Tailoring Bifunctional Periodic Mesoporous Organosilicas for Cooperative Catalysis

This paper presents a novel approach to create bifunctional periodic mesoporous organosilicas containing thiol and sulfonic acid groups (SH m /SO3H n @PMO) by co-condensation reactions of an own designed bis-silane precursor (EtO)3Si–CH2CH­(SH)–Si­(OEt)3 containing thiols groups with its predecessor (EtO)3Si–CH2CH­(SCOCH3)–Si­(OEt)3. This bifunctional strategy involves the in situ oxidation of thiol to sulfonic acid groups during the formation of the mesostructure followed by the hydrolysis of the −SCOCH3 to −SH groups during the subsequent surfactant extraction process. The good structural ordering and mesoporosity of the bifunctional materials were confirmed by powder X-ray diffraction (PXRD) and nitrogen adsorption–desorption measurements, respectively. The successful incorporation of dual functionality in the pore walls was confirmed by elemental analysis, X-ray electron spectroscopy (XPS), and solid-state nuclear magnetic resonance of 13C (13C CP/MAS NMR) and 29Si (29Si NMR) measurements. The existence of cooperative effect between both functional groups was evaluated in the bisphenol A formation. The catalytic data showed that the bifunctional materials present a better selectivity to the p,p′-isomer of bisphenol A compared to materials containing only one functionality, reaching the optimal value in the material with a thiol/sulfonic acid ratio of 1:1.