Highly sensitive "turn-on" fluorescent chemical sensor for trace analysis of Cr using electro-synthesized poly(N-(9-fluorenylmethoxycarbonyl)-l-histidine).

Trivalent chromium (Cr) can cause severely environment pollution, declining quality of edible agro-products in plants and animals, and human diseases. Poly(N-(9-fluorenylmethoxycarbonyl)-l-histidine) (PFLH) synthesized by the direct electro-polymerization of its corresponding commercially available monomer in both boron trifluoride diethyl etherate and dichloromethane mixed system. The "turn-on" type fluorescent sensor based on PFLH displayed high sensitivity and selectivity for Cr detecting. The structure of PFLH was rationally proved by H NMR spectra, FT-IR spectra, quantum chemical calculations, and its optical properties were characterized. The electro-synthesized PFLH exhibited a "turn-on" fluorescent response towards Cr, which was employed as a sensing platform for the "turn-on" fluorescent analysis of Cr in a wide linear range from 5.1nM to 25μM with a low limit of detection as low as 1.7nM. The possible mechanism of fluorescent "turn-on" sensor based on PFLH for Cr was proposed. The sensor displayed high sensitivity, good selectivity, satisfactory practicability, suggesting that PFLH has potential fluorescent application for "turn-on" sensing Cr in agricultural environments and edible agro-products of plants and animals.