Novel highly selective fluorescent sensor based on electrosynthesized poly(9-fluorenecarboxylic acid) for efficient and practical detection of iron(III) and its agricultural application

An efficient and practical conjugated polymer-based fluorescent sensor for the nanomolar detection of iron(III) in color rice samples has been successfully fabricated using an alcohol-soluble poly(9-fluorenecarboxylic acid) (PFCA), which was facilely electrosynthesized in boron trifluoride diethyl etherate. PFCA displayed high selectivity toward Fe3+ over different substances existing in agricultural crops and their products, such as common metal ions, anions, natural amino acids, carbohydrates, and organic acids, even organs of crops. Fluorescent intensities of PFCA showed a linear response to Fe3+ in the concentration range of 1 nM–0.782 mM with a detection limit of 0.611 nM. Fe3+ was tested by PFCA in real samples with satisfactory results, suggesting that the PFCA-based fluorescent sensor will provide a good model for constructing an advanced and promising fluorescent sensing platform for the determination of Fe3+ in agricultural samples. The sensing mechanism that Fe3+ induced the significant aggregation of PFCA chains and led to a significant fluorescent quenching of PFCA was proposed.