Unconventional Multicolor Fluorescent Aliphatic Hyperbranched Polyphosphate Esters with Enhanced Spatial Electronic Communication for Ion Detection and Fluorescent Hydrogel Fabrication

Unconventional fluorescent polymers exhibiting multicolor emission have garnered significant interest due to their unique optical properties and broad applications in bioimaging, chemical sensing, and security encryption. In this study, a series of multicolor fluorescent aliphatic hyperbranched polyphosphate esters were synthesized from a natural product. The prepared polymers demonstrated notable red emission, excitation-dependent fluorescence, concentration-enhanced luminescence, and aggregation-induced red-shifted emission. Experimental data combined with theoretical calculations revealed that intermolecular and intramolecular interactions promoted molecular aggregation, thereby enhancing n-π interactions. These strengthened n-π interactions further facilitated spatial electronic communication, leading to prominent multicolor fluorescence. The balance between hydroxyl and triethyl phosphate groups within the polymers promoted aggregation and spatial electronic communication, resulting in longer wavelength emission. Studies showed that the electrostatic potential distribution of the polymers played an important role in regulating their emission properties. Moreover, these polymers were successfully applied in ion sensing and fluorescent hydrogel preparation. This work provides new insights into the emission mechanism of unconventional fluorescent polymers.