Terbium based (poly)ionic liquids for anti-counterfeiting and droplet manipulation

Rare earth elements show unique optical and magnetic properties, with great potential in sensing, imaging, light harvesting, and magnetically responsive materials. In this study, a typical lanthanide terbium based ionic liquid, vinylimidazolium tetranitroterbium (Vim[Tb(NO 3 ) 4 ]), and the corresponding polymer, poly(vinylimidazolium tetranitroterbium) (PVim[Tb(NO 3 ) 4 ]), are synthesized by introducing terbium into conterions. Vim[Tb(NO 3 ) 4 ] and PVim[Tb(NO 3 ) 4 ] are characterized by 1 H NMR and negative ion mass spectroscopy. Magnetic property tests show that the monomer and polymer are paramagnetic, and the susceptibility of PVim[Tb(NO 3 ) 4 ] is higher than that of Vim[Tb(NO 3 ) 4 ]. The corresponding aqueous droplets are deformed by an external magnetic field, and the contact angle changes with the magnetic field intensity and direction, changing the surface tension as a result. Meanwhile, the magnetic monomer and polymer show bright fluorescence under ultraviolet excitation, while there is no color under sunlight. Vim[Tb(NO 3 ) 4 ] exhibits stronger fluorescence than PVim[Tb(NO 3 ) 4 ] in solution, while pure PVim[Tb(NO 3 ) 4 ] exhibits stronger fluorescence than pure Vim[Tb(NO 3 ) 4 ]. Noncontact manipulation of aqueous droplets in a dark enviroment is favored for special applications under a strong magnetic field. Therefore, Vim[Tb(NO 3 ) 4 ] exhibits better fluorescence performance in solution, while PVim[Tb(NO 3 ) 4 ] is more suitable for anti-counterfeiting applications and droplet manipulation. A magnetic ionic liquid and magnetic poly(ionic liquid) with Tb(NO 3 ) 4 − as counteranions are prepared. The resulting M(P)ILs show magnetic and luminescent properties, which are used in droplet manipulation and anti-counterfeiting application.