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 BO 3 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 Fe 3+ 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.