Dynamic Structure and Novel Functions of Dicobalt Complexes

我们用二钴配合物构建了氧化还原可切换的分子容器。分子开关是分子电子器件中极具吸引力的元件，能够在电流、光和热等外界刺激下引起化学和物理变化。在本研究中，利用双钴络合物的结构变化建立了开关体系。钴配合物在Co(III)状态下倾向于六配位结构，而Co(II)物种倾向于四配位结构。Co(III)和Co(II)之间双钴络合物的可逆氧化还原转变提供了一个稳定的分子开关体系。当二胺作为轴向配体时，二胺的每个氨基都配位到具有桥联结构的平面双钴络合物的钴(III)中心。二胺的解离伴随着双钴(III，III)中心在电化学刺激下被还原为Co(II，II)形式。通过钴…的氧化恢复了桥联结构更多的中锋。我们利用这一策略构建了一个分子容器，在二氨基分子中含有冠醚部分。一锅法合成了具有两个钴-碳键的新型水溶性双钴配合物。用核磁共振氢谱、紫外-可见光谱和电喷雾质谱对其结构进行了表征。这些配合物是光敏性的，在可见光照射下钴碳键的光解产生甲基自由基，用ESR自旋捕获技术检测到。合成了一种新型的双核双钴配合物，其中双核配体具有两个N2O2金属结合中心，并通过苯基间隔连接在四氢呋喃中，用循环伏安法研究了其在四氢呋喃中的氧化还原行为。在刚性和平面型双钴络合物存在下，卤代烷在-1.60V和Ag/AgCl存在下的控制电位电解导致了还原偶合。首次证明了刚性平面二钴络合物用于烷基卤化物的还原二聚反应。较少

We constructed redox switchable molecular containers with dicobalt complexes. Molecuar switches are the attractive components of molecular electronic devices capable of inducing chemical and physical changes in response to external stimuli such as electrical current, light, and heat. In this study, switching systems were established by using the structural change of dicobalt complexes. Cobalt complexes prefer a six-coordinated structure at the Co(III) state while the Co(II) species prefer a four-coordinated structure. Reversible redox change of dicobalt complexes between Co(III) and Co(II) provides a stable molecular switching system. When diamine was used as axial ligand, each amino groups of diamine were coordinated to cobalt (III) center of planar dicobalt complex with bridged structure. Dissociation of diamines were accompanied by the reduction of dicobalt (III, III) centers to Co(II, II) form by electrochemical stimulus. The bridged structure was recovered with oxidation of cobalt … More centers. We constructed a switching system using this strategy as a molecular container containing a crown ether moiety in diamino-molecules.One-pot syntheses of new water-soluble dicobalt complexes having two cobalt-carbon bonds were investigated. The complexes were characterized by 'H NMR and UV-vis spectroscopies as well as ESI-MS. These complexes were photo-sensitive and the photo-cleavage of the cobaltcarbon bonds upon irradiation with visible light produced methyl radicals which were detected by ESR spin-trapping techniques. The dicobalt complexes exhibited a high ability for DNA cleavage in comparison to that for the corresponding monocobalt complex.A novel dicobalt complex, where a dinucleating ligand has two N2O2 metal-binding sites which are linked to each other with a phenyl spacer, was synthesized and its redox behavior was investigated in THF using cyclic voltammetry in comparison with that for the corresponding mononuclear complex. The controlled-potential electrolysis of alkyl halides at-1.60 V vs. Ag/AgCl in the presence of the rigid and planar dicobalt complex led to reductive coupling. The use of rigid, planar dicobalt complex to effect the reductive dimerization of alkyl halides has been demonstrated for the first time. Less