Two‐Coordinate Gold(I) Complex with Rotational Freedom: A Platform Integrating Thermally Activated Delayed Fluorescence, Polymorphism, and Linearly Polarized Luminescence

Abstract Two‐coordinate coinage metal complexes have been exploited for various applications. Herein, a new donor‐metal‐acceptor (D–M–A) complex PZI‐Au‐TOT , using bulky pyrazine‐fused N‐heterocyclic carbene (PZI) and trioxytriphenylamine (TOT) ligands, was synthesized. PZI‐Au‐TOT displays decent thermally activated delayed fluorescence (TADF) with a quantum yield of 93 % in doped film. The crystals of PZI‐Au‐TOT show simultaneous TADF, polymorphism, and linearly polarized luminescence (LPL). The polymorph‐dependent emission properties with widely varied peaks from 560 to 655 nm are attributed to different packing modes in terms of isolated monomers, discrete π–π stacked dimers or dimer PLUS. Two well‐defined microcrystals of PZI‐Au‐TOT exhibit linearly polarized thermally activated delayed fluorescence with a degree of polarization up to 0.64. This work demonstrates that the molecular rotational flexibility of D–M–A type complexes endows an integration of multiple functions into one complex through manipulation of supramolecular aggregation. This type of complexes is expected to serve as a versatile platform for the fabrication of crystal materials for advanced photonic applications.