Scheins Stephan, Messerschmidt Marc, Morgenroth Wolfgang, Paulmann Carsten, Luger Peter
Institute for Chemistry and Biochemistry/Crystallography, Free University of Berlin, Fabeckstrasse 36a, 14195 Berlin, Germany.
J Phys Chem A. 2007 Jun 28;111(25):5499-508. doi: 10.1021/jp0709252. Epub 2007 May 26.
The electron densities of five morphine related molecules (codeine, diprenorphine, naltrexone in the neutral and protonated states, and dextromethorphan) were determined from high-resolution X-ray diffraction experiments (Mo Kalpha and synchrotron primary radiation) at low temperature and CCD area detection techniques. Bond topological analyses were applied, and a partitioning of the molecules into atomic regions making use of Bader's zero flux surfaces yielded atomic volumes and charges. The obtained atom and bonding properties were compared to the results of a previous experimental study of morphine and to theoretical calculations. Experimental and theoretical properties for all chemically equivalent bonds agree within an uncertainty range as is otherwise seen for different theoretical calculations. Hence, the transferability of chemically equivalent submolecular properties, being a key issue of the atoms in molecules (AIM) theory, has been verified experimentally in this class of chemically related molecules. On the other hand, topological differences could clearly be verified in regions with different chemical environments. Electron density differences between the two forms of naltrexone were examined and made visible in an extended region around the nitrogen atom which is once in a neutral state and once in a positively charged state.
通过低温下的高分辨率X射线衍射实验（钼Kα射线和同步加速器初级辐射）以及电荷耦合器件（CCD）面积检测技术，测定了五种吗啡相关分子（可待因、二丙诺啡、中性和质子化状态的纳曲酮以及右美沙芬）的电子密度。应用了键拓扑分析，并利用巴德零通量面将分子划分为原子区域，从而得到原子体积和电荷。将所获得的原子和键性质与先前对吗啡的实验研究结果以及理论计算结果进行了比较。所有化学等价键的实验和理论性质在不确定范围内一致，这与不同理论计算的情况相同。因此，化学等价亚分子性质的可转移性，这是分子中原子（AIM）理论的一个关键问题，已在这类化学相关分子中通过实验得到验证。另一方面，在具有不同化学环境的区域中可以清楚地验证拓扑差异。研究了纳曲酮两种形式之间的电子密度差异，并在氮原子周围的扩展区域中显示出来，该氮原子一次处于中性状态，一次处于带正电状态。
