Dear all, I have calcuated the octanol-water partitioning coefficient of around 500 ionic organic substances (that are also ionic at pH 7.4) with the logP/logD panel in COSMOtherm. When comparing the calculated values to measured ones from the database of the European Chemicals Agency (ECHA), there is no correlation at all. I otherwise do get a very good correlation for the neutral organic substances. So I wonder whether COSMOtherm cannot calculate the octanol-water partitioning coefficient very accurate for ionic organic substances or wheather the experimental values are erroneous.