Inframolecular protonation process of norbadione A: influence of the ionic environment and stereochemical consequences.
Inframolecular protonation process of norbadione A: influence of the ionic environment and stereochemical consequences.
复制标题
降巴二酮 A 的分子下质子化过程：离子环境的影响和立体化学后果。
DOI：
10.1021/ja0483185
复制
发表时间：
2005
影响因子：
15
通讯作者：
B. Spiess
中科院分区：
文献类型：
--
作者：
Paul Kuad;M. Borkovec;M. Desage;Thierry Le Gall;C. Mioskowski;B. Spiess
用~1H NMR滴定法和原子团膨胀法研究了从蘑菇中提取的色素norbadione A的微观质子化机理。这项研究揭示了pH依赖性Z到E异构体的转换，发生在两个枕状部分。因此，降冰片二酮A可以以四种立体异构体形式（E-E、E-Z、Z-E和Z-Z）存在于溶液中，这在分子水平器件的开发中可能是令人感兴趣的。在0.15 M NaCl的存在下，计算的微常数显示出一个不寻常的表观的烯醇基团之间的协同性，这是由于释放的钠阳离子质子化降冰片二酮A。
The microscopic protonation mechanism, at an inframolecular level, of norbadione A, a pigment extracted from mushrooms and known to complex cesium cations, was determined by using 1H NMR titrations and the cluster expansion method. This study revealed a pH dependent Z to E isomer switch that occurs in both pulvinic moieties. As a consequence, norbadione A can exist in solution in four stereomeric forms (E-E, E-Z, Z-E, and Z-Z), which can be of interest in the development of molecular-level devices. In the presence of 0.15 M NaCl, the calculated microconstants showed an unusual apparent cooperativity between the enol groups, which results from the release of the sodium cations upon protonation of norbadione A.