A quantitative structure–property relationships study of the stability constant of crown ethers by molecular modelling: new descriptors for lariat effect

Abstract

Quantitative structure–property relationships (QSPR) modeling of stability constant (log K) for complexes of 15-Crown-5 ethers with sodium cation (Na+) at 25 °C in methanol solution as a function of the new and Dragon generated descriptors was established by multiple linear regression and partial least squares regression. The possibility of three-dimensional cation encapsulation by the crown ether unit and the side arms and cooperative interaction between ring and side-arm in lariat crown ethers are investigated. These side arms can alter the cation-binding constant and the relative cation selectivity significantly when comparing with their parent crown ethers. In order to consider lariat and side arm effect and conformation changing in the crown ether rings on complexation of reactions, we defined and calculated some novel descriptors to address these effects. Three new descriptors are involved in the QSPR model and had significant effect on stability constants. The quality of the model was evaluated using leave-one-out cross-validation and randomization test method. We showed that a combination of new defined and Dragon based descriptors could lead to relevant QSPR models, that in comparison with model solely generated by Dragon descriptors has improved and showed more robustness and prediction ability.