X-RAY CRYSTAL-STRUCTURES AND MOLECULAR MODELING STUDIES OF CALIX[4]DIBENZOCROWNS-6 AND THEIR ALKALI-METAL CATION COMPLEXES

We present X-ray structures of complexes of KClO4. H2O and CsPic . H2O with a new calix[4]arene bearing a dibenzocrown-6 ether bridge. Alkal i metal cation complexes with this macrocycle have been studied by mol ecular dynamics simulations in vacuo, taking account of the counterion , and in an explicit water phase, in order to compare the computed str uctures to those determined by X-ray crystallography. Two different se ts of atomic charges were used in order to evaluate the influence of t he electrostatic representation on the computed structures. The result s obtained show that MNDO scaled charges give simulation results in be tter agreement with the available experimental data than MNDO/ESP.