Lanthanides-based luminescent hydrogels applied as luminescent inks for anti-counterfeiting

Lanthanides-based luminescent hydrogels emitting green and red luminescence have been fabricated successfully by the coordinative self-assembly of 1,3,5-benzenetricarboxylic acid (H 3 BTC) and lanthanide ions (Tb 3+ or Eu 3+ ). And the hydrogel with yellow emission color can be obtained by controlling the molar ratio of Tb 3+ to Eu 3+ at 9/1. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the formation of coordination bonds between H 3 BTC and lanthanides. Scanning electron microscopy images showed that the hydrogels formed 3D porous structures. Luminescent spectra, luminescent decay curves, and digital images indicated that the H 3 BTC-lanthanides hydrogels can be applied as luminescent inks for anti-counterfeiting. Importantly, the rational designed multiple encryption strategies were applied for improving the anti-counterfeiting level. This work provides an alternative strategy to prepare lanthanides-based luminescent materials for anti-counterfeiting.