J.R. Blas, M. Marquez, J.L. Sessler, F.J.Luque, M. Orozco
Univ Barcelona, Dept Bioquim & Biol Mol, Fac Quim, Marti & Franques 1, E-08028 Barcelona, Spain


Blas JR, Marquez M, Sessler JL, Luque FJ, Orozco M J. Am. Chem. Soc. 2002,124,12796
Theoretical study of anion binding to calix[4]pyrrole: the effects of solvent, fluorine substitution, cosolute, and water traces
The binding of different anions to calix[4]pyrrole has been studied by means of molecular dynamics coupled to thermodynamic integration calculations. The effect of different apolar solvents, octafluoro substitution, and the change in binding free energy derived from the presence of cosolute and water traces (the hydrated salt used to introduce the anion in the solution) were examined. Calculations allow us to rationalize the differential binding of ions to calix[4]pyrrole and octafluorocalix[4]pyrrole as well as to predict the behavior in new solvents for which experimental data are not available yet. It is found that both calix[4]pyrrole and octafluorocalix[4]pyrrole have a dramatic preference for F- in the gas phase and pure aprotic solvents, but the situation can change dramatically in protic solvents or in the presence of the hydrated cation which is used as cosolute of the anion. Overall, our results provide interesting clues for a better understanding of the process detected experimentally as "binding".


XH4 calix[4]pyrrole
CX4 octafluorocalix[4]pyrrole
united atom acetonitrile
ACNBOX -> box of 264 united atom acetonitrile molecules
ACN -> acetonitrile molecule

united atom CH2Cl2
DCMBOX -> box of 257 dichloromethane molecules
DCM -> dichloromethane molecule
gg -> dichloromethane parameters (taken from OPLS, WL Jorgensen, Yale)
If you need more than one DCMBOX to fully solvate your system, some "strange" lanes may appear between adjacent boxes. This arises because of the closeness parameter employed by the "solvatebox" leap command. The system is easily brought to the right density by a 100-200ps short MD.

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Last modified Mon Jan 20 09:00:39 GMT 2003