Single Heteroatom Fine-Tuning of the Emissive Properties in Organoboron Complexes with 7-(Azaheteroaryl)indole Systems

Abstract

The application of organoboron compounds as light-absorbing or light-emitting species in areas as relevant as organic electronics or biomedicine has motivated the search for new materials which contribute to the progress of those applications. This article reports the synthesis of four-coordinate boron complexes based on the unexplored 7-(azaheteroaryl)indole ligands. An easy synthetic approach has enabled the fine-tuning of the electronic structure of the organoboron species by modifying a heteroaromatic component in the conjugated system. Furthermore, a comprehensive characterization by X-ray diffraction, absorption and emission spectroscopy, both in solution and in the solid state, cyclic voltammetry, and computational methods has evidenced the utility of this simple strategy. Large Stokes shifts have been achieved in solid thin-films which show a range of emitted light from blue to orange. The synthesized compounds have been used as biocompatible fluorophores in cell bioimaging.

Rationally Designed Furocarbazoles as Multifunctional Aggregation Induced Emissive Luminogens for the Sensing of Trinitrophenol (TNP) and Cell Imaging

“…Above all, the widespread use of explosive formulations poses a serious threat to the human condition, including skin irritation, anemia, and carcinogenicity, among several others . Therefore, the analysis of explosives has been of importance and several attempts have been committed to designing new materials for detecting nitroaromatics (NACs) . The high risk associated with TNT urged us to use trinitrophenol (TNP) as an analyte, which interestingly has superior explosive power when compared to TNT as well as higher water solubility which also threatens the aquatic life and biodiversity.…”

Pyrrolylquinoline-BF2 and BPh2 BODIPY-Type Analogues: Synthesis, Structural Analysis and Photophysical Properties

“…This suggests that there is no induced strain on the aromatic system of 8 (Figure 2). The corresponding pyrrolylquinoline BPh2 complex 9 was accessed according to the procedure employed by Curiel and co-workers for the synthesis of the analogous indole 3 [41]. The pyrrolylquinoline intermediate 13 was treated with two equivalents of triphenylborane 14 in toluene under reflux.…”

“…Despite these studies, to the best of our knowledge, the boron(III) chelated pyrrolylquinoline type fluorescent dyes shown in Figure 1c have not been reported. These are analogues of the simple pyridine-indole chelate 3 [41] in which the benzo-ring fusion has been transposed between the heteroaromatic cores. In this report, we detail the synthesis of such compounds using Suzuki coupling (bromo-quinoline-pyrrole boronic acid cross- Despite these studies, to the best of our knowledge, the boron(III) chelated pyrrolylquinoline type fluorescent dyes shown in Figure 1c have not been reported.…”

“…In this report, we detail the synthesis of such compounds using Suzuki coupling (bromo-quinoline-pyrrole boronic acid cross- Despite these studies, to the best of our knowledge, the boron(III) chelated pyrrolylquinoline type fluorescent dyes shown in Figure 1c have not been reported. These are analogues of the simple pyridine-indole chelate 3 [41] in which the benzo-ring fusion has been transposed between the heteroaromatic cores. In this report, we detail the synthesis of such compounds using Suzuki coupling (bromo-quinoline-pyrrole boronic acid cross-coupling) as the initial step to build the core structure, followed by N-tert-butyloxycarbonyl removal and subsequent boron complexation reactions to access the desired fluorophores.…”

BF2‐Complexes of Carbazole–Benzimidazole Conjugates: Synthesis, Structures, and Spectroscopic Properties

“…have shown the incorporation of carbazole units to porphyrinoids and BODIPY frameworks generated interesting photophysical properties . A recent report on four‐coordinate organoboron complexes derived from indole‐azaheteroaryl ligands showed wide range of emission from blue to orange . However, small Stokes shifts (<15 nm) are one of the main drawbacks for the application of BODIPY dyes in molecular imaging due to the self‐absorption effect resulting in less intensive emission .…”