Thermal Behavior of d-Ribose Adsorbed on Silica: Effect of Inorganic Salt Coadsorption and Significance for Prebiotic Chemistry

• Published in: Chemistry : a European journal Vol. 22; no. 44; pp. 15834 - 15846
• Main Authors: Akouche, Mariame, Jaber, Maguy, Zins, Emilie-Laure, Maurel, Marie-Christine, Lambert, Jean-Francois, Georgelin, Thomas
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 24-10-2016; Wiley Subscription Services, Inc; Wiley-VCH Verlag
• Subjects: Activation; Catalysis; Cations; Chemical Sciences; Chemistry; heterogeneous catalysis; Inorganic salts; Metals - chemistry; Prebiotics; Ribonucleic acids; Ribose; Ribose - chemistry; Ring opening; RNA; RNA - chemistry; Salts - chemistry; silicon; Silicon dioxide; Silicon Dioxide - chemistry; surface analysis; surface chemistry; surface analysis; silicon; surface chemistry; RNA; heterogeneous catalysis
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201601418

Understanding ribose reactivity is a crucial step in the “RNA world” scenario because this molecule is a component of all extant nucleotides that make up RNA. In solution, ribose is unstable and susceptible to thermal destruction. We examined how ribose behaves upon thermal activation when adsorbed on silica, either alone or with the coadsorption of inorganic salts (MgCl2, CaCl2, SrCl2, CuCl2, FeCl2, FeCl3, ZnCl2). A combination of 13C NMR, in situ IR, and TGA analyses revealed a variety of phenomena. When adsorbed alone, ribose remains stable up to 150 °C, at which point ring opening is observed, together with minor oxidation to a lactone. All the metal salts studied showed specific interactions with ribose after dehydration, resulting in the formation of polydentate metal ion complexes. Anomeric equilibria were affected, generally favoring ribofuranoses. Zn2+ stabilized ribose up to higher temperatures than bare silica (180 to 200 °C). Most other cations had an adverse effect on ribose stability, with ring opening already upon drying at 70 °C. In addition, alkaline earth cations catalyzed the dehydration of ribose to furfural and, to variable degrees, its further decarbonylation to furan. Transition‐metal ions with open d‐shells took part in redox reactions with ribose, either as reagents or as catalysts. These results allow the likelihood of prebiotic chemistry scenarios to be evaluated, and may also be of interest for the valorization of biomass‐derived carbohydrates by heterogeneous catalysis.
On silica chemistry: Ribose reactivity upon thermal activation when adsorbed on silica, either alone or with the coadsorption of inorganic salts, in the “RNA world” scenario is examined (see scheme). These results allow the likelihood of prebiotic chemistry scenarios to be evaluated, and may also be of interest for the valorization of biomass‐derived carbohydrates by heterogeneous catalysis.