Hyperbranched Polyborate: A Non-conjugated Fluorescent Polymer with Unanticipated High Quantum Yield and Multicolor Emission

Non-conjugated fluorescent polymers have attracted great attention due to their excellent biocompatibility and environmental friendliness. However, it remains a huge challenge to obtain a polymer with high fluorescence quantum yield (QY) and multicolor emission simultaneously. Herein, we reported three kinds of nonaromatic hyperbranched polyborates (P1-P3) with multicolor emission, surprisingly, P2 also exhibits an unanticipated high QY (54.1 %). The natural bond orbital (NBO) analysis and density functional theory (DFT) calculation results revealed that the synergistic effect of rigid BO3 planar and flexible carbon chain, as well as the through-space dative bond in supramolecular aggregate, were the key factors contributing to the ultrahigh QY of P2. Moreover, the applications of P2 in Fe3+ ions detection and cell imaging were also investigated. This work provides a new perspective for designing non-conjugated fluorescent polymers with both high QY and multicolor emission.

Automated summary

Non-conjugated fluorescent polymers with high fluorescence quantum yield (QY) and multicolor emission are highly desired but challenging to achieve. In this study, a new type of nonaromatic hyperbranched polyborates was reported, which exhibited both high QY and multicolor emission. The key factors contributing to the ultrahigh QY were identified as the synergistic effect of a rigid BO3 planar and flexible carbon chain, as well as the through-space dative bond in supramolecular aggregate. This work provides a new perspective for designing non-conjugated fluorescent polymers with high QY and multicolor emission.