An AIE-active hemicellulose-based fluorescent polymer derived for Fe3+-responsive optical sensing

Renewable hemicelluloses such as xylan offer an attractive platform for constructing sustainable functional materials due to their abundance, structural versatility, and rich chemical functionality. In this work, an aggregation-induced emission (AIE)-active hemicellulose derivative (TPE-Xylan) was synthesized via covalent grafting of 1,1,2,2-tetrakis(4-carboxyphenyl)ethylene (TPE) onto a xylan backbone. FT-IR and 2D NMR analyses confirmed successful incorporation of TPE moieties while preserving the polysaccharide framework. TPE-Xylan exhibited typical solvent-induced AIE behavior, with the fluorescence intensity being enhanced by a factor of approximately 57.75 when the solvent composition was adjusted from DMSO:H2O = 10:0 to 1:9. Compared with free TPE at the same mass concentration (4.5 mg/mL), the grafted system displayed significantly enhanced emission, demonstrating the amplifying effect of the xylan scaffold. The material maintained stable fluorescence over time and across a broad pH range. Notably, TPE-Xylan showed a distinguishable fluorescence quenching response toward Fe3+, with concentration-dependent attenuation observed in the range of 0~500 μM, accompanied by systematic chromaticity variation. These results highlight the advantages of xylan as a biomass-derived matrix for amplifying AIE characteristics and demonstrate the potential of hemicellulose-based fluorescent polymers for Fe3+-responsive optical materials.