Electrostatic interaction between cationic calix[4]pyrroles and anionic porphyrins in water

Abstract

The formation and characterization of molecular assemblies resulting from mixing of solutions of tetracationic calix[4]pyrroles and tetraanionic porphyrins in water are reported. The self-assembly of the complementary building blocks was quantitatively studied by UV–vis, 1H NMR, Fluorescence and ESI–MS. Binding constants calculated by absorption spectroscopic titrations were in the range of 103–105 M−1. The results indicate that the cationic thiacalix[4]pyrroles show greater binding affinity towards metal free porphyrins than metalloporphyrins under neutral conditions.