Temperature‐dependent dual fluorescence and switchable circularly polarized luminescence (CPL) are two highly pursued but challenging properties for small organic molecules (SOMs). We herein disclose a triarylborane π‐system based on a 2,2′‐diamino‐6,6′‐diboryl‐1,1′‐binaphthyl scaffold that can serve as a versatile building block for achieving these two properties by simply choosing different amino groups. BNMe2‐BNaph with less bulky dimethylamino groups displays temperature‐dependent dual fluorescence, and can thus be used as a highly sensitive ratiometric fluorescence thermometer. On the other hand, BNPh2‐BNaph with bulky diphenylamino groups exhibits intense fluorescence in both solution and in the solid state. A change of solvent from nonpolar cyclohexane to highly polar MeCN not only shifts the CPL position to much longer wavelength but also inverts the CPL sign. In addition, the complexation of BNPh2‐BNaph with fluoride greatly enhances the CPL intensity.

We developed a simple approach to synthesizing ionic vinylene-linked two-dimensional covalent organic frameworks (COFs) through a quaternization-promoted Knoevenagel condensation at three aromatic methyl carbon atoms of Nethyl-2,4,6-trimethylpyridinium halide with multitopic aromatic aldehyde derivatives. The resultant COFs exhibited a honeycomb-like structure with high crystallinity and surface areas as large as 1343 m 2 g À1 . The regular shape-persistent nanochannels and the positively charged polymeric frameworks allowed the COFs to be uniformly composited with linear polyethylene oxide and lithium salt, displaying ionic conductivity as high as 2.72 10 À3 S cm À1 .

Two novel B,N-embedded double heterohelicenes, Ph-NBNDH and Naph-NBNDH, with intensively twisted quasi-C 2 symmetrical structures are synthesized for the first time via a highly regioselective intramolecular Scholl reaction. The π-extended skeletons render them with exceptional physical properties, such as the highest fluorescence quantum yields up to 0.83 among multiple helicenes. Moreover, the isolated (M,M)-and (P,P)-enantiomers of Naph-NBNDH deliver intense circularly polarized luminescence. As the emitting layer, Ph-NBNDH exhibits strong electroluminescence at high working voltage.

Triarylboranes have attracted significantly increasing research interest as a remarkable class of photoelectronic π-electron materials. Because of the presence of vacant p orbital on the B center, the boryl group is a very unique electron acceptor that exhibits not only electron-accepting ability through p-π* conjugation but also high Lewis acidity to coordinate with Lewis bases and steric bulk arising from the aryl substituent on the B center to get enough kinetic stability. Thus, the incorporation of a trivalent B element into π-conjugated systems is an efficient strategy to tune the electronic and stereo structures and thus the photoelectronic properties of π-electron systems. When an electron-donating group, such as amino, is present, triarylboranes would likely display intramolecular charge-transfer transitions. These kinds of molecules are often highly emissive. In addition, the geometry of the molecules has a great impact on the emission properties. In this Forum Article, we herein describe our recent progress on the charge-transfer emitting triarylborane π-electron systems with novel geometries, which include the lateral boryl-substituted π-system with amino groups at the terminal positions, the o,o'-substituted biaryl π-system with boryl and amino groups at the o,o'-positions, a triarylborane-based BODIPY system, and a B,N/S-bridged ladder-type π-system. We mainly put the emphasis on the molecular design concept, structure-property relationships, intriguing emission properties and great applications of the corresponding triarylborane π-systems.

A Brønsted-acid-promoted alkyne benzannulation approach was developed to synthesize the aminosubstituted dibenze[a,j]anthracence derivatives in excellent yields, which were directly converted to fully zigzag-edged polycyclic heteroaromatic hydrocarbons via a nitrogendirected electrophilic borylation. As the dopant in a bluegreen electroluminescent device, the resulted compound exhibited relatively high stability.