A heat-set lanthanide metallogel capable of emitting stable luminescence under thermal, mechanical and water stimuli

Abstract

Preparing luminescence-stable lanthanide materials in a facile manner has always been an intriguing challenge. Herein we report an easy approach to the preparation of a heat-set lanthanide-based metallogel (H₆L/Tb gel) with stable luminescence from 5,5′,5′′-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl) triisophthalate (H₆L) as a Tb³⁺ coordinating ligand. The heat-set H₆L/Tb gel exhibits luminescence that mostly retains its intensity in the 0–90 °C temperature range and under mechanical stimulus. In addition, the H₆L/Tb xerogel is also luminescent in aqueous solution. UV-vis and FT-IR spectroscopy and XRD studies reveal that the stable luminescence of the H₆L/Tb gel depends on heat-set-induced strong hydrogen bonding, π–π stacking, and metal–ligand interactions. This study provides a heat-set approach to the preparation of luminescence-stable metallogel materials, such metallogels are potentially useful in anti-counterfeiting and sensing fields, among others.