Self-assembled tetraphenylethylene macrocycle nanofibrous materials for the visual detection of copper(II) in water

A tetraphenylethylene (TPE) Schiff base macrocycle with an aggregation-induced emission (AIE) effect was synthesized by the condensation reaction of the TPE dialdehyde and 1,2-benzenediamine. The macrocycle could aggregate into nanofibers in an aqueous solution to give a stable and fluorescent suspension. The fluorescent nanofibers showed a highly selective response to copper ions in an aqueous solution with the detection sensitivity up to a nanomolar level. Meanwhile, the emission of the nanofibers displayed a very large Stokes shift up to 260 nm because of the AIE effect, which brought the emission into the red area and avoided background interference. Therefore, the macrocycle probe showed great potential for the detection of Cu(II) in real water samples including pork juice-containing water. In addition, the macrocycle reacted with Cu(II) to give a color change and so the copper ion can be detected at the 10 mu M level by the naked eye.