Bisphosphorylpillar[5]arenes (H1 and H2) were synthesized and used to study the host–guest complexation in organic solvents and water. The interactions between the guests and the phosphate of the hosts lead to strong binding towards alkyl dihalides and alkyldiammonium ions. H2 may be used to detect or separate alkyl dihalides in water due to the rapid precipitation of the complex.