Osswald Peter, Würthner Frank
Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
J Am Chem Soc. 2007 Nov 21;129(46):14319-26. doi: 10.1021/ja074508e. Epub 2007 Oct 27.
The activation parameters for the interconversion of atropisomers (P- and M-enantiomer) of core-twisted perylene bisimides have been determined by dynamic NMR spectroscopy (DNMR) and time- and temperature-dependent CD spectroscopy. By comparing the activation parameters of a series of perylene bisimides containing halogen or aryloxy substituents in the bay area (1,6,7,12-positions), a clear structure-property relationship has been found that demonstrates that the kinetic and thermodynamic parameters for the inversion of enantiomers are dependent on the apparent overlap parameter Sigmar* of the bay substituents. This study reveals a high stability (DeltaG(368 K) = 118 kJ/mol) for the atropo-enantiomers of tetrabromo-substituted perylene bisimide in solution. Accordingly, the enantiomers of this derivative could be resolved by HPLC on a chiral column. These enantiomers do not racemize in solution at room temperature and, thus, represent the first examples of enantiomerically pure core-twisted perylene bisimides.
通过动态核磁共振光谱（DNMR）以及时间和温度依赖的圆二色光谱，已确定了核心扭曲苝二酰亚胺的阻转异构体（P-和M-对映体）相互转化的活化参数。通过比较一系列在湾区（1,6,7,12-位）含有卤素或芳氧基取代基的苝二酰亚胺的活化参数，发现了明确的结构-性质关系，这表明对映体反转的动力学和热力学参数取决于湾区取代基的表观重叠参数Sigmar*。该研究揭示了四溴取代苝二酰亚胺的阻转对映体在溶液中的高稳定性（ΔG(368 K) = 118 kJ/mol）。因此，该衍生物的对映体可通过在手性柱上的高效液相色谱法拆分。这些对映体在室温下在溶液中不会外消旋，因此代表了对映体纯的核心扭曲苝二酰亚胺的首个实例。
