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Structural Insights into Ligand Dynamics: Correlated Oxygen and Picket Motion in Oxycobalt Picket Fence Porphyrins
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2012-06-12 , DOI: 10.1021/ja303475a Jianfeng Li 1 , Bruce C Noll , Allen G Oliver , W Robert Scheidt
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2012-06-12 , DOI: 10.1021/ja303475a Jianfeng Li 1 , Bruce C Noll , Allen G Oliver , W Robert Scheidt
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Two different oxygen-ligated cobalt porphyrins have been synthesized and the solid-state structures have been determined at several temperatures. The solid-state structures provide insight into the dynamics of Co-O(2) rotation and correlation with protecting group disorder. [Co(TpivPP)(1-EtIm)(O(2))] (TpivPP = picket fence porphyrin) is prepared by oxygenation of [Co(TpivPP)(1-EtIm)(2)] in benzene solution. The structure at room temperature has the oxygen ligand within the ligand binding pocket and disordered over four sites and the trans imidazole is disordered over two sites. The structure at 100 K, after the crystal has been carefully annealed to yield a reversible phase change, is almost completely ordered. The phase change is reversed upon warming the crystal to 200 K, whereupon the oxygen ligand is again disordered but with quite unequal populations. Further warming to 300 K leads to greater disorder of the oxygen ligands with nearly equal O(2) occupancies at all four positions. The disorder of the tert-butyl groups of the protecting pickets is correlated with rotation of the O(2) around the Co-O(O(2)) bond. [Co(TpivPP)(2-MeHIm)(O(2))] is synthesized by a solid-state oxygenation reaction from the five-coordinate precursor [Co(TpivPP)(2-MeHIm)]. Exposure to 1 atm of O(2) leads to incomplete oxygenation, however, exposure at 5 atm yields complete oxygenation. Complete oxygenation leads to picket disorder whereas partial (40%) oxygenation does not. Crystallinity is retained on complete degassing of oxygen in the solid, and complete ordering of the pickets is restored. The results should provide basic information needed to better model M-O(2) dynamics in protein environments.
中文翻译：
配体动力学的结构洞察：氧钴栅栏卟啉中相关的氧和桩运动
已经合成了两种不同的氧连接钴卟啉，并在几个温度下确定了固态结构。固态结构提供了对 Co-O(2) 旋转动力学以及与保护基团无序相关性的深入了解。 [Co(TpivPP)(1-EtIm)(O(2))]（TpivPP = 栅栏卟啉）是通过 [Co(TpivPP)(1-EtIm)(2)] 在苯溶液中氧化制备的。室温下的结构在配体结合袋内具有氧配体并且在四个位点上无序，并且反式咪唑在两个位点上无序。晶体经过仔细退火以产生可逆相变后，100 K 下的结构几乎是完全有序的。将晶体加热至 200 K 后，相变发生逆转，氧配体再次无序，但数量相当不平等。进一步升温至 300 K 会导致氧配体更加无序，所有四个位置上的 O(2) 占据几乎相等。保护桩的叔丁基的无序性与O(2)围绕Co-O(O(2))键的旋转相关。 [Co(TpivPP)(2-MeHIm)(O(2))]由五配位前体[Co(TpivPP)(2-MeHIm)]通过固态氧化反应合成。暴露于 1 atm 的 O(2) 会导致不完全氧化，然而，暴露于 5 atm 时会产生完全氧化。完全氧合会导致纠察混乱，而部分（40%）氧合则不会。固体中的氧完全脱气后，结晶度得以保留，并且桩的完全有序性得以恢复。结果应提供更好地模拟蛋白质环境中 MO(2) 动力学所需的基本信息。
更新日期：2012-06-12
中文翻译：
配体动力学的结构洞察：氧钴栅栏卟啉中相关的氧和桩运动
已经合成了两种不同的氧连接钴卟啉，并在几个温度下确定了固态结构。固态结构提供了对 Co-O(2) 旋转动力学以及与保护基团无序相关性的深入了解。 [Co(TpivPP)(1-EtIm)(O(2))]（TpivPP = 栅栏卟啉）是通过 [Co(TpivPP)(1-EtIm)(2)] 在苯溶液中氧化制备的。室温下的结构在配体结合袋内具有氧配体并且在四个位点上无序，并且反式咪唑在两个位点上无序。晶体经过仔细退火以产生可逆相变后，100 K 下的结构几乎是完全有序的。将晶体加热至 200 K 后，相变发生逆转，氧配体再次无序，但数量相当不平等。进一步升温至 300 K 会导致氧配体更加无序，所有四个位置上的 O(2) 占据几乎相等。保护桩的叔丁基的无序性与O(2)围绕Co-O(O(2))键的旋转相关。 [Co(TpivPP)(2-MeHIm)(O(2))]由五配位前体[Co(TpivPP)(2-MeHIm)]通过固态氧化反应合成。暴露于 1 atm 的 O(2) 会导致不完全氧化，然而，暴露于 5 atm 时会产生完全氧化。完全氧合会导致纠察混乱，而部分（40%）氧合则不会。固体中的氧完全脱气后，结晶度得以保留，并且桩的完全有序性得以恢复。结果应提供更好地模拟蛋白质环境中 MO(2) 动力学所需的基本信息。
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