Crosslinked poly(ionic liquid) anchored with organic probe as a new promising platform for organic solvent-free recognition, quantification, and selective removal of heavy metal ion

Recognition, quantification, and selective removal of target heavy metal ion with a single material are of great practical importance, while there still remains a formidable challenge of accomplishing these multiple tasks in pure aqueous media. Herein, we utilized crosslinked poly(ionic liquid) as support of organic probe to devise a new class of multifunctional material for addressing this issue while simultaneously providing some additional benefits. To illustrate this strategy, an imidazolium-type crosslinked poly(ionic liquid) anchored with rhodamine derivative, P(RhBHSA–BVD), was designed and applied for qualitative/quantitative analysis and selective removal of Cu 2+ . In significant contrast from previously reported organic probe/support composites that were typically hydrophobic and usually required use of organic solvent to disperse them before use, the P(RhBHSA–BVD) was highly hydrophilic and readily dispersed in pure water. Moreover, due to the positively charged nature of polymeric backbone, the P(RhBHSA–BVD) had a potential advantage of avoiding non-receptor binding. Observation with naked eye confirmed the highly selective and sensitive response of P(RhBHSA–BVD) to Cu 2+ , and accordingly a convenient colorimetric sensing method for detection of Cu 2+ was successfully established. Furthermore, it was demonstrated that the P(RhBHSA–BVD) could selectively remove Cu 2+ from multi-ions solution with high efficiency and excellent reusability.