Synthesis and characterization of a pH-responsive mesalazine-polynorbornene supramolecular assembly

A pH-responsive mesalazine–crown ether and perfluoro tert-butyl functionalized polynorbornene supramolecular assembly (smc-1-4-cp-1-5) has been prepared. A promoted mesalazine (1) anti-inflammatory drug sustained release has been observed at elevated pH (7–9) enabling targeted topical and sustained drug dosing in the inflamed lower gastrointestinal (GI) tract. Thermoanalytical and solid-state NMR investigations of the supramolecular assembly revealed an amorphous, solid solvent structure showing that 1 is evenly distributed in the supramolecular polymer framework. In situ1H NMR investigation revealed a downshift of the respective hydrogens upon mesalazine–supramolecular polymer assembly formation. The equilibrium constant of the complex of crown ether-functionalized norbornene monomer (5) and 1 (log K = 3.4 ± 0.5, in a DMSO-d6–CD2Cl2 1 : 1 mixture) was calculated.