Regulation of Redox behavior and Proton-coupled Electron Transfer of Transition Metal Complexes with Heteroaromatic Coenzymes as Ligands

对杂芳香辅酶与三（2-吡啶基甲基）胺及其衍生物的钌配合物进行了合成和表征。这些新型配合物通过光谱和电化学测量以及x射线晶体学进行了表征。1)钌-蝶呤配合物为了明确蝶呤框架中2-氨基的作用，我们用6,7-二甲基蝶啶（H_2dmp）代替2-N， n -二甲基-6,7-二甲基蝶啶（H_2dmdmp）合成了钌(II)-TPA配合物。用x射线晶体学、光谱方法和电化学测量对新络合物[Ru(Hdmp)(TPA)]CIO_4进行了表征。晶体结构显示，2-氨基与翼蛋白骨架的8位之间存在分子间氢键，在晶体中形成二聚基序。这表明8-氮具有较高的碱度，在蝶呤的可逆质子化-去质子化两步过程中，8-氮首先接受质子。用光谱和电化学方法评价质子耦合电子转移的结果表明：1。2-氨基上的氢键增强了pterin的质子可及性，提高了pterin氧化还原过程的可逆性。2-氨基在促进翼蛋白的质子耦合电子平稳转移中起着重要作用。2)钌-异氧嗪配合物。我们合成了一种新型的钌(II)-TPA配合物，它是黄素的类似物，并成功地通过晶体结构测定揭示了一种前所未有的配位模式。这种不寻常的配位模式使我们能够观察到氢键加合物与互补的2,6-双（乙酰胺）吡啶氢键受体。加合物的晶体结构被确定为明确地证明了受体被异氧嗪复合物的三点识别。这种氢键不仅改变了配体的氧化还原电位，而且扰乱了配体的单电子还原π-阴离子自由基的电子结构。这些结果表明，酶中黄素辅因子的氢键对辅酶的反应性起着重要的调节作用，从而控制酶的反应性。有关这方面的论文将发表在《新英语》杂志上。化学。, Int。作为非常重要的论文（VIP）。少

Synthesis and characterization were made on ruthenium complexes of heteroaromatic coenzymes with tris(2-pyridylmethyl)amine and its derivatives. Those novel complexes were characterized by spectroscopic and electrochemical measurements, in addition to X-ray crystallography.1) Ruthenium-Pterin ComplexesIn order to clarify the role of the 2-amino group of the pterin framework, we synthesized a ruthenium(II)-TPA complex with 6,7-dimethylpteridine (H_2dmp) in place of 2-N, N-dimethy1-6,7-dimethylpteridine (H_2dmdmp). The new complex, [Ru(Hdmp)(TPA)]CIO_4, was characterized by X-ray crystallography, spectroscopic methods, and electrochemical measurements.The crystal structure was revealed to exhibit intermolecular hydrogen bonding between the 2-amino group and the 8-position of the pterin skeleton to form a dimeric motif in the crystal. This indicates the high basicity of the 8-nitrogen, which accepts proton first in the two-step reversible protonation-deprotonation process of the pterin li … More gands in the Ru-TPA environments.The results obtained in the spectroscopic and electrochemical approach to evaluate the proton-coupled electron transfer indicated following points:1. Hydrogen bonding toward the 2-amino group enhances the proton accessibility of the pterin and improves the reversibility of the redox processes of pterins..2. The 2-amino group plays important roles in promoting smooth proton-coupled electron transfer of pterins.2) Ruthenium-Alloxazine Complexes.We synthesized a novel ruthenium(II)-TPA complex with alloxazine which is an analogue of flavins and succeeded in the crystal structure determination to reveal an unprecedented coordination mode of the alloxazine ligand. The unusual coordination mode allowed us to observe the hydrogen bonding adduct with a complementary hydrogen bonding receptor of 2,6-bis(acetoamide)pyridine. The crystal structure of the adduct was determined to demonstrate unambiguously the three-point recognition of the receptor by the alloxazine complex. This hydrogen bonding not only altered the redox potential of the alloxazine ligand, but perturbed the electronic structure of the one-electron reduced π-anion radical of the coordinated alloxazine. These results imply that the hydrogen bonding toward the flavin cofactors in the enzymes play crucial roles to regulate the reactivity of the coenzymes, which result in the control of the reactivity of the enzymes. A paper about this will appear in Angew. Chem., Int. Ed. as a Very Important Paper (VIP). Less