Solution‐ and Solid‐State Luminescent Borate Complexes Based on a Substituted π‐Conjugated 2‐(6′‐Hydroxy‐5′‐benzofuryl) Scaffold

Abstract

International audienceThis paper describes the synthesis of π-​conjugated fluorophores based either on an anil or a benzoxazole scaffold incorporating a rigid 2-​(6'-​hydroxy-​5'-​benzofuryl) fragment. Their subsequent coordination to a BF2 motif led to highly luminescent BIII complexes called boranils or HBBO borate complexes, resp. All the new compds. were characterized by NMR spectroscopy, mass spectrometry, and elemental anal. The study of their optical properties in soln. revealed two distinct photophys. behaviors depending on the substitution. Complexes bearing a strong electron-​donating p-​nBu2NC6H4 group displayed a marked internal charge transfer (ICT) leading to a pronounced solvatochromism with λem ranging from 507 to 663 nm and quantum yields of up to 87 %. Alternatively, borate complexes functionalized with p-​tBuC6H4 or p-​OMeC6H4 displayed fluorescence in the visible range that is not influenced by the nature of the solvent. Although the emission of the boranils was quenched in the solid state, HBBO borate complexes displayed intense fluorescence from 489 to 567 nm and quantum yields of up to 23 %. Finally, the excited states of a selection of borate complexes were modeled by using time-​dependent DFT, which allowed calcn. of the dipole moments of the dyes in their excited states

Tuning the Electronic Properties of the Dative N−B Bond with Associated O−B Interaction: Electron Localizability Indicator from X‐Ray Wavefunction Refinement

“…The situation changes when one considers a boron atom chelated between two differently substituted nitrogen atoms or, in a more extreme example, between two different atoms, such as nitrogen and oxygen. These structures are known as ketoiminates or boranils . Their properties, with an emphasis on electron distribution in the light of electronic absorption, were studied by using theoretical methods by Jacquemin et al., whereas the first review publication that focused on difluoroborates with the exception of BODIPYs was published by Ziessel et al …”

“…These structures are knowna sk etoiminates [11][12][13][14][15] or boranils. [16,17] Their properties, with an emphasis on electron distribution in the light of electronic absorption, were studied by using theoretical methods by Jacquemin et al, [18,19] whereas the first review publication that focusedo nd ifluoroboratesw ith the exception of BODIPYs was published by Ziessel et al [20] Because difluoroborates are compounds that are in the limelight nowadays, detailedk nowledge of their electronic proper-Despite the immense growth in interest in difluoroborate dyes, the nature of the interactions of the boron atom within the N-BF 2 -O kerneli sn ot yet fully understood. Herein, as et of realspace bondingi ndicators is used to quantify the electronic characteristics of the dative NÀBbondindifluoroborate derivatives.…”

Porosity-induced emission: exploring color-controllable fluorescence of porous organic polymers and their chemical sensing applications

“…(2) The phenomenon that as the DPP density increased, the fluorescence intensity of DPP increased to a maximum but then dropped, was illustrated through a comparative analysis of the fluorescent quantum yield (Φ FL ) and the BET surface area of a series of FL-SNW-DPPs, which revealed the mechanism of "Porosity Induced Emission". The following are the conclusions.…”

“…Fluorescent materials has spurred flourishing research interests, for they lie at the crossroad of a wide range of applications, such as light-emitting motifs, fluorescent sensors, probes, and various luminescent displays [1][2][3] . Many fundamental researches of these materials, especially in the fields of analytical and biological chemistry, are conducted in solutions, due to their excellent selectivity, a wide linear range of analysis and convenience in handling [4][5][6] .…”

BOIMPY: Fluorescent Boron Complexes with Tunable and Environment‐Responsive Light‐Emitting Properties

“…Existing strategies to lower the symmetry of the parent dipyrromethene ligand system (Figure ) involve: 1) replacing the amido N‐donor with anionic imidazolate, indolate, carbazolate, anilide, O‐donor, or C‐donor units; 2) replacing the imino N‐donor with charge‐neutral pyridine, quinoline, pyrimidine, thiazole, or imine groups.…”