Borylation and rearrangement reactions of azasilaanthracenes to afford B,N-doped nanographenes

25 April 2024, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

An air-stable B3,N3-containing dibenzobisanthene (8) was prepared in 29% yield by heating a 1,3,5-tri(azasilaanthryl)benzene (5) with BBr3 (180 °C). Under these conditions, the reaction does not stop after threefold SiMe2/BBr exchange but proceeds further via two rearrangement and two intramolecular C–H borylation steps. Some mechanistic details were unveiled by using smaller model systems and applying lower reaction temperatures. According to X-ray crystallography, compound 8 has a helically distorted scaffold. Due to its multiple resonance structure, it shows a narrow-band blue-green emission (λem = 493 nm; ΦPL = 84%; FWHM = 0.20 eV; THF); samples measured in PMMA gave prompt and delayed fluorescence lifetimes of 10.7 ns and 136 μs, respectively. The optical properties of 8 and of structurally related species were also investigated by quantum-chemical means: Most of these compounds exhibit a small energy gap ΔEST between the lowest excited singlet (S1) and triplet (T1) states and a non-negligible spin-orbit coupling (SOC) between S1 and T1/T2, demonstrating their potential as thermally activated delayed fluorescence (TADF) emitters

Keywords

Light emitting materials
Multi Resonant Thermally Activated Delayed Fluorescence

Supplementary materials

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Title
Borylation and rearrangement reactions of azasilaanthracenes to afford B,N-doped nanographenes
Description
Synthetic and computational details
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Title
Supplementary materials
Description
Supporting information of the working paper
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