Multicolor Emissive Hyperbranched Polysilicophosphate Ester from n-π Interaction and Concentrated Negative Electrostatic Potential-Enhanced Spatial Electronic Communication

Unconventional fluorescent polymers have attracted wide attention due to their excellent biocompatibility, facile preparation, and unique fluorescent properties. However, developing high-performance polymers and revealing the emission mechanism are still challenging. Herein, to explore the relationship between chemical structures and fluorescent properties, four hyperbranched poly(silicophosphate) esters (HSiP0-HSiP3) were prepared. Increasing the P═O(O)₃:Si(O)₃ ratios generated enhanced red fluorescence. Experimental and theoretical calculation results showed that the enhanced n-π interactions between P═O and the O/N atoms promoted the concentration of negative electrostatic potential and enhanced spatial electronic communications, and then decreased the energy gap and generated strong red emission. Meanwhile, the cluster of functional groups attracted a negative charge of isolated functional groups, which further enhanced the fluorescence. Additionally, these polymers showed excellent potential in bacterial imaging and information encryption. Thus, this work provides an efficient method for developing long-wavelength materials while providing new insights into the emission origin.