Large Stokes Shift Induced by Intramolcular Charge Transfer in N,O-Chelated Naphthyridine–BF2 Complexes

Crystal structure of 9-(dibromomethyl)-1,1-difluoro-3,7-dimethyl-1H-[1,3,5,2]oxadiazaborinino[3,4-a][1,8]naphthyridin-11-ium-1-uide

The mol­ecule in the title compound, C₁₂H₁₀BBr₂F₂N₃O, exhibits point group symmetry m.

The mol­ecule of the title 1,8-naphthyridine-BF₂ derivative, C₁₂H₁₀BBr₂F₂N₃O, is located on a mirror plane running parallel to the entire ring system and the attached methyl C atoms. Individual mol­ecules are stacked along the b-axis direction. The cohesion in the crystal structure is accomplished by C—H⋯F hydrogen bonds and additional off-set π–π inter­actions [centroid-to-centroid distance = 3.6392 (9) Å, slippage 0.472 Å], leading to the formation of a three-dimensional supra­molecular network.

1,1-Difluoro-3-phenyl-9-(pyridin-2-yl)-1H-1λ4,11λ4-1,3,5,2-oxadiazaborinino[3,4-a][1,8]naphthyridine

In the title compound, C20H13BF2N4O, the central fused three-ring oxadiazaborininonaphthyridine system is planar (r.m.s. deviation of 0.03 Å). The phenyl ring lies in the plane of this ring system, making a dihedral angle of 0.61 (14)°, and is inclined to the pyridine ring by 9.02 (19)°. In the crystal, molecules are connected by C—H...F hydrogen bonds, forming chains propagating along theb-axis direction. The chains are linked by offset π–π interactions [intercentroid distance = 3.4550 (13) Å], forming a three-dimensional supramolecular architecture.

The Influence of the π-Conjugated Spacer on Photophysical Properties of Difluoroboranyls Derived from Amides Carrying a Donor Group

A series of difluoroboranyls derived from amides carrying a variable π-conjugated spacer between the electron-donating (D) and electron-accepting (A) groups was synthesized and characterized with (1)H, (11)B, (13)C, (15)N, and (19)F NMR, electronic absorption, fluorescence spectroscopies, and first-principle calculations. The D-to-A distance in the series varied from 1.5 to 4.5 Å, causing bathochromic shifts of both the absorption and fluorescence maxima by more than 120 and 213 nm, respectively. These trends are rationalized by quantum-mechanical calculations that allow for quantification of the charge-transfer distance. Theoretical calculations were also performed to determine the vibronic couplings and thus to reproduce the experimental band shapes.

Effects of cyano groups on the properties of thiazole-based β-ketoiminate boron complexes: aggregation-induced emission and mechanofluorochromism

The triphenylamine-functionalized thiazole-based β-ketoiminate boron complexBF2-TT-CNexhibited strong cyano-dependent aggregation-induced emission (AIE) and mechanofluorochromic (MFC) properties.

Synthesis of novel boron chelate complexes and proposed mechanism of new rearrangement

We synthesized novel boron chelate complexes by the reaction of pyrazoline derivatives and boron trifluoride diethyl etherate followed by a new rearrangement. The structures of the compounds were characterized by IR, NMR and HRMS, especially, a typical compound 3c was confirmed by X-ray single crystal analysis. We proposed a mechanism of the rearrangement. Moreover, the absorption and fluorescence spectroscopy of these compounds were measured.

High solid-state luminescence in propeller-shaped AIE-active pyridine–ketoiminate–boron complexes

Two pyridine-ketoiminate-based organoboron complexes were demonstrated to possess aggregation-induced emission, large Stokes shift and high quantum yield in the solid-state, which were rationalized through X-ray crystal analysis and electronic structure calculations.

Diboron complexes with bis-spiro structures as high-performance blue emitters for OLEDs

By using blue-emissive diboron complexes with bis-spiro structures as emitting layers, the most efficient blue OLEDs based on four-coordinate organoboron compounds have been achieved.

