HYDROGEN BONDING IN METALLOPORPHYRIN REACTIONS

金属卟啉反应中的氢键

• 批准号: 3072306
• 负责人: DWIGHT A SWEIGART
• 金额: $ 5.64万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-07-01 至 1988-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3072306
• 关键词: catalase; chemical reaction; cobalt; cytochromes; electrochemistry; hemoglobin; hemoprotein; hydrogen bond; imidazole; ligands; metalloporphyrins; myoglobin; oxidation reduction reaction; peroxidases; ruthenium; solvents; thermodynamics

The aim of the proposed research is to quantitatively establish the effect of hydrogen bonding on the kinetics, thermodynamics, and redox properties of metalloporphyrin reactions. The hydrogen-bonding is of two types: to an axially coordinated ligand (distal effect) and from an axially coordinated ligand (proximal effect). Preliminary experiments suggest that distal hydrogen-bonding can greatly influence the kinetics and thermodynamics of ligand dissociation and association when the coordinated ligand is anionic. One of the reactions to be investigated is Fe(porphyrin)X + 2 RIm greater than Fe(porphyrin) (RIm)2+, X-, where X is one of a variety of anionic ligands and RIm is an imidazole. This reaction goes through the unstable monoimidazole intermediate Fe(porphyrin) (RIm)X which is a model for a number of hemoproteins. The influence of hydrogen-bonding from RIm and to X- in Fe(porphyrin)(RIm)X will be thoroughly investigated by rapid reaction techniques (low temperature stopped-flow, NMR) and electrochemical techniques (stationary electrode voltammetry, polarography). Several other metalloporphyrins, principally those of cobalt and ruthenium containing coordinated dioxygen, will also be investigated. The hydrogen-bonding to be studied can be from the solvent, nucleophile, or other external source to the distal ligand or from coordinated imidazole to solvent or other basic species. The elucidation of the importance of hydrogen-bonding on the ligand association and dissociation rates, reaction thermodynamics, and metalloporphyrin redox potentials will provide a basis for understanding the importance of these effects in reactions mediated by hemoproteins such as hemoglobin, myoglobin, catalases, peroxidases, and cytochromes.

拟议研究的目的是定量确定效果 氢键对动力学、热力学和氧化还原性质的影响 金属卟啉反应。 氢键有两种类型： 轴向配位配体（远端效应）和来自轴向配位 配体（近端效应）。 初步实验表明，远端 氢键可以极大地影响动力学和热力学 当配体配位时配体解离和缔合 阴离子。 要研究的反应之一是 Fe(卟啉)X + 2 RIm 大于 Fe(卟啉) (RIm)2+, X-，其中 X 是多种之一 阴离子配体，RIm 是咪唑。 该反应经过 不稳定的单咪唑中间体 Fe(卟啉) (RIm)X 是一个模型 对于许多血红素蛋白。 RIm 氢键的影响 Fe(卟啉)(RIm)X中的X-和X-将通过快速彻底研究 反应技术（低温停流、NMR）和电化学 技术（固定电极伏安法、极谱法）。 其他几个 金属卟啉，主要是含钴和钌的金属卟啉 协调的双氧，也将被研究。 氢键作用为 可以从溶剂、亲核试剂或其他外部来源进行研究 到远端配体或从配位咪唑到溶剂或其他 基本种。 阐明氢键的重要性 配体缔合和解离速率、反应热力学以及 金属卟啉氧化还原电位将为理解提供基础 这些效应在血红素蛋白介导的反应中的重要性，例如 如血红蛋白、肌红蛋白、过氧化氢酶、过氧化物酶和细胞色素。