We demonstrate that multi-fluorinated boron-fused azobenzene (BAz) complexes can work as a strong electron acceptor in electron donor-acceptor (D-A) type π-conjugated polymers. Position-dependent substitution effects were revealed, and the energy level of the lowest unoccupied molecular orbital (LUMO) was critically decreased by fluorination. As a result, the obtained polymers showed near-infrared (NIR) emission (λPL=758–847 nm) with high absolute photoluminescence quantum yield (ΦPL=7–23%) originating from low-lying LUMO energy levels of the BAz moieties (−3.94 to −4.25 eV). Owing to inherent solid-state emissive properties of the BAz units, deeper NIR emission (λPL=852980 nm) was detected in film state. Clear solvent effects prove that the NIR emission is from a charge transfer state originating from a strong D-A interaction. The effects of fluorination on the frontier orbitals are well understandable and predictable by theoretical calculation with density functional theory. This study demonstrates the effectiveness of fluorination to the BAz units for producing a strong electron-accepting unit through fine-tuning of energy gaps, which can be the promising strategy for designing NIR absorptive and emissive materials. 相似文献
A series of boron ketoiminate derivatives that exhibited clear aggregation‐induced emission (AIE) characteristics (in THF: ΦPL≤0.01; in the solid state: ΦPL=0.30–0.76) were prepared by the reactions of 1,3‐enaminoketone derivatives with boron trifluoride–diethyl etherate. The structures and optical properties were investigated by UV‐visible spectroscopy, photoluminescent (PL) spectroscopy, and X‐ray single‐crystal measurements. These results indicate that the AIE characteristics were derived from molecular motions of the boron‐chelating rings with a boron? nitrogen (B? N) bond. Furthermore, the optical properties were controllable by steric hindrance of the substituted groups on the nitrogen atom. 相似文献
In this research, the synthesis of boron‐ketoiminate‐containing polymers is reported with large molecular weights ( = 20 000) and their optical properties are examined by UV–vis absorption and photoluminescence spectrometries. It is shown that the polymers exhibit strong emission both in the solution and solid states (ΦPL,THF = 0.46–0.80, ΦPL,film = 0.13–0.38). These optical properties can be explained by a donor–acceptor interaction between the boron ketoiminate and the electron‐donating comonomer such as fluorene or bithiophene. Furthermore, in the solid states, their emission colors can be successfully tuned from blue to orange by the substituents on the nitrogen atom with the difference of the steric hindrance (λPL,THF = 464–546 nm, λPL,film = 486–604 nm).
This article describes a series of nine complexes of boron difluoride with 2′‐hydroxychacone derivatives. These dyes were synthesized very simply and exhibited intense NIR emission in the solid state. Complexation with boron was shown to impart very strong donor–acceptor character into the excited state of these dyes, which further shifted their emission towards the NIR region (up to 855 nm for dye 5 b , which contained the strongly donating triphenylamine group). Strikingly, these optical features were obtained for crystalline solids, which are characterized by high molecular order and tight packing, two features that are conventionally believed to be detrimental to luminescence in organic crystals. Remarkably, the emission of light from the π‐stacked molecules did not occur at the expense of the emission quantum yield. Indeed, in the case of pyrene‐containing dye 4 , for example, a fluorescence quantum yield of about 15 % with a fluorescence emission maximum at 755 nm were obtained in the solid state. Moreover, dye 3 a and acetonaphthone‐based compounds 1 b , 2 b , and 3 b showed no evidence of degradation as solutions in CH2Cl2 that contained EtOH. In particular, solutions of brightly fluorescent compound 3 a (brightness: ε×Φf=45 000 M ?1 cm?1) could be stored for long periods without any detectable changes in its optical properties. All together, these new dyes possess a set of very interesting properties that make them promising solid‐state NIR fluorophores for applications in materials science. 相似文献
Herein, two new quadrupolar acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) chromophores have been prepared featuring a strongly electron‐donating diborene core and strongly electron‐accepting dimesitylboryl (BMes2) and bis(2,4,6‐tris(trifluoromethyl)phenyl)boryl (BFMes2) end groups. Analysis of the compounds by NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis‐NIR absorption and emission spectroscopy indicated that the compounds have extended conjugated π‐systems spanning their B4C8 cores. The combination of exceptionally potent π‐donor (diborene) and π‐acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO–LUMO gaps, resulting in strong absorption in the near‐IR region with maxima in THF at 840 and 1092 nm and very high extinction coefficients of ca. 120 000 m ?1 cm?1. Both molecules also display weak near‐IR fluorescence with small Stokes shifts. 相似文献
