Multimetal site-determined d-orbital occupancy state modulation improves electromagnetic wave absorption performance

The correlation between the orbital occupancy of transition-metal d electrons and macroscopic electromagnetic behavior remains insufficiently understood. Herein, we demonstrate that HHTP-based conductive metal-organic frameworks act as molecular platforms for regulating d-orbital configurations by incorporating Co 3d 7 , Ni 3d 8 , and Zn 3d 10 centers. Partially occupied Co/Ni 3d orbitals enrich Fermi-level states and enhance d-π coupling with the HHTP skeleton, facilitating delocalized charge transport. Conversely, fully occupied Zn 3d 10 centers act as electronic symmetry-breaking nodes, disrupting local charge symmetry and inducing intense dynamic dipole polarization. By systematically adjusting the Zn ratio in CoNiZn x -HHTP, the dynamic interplay between delocalized charge transport and localized polarization relaxation is optimized, achieving a harmonized balance between dielectric attenuation and impedance matching. Furthermore, the coexistence of heterogeneous metal sites disrupts in-plane charge symmetry, generating intensified localized dipoles and intrinsic polarization centers. Through the synergistic reconstruction of d-d and d-π hybridizations, trimetallic CoNiZn-HHTP resolves the attenuation-matching trade-off by coupling controlled charge transport with cation-induced dielectric relaxation. As a result, CoNiZn-HHTP achieves a minimum reflection loss of −61.85 dB at 1.7 mm and a 5.63 GHz at 2.01 mm effective absorption bandwidth, delivering >99.9999% energy dissipation efficiency. In short, this work establishes d-orbital occupancy engineering as an electronic track-level strategy for designing high-efficiency electromagnetic functional materials.