Readily soluble cellulose-based fluorescent probes for the detection and removal of Fe³⁺ ion

Cellulose is an economical, biodegradable, widely available, and eco-friendly natural macromolecule. But its utilization has been restricted due to its insolubility in water and common organic solvents. In this work, soluble fluorescent probes based on cellulose were synthesized. Firstly, the primary hydroxyl group in glucose units was reacted with SOCl₂ to introduce Cl and obtain chloro-cellulose (Cell-Cl). This operation breaks down the regular structure and hydrogen bonding of the original cellulose, enabling it to dissolve in DMSO. Secondly, the Cell-Cl reacted with CS₂ and 2-mercaptobenzothiazole to obtain a cellulose-based macromolecular RAFT reagent (Cell-CTA). Finally, the fluorescent monomers which bears -C=C- and naphthalimide, and methacrylic acid (MAA) were grafted onto the main chain of cellulose through RAFT polymerization. Thus, cellulose-based readily soluble macromolecular fluorescent probes were obtained. The cellulose-based probes can specifically recognize Fe³⁺ in pure water and can be recycled and regenerated. Additionally, the cellulose-based probes exhibit remarkable adsorption and separation properties for Fe³⁺ ions. The modification of cellulose decreases its crystallinity and introduces hydrophilic groups and fluorophores, which enables cellulose to be soluble in both pure water and the organic solvent DMSO. This work expands the application range of cellulose-based copolymers.