New supramolecular nanoscopic hybrid gate-like ensembles with dual –pH and cation-driven- aperture control

Abstract

• Synthesize and characterize the nanostructured material that is going to act as the inorganic support of the hybrid gate system. In or case an MCM-41 type material in two different morphologies, microparticles and nanoparticles, has been used. • Then, using a post-synthesis method, it has been necessary to anchor a suitable organic group, able to respond to the external stimuli and actuate as the opening- closing moiety of the gated-system. In our design, carboxilate function has been chosen in order to obtain a response to the pH but also to the presence of cationic species. In particular, we have chosen the propylethylenediamine tetracetate moiety to be anchored on the pore outlets of the inorganic material. • After the hybrid system has been synthesized the next step has been to corroborate its anticipated response. The gate we have prepared should show a pH and cation-driven control. The idealized open-closed mechanism would arise from simple interactions between carboxylic acids (open-gate) and coulombic repulsion between carboxylate groups (close-gate). The study has been accomplished through the release of a loaded dye, from the pore voids to the bulk solution, at a different pH values and in the presence of a range of cations with different structural dimensions.