Abstract |
Ribose-borate esters or Borate-Bound Species (BBS) with ribose were studied in aqueous solution by NMR and infrared (ATR) spectroscopies, as well as by DSC, PXRD and infrared spectroscopy (DRIFT) after mixing D-ribose and borate by mechanochemical procedures. NMR titrations of solutions of D-ribose by borate and borate by D-ribose were carried out, followed by H-1 and B-11 NMR analysis, revealing that an excess of D-ribose (relative to borate) leads to the formation of diesters and monoesters; both types of esters are stable under the studied conditions. The occurrence of furanose and the number of chemical bonds to the boron atom were confirmed by infrared spectroscopy. Interaction of Na+ with BBS revealing an ionic character was clarified by Na-23 NMR spectroscopy. The samples obtained by mechanochemical procedures were amorphous, and with excess of borate present, increase their thermal stability at least up to 140 degrees C. These results expand the conditions of BBS as reagents in prebiotic reactions. Additionally, BBS exhibit uncommon chemical characteristics. (C) 2019 Elsevier B.V. All rights reserved. |