Research Group of Environmental Chemistry, Ecotoxicology & Food Toxicology, Institute of Environmental Sciences & Public Health, University of Gdańsk, Gdańsk, Poland.
J Environ Sci Health B. 2012;47(2):111-28. doi: 10.1080/03601234.2012.616779.
Polychlorinated azobenzenes (PCABs) can be found as contaminant by products in 3,4-dichloroaniline and its derivatives and in the herbicides Diuron, Linuron, Methazole, Neburon, Propanil and SWEP. Trans congeners of PCABs are physically and chemically more stable and so are environmentally relevant, when compared to unstable cis congeners. In this study, to fulfill gaps on environmentally relevant partitioning properties of PCABs, the values of n-octanol/water partition coefficients (log K(OW)) have been determined for 209 congeners of chloro-trans-azobenzene (Ct-AB) by means of quantitative structure-property relationship (QSPR) approach and artificial neural networks (ANN) predictive ability. The QSPR methods used based on geometry optimalization and quantum-chemical structural descriptors, which were computed on the level of density functional theory (DFT) using B3LYP functional and 6-311++G basis set in Gaussian 03 and of the semi-empirical quantum chemistry method (PM6) of the molecular orbital package (MOPAC). Polychlorinated dibenzo-p-dioxins (PCDDs), -furans (PCDFs) and -biphenyls (PCBs), to which PCABs are related, were reference compounds in this study. An experimentally obtained data on physical and chemical properties of PCDD/Fs and PCBs were reference data for ANN predictions of log K(OW) values of Ct-ABs in this study. Both calculation methods gave similar results in term of absolute log K(OW) values, while the models generated by PM6 are considered highly efficient in time spent, when compared to these by DFT. The estimated log K(OW) values of 209 Ct-ABs varied between 5.22-5.57 and 5.45-5.60 for Mono-, 5.56-6.00 and 5.59-6.07 for Di-, 5.89-6.56 and 5.91-6.46 for Tri-, 6.10-7.05 and 6.13-6.80 for Tetra-, 6.43-7.39 and 6.48-7.14 for Penta-, 6.61-7.78 and 6.98-7.42 for Hexa-, 7.41-7.94 and 7.34-7.86 for Hepta-, 7.99-8.17 and 7.72-8.20 for Octa-, 8.35-8.42 and 8.10-8.62 for NonaCt-ABs, and 8.52-8.60 and 8.81-8.83 for DecaCt-AB. These log K(OW) values shows that Ct-ABs are compounds of relatively low environmental mobility (log K(OW) > 4.5) and of significant bioaccumulation potential.
多氯偶氮苯（PCABs）可作为 3,4-二氯苯胺及其衍生物和除草剂敌草隆、利谷隆、甲唑、尼伯隆、普瑞帕利和 SWEP 的污染物副产物。与不稳定的顺式同系物相比，PCABs 的反式异构体在物理和化学上更稳定，因此在环境方面更相关。在这项研究中，为了满足对 PCABs 环境相关分配性质的研究空白，通过定量结构-性质关系（QSPR）方法和人工神经网络（ANN）预测能力，确定了 209 种氯代反式偶氮苯（Ct-AB）同系物的正辛醇/水分配系数（log K（OW））值。所使用的 QSPR 方法基于几何优化和量子化学结构描述符，这些描述符是在密度泛函理论（DFT）水平上使用 B3LYP 函数和 Gaussian 03 中的 6-311++G 基组计算的，以及分子轨道包（MOPAC）中的半经验量子化学方法（PM6）。多氯二苯并对二恶英（PCDDs）、呋喃（PCDFs）和联苯（PCBs）与 PCABs 有关，是本研究中的参考化合物。本研究中，PCDD/Fs 和 PCBs 的物理化学性质的实验数据是 Ct-ABs 的 ANN 预测 log K（OW）值的参考数据。这两种计算方法在绝对 log K（OW）值方面给出了相似的结果，而与 DFT 相比，PM6 生成的模型在时间效率方面被认为是非常高效的。209 种 Ct-ABs 的估计 log K（OW）值在单氯代物中为 5.22-5.57 和 5.45-5.60，在二氯代物中为 5.56-6.00 和 5.59-6.07，在三氯代物中为 5.89-6.56 和 5.91-6.46，在四氯代物中为 6.10-7.05 和 6.13-6.80，在五氯代物中为 6.43-7.39 和 6.48-7.14，在六氯代物中为 6.61-7.78 和 6.98-7.42，在七氯代物中为 7.41-7.94 和 7.34-7.86，在八氯代物中为 7.99-8.17 和 7.72-8.20，在九氯代物中为 8.35-8.42 和 8.10-8.62，在十氯代物中为 8.52-8.60 和 8.81-8.83。这些 log K（OW）值表明 Ct-ABs 是环境迁移性相对较低（log K（OW）>4.5）和具有显著生物累积潜力的化合物。
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