Carboxymethyl Cellulose-Based Luminescent Hydrogels Constructed through the Synergistic Effect of Coordination Bonds and Hydrogen Bonds for Reversible Luminescent Switching of l-Ascorbic Acid

As a well-known biodegradable and renewable polymer, cellulose has recently gained significant attention in the development of luminescent material, while it still remains a significant challenge to achieve multifunctional luminescent hydrogels. Here we report the construction of stimuli-responsive luminescent hydrogels through the synergistic combination of metal–ligand coordination interactions of lanthanide (Ln3+) complexes and hydrogen bonding between carboxymethyl cellulose (CMC), poly(ethylene glycol) (PEG), and pyridine-2,6-dicarboxylic acid (DPA) molecules. This molecular anchoring strategy based on the hydrogen-bonding interactions effectively suppresses the aggregation of DPA molecules and enhances the stability of Ln3+-DPA complexes in hydrogels through synergistic Ln3+-DPA coordination bond interactions, resulting in luminescent hydrogels possessing excellent luminescence performance. The dynamic double-network structure formed between CMC and PEG through hydrogen bonding interactions confers enhanced mechanical property and self-healing ability to the luminescent hydrogels. Based on changes in the luminescence brightness and emission intensity, the luminescent hydrogels can act as smart sensor for the naked-eye detection of l-ascorbic acid with good reversibility and selectivity. Furthermore, the reversible luminescence behavior of the luminescent hydrogels could be manipulated by the successive addition of l-ascorbic acid and arginine. This work may provide an interesting perspective for the design of luminescent hydrogels integrated with Ln3+ complexes and CMC-based networks.