同模式的卟啉 非平面变形(马鞍形、褶皱形、圆顶形、波浪形)、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 对于平面卟啉的此类研究很少，对于非平面的则没有。 复合体。合并后的研究将提供对 四吡咯辅助因子在体内的功能和光谱性质。

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.