National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
Phys Chem Chem Phys. 2009 Dec 28;11(48):11400-3. doi: 10.1039/b913711d. Epub 2009 Sep 25.
Porphyrin is a very important component of natural and artificial catalysis and oxygen delivery in blood. Here, we report that, based on first-principles density-functional calculations, a hydrogen molecule can be adsorbed non-dissociatively onto Ti-, V-, and Fe-porphyrins, similar to oxygen adsorption in heme-containing proteins, with a significant energy gain, greater than 0.3 eV per H(2). The dihydrogen-heme complex will be non-magnetic, as is oxyhemoglobin. In contrast to the backward electron donation of Fe(III)-O(2)(-) in oxyhemoglobin, the dihydrogen binding originates from electron donation from H(2) to the Fe(II). We have identified that the local symmetry of the transition metal center of porphyrins uniquely determines the binding strength, and, thus, one can even manipulate the strength by intentionally and systematically breaking symmetry.
卟啉是天然和人工催化以及血液中氧气输送的重要组成部分。在这里，我们报告说，基于第一性原理密度泛函计算，一个氢分子可以非解离地吸附到 Ti、V 和 Fe 卟啉上，类似于血红素蛋白中氧的吸附，具有显著的能量增益，大于每个 H(2)的 0.3eV。双氢-血红素配合物将是非磁性的，就像氧合血红蛋白一样。与氧合血红蛋白中 Fe(III)-O(2)(-)的反向电子供体不同，双氢结合源于 H(2)向 Fe(II)的电子供体。我们已经确定，卟啉中过渡金属中心的局部对称性独特地决定了结合强度，因此，人们甚至可以通过有意和系统地破坏对称性来操纵强度。
