Theoretical studies on interaction between the calix[4]pyrrole and anion complex systems - Density functional theory on the calix[4]pyrrole-halide anion complex system

The density functional theory B3LYP/LANL2DZ methods were performed on the lowest energy conformation of free calix[4]pyrrole and the calix[4]pyrrole-halide anion complexes. The calculated results indicated that the interaction between calix[4]pyrrole and halide anions mainly involved hydrogen bonds interaction. The calculated results also implied the regular changes in molecular geometry features, in the differences of charge transfer, of frontier orbital energies, and of bonding, and in the thermochemistry parameters in recognition. These induced that the interaction between calix[4]pyrrole and halide anions decreased along the halide elemental period.