Symmetrical Imidazo[1,5‐ a ]pyridine Dimers as Novel Organic Light Emitters: Bidirectional Synthesis and Photoluminescence Characterization

A series of novel substituted biimidazo[1,5‐ a ]pyridine derivatives are synthesized via a robust three‐step, bidirectional approach. The strategy involves an initial Negishi homocoupling of bromopicolinonitrile, followed by the formation of diketones with aryl Grignard reagents, and concludes with a double cyclization using substituted arylamines to afford a library of biimidazo[1,5‐ a ]pyridines. Selected dimers are structurally characterized by single‐crystal X‐ray diffraction. In addition, the impact of substitution patterns and connectivity within the biimidazo[1,5‐ a ]pyridine framework on their photoluminescent properties is systematically investigated. The key substitution position on imidazo[1,5‐ a ]pyridine core for tuning optical properties is identified. Furthermore, density functional theory (DFT) calculations are conducted to complement the experimental findings, offering a deeper understanding of the electronic structure, planarity, highest occupied molecular orbital and lowest unoccupied molecular orbital properties that influence their performance as organic light‐emitting materials for optoelectronic applications.