Recently, RNA bulges, three-dimensional structural motifs that function as molecular handles in RNA, were identified in various sequences and have been proposed as the interaction site for RNA-binding drugs. However direct and sensitive monitoring methods specific to RNA bulges have not been well developed. We describe here pyrene-labeled uridine derivatives which were incorporated into HIV TAR RNA bulge sites resulting in greatly enhanced fluorescence, allowing the effective monitoring of base conformations in HIV TAR RNA. To clarify this fluorescence enhancement, Hartree–Fock calculations were performed for natural and pyrene-labeled HIV TAR RNA. The calculated results showed a considerable rotation of the pyrene moiety at U25 due to argininamide-induced conformational changes in the RNA bulge. This simple and efficient method can be used to elucidate conformational changes in specific bulge regions.

Blue phosphorescent organic light–emitting diodes (PhOLEDs) face challenges in achieving high efficiency, color purity, and long device lifetime due to exciton quenching and high energy requirements. In this study, two tetradentate Pt(II) complexes, Pt‐impy and Pt‐Me‐impy , are designed and synthesized by incorporating pyridocarbene in their ligands. Pyridocarbene enhances the electrochemical stability, strengthens triplet metal‐to‐ligand charge transfer characteristics, and improves the spin–orbit coupling, effectively shortening the exciton lifetime and minimizing the quenching effects. Additionally, the introduction of a methyl group as a conformation manager in Pt‐Me‐impy further improves the color purity by blue‐shifting and narrowing the emission spectrum. As a result, Pt‐impy and Pt‐Me‐impy exhibit external quantum efficiencies of 24.5% and 27.4% at the 3 wt.% doping concentration, respectively. In particular, Pt‐impy and Pt‐Me‐impy doped blue PhOLEDs optimized for stability demonstrate a device lifetime of up to 95% of the initial luminance of 543 and 228 h at 1,000 cd m ⁻² , which has never been achieved in the blue PhOLEDs. This study demonstrates that the synergistic combination of pyridocarbene and the methyl conformation manager is an effective strategy for improving blue PhOLED performance, enhancing their potential for practical applications.