Synthesis of cellulose derivatives bearing regioselective bulky thiazolyl substituents at 2,3- and 6-positions for efficient fluorescence and UV-visible detection of Cu2+/Fe3+ ions.

Two novel cellulose phenylcarbamate derivatives bearing 3,5-dimethylphenylcarbamate substituents at 2,3-positions and 4-(4-(3-(2-benzo[d]thiazolyl)ureayl)benzyl)) (Cel-1) or 4-(4-(3-4-(2-benzo[d]thiazolyl)phenyl)ureayl)benzyl)) (Cel-2) at 6-position of glucose units were prepared. Their metal ion discrimination properties were then carefully scrutinized using 12 metal ions. Combined the 2,3-dimethylphenylcarbamates with a more bulky benzothiazolyl phenylcarbamate at 6-position, the derivative Cel-2 exhibited excellent recognition ability for both Cu2+ and Fe3+, and achieved high selective detection at extremely low concentrations through fluorescence and UV-visible modes. The limit of detection of Cel-2 for the two metal ions in both modes were 2.0 μM (Cu2+) and 1.0 μM (Fe3+) (in fluorescence mode), 1.3 μM (Cu2+) and 0.7 μM (Fe3+) (in UV-visible mode), respectively, which were much lower than the maximum pollution level for copper ions (20 μM) and iron ions (5.4 μM) in the potable water. In addition, good anti-interference ability of Cel-2 was also observed for specific detection of Cu2+/Fe3+ in the combined system containing other metal ions. It revealed that the obtained regioselectively substituted phenylcarbamate of cellulose possessed powerful performance for efficient detection of Cu2+/Fe3+ in various circumstance via fluorescence and UV-visible modes. Furthermore, Cel-2 was also been prepared into smart ink, presenting its possible potential in the anti-counterfeiting application.