Cis-dicarbonyl binding at cobalt and iron porphyrins with saddle-shape conformation
Cis-dicarbonyl binding at cobalt and iron porphyrins with saddle-shape conformation
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DOI：
10.1038/nchem.956
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发表时间：
2011-02-01
期刊：
影响因子：
21.8
通讯作者：
Barth, Johannes V.
中科院分区：
文献类型：
--
作者：
Seufert, Knud;Bocquet, Marie-Laure;Barth, Johannes V.
与络合的铁或钴中心相连的双原子分子在许多生物过程中都很重要。在自然系统中，金属四氢吡咯单元携带呼吸气体或提供传感和催化功能。构思合成模型系统有助于确定此类过程的相关化学基础，最近的工作强调了假体基团的构象灵活性作为影响其功能性质的复杂变量的重要性。在这里，我们提供了简单的模型系统，在单分子水平上研究一氧化碳与马鞍形铁和钴卟啉构象的相互作用，这些构象已经稳定为二维阵列在定义良好的表面。使用扫描隧道显微镜，我们发现了一种新的成键方案，该方案在功能金属-大环单元上以倾斜的单羰基和顺式二羰基构型表达。密度泛函理论模拟表明，由于卟啉笼具有明显的马鞍形构象，弱成键的双原子羰基加合物能够有效地将特定的吡咯基团与金属原子连接起来。
Diatomic molecules attached to complexed iron or cobalt centres are important in many biological processes. In natural systems, metallotetrapyrrole units carry respiratory gases or provide sensing and catalytic functions. Conceiving synthetic model systems strongly helps to determine the pertinent chemical foundations for such processes, with recent work highlighting the importance of the prosthetic groups' conformational flexibility as an intricate variable affecting their functional properties. Here, we present simple model systems to investigate, at the single molecule level, the interaction of carbon monoxide with saddle-shaped iron- and cobalt-porphyrin conformers, which have been stabilized as two-dimensional arrays on well-defined surfaces. Using scanning tunnelling microscopy we identified a novel bonding scheme expressed in tilted monocarbonyl and cis-dicarbonyl configurations at the functional metal-macrocycle unit. Modelling with density functional theory revealed that the weakly bonded diatomic carbonyl adduct can effectively bridge specific pyrrole groups with the metal atom as a result of the pronounced saddle-shape conformation of the porphyrin cage.