Wittekindt Carsten, Goss Kai-Uwe
COSMOlogic GmbH & Co. KG, Burscheider Str. 515, 51381 Leverkusen, Germany.
Chemosphere. 2009 Jul;76(4):460-4. doi: 10.1016/j.chemosphere.2009.03.046. Epub 2009 Apr 25.
For 8500 organic chemicals from the Canadian Domestic Substances List, air/water and octanol/water partition coefficients have been calculated with COSMOfrag a predictive a priori method based on quantum mechanics and statistical thermodynamics provided by COSMOlogic. The results were compared with predictions from the EPI Suite. On average a difference of 1.8 log units between both methods was observed for the predicted logK(aw) values. This has consequences for the classification in terms of atmospheric long range transport potential and bioaccumulation in the terrestrial food chain where 11% and 17% of all compounds were classified differently. Much better agreement was observed for the predicted logK(ow). Principal differences became obvious for compounds that occur as isomers or conformers. The modules of the EPI Suite are not designed to account for information on stereochemistry of molecules or E/Z isomers. Intramolecular H-bonds are only accounted for if specific correction factors exist from the calibration procedure. In contrast, COSMOfrag in combination with COSMOtherm can identify the existence of such isomers or H-bond conformers and account for these effects in the calculations.
对于加拿大国内物质清单中的8500种有机化学品，利用COSMOfrag计算了气/水和辛醇/水分配系数，COSMOfrag是一种基于COSMOlogic提供的量子力学和统计热力学的先验预测方法。将结果与EPI Suite的预测结果进行了比较。对于预测的logK(aw)值，两种方法之间平均观察到1.8个对数单位的差异。这对大气长距离传输潜力和陆地食物链生物累积方面的分类产生了影响，其中所有化合物中有11%和17%的分类不同。对于预测的logK(ow)，观察到的一致性要好得多。对于以异构体或构象体形式存在的化合物，主要差异变得明显。EPI Suite的模块并非设计用于考虑分子立体化学或E/Z异构体的信息。只有在校准程序存在特定校正因子时，才会考虑分子内氢键。相比之下，COSMOfrag与COSMOtherm相结合可以识别此类异构体或氢键构象体的存在，并在计算中考虑这些影响。
