Dibenzosuberenylidene-ended fluorophores: rapid and efficient synthesis, characterization, and aggregation-induced emissions

A series of pi-conjugated compounds ending with dibenzosuberenylidene were synthesized efficiently. Their luminescence efficiencies were well-tuned by structural modification. Moreover, relative emission intensities were strongly affected by their existing appearances and exhibited aggregation-induced emission (AIE) behavior. Thus, emissions from nanoparticles, films, or powders were found to be more efficient than those from solutions. It demonstrated that these synthesized compounds might be practically used as fluorescent materials for potential optoelectronic applications.     

Designing anticancer combretastatin A-4 analogues with aggregation-induced emission characteristics

Science China Chemistry - Herein a series of combretastatin A-4 (CA-4) analogues with aggregation-induced emission characteristics (compounds a1–a19) were rationally designed and synthesized....     

Recent advances in organic mechanofluorochromic materials

Mechanofluorochromic materials, which are dependent on changes in physical molecular packing modes, have attracted considerable interest over the past ten years. In this review, recent progress in the area of pure organic mechanofluorochromism is summarized, and majority of the reported organic mechanofluorochromic systems are discussed, along with their derived structure-property relationships. The existence of a structural relationship between aggregation-induced emission compounds and mechanofluorochromism is recognized based on our recent results, which considered aggregation-induced emission compounds as a well of mechanofluorochromic materials. The established structure-property relationship will guide researchers in identifying and synthesizing more mechanofluorochromic materials.     

Enhanced photoluminescence from group 14 metalloles in aggregated and solid solutions

The unusual photoluminescence characteristics of a series of six group 14 metalloles (1,1-dimethyl-2,3,4,5-tetraphenylmetalloles and 1,1-diphenyl-2,3,4,5-tetraphenylmetalloles) containing silicon, germanium, or tin have been investigated. Although the compounds are weakly luminescent in dilute fluid solution at room temperature, they undergo a substantial enhancement of photoluminescence when forced to aggregate, as in mixed solvent systems. The compounds also exhibit considerable emission when incorporated into rigid room-temperature glasses of sucrose octaacetate. Absorption and emission characteristics of the compounds, including luminescence quantum yields, in fluid solution, solution-phase aggregates, and room-temperature glasses are reported. Quantum yields increase by as much as 2 orders of magnitude in the aggregates and glasses, compared to fluid solution. Experimental evidence supports the conclusion that the aggregation-induced enhancement of luminescence results from restricted intramolecular rotations in the packed metalloles. The unusual aggregation-induced enhancement of these compounds makes them potentially useful for the fabrication of a variety of electrooptical devices and sensors. In addition, the X-ray crystal structure of hexaphenylgermole is reported.     

Triphenylamine,Carbazole or Tetraphenylethylene-Functionalized Benzothiadiazole Derivatives: Aggregation-Induced Emission (AIE), Solvatochromic and Different Mechanoresponsive Fluorescence Characteristics

The development of mechanochromic fluorophors with high-brightness, solid-state fluorescence is very significant and challenging. Herein, highly solid-state emissive triphenylamine, carbazole and tetraphenylethylene-functionalized benzothiadiazole derivatives were developed. These compounds showed remarkable aggregation-induced emission and solvatochromic fluorescence characteristics. Furthermore, these fluorogenic compounds also displayed different mechanically triggering fluorescence responses.     

压致变色聚集诱导发光材料

聚集诱导发光化合物分子具有特殊的螺旋桨形扭曲构象结构, 导致其很难在结晶状态下进行紧密堆砌, 使得其结晶结构容易在外力的作用发生改变, 致使其分子能级水平和发光光谱发生变化, 产生压致发光变色现象. 因此, 聚集诱导发光化合物是压致发光变色材料的一个重要来源. 压致变色聚集诱导发光材料是一类重要的压致发光变色材料, 其既具有压致发光变色的性能, 又具有聚集诱导发光的性能. 它是一类智能材料, 在应力传感、商标防伪和发光器件等领域具有重要的潜在应用, 近年来受到人们极大的关注. 本文分类介绍了近年来压致变色聚集诱导发光材料的研究进展.     

Crystallization-induced light-emission enhancement of diphenylmethane derivatives

A family of diphenylmethane derivatives has been synthesized and their luminescence properties characterized. While in solution the compounds are weakly emissive, showing no aggregation-induced emission enhancement, the crystals of three dialkyl 5,5′-methylenebis(2-hydroxybenzoate) samples exhibit intense emission. This emission enhancement upon crystallization is ascribed to particular molecular packing, which stiffens the structure of the compounds via hydrogen bonds, preventing consecutive π–π interactions.     

Tetraphenylethene-based highly emissive fluorescent molecules with aggregation-induced emission (AIE) and various mechanofluorochromic characteristics

Three tetraphenylethene-based compounds with different substituents were successfully synthesized. All these fluorescent molecules exhibited typical aggregation-induced emission (AIE) effect. In addition, these luminogens showed various mechanochromic luminescence phenomena. Moreover, the mechanofluorochromic behavior of luminogen 1 was self-reversible.     

New thermally stable aggregation-induced emission enhancement compounds for non-doped red organic light-emitting diodes

New thermally stable aggregation-induced emission enhancement compounds were synthesized. A non-doped red device showed a maximum brightness of 13,535 cd m(-2), a maximum current efficiency of 6.81 cd A(-1), a maximum power efficiency of 4.96 lm W(-1) and a low turn-on voltage of 4.3 V.     

