Modification of agarose: 6-Aminoagarose mediated syntheses of fluorogenic pyridine carboxylic acid amides

• Hydrogel forming 6-amino agarose (AA) was synthesized by Mitsunobu reaction.
• AA was modified with nicotinic acid (NA) to yield an amide (AA-NA).
• AA was modified with picolinic acid (PA) to yield another amide (AA-PA).
• Both the AA-NA and AA-PA exhibited strong fluorescent property.

A facile 6-aminoagarose (AA) mediated synthesis of new fluorogenic amides of agarose with nicotinic (AA-NA) and picolinic acids (AA-PA) employing carbodiimide chemistry have been described. 6-Amino agarose (AA) was synthesized in a facile Mitsunobu-inspired microwave mediated method involving the reaction of agarose with phthalimide in presence of diisopropyl azodicarboxylate and triphenylphosphene (DIAD/TPP) followed by hydrazinolysis. All compounds were characterized by GPC, UV spectrophotometry, fluorescence spectroscopy, FT-IR, 1H and 13C NMR spectra. The fluorescence emissions (λmax 430 and 412 nm) of 1 × 10−3 M solutions of AA-NA and AA-PA in water were significantly higher (ca. 82% and ca. 90%) than those of the molar equivalents (0.2 mg) of NA and PA present in the 1 × 10−3 M solutions of the amides, respectively. These fluorogenic pyridine carboxylic acid amides of agarose may find applications as sensors in biomedical and pharmaceutical industries.