RAMAN STUDIES OF PORPHYRIN DIMERS AND BINUCLEAR SYSTEMS

生物体内能量传递机制的阐明 系统需要表征的结构，磁性和 （i）二聚体和较大聚集体的光谱性质 发色团和（ii）分子，其中多个金属中心位于 近距离 这项研究的目的是探讨这些 一系列代表性的二聚体和双核系统的性质， 它们的组成单体使用共振拉曼（RR）光谱。 这些 系统包括（i）单体Fe、Ru、Os、Co、Rh、Ir、Cr、Mn和Hg 卟啉，（ii）单体Mg、Ni和Fe二氢卟酚和脱镁叶绿酸（iii） 单原子桥联铁卟啉和二氢卟酚二聚体，（iv）金属-金属 键合的（Ru，Os，Rh）和夹心（Hg，Ce）卟啉二聚体和（v） 含交换偶联Fe、Cu和Cr的非卟啉双核配合物 离子。 金属卟啉和金属二氢卟啉的RR光谱是 在各种温度和激发波长下获得 范围从紫外线到光谱的红色区域。 RR激励 轮廓正在构建中，去极化的分散 测量拉曼带的比率。 这些具体目标 RR研究有三个方面：（i）严格表征振动 光谱和电子结构的系统，（ii）阐明 二聚引起的单体系统的扰动和（iii） 寻找显着耦合（激子相互作用）之间的证据 二聚体单元的组成单体。 电子顺磁 共振和理论研究也正在进行一些 系统，以表征其磁特性。 的 非卟啉双核过渡金属配合物的研究包括 获得光谱的近UV区域中的RR光谱，其中 发生配体-金属电荷转移跃迁。 这些研究的目的 是确定低电子态之间的跃迁 其包括交换耦合系统的自旋流形， 直接用RR光谱法观察。 综合起来， 各种单体、二聚体和双核系统应有助于提供 更全面地了解分子和电子 交互.

The elucidation of the mechanism of energy transduction in biological systems requires the characterization of the structural, magnetic and spectroscopic properties of (i) dimeric and larger aggregates of chromophores and (ii) molecules in which multiple metal centers lie in close proximity. The purpose of the proposed research is to probe these properties of a series of representative dimeric and binuclear systems and their constituent monomers using resonance Raman (RR) spectroscopy. These systems include (i) monomeric Fe, Ru Os, Co, Rh, Ir, Cr, Mn and Hg porphyrins, (ii) monomeric Mg, Ni, and Fe chlorins and pheophorbides (iii) single-atom bridged Fe porphyrin and chlorin dimers, (iv) metal-metal bonded (Ru, Os, Rh) and sandwich (Hg, Ce) porphyrin dimers and (v) nonporphyrin binuclear complexes containing exchange-coupled Fe, Cu and Cr ions. The RR spectra of the metalloporphyrins and metallochlorins are being obtained at a variety of temperatures and at excitation wavelengths ranging from the UV to the red region of the spectrum. RR excitation profiles are being constructed and the dispersions of the depolarization ratios of the Raman bands are being measured. The specific aims of these RR studies are threefold: (i) rigorously characterize the vibrational spectra and electronic structure of the systems, (ii) elucidate perturbations of the monomer system induced by dimerization and (iii) search for evidence of significant coupling (exciton interactions) between the constituent monomers of the dimeric unit. Electron paramagnetic resonance and theoretical studies are also being conducted on a number of the systems in order to characterize their magnetic properties. The studies of nonporphyrin binuclear transition-metal complexes involve obtaining RR spectra in the near UV region of the spectrum, where ligand-metal charge-transfer transitions occur. The goal of these studies is to determine whether transitions between the low-lying electronic states which comprise the spin manifold of the exchange-coupled system can be directly observed with RR spectroscopy. Taken together, the studies of the various monomeric, dimeric and binuclear systems should help to provide a more comprehensive picture of the nature of molecular and electronic interactions.