Covalent linkage of N-methyl-6-oxyquinolinium betaine to trehalose

The common route to link quinolinium and pyridinium fluorophores to biomolecules via bromoacetic acid has failed in labeling the disaccharide trehalose with N-methyl-6-oxyquinolinium betaine: the unexpected, extremely high instability of the N-carboxymethyl ester was overcome by direct N-alkylation of the quinoline derivative with trehalose triflate.

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► Facile preparation of N-methyl-6-oxyquinolinium betaine labeled trehalose.
► N-Carboxymethyl ester of trehalose rapidly hydrolyses in neutral protic media.
► Fluorescently labeled trehalose for studying solvation dynamics.