QSPR ensemble modelling of alkaline-earth metal complexation

QSPR ensemble modeling of the stability constant log K of the complexes of Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ with diverse 273 (Mg 2+ ), 284 (Ca 2+ ), 147 (Sr 2+ ) and 198 (Ba 2+ ) organic ligands in water for the M 2+ + L = (M 2+ )L equilibrium at 298 K and an ionic strength 0.1 M has been performed. For each compound, predicted log K was calculated as an arithmetic average over the outputs of individual multiple linear regression models based on fragment descriptors. The root mean squared errors in fivefold cross-validation are 0.75 (Mg 2+ ), 0.77 (Ca 2+ ), 0.72 (Sr 2+ ) and 0.87 (Ba 2+ ). Additional external validation of the models has been performed on the complexes of 11 ligands recently reported in the literature. Several methodological developments related to (i) descriptors selection for an individual model and (ii) discarding redundant models have been proposed. Developed models have been integrated in the COmplexation of METals (COMET) predictor available as WEB application.