Photophysical Switching between Aggregation-Induced Phosphorescence and Dual-State Emission by Isomeric Substitution

It is attractive but highly challenging to achieve controllable regulation of photophysical properties of pure organic luminogens, due to distinct work mechanisms and molecular structures. Here, a strategy to regulate in a controllable way the emission behavior of luminogens is reported, according to which long-lived aggregation-induced emission (AIE) can be switched to short-lived dual-state emission (DSE) by an isomer-based substitution reaction. Three luminogens with sharply different photophysical behaviors, including aggregation-induced phosphorescence and dual-state fluorescence emission, were obtained through a substitution reaction with three isomers. Freely rotating structures are attributed to aggregation-induced phosphorescence behavior, whereas twisted rigidification of the molecule greatly contributes to its dual-state emission phenomenon. This work contributes to the controlled regulation of photophysical behaviors through simple reactions and provides a solid evidence to support the key role of the prohibition of intramolecular rotation in aggregation-induced emission process and molecular design of dual-state emitters.     

Rational design of systematic AIEEgens further modified by substituents from a novel chain structure

The expansion of new structures in aggregation-induced emission/aggregation-induced emission enhancement(AIE/AIEE)systems has attracted persistent attention recently,from which more luminescent functional molecules with characteristic skeletons are derived to satisfy specialized applications.In this study,a series of derivatives cored by tetraphenyl enamine with various terminal groups were designed and synthesized based on a novel p-πconjugate chain structure(–C=C–N–).Experimental and theoretical studies reveal that attaching modified groups to enamine core is decisive to achieve successful conversion from non-luminance to AIEE-activity.Moreover,due to different substituent effect on electronic structure,molecular conformation and molecular packing,diverse enamine compounds exhibited prominent substituent tunable emission properties,realizing regulated AIEE effect and multicolor emitting.These results not only offer a new method to design AIEgens/AIEEgens with p-πconjugate chain structures,but also provide in-depth knowledge for functional modifications of more novel AIE/AIEE units and materials.     

Unsymmetrical photochromic bithienylethene-bridge tetraphenylethene molecular switches: Synthesis,aggregation-induced emission and information storage

Aggregation-induced emission(AIE) active photochromic molecules have attracted growing attention for their versatile applications.Here we designed and synthesized five newly unsymmetrical photochromic diarylethene(DAE) dyads(BTE1-5) by connecting tetraphenylethene(TPE) and aromatic substituent via bithienylethene(BTE) bridge.The chemical structures of those compounds were identified by ^1H NMR,¹³C NMR and HRMS.The absorption and emission of these dyads were investigated by UV-vis and fluore scence spectroscopy,respectively.The results showed that all those compounds exhibited typically AIE or aggregation-induced emission enhancement(AIEE) characteristic.Particularly,when an aggregationcaused quenching(ACQ) fluorophore(triphenylamine) was grafted to the molecule,connecting with TPE via BTE-bridge,the ACQ phenomenon was dissipated and converted to an AIE luminophore,and those compounds exhibited photochromism upon irradiation with alternative UV and visible light.The solution or solid of those compounds showed distinctly fluorescence switching "ON" or "OFF" observation upon irradiation with alternative UV and visible light.It is interesting that BTE1 could be applied in recording and rewritable information storage,and the cyclization quantum yields could be affected by substituent significantly.     

Synthesis, two-photon absorption and AIE properties of multibranched thiophene-based triphenylamine derivatives with triazine core

Two new multibranched thiophene-based triarylamine derivatives with 1,3,5-triazine core are synthesized and characterized. Their one-and two-photon absorption properties and aggregation-induced emission effect have been investigated. Both the STAPA-based compounds are AIE active. The two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique are determined to be 620 and 1610 GM for STAPA-a and STAPA-b in chloroform,respectively, which dramatically increase with the introduction of alkyl chains. The relationship between their structures and properties on one-and two-photon absorption and aggregation-induced emission is discussed, which allows us to examine the effect of introducing alkyl chains. In addition, solvent effects also show a significant influence on the 2PA cross section. The two compounds with excellent AIE and 2PA properties provide attractive alternatives for the biophotonic materials.     

Multicolor tuning of aggregation-induced emission through substituent variation of diphenyl-o-carborane

We demonstrate multicolor tuning of aggregation-induced emission (AIE) derived from o-carborane. Both electron-donating and electron-accepting arylacetylenes underwent efficient palladium coupling reaction with bis(4-bromophenyl)-o-carborane, resulting in moderate yields. The emission spectra of these compounds span almost the entire visible spectrum (λ(max) = 452-662 nm). Study on AIE mechanism indicated that CT-based emission of o-carborane derivatives was enhanced by the restriction of molecular motions. The computational study also suggests the possibility of precise color-control of AIE through substituent variation.     

Recent Progress in the Development of Solid-State Luminescent o-Carboranes with Stimuli Responsivity

o-Carborane, a cluster compound containing boron and adjacent carbon atoms, displays intriguing luminescent properties. Recently, compounds containing o-carborane units were found to show suppressed aggregation-induced quenching and intense solid-state emission; they also show potential for the development of stimuli-responsive luminochromic materials. In this Minireview, we introduce three kinds of fundamental photochemical properties: aggregation-induced emission, twisted intramolecular charge transfer in crystals, and environment-sensitive excimer formation in solids. Based on these properties, several types of luminochromism, