Complexation of upper rim phosphorylated calix[4]arenes with uracil derivatives in water-containing solution

The host-guest complexation of the upper rim diisopropoxyphosphoryl derivatives of dipropoxy- or tetrapropoxycalix[4]arenes and the upper rim unsubstituted parent calixarenes with uracil and 5-amino-, 5-chloro-, 5nitro-, 6-methyl and 6-amino-1,3-dimethyluracil in methanol-acetonitrile-tetrahydrofuran-water (15:10:5:70, v/v) solution was investigated by reversed-phase high-performance liquid chromatography. The association constants of the 1: 1 host-guest complexes of the uracils with the calixarenes within the range 1200-54 300M(-1) were calculated from the relationship between the capacity factor of the uracil solutes and concentration of the calixarenes in the mobile phase. The association constants were dependent on the nature of uracil guests, the manner of the lower rim substitution of the calixarene skeleton and the number of the phosphoryl groups at the upper rim. Molecular dynamics (MD) simulations of host-guest interactions were performed. Based on the MD trajectories, the atomic partition to the net molecular solvent-exposed surface was analysed for the separate host and guest molecules and for the complexes. Copyright (c) 2005 John Wiley & Sons, Ltd.