REVERSIBLE OXYGEN ADDUCT FORMATION IN FERROUS COMPLEXES DERIVED FROM A PICKET FENCE PORPHYRIN - MODEL FOR OXYMYOGLOBIN
REVERSIBLE OXYGEN ADDUCT FORMATION IN FERROUS COMPLEXES DERIVED FROM A PICKET FENCE PORPHYRIN - MODEL FOR OXYMYOGLOBIN
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DOI：
10.1021/ja00804a054
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发表时间：
1973-01-01
影响因子：
15
通讯作者：
REED, CA
中科院分区：
文献类型：
--
作者：
COLLMAN, JP;GAGNE, RR;REED, CA
几十年来，化学家们一直在努力。许多关于亚铁络合物可逆地结合分子氧的说法已经提出，1- 9但没有一个得到充分证实，有些后来被证明是无效的，10'11，大多数都依赖于观察一个单一的物理参数，通常是可见光谱的变化，作为氧吸收和可逆性的标准。低温似乎足以延缓某些系统中的不可逆氧化作用8· 9· 12，从而允许观察到某些可逆氧化作用。然而，鉴于现在公认的铁络合物的配体氧化还原反应，13只依赖于溶液光谱变化的标准的可逆氧化的权利要求必须极其谨慎地对待。我们在这里交流的合成和全面表征的结晶dioxygen 14复杂的衍生自一个专门设计的亚铁卟啉complex.可逆氧化的肌红蛋白和血红蛋白似乎是由于固定在疏水口袋内的五坐标高自旋铁（II）卟啉。16铁的不可逆氧化显然是由涉及两个Fe（II）络合物与一个O2分子的双分子相互作用16或质子化产生随后与Fe（II）反应的H2 O2引起的。利用邻位取代的meso-tetraphenylpyrinins中联苯型阻转异构体的概念，我们构建了一种“栅栏”卟啉，其一侧的空间体积为小配体的配位创建了非质子空腔，同时还保护这些配体免受双分子反应的影响。
frustrated chemists for decades. Many claims of ferrous complexes that reversibly bind molecular oxy-gen have been made, 1-9but none have been fully sub-stantiated, some have later proved to be invalid, 10'11 and most have rested on the observation of a single physical parameter, often a change in the visible spec-trum, as a criterion of oxygen uptake and reversibility. Low temperature seems to sufficiently retard irreversible oxidation in some systems8· 9· 12 to permit the observa-tion of some reversible oxygenation. However, in view of the now well-recognized facile ligand redox re-actions of iron complexes, 13 claims of reversible oxygenation which rely solely on the criterion of solution spectral change must be treated with utmost caution. We communicate here the synthesis and full characterization of a crystalline dioxygen14 complex derived from a specifically designed ferrous porphyrin com-plex.Reversible oxygenation of myoglobinand hemoglobin appears to result from a five-coordinate high-spin iron (II) porphyrin immobilized within a hydro-phobic pocket. 16 Apparently irreversible oxidation of iron results from either a bimolecular interaction involving two Fe (II) complexes with one 02 molecule16 or protonation affording H202 which subsequently reacts with the Fe (II). Exploiting the concept of biphenyl-type atropisomerism17 in ortho-substituted meso-tetraphenylporphyrins, we have constructed a “picket fence” porphyrin whose steric bulk on one side creates a nonprotic cavity for the coordination of small ligands while also protecting such ligands from bimolecular reactions.