Functions of Aromatic Rings in the Metal Coordination Sphere.

通过对模型化学体系和金属蛋白的研究，探索了金属离子附近芳环的新配位化学。各种特殊的非共价相互作用，如金属-芳香族、芳香族-芳香族堆积相互作用，已经通过结构、光谱和热力学方法建立起来。其特殊结构包括金属蝶呤、金属苯酚、金属吲哚环、金属碘化苯酚、苯酚自由基和蝶呤自由基。目前的研究集中在以下几个方面：1)金属离子附近芳环的弱相互作用，2)金属-芳环相互作用，3)金属配位空间的氧化还原反应和自由基的形成，以及4)涉及特定弱相互作用的功能体系的构建。这些观点揭示了化学反应活性是如何受涉及芳环的特定结构控制的，这为理解更复杂的含有金属蛋白的体系奠定了基础。金属蛋白质的带电基团或芳香族侧链之间的分子间相互作用控制着蛋白质的结构和氧化还原性质，从而控制蛋白质的电子转移等功能。

New coordination chemistry of aromatic rings in the proximity of a metal ion was pursued by the studies of the model chemical systems and metalloproteins. Various specific noncovalent interactions such as metal-aromatic, aromatic-aromatic stacking interactions have been established by structural, spectroscopic, and thermodynamic methods. The specific structures revealed the metal-pterin, metal-phenol, metal-indole ring, metal-iodinated phenol, phenol radical, and pterin radical. The present studies focused on the following points :1) weak interactions involving aromatic rings in the proximity of a metal ion, 2) metal-aromatic ring interactions, 3) redox reactions and radical formation in the metal coordination sphece, and 4) construction of functional systems involving specific weak interactions. These points revealed how the chemical reactivity is controlled by the specific structure involving aromatic rings, which serves as a bases for understanding more complex systems containing metalloproteins. Intermolecular interactions between charged groups or aromatic side chains of metalloproteins control the structures and redox properties and thus the function of proteins such as electron transfer.