document: Assessment of the macrocyclic effect for the complexation of crown-ethers with alkali cations using the substructural molecular fragments method The Substructural Molecular Fragments method -LRB- Solov ` ev , V. P. ; Varnek , A. A. ; Wipff , G. J. Chem . Inf . Comput . Sci . 2000 , 40 , 847-858 -RRB- was applied to assess stability constants -LRB- logK -RRB- of the complexes of crown-ethers , polyethers , and glymes with Na/sup + / , K/sup + / , and Cs/sup + / in methanol . One hundred forty-seven computational models including different fragment sets coupled with linear or nonlinear fitting equations were applied for the data sets containing 69 -LRB- Na/sup + / -RRB- , 123 -LRB- K/sup + / -RRB- , and 31 -LRB- Cs/sup + / -RRB- compounds . To account for the `` macrocyclic effect '' for crown-ethers , an additional `` cyclicity '' descriptor was used . `` Predicted '' stability constants both for macrocyclic compounds and for their open-chain analogues are in good agreement with the experimental data reported earlier and with those studied experimentally in this work . The macrocyclic effect as a function of cation and ligand is quantitatively estimated for all studied crown-ethers
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