A series of planarized B,N‐diarylated dibenzoazaborine compounds (5a–5e) in which various functional groups are introduced into the B‐Ph and N‐Ph moieties of nonsubstituted dibenzoazaborine compound (I) were prepared. All compounds exhibit strong low‐energy absorptions at ca. 410–426 nm with a gradual red‐shift depending on the electron‐accepting property of the four substituents (4‐R = 4‐Ph < 4‐Pm < 4‐CNPh <4‐CN) on the B‐Ph ring in 5a–5d. Introduction of an electron‐donating tBu group into the N‐Ph ring further shifts slightly the absorption band toward a lower‐energy region (5e). Importantly, all compounds undergo gradual red‐shifts in the emission leading to deep blue fluorescence for CN‐substituted 5d and 5e. Furthermore, the emissions have narrow full width at half maximum values of ca. 30 nm, high photoluminescence quantum yields (ΦPL ≈ 100%), and small Stokes shifts (11–16 nm). The electrochemical and theoretical studies further support the bandgap control and photophysical properties of compounds.

Three donor−acceptor-type thermally activated delayed fluorescence (TADF) emitters (PXZBAO (1), PXZBTO (2), and PXZBPO (3)) comprising a phenoxazine (PXZ) donor and differently π-expanded boroncarbonyl (BCO) hybrid acceptor units are proposed. The emitters exhibit red (1) to orange (3) emissions with an increase in the π-expansion in the BCO acceptors. The control of the strength of local aromaticity for the BCO unit and the corresponding LUMO level is attributed to inducing the unusual emission color shifts. The photoluminescence quantum yield and delayed fluorescence lifetime of the emitters are also adjusted by the π-expansion. Notably, although 1 possesses a 3 nπ* state in the acceptor unit as a local triplet excited state ( 3 LE, T 2 ), the T 2 states of 2 and 3 mainly comprise a 3 ππ* state in the acceptor. Consequently, all of the emitters exhibit strong spin−orbit coupling between their T 2 and excited singlet (S 1 ) states, leading to a fast reverse intersystem crossing with rate constants of ∼10 6 s −1 . By employing the emitters as dopants, we realize efficient red-to-orange TADF-OLEDs. Maximum external quantum efficiencies of 17.7% for the yellowish-orange (3), 15.5% for the orange (2), and 13.9% for the red (1) devices are achieved, and the values are very close to the theoretical limit predicted from the optical simulation.

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Breast cancer is the most substantial cancer among women in the world. The uncontrollably high DNA Methyltransferase-1 (DNMT1) activity which leads to abnormal gene expression is one of the primary cause of breast cancer. Therefore, DNMT1, as an essential enzyme in epigenetic regulation, is considered as a potential therapeutic target for breast cancer treatment. In this research, the inhibitors of DNMT1 were designed through fragment-based drug design. About 168,646 natural products from PubChem database were used as fragment candidates. Initial screening based on toxicity and Lipinski's Rule of Three was performed to obtain 2,601 favorable fragments. Pharmacophore-based rigid and flexible molecular docking simulation was employed with DNMT1 as the target protein. The selected fragments from docking simulation underwent fragment linking modification and second toxicity screening, generating 23 ligands. Subsequently, the newly designed ligands were subjected to pharmacophore-based flexible molecular docking simulation. Two ligands, HAMI 9 and HAMI 14, with Gibbs free binding energy of -11.6095 and -11.5904 kcal/mol, respectively, are considered as a promising inhibitor of DNMT1. The pharmacological properties of the ligands were analyzed using DataWarrior v04.07.02, Toxtree v2.6.13, SwissADME, admetSAR, and Molinspiration. The ligands show not only superior affinity and molecular interaction to DNMT1 but also have advantageous pharmacological properties compared to the standards. Additional in silico as well as in vivo experiments are needed to further assess the potency of HAMI 9 and HAMI 14 as drug candidates against breast cancer.