Cellulose/amylose derivatives bearing bulky substituents as reversible fluorescent sensors for detection of Fe3+

Two novel cellulose and amylose derivatives bearing bulky tris(2-benzothienylformate) pendants (Cel-3 and Amy-3) were expeditiously prepared by one-step esterification. The fluorescent sensing performance of six polysaccharide derivatives, including Cel-3/Amy-3, and other four previously prepared benzothienyl- or benzofuranyl-phenylcarbamates of cellulose and amylose (Cel-1/Amy-1, Cel-2/Amy-2), were carefully evaluated using eight metal ions, including Co2+, K+, Na+, Li+, Hg2+, Ni2+, Ca2+ and Fe3+. All six derivatives exhibited excellent fluorescence quenching property to Fe3+ ions with high sensitivity and selectivity. Especially, the limit of detection of Amy-2 with benzofuranylphenylcarbamates for Fe3+ was 3.0 & mu;M, much lower than the maximum contaminant level for Fe3+ in the drinking water. Additionally, the six bulky derivatives displayed the interesting fluorescence turn-off and turn-on observation, indicating a desirable reversibility for Fe3+ detection. The high anti-interference ability was also observed for detection of Fe3+ on the benzothienyl/benzofuranyl derivatives of cellulose and amylose in the combined system containing Co2+, K+, Na+, Li+, Hg2+, Ni2+ and Ca2+. It suggested that the obtained polysaccharide derivatives with bulky chromophores possessed good potentials for detection of Fe3+ as high-efficient fluorescent sensors in diverse applications. The sensing mechanism for detection of Fe3+ was further proposed based on the Stern-Volmer plots and fluorescence titration analysis.

Automated summary

Two novel cellulose and amylose derivatives with bulky tris(2-benzothienylformate) pendants were rapidly synthesized by one-step esterification. The fluorescence sensing performance of these derivatives, as well as other benzothienyl- or benzofuranyl-phenylcarbamates of cellulose and amylose, was carefully evaluated for the detection of Fe3+ ions. The derivatives exhibited high sensitivity and selectivity towards Fe3+ ions, and also demonstrated good reversibility and anti-interference ability in the presence of other metal ions.