Fig. 6

Limitations of EEM charges illustrated on a series of substituted benzoic acid derivatives. a Denotation of relevant atomic charges in the neutral and dissociated molecules. b The reference QM charges have a narrow spread despite the different position and wide range of electron donating or withdrawing effects of the subsituents. EEM charges are not accurate enough to reflect the small changes induced by different substituents. c The QSPR descriptors are EEM charges of the atoms of the carboxylic group in both the neutral (\(q_H\), \(q_{O1}\), \(q_{O2}\), \(q_{C1}\)) and dissociated forms (\(q_{O1D}\), \(q_{O2D}\), \(q_{C1D}\)). The symbols \(p_H\), \(p_{O1}\), \(p_{O2}\), \(p_{C1}\), \(p_{O1D}\), \(p_{O2D}\), \(p_{C1D}\), and p are parameters of the QSPR model. The graph displays the correlation between experimental \(pK_a\) values, and the values predicted by one of the QSPR models developed in this study. EEM charge descriptors are sufficiently accurate for the prediction of dissociation constants of benzoic acid derivatives