Theoretical study on halide anion recognitions by pyrrole- and benzene-strapped calix[4]pyrroles

► The geometrical complexes of strapped calix[4]pyrroles and halide anions were obtained. ► AIM, NBO and EDA have been used to analyze the recognition interactions. ► The order of selectivity is F− > Cl− > Br−, PCP possessed a higher affinity. ► The computational results explain sufficiently the experimental phenomena.