We report here that methyl-substituted hexamethoxytrityl (HMT) and the derived trioxatriangulene (TOTA) salts react with aldehydes, forming π-extended tristyryl-substituted HMT and TOTA dyes via a dynamic Knoevenagel condensation. These cations undergo a reversible electrochemical (or chemical) reduction, forming neutral radicals, including the first persistent TOTA radical. This reaction represents a promising platform to generate novel π-conjugated systems.

Although organoboron compounds have long been used in optoelectronics, the majority of research has involved boron difluoride and borane type moieties. In recent years, there has been increased interest in the luminescence of boronic acids and their heteroatom condensates (BAHCs), a class which can demonstrate properties of fluorescence, mechanoluminescence, room temperature phosphorescence, aggregation induced emission (AIE), and thermally activated delayed fluorescence (TADF). This Review covers the literature until the end of 2020 on the inherent luminescence of tricoordinate arylboronates, grouped into azaborolines (Ar−BNY), boronic acids and esters (Ar−BO 2 ), with a particular focus on the impact of the boron atom on photophysical properties.

Abstract In organic compounds, room temperature phosphorescence (RTP) is a rare, yet highly desirable, property that is important for a wide variety of applications, including tissue imaging, anticounterfeiting technologies, photodynamic therapy, and organic light‐emitting devices. While most organic RTP molecules rely on heavy atoms or carbonyl functional groups to accelerate singlet‐to‐triplet intersystem crossing, in the past few years there have been several reports of RTP induced by boron‐containing functional groups. This minireview covers the recent literature on RTP of crystalline boroorganic compounds and analyzes the connections between molecular structure, intermolecular interactions, and the resulting phosphorescence.

This study describes the synthesis, structure, and photophysical properties of a new luminescent polyaromatic boronic acid scaffold, diazaboryl-naphthyl-ketones (DNKs). These stable compounds display extremely bright fluorescence, aggregation-induced emission, positive solvatochromism, and solid-state fluorescence. DFT calculations and X-ray crystallographic study revealed notable electronic and structural differences between these compounds and the parent diaminonaphthalene (DAN) adducts. Acylation of the DAN system causes a localization of both HOMO and LUMO onto the DNK unit, which validates the negligible influence of the B-aryl substituent. The LUMO energy is lowered, and its shape significantly altered. Photophysical data in solution and the solid state revealed blue-shifted, narrowed, and intense emissions for DNKs (up to 89 % quantum yield). The potential utility of the fluorogenic DNK system was demonstrated with a proof-of-concept for the determination of trace boronic acid contaminants in solid samples, down to one-ppm level, using HPLC with fluorescence detection. This method could be useful in pharmaceutical development for the quantitation of difficult-to-detect and potentially mutagenic residual boronic acid from late cross-coupling reactions in drug syntheses.