Unusual solvent-dependent photophysical and self-assembly properties of NO2 substituted T-shaped phenazines

The importance of NO₂ substituent placement on T-shaped phenazines relative to electronic, photophysical, and organogelation properties.

AIE-active organoboron complexes with highly efficient solid-state luminescence and their application as gas sensitive materials

Four benzothiazole–ketoiminate-based organoboron complexes were demonstrated to show aggregation-induced emission, a large Stokes shift and high quantum yield in the solid-state, which were rationalized through X-ray crystal analysis, and electronic structure calculations.

Synthesis and photophysical properties of amino-substituted benzodithiophene-based fluorophores

A series of fluorophores based on amino-substituted BDT were synthesized, which exhibit good fluorescence in both solution and film. The emission color can be easily modulated from green to red.

R, Sun SS. Structural diversity of new solid-state luminophores based on quinoxaline-β-ketoiminate boron difluoride complexes with remarkable fluorescence switching properties

Highly tunable organoboron luminophores with intense solid-state fluorescence showed outstanding photoswitching properties modulated by acid/base vapors.

New members of fluorescent 1,8-naphthyridine-based BF2 compounds: selective binding of BF2 with terminal bidentate N^N^O and N^C^O groups and tunable spectroscopy properties

Intensely luminescent 1,8-naphthyridine-BF2 complexes 1-9 containing terminal bidentate N^N^O and/or N^C^O groups are synthesized and structurally characterized by X-ray diffraction, electrospray ionization mass spectrometry, (1)H and (19)F NMR spectroscopy and elemental analysis. Complexes 1-4 are synthesized from 2-acetamino-1,8-naphthyridine derivatives by a facile route. Selective bonding modes and the chemical stability of complexes 5 and 6 obtained by reacting BF3·Et2O with 1,8-naphthyridine derivatives bearing dual-functional groups (N^C^O and N^N^O) are investigated by crystal structure analysis and time-dependent density functional theory calculations. The products containing a BF2 core bound to a N^C^O chelating group are energetically favorable and can expand the range of derivatives by substitution at the 2-position. In this regard, a free -NH2 group at the 2-position of complex 7 obtained from 5 can be functionalized under a variety of pH conditions to generate complexes 8 and 9, which bear flexible coordination arms that can be used to recognize certain transition metals. The photophysical properties of the complexes are examined in solution and solid state at room temperature. Compared with those of the starting naphthyridine-based compounds, the naphthyridine-BF2 complexes display desirable light-absorbing properties and intense solution and solid-state emission with large Stokes shifts. Complex 4 in solution exhibited an emission quantum yield of 0.98. In complexes 5-9, the binding sites for the BF2 core change from N^N^O to N^C^O, which leads to red shifts of absorption and emission, excellent chemical stability and high emission quantum yields.

Highly fluorescent BF2 complexes of hydrazine-Schiff base linked bispyrrole

A series of BF2 complexes of hydrazine-Schiff base linked bispyrrole have been prepared from a simple two-step reaction from commercially available substances and are highly fluorescent in solution, film, and solid states with larger Stokes shift and excellent photostabilities comparable or even super to those of their BODIPY analogues. These resultant fluorescent dyes are highly susceptible to the postfunctionalization, as demonstrated in this work via the Knoevenagel condensation to introducing functionalities or tether groups to the chromophore.

Facile synthesis of highly fluorescent BF2 complexes bearing isoindolin-1-one ligand

A new class of isoindolin-1-one based BF₂ complexes containing pyridine or benzothiazole groups has been prepared from a “one-pot” reaction.

Structural modification strategies for the rational design of red/NIR region BODIPYs

The structure–property relationships of red/NIR region BODIPY dyes is analyzed, so that trends in their photophysical properties can be readily compared.

A new fluorescent probe for Zn2+ with red emission and its application in bioimaging

Selectively probing Zn²⁺in vivo! A new fluorescent probe highly sensitive and selective for Zn²⁺ based on the ICT effect was designed. This probe showed potential application in biology.