Observation of 1,6-Anhydro-β-maltose and 1,6-Anhydro-β-D-glucopyranose Complexed with Rubidium by NMR Spectroscopy and Electrospray Ionization Mass Spectrometry

Abstract

A complex of 1,6-anhydro-β-maltose with rubidium and that of 1,6-anhydro-β-D-glucopyranose with rubidium were characterized using ⁸⁷Rb NMR spectroscopy, diffusion-ordered NMR spectroscopy (DOSY) and electrospray ionization mass spectrometry (ESI-MS). Although subtle differences were observed in the ¹H chemical shifts of 1,6-anhydro-β-maltose in between the presence and absence of rubidium in deuterium oxide, measurements of the spin-lattice relaxation time (T₁) of the ⁸⁷Rb nucleus, the diffusion coefficients of 1,6-anhydro-β-maltose using 1H DOSY and ESI-MS indicated the complex formation of 1,6-anhydro-β-maltose with rubidium. The complex formation with rubidium was also identified for 1,6-anhydro-β-D-glucopyranose using NMR and ESI-MS techniques.