The preparation and characterization of a novel pillar[5]arene based supramolecular system with mesalazine, a prescribed aminosalicylate drug was successfully achieved. Pyridinium-pillar[5]arene was efficiently prepared in three steps from hydroquinone bis(2-hydroxyethyl) ether derivative in high yield. It was demonstrated that the association between the compounds is pH dependent with an association constant of 3.4 × 103 L mol-1 near physiological conditions, leading to quenching of the fluorescence emission of mesalazine in the presence of the cationic macrocycle. Theoretical calculations indicate that the association between both molecules is of electrostatic nature. Formation of aggregates was also demonstrated in low concentrations of pillar[5]arene that is related to the non-linear behavior of the Stern-Volmer plot for quenching of mesalazine fluorescence emission.

In this work, we report the preparation of a copper-silica material (Cu/SiO2) by a sol-gel methodology and its characterization concerning composition and textural properties. The Cu/SiO2 material was successfully applied as a Lewis acid heterogeneous catalyst for the A3-coupling from 2-aminopyridine, aldehydes and alkynes to imidazo[1,2-a]pyridines (45-82%), which are relevant pharmacological scaffolds. The synthesis shows a number of advantages, such as easy separation from the reaction media and the minimal formation of metal aqueous wastes. Investigation of the mechanism supports the involvement of the formation of reaction intermediates inside the pores of the mesoporous material prior to 5-exo-dig cyclization.