Several metal complexes with a boron dipyrromethene (BODIPY)‐functionalized N‐heterocyclic carbene (NHC) ligand 4 were synthesized. The fluorescence in [( 4 )(SIMes)RuCl2(ind)] complex is quenched (Φ=0.003), it is weak in [( 4 )PdI2(Clpy)] (Φ=0.033), and strong in [( 4 )AuI] (Φ=0.70). The BODIPY‐tagged complexes can experience pronounced changes in the brightness of the fluorophore upon ligand‐exchange and ligand‐dissociation reactions. Complexes [( 4 )MX(1,5‐cyclooctadiene)] (M=Rh, Ir; X=Cl, I; Φ=0.008–0.016) are converted into strongly fluorescent complexes [( 4 )MX(CO)2] (Φ=0.53–0.70) upon reaction with carbon monoxide. The unquenching of the Rh and Ir complexes appears to be a consequence of the decreased electron density at Rh or Ir in the carbonyl complexes. In contrast, the substitution of an iodo ligand in [( 4 )AuI] by an electron‐rich thiolate decreases the brightness of the BODIPY fluorophore, rendering the BODIPY as a highly sensitive probe for changes in the coordination sphere of the transition metal. 相似文献
The push–pull character of a series of donor–bithienyl–acceptor compounds has been tuned by adopting triphenylamine or 1,1,7,7‐tetramethyljulolidine as a donor and B(2,6‐Me2‐4‐RC6H2)2 (R=Me, C6F5 or 3,5‐(CF3)2C6H3) or B[2,4,6‐(CF3)3C6H2]2 as an acceptor. Ir‐catalyzed C?H borylation was utilized in the derivatization of the boryl acceptors and the tetramethyljulolidine donor. The donor and acceptor strengths were evaluated by electrochemical and photophysical measurements. In solution, the compound with the strongest acceptor, B[2,4,6‐(CF3)3C6H2]2 ((FMes)2B), has strongly quenched emission, while all other compounds show efficient green to red (ΦF=0.80–1.00) or near‐IR (NIR; ΦF=0.27–0.48) emission, depending on solvent. Notably, this study presents the first examples of efficient NIR emission from three‐coordinate boron compounds. Efficient solid‐state red emission was observed for some derivatives, and interesting aggregation‐induced emission of the (FMes)2B‐containing compound was studied. Moreover, each compound showed a strong and clearly visible response to fluoride addition, with either a large emission‐color change or turn‐on fluorescence. 相似文献
Pyrene‐bridged boron subphthalocyanine dimers were synthesized from a mixed‐condensation reaction of 2,7‐di‐tert‐butyl‐4,5,9,10‐tetracyanopyrene and tetrafluorophthalonitrile, and their syn and anti isomers arising from the result of connecting two bowl‐shaped boron subphthalocyanine molecules were successfully separated. Expansion of the conjugated system of boron subphthalocyanine through a pyrene bridge caused a redshift of the Q band absorption relative to the parent pyrene‐fused monomer, whereas combining the curved π‐conjugation of boron subphthalocyanine with the planar π‐conjugation of pyrene enabled facile embracement of C60 molecules, owing to the enhanced concave–convex π–π stacking interactions. 相似文献
Developing red thermally activated delayed fluorescence (TADF) emitters, attainable for both high‐efficient red organic light‐emitting diodes (OLEDs) and non‐doped deep red/near‐infrared (NIR) OLEDs, is challenging. Now, two red emitters, BPPZ‐PXZ and mDPBPZ‐PXZ, with twisted donor–acceptor structures were designed and synthesized to study molecular design strategies of high‐efficiency red TADF emitters. BPPZ‐PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with a photoluminescence quantum yield (ΦPL) of 100±0.8 % and external quantum efficiency (EQE) of 25.2 % in a doped OLED. Its non‐doped OLED has an EQE of 2.5 % owing to unavoidable intermolecular π–π interactions. mDPBPZ‐PXZ releases two pyridine substituents from its fused acceptor moiety. Although mDPBPZ‐PXZ realizes a lower EQE of 21.7 % in the doped OLED, its non‐doped device shows a superior EQE of 5.2 % with a deep red/NIR emission at peak of 680 nm. 相似文献
A recent report illustrated superior optical properties, such as near‐infrared emission, of polymers connected at the 4,4′‐positions to a fused azobenzene–boron complex (BAz). In this study, it is initially demonstrated that further narrowing of the band gap can be realized through the substituent effect with bromine groups at the 5,5′‐positions of BAz compared with those at the 4,4′‐positions. From a series of mechanistic studies, perturbation of the energy levels was rationally explained by the difference in contributions of the inductive effect and the variable resonance effect, which was correlated with the degree of electron distribution of molecular orbitals at the substituent positions. Moreover, it was found that unique electronic states, such as delocalized HOMOs and LUMOs, should appear on the main chains of the BAz‐containing copolymers with fluorene and bithiophene units, according to the optical and electrochemical data and theoretical calculations. By taking advantage of property tunability and the dramatically low LUMO energy level (near ?4.0 eV) of the BAz unit, it can be said that BAz should be a conjugated building block favorable for building advanced optoelectronic devices. 相似文献
