Electronic Structure and Biologically Relevant Reactivity of Low-Spin {FeNO}8 Porphyrin Model Complexes: New Insight from a Bis-Picket Fence Porphyrin
Electronic Structure and Biologically Relevant Reactivity of Low-Spin {FeNO}8 Porphyrin Model Complexes: New Insight from a Bis-Picket Fence Porphyrin
复制标题
DOI：
10.1021/ic400977h
复制
发表时间：
2013-07-01
影响因子：
4.6
通讯作者：
Lehnert, Nicolai
中科院分区：
文献类型：
--
作者：
Goodrich, Lauren E.;Roy, Saikat;Lehnert, Nicolai
由于HNO在生物学中作为一种重要的效应分子的新兴作用，目前对HNO及其去质子化形式，硝酰基阴离子（NO-）与血红素的配位化学有很大的兴趣。本文报道了用三种贫电子卟啉配体和双尖栅卟啉H-2[3，5-Me-BAFP]（3，5-Me-BAFP（2-）= 3，5-甲基-双（芳氧基）-尖栅卟啉二价阴离子）合成四种新的亚铁血红素-硝酰基模型配合物{FeNO}（8）的Enemark-Feltham记法。[Fe（3，5-Me-BAFP）（NO）]（1-NO）的电化学还原诱导nu（N-O）从1684移动到1466 cm（-1），指示形成[Fe（3，5-Me-BAFP）（NO））（-）（1-NO-），并且用贫电子血红素获得类似的结果。这些结果提供了基础，分析亚铁血红素-硝酰基配合物的性能的一般趋势的第一次。特别是，我们发现类似{FeNO}（7）和{FeNO}（8）配合物的电子结构之间存在很强的相关性，我们使用密度泛函理论（DFT）计算进行了分析。为了进一步研究它们的反应活性，我们发展了一种通过相应的[Fe（卟啉）]（-）物种制备纯血红素{FeNO}（8）配合物块体材料的新方法。以这种方式制备的[Fe（To-F2 PP）（NO）]（-）（To-F2 PP 2- =四（邻-二氟苯基）卟啉二价阴离子）与乙酸反应产生相应的{FeNO}（7）配合物，沿着H-2的释放。重要的是，当使用双栅栏卟啉配合物[Fe（3，5-Me-BAFP）（NO）]（-）时，这种歧化反应可以被抑制，令人兴奋的是，使用该系统，我们能够产生迄今为止报道的第一个亚铁血红素-NHO模型配合物。卟啉的栅栏使得该HNO络合物非常稳定，在室温下在溶液中的半衰期类似于5小时。最后，用类似的{FeNO}（8）和{FeNHO}（8）配合物，然后探索它们对NO的生物学相关反应性。
Because of HNO's emerging role as an important effector molecule in biology, there is great current interest in the coordination chemistry of HNO and its deprotonated form, the nitroxyl anion (NO-), with hemes. Here we report the preparation of four new ferrous heme-nitroxyl model complexes, {FeNO}(8) in the Enemark-Feltham notation, using three electron-poor porphyrin ligands and the bis-picket fence porphyrin H-2[3,5-Me-BAFP] (3,5-Me-BAFP(2-) = 3,5-methyl-bis(aryloxy)-fence porphyrin dianion). Electrochemical reduction of [Fe(3,5-Me-BAFP)(NO)] (1-NO) induces a shift of nu(N-O) from 1684 to 1466 cm(-1), indicative of formation of [Fe(3,5-Me-BAFP)(NO))(-) (1-NO-), and similar results are obtained with the electron-poor hemes. These results provide the basis to analyze general trends in the properties of ferrous heme-nitroxyl complexes for the first time. In particular, we found a strong correlation between the electronic structures of analogous {FeNO}(7) and {FeNO}(8) complexes, which we analyzed using density functional theory (DFT) calculations. To further study their reactivity, we have developed a new method for the preparation of bulk material of pure heme {FeNO}(8) complexes via corresponding [Fe(porphyrin)](-) species. Reaction of [Fe(To-F2PP)(NO)](-) (To-F2PP2- = tetra(ortho-difluorophenyl)porphyrin dianion) prepared this way with acetic acid generates the corresponding {FeNO}(7) complex along with the release of H-2. Importantly, this disproportionation can be suppressed when the bis-picket fence porphyrin complex [Fe(3,5-Me-BAFP)(NO)](-) is used, and excitingly, with this system we were able to generate the first ferrous heme-NHO model complex reported to date. The picket fence of the porphyrin renders this HNO complex very stable, with a half-life of similar to 5 h at room temperature in solution. Finally, with analogous {FeNO}(8) and {FeNHO}(8) complexes in hand, their biologically relevant reactivity toward NO was then explored.