Multiple Helicenes Defected by Heteroatoms and Heptagons with Narrow Emissions and Superior Photoluminescence Quantum Yields**

Abstract

The incorporation of heteroatoms and/or heptagons as the defects into helicenes expands the variety of chiroptical materials with novel properties. However, it is still challenging to construct novel boron‐doped heptagon‐containing helicenes with high photoluminescence quantum yields (PLQYs) and narrow full‐width‐at‐half‐maximum (FWHM) values. We report an efficient and scalable synthesis of a quadruple helicene 4Cz‐NBN with two nitrogen‐boron‐nitrogen (NBN) units and a double helicene 4Cz‐NBN‐P1 bearing two NBN‐doped heptagons, the latter could be formed via a two‐fold Scholl reaction of the former. The helicenes 4Cz‐NBN and 4Cz‐NBN‐P1 exhibit excellent PLQYs up to 99 % and 65 % with narrow FWHM of 24 nm and 22 nm, respectively. The emission wavelengths are tunable via stepwise titration experiments of 4Cz‐NBN‐P1 toward fluoride, enabling distinguished circularly polarized luminescence (CPL) from green, orange (4Cz‐NBN‐P1‐F1) to yellow (trans/cis‐4Cz‐NBN‐P1‐F2) with near‐unity PLQYs and broader circular dichroism (CD) ranges. The five structures of the aforementioned four helicenes were confirmed by single crystal X‐ray diffraction analysis. This work provides a novel design strategy for construction of non‐benzenoid multiple helicenes exhibiting narrow emissions with superior PLQYs.

Heteroatom-boron-heteroatom-doped π-conjugated systems: structures, synthesis and photofunctional properties

“…9a). 31 Both these multi-helicenes exhibit saddle-shaped frameworks in their crystal structures. Due to the distorted structure, the NBN-heptagon in 33 possesses a negative curvature of −2.3°, which is zero in NBN-centered PAHs 24 .…”

Heteroatom-facilitated blue to near-infrared emission of nonconjugated polyesters

“…In traditional π-conjugated chromophores, the introduction of heteroatoms has been proven as an efficient strategy for regulating the luminescence properties. 28 So, is it possible to increase the λ em by introducing more heteroatoms into the polyester and generating multiple TSI among carbonyl groups and heteroatoms?…”

Synthesis and Photophysical Properties of Carbazole-Functionalized Diazaphosphepines via Sequent P–N Chemistry

“…into molecular backbones has become an efficient strategy for fine-tuning the photophysical characteristics, redox properties, molecular organizations, and energy/charge carrier transports of OCMs. For example, the B-center with an empty p-orbital endowed the OCMs with excellent toxic anion responsive emission. − Combining the electron-withdrawing B-center and electron-donating N-center afforded OCMs with strong intramolecular charge transfer character and thermally delayed fluorescence properties. − Presence of a S-center had a strong impact on the solid-state organization and redox character of OCMs. , …”