Water-soluble imidazole-based fluorescent polymer as a ratiometric probe for Zn(II) ions sensing

Zn 2+ ions sensing is vital for human health and environment, and developing low-cost, water-soluble, efficient probes is still highly demanded. Herein, we report a water-soluble imidazole-based fluorescent polymer as a ratiometric probe for Zn 2+ ions sensing. By a facile radical co -polymerization, the water-soluble fluorescent polymer of PVIV-0.5BTAM was obtained carrying imidazole and imidazolium moieties together with a small amount of diphenylbenzothiadiazole (BTAM) units. Upon excitation, PVIV-0.5BTAM gave rise to dual emission bands centered at 430 nm and 540 nm, corresponding to imidazole/imidazolium and BTAM, respectively. The addition of Zn 2+ ions can coordinate with imidazole rings via multi-valent mode and act as a crosslinker, leading to the intra- and/or inter-macromolecular aggregation. Accordingly, the yellow emission of BTAM was enhanced proportionally, while the blue emission of imidazole/imidazolium kept stable and served as internal standard. The linear working curve can be established by plotting the value of I 540 /I 430 as a function of Zn 2+ ions concentration. Thus, a low-cost, water-soluble, ratiometric fluorescent polymer probe was provided as a promising candidate for Zn 2+ ions sensing.