Aggregation‐Induced Dual Phosphorescence from (o‐Bromophenyl)‐Bis(2,6‐Dimethylphenyl)Borane at Room Temperature

Abstract

Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non‐radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p‐bromophenyl)‐bis(2,6‐dimethylphenyl)boranes. Among the 3 isomers (o‐, m‐ and p‐BrTAB) synthesized, the ortho‐one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o‐BrTAB, the short lifetime component is ascribed to the T1M state of the monomer which emits the higher energy phosphorescence. The long‐lived, lower energy phosphorescence emission is attributed to the T1A state of an aggregate, with multiple intermolecular interactions existing in crystalline o‐BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.

Triarylboron‐Doped Acenethiophenes as Organic Sonosensitizers for Highly Efficient Sonodynamic Therapy with Low Phototoxicity

“…Inset table: R values of AnTh, TeTh, BAnTh, and BTeTh using the equation $$R\ = \ {\left[ {\langle {{\rm{S}}_n}\left| {{{\rm{H}}_{{\rm{SO}}}}} \right|{{\rm{T}}_m}\rangle /\Delta {E_{{{\rm{S}}_n}{{\rm{T}}_m}}}} \right]^{\;2}}\ \propto \ {k_{{\rm{ISC}}}}$$. [ 63–68 ]…”

“…ISC . [63][64][65][66][67][68] BTeTh than for precursors AnTh and TeTh, leading to a significant increase in the ISC rate constant (k ISC ). As shown in Figure 2c (see also Tables S9 and S10, Supporting Information), the k ISC is negligible for the precursors AnTh and TeTh with R values much lower than 1.…”

Structural and mechanistic studies of excitation- and temperature-tunable multicolor luminescence of triarylborane

“…These room-temperature phosphorescent functional groups with excellent luminescence properties have greatly stimulated the development of the phosphorescence field, leading to the emergence of many new room-temperature phosphorescent groups. Recently, several studies have shown that unique phosphorescence can be observed for boroorganic materials [42][43][44][45][46][47][48][49][50] especially triarylborane compounds due to unusual electronic structures. For example, Marder's group 47,50 found that triarylboranes without any lone pair of electrons can exhibit excellent RTP properties, e.g., tris (2,6dimethylphenyl)borane showing an ultralong phosphorescence lifetime of 478 ms. Zhao's group 46 reported that Br substituted triarylboranes exhibit RTP of 73 and 52 μs in the solid state.…”

“…Recently, several studies have shown that unique phosphorescence can be observed for boroorganic materials [42][43][44][45][46][47][48][49][50] especially triarylborane compounds due to unusual electronic structures. For example, Marder's group 47,50 found that triarylboranes without any lone pair of electrons can exhibit excellent RTP properties, e.g., tris (2,6dimethylphenyl)borane showing an ultralong phosphorescence lifetime of 478 ms. Zhao's group 46 reported that Br substituted triarylboranes exhibit RTP of 73 and 52 μs in the solid state. More interestingly, Jäkle et al reported that the RTP can also be observed in triarylborane polymers.…”

Synthesis, structural, and photophysical properties of pyrazolyl bis(pentafluorophenyl)boron complexes

“…2 Attractive photophysical properties were achieved by incorporating main-group elements in the framework of organic molecules. 3 Among the different main-group incorporated organic fluorophores, boron-embedded fluorophores 4 have gained attention due to their stability, electron acceptability and tuneable luminescence. 5 In particular, tetra-coordinated N , O -chelated boron compounds have emerged as promising candidates due to their interesting photophysical properties such as solvatochromism, aggregation-induced enhanced emission (AIEE), and mechanochromism, as well as their exhibited potential applications in electroluminescent and bio-imaging materials.…”