Atomic-level organization of vicinal acid-base pairs through the chemisorption of aniline and derivatives onto mesoporous SBA15

• Published in: Chemical science (Cambridge) Vol. 7; no. 9; pp. 699 - 615
• Main Authors: Hamzaoui, Bilel, Bendjeriou-Sedjerari, Anissa, Pump, Eva, Abou-Hamad, Edy, Sougrat, Rachid, Gurinov, Andrei, Huang, Kuo-Wei, Gajan, David, Lesage, Anne, Emsley, Lyndon, Basset, Jean-Marie
• Format: Journal Article
• Language: English
• Published: England The Royal Society of Chemistry 01.01.2016; Royal Society of Chemistry
• Subjects: Analytical chemistry; Aniline; Aromatic compounds; Catalysis; Chemical Sciences; Chemisorption; Chemistry; Correlation; Derivatives; Moisture; Siloxanes
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c6sc01229a

The design of novel heterogeneous catalysts with multiple adjacent functionalities is of high interest to heterogeneous catalysis. Herein, we report a method to obtain a majority of bifunctional acid-base pairs on SBA15. Aniline reacts with SBA15 by opening siloxane bridges leading to N -phenylsilanamine-silanol pairs. In contrast with ammonia treated surfaces, the material is stable under air/moisture. Advanced solid state MAS NMR (2D 1 H- 1 H double-quantum, 1 H- 13 C HETCOR) experiments and dynamic nuclear polarization enhanced 29 Si and 15 N spectra demonstrate both the close proximity between the two moieties and the formation of a covalent Si-N surface bond and confirm the design of vicinal acid-base pairs. This approach was successfully applied to the design of a series of aniline derivatives of bifunctional SBA15. A correlation between the substituent effects on the aromatic ring (Hammett parameters) with the kinetics of a model Knoevenagel reaction is observed. The design of novel heterogeneous catalysts with multiple adjacent functionalities is of high interest to heterogeneous catalysis.