Pyrimidine‐based diboron complexes bearing β‐iminoenolate ligands and phenyl groups as bulky substituents on the boron atoms were synthesized as novel fluorescent dyes, and their fluorescence properties were investigated in solution and in the solid state. The diboron complexes with donor–π–acceptor structures showed positive solvatochromism in the fluorescence spectra. The cyano derivative exhibited the most dramatic redshift of the fluorescence maximum Fmax with increasing solvent polarity (from 551 nm in n‐hexane to 710 nm in acetonitrile). The diboron complexes showed solid‐state fluorescence in the range of 578–706 nm with fluorescence quantum yields of 0.06–0.28. Additionally, the trifluoromethyl derivative exhibited solvent‐inclusion solid‐state fluorescence. The trifluoromethyl derivative formed toluene‐inclusion and ethyl acetate‐inclusion crystals. The toluene‐inclusion crystal (Fmax=668 nm, Φf=0.16) showed a blueshifted Fmax and higher Φf value compared to the original trifluoromethyl derivative (Fmax=694 nm, Φf=0.08) in the solid state. On the other hand, the Fmax (709 nm) and Φf (0.04) values of the ethyl acetate‐inclusion crystal were redshifted and lower, respectively. 相似文献
Are different B(boron)–π–N(nitrogen) embedded patterns to bring about significant different (opto)electronic properties for the same macrocyclic molecular backbone? A series of B–π–N‐embedded alternate‐meta‐para‐linked cyclophanes 1 – 3 have been prepared and characterized as a new class of ambipolar π‐conjugated B–π–N macrocycles. The answer to the opening question is yes. These macrocycles revealed the intramolecular charge transfer in the oxidized states and the intriguing photophysical proprerties in accordance with the embedded patterns, suggesting the electronic structures are tunable by introducing multiple B–π–N moieties. 相似文献
We report the synthesis and characterization of a three‐dimensional tetraphenylethene‐based octacationic cage that shows host–guest recognition of polycyclic aromatic hydrocarbons (e.g. coronene) in organic media and water‐soluble dyes (e.g. sulforhodamine 101) in aqueous media through CH???π, π–π, and/or electrostatic interactions. The cage?coronene exhibits a cuboid internal cavity with a size of approximately 17.2×11.0×6.96 Å3 and a “hamburger”‐type host–guest complex, which is hierarchically stacked into 1D nanotubes and a 3D supramolecular framework. The free cage possesses a similar cavity in the crystalline state. Furthermore, a host–guest complex formed between the octacationic cage and sulforhodamine 101 had a higher absolute quantum yield (ΦF=28.5 %), larger excitation–emission gap (Δλex‐em=211 nm), and longer emission lifetime (τ=7.0 ns) as compared to the guest (ΦF=10.5 %; Δλex‐em=11 nm; τ=4.9 ns), and purer emission (ΔλFWHM=38 nm) as compared to the host (ΔλFWHM=111 nm). 相似文献
A family of highly emissive dithiazolo[5,4‐b:4′,5′‐d]phospholes has been designed and synthesized. The structures of two trivalent P species, as well as their corresponding P oxides, have been confirmed by X‐ray crystallography. The parent dithiazolo[5,4‐b:4′,5′‐d]phosphole oxide exhibits strong blue photoluminescence at λem=442 nm, with an excellent quantum yield efficiency of ?PL=0.81. The photophysical properties of these compounds can be easily tuned by extension of the conjugation and modification of the phosphorus center. Compared with the established dithieno[3,2‐b:2′,3′‐d]phosphole system, the incorporation of electronegative nitrogen atoms leads to significantly lowered frontier orbital energy levels, as validated by both electrochemistry and theoretical calculations, thus suggesting that the dithiazolo[5,4‐b:4′,5′‐d]phospholes are valuable, air‐stable, n‐type conjugated materials. These new building blocks have been further applied to the construction of an extended oligomer with fluorene. Extension of the dithiazolophosphole core with triazole units through click reactions also provides a suitable N,N‐chelating moiety for metal binding and a representative molecular species was successfully used as a selective colorimetric and fluorescent sensor for CuII ions. 相似文献
The development of disilane‐bridged donor–acceptor–donor (D‐Si‐Si‐A‐Si‐Si‐D) and acceptor–donor–acceptor (A‐Si‐Si‐D‐Si‐Si‐A) compounds is described. Both types of compound showed strong emission (λem=ca. 500 and ca. 400 nm, respectively) in the solid state with high quantum yields (Φ: up to 0.85). Compound 4 exhibited aggregation‐induced emission enhancement in solution. X‐ray diffraction revealed that the crystal structures of 2 , 4 , and 12 had no intermolecular π–π interactions to suppress the nonradiative transition in the solid state. 相似文献