Highly Efficient Main-Chain Cationic Polyelectrolytes for Selective Sensing of Permanganate, Perrhenate, and Heparin

The development of chemosensors with very high sensitivity and selectivity for the detection of biomolecules (anticoagulants, such as heparin) or toxic oxoanions (TcO4–, MnO4–) is challenging. However, real-time monitoring of radioactive pertechnetate (TcO4–) via selective sensing remains challenging even after using the nonradioactive surrogate perrhenate anion (ReO4–). Herein, we report the design and synthesis of a series of main-chain cationic polyelectrolytes bearing pyridinium-end p-phenylenevinylene units with different alkyl side chains via nucleophilic substitution polymerization. These polyelectrolytes show bright-orange fluorescence and act as efficient "turn-off'' fluorescent probes for selective sensing of the organic biomolecule heparin as well as toxic inorganic oxoanions perrhenate and permanganate. For heparin, a large decrease in emission intensity is observed with a very low detection limit (LOD) of 50 nM and a high Stern–Volmer constant (Ksv) of 4.1 × 105 M–1. Additionally, these polyelectrolytes are capable of detecting MnO4– (LOD = 20 × 10–8 M and Ksv = 5.6 × 104 M–1) and ReO4– (∼305-fold reduction in emission intensity with LOD = 5.8 × 10–7 M and Ksv = 45 × 103 M–1) selectively among different inorganic anions. Interestingly, absorption spectra reveal that sensing of the analytes presumably stems from aggregation-caused quenching in the case of heparin and perrhenate, while interaction with the vinylic part is observed for MnO4– ions. Most importantly, our polyelectrolytes are superior to most previously reported sensors since they can act as efficient multitasking materials with the opportunity to detect biomolecules and toxic oxoanions using both colorimetric and fluorometric approaches. To the best of our knowledge, this is the first report on sensing heparin, perrhenate, and permanganate using main-chain cationic polyelectrolytes, which could offer a promising methodology for real-time monitoring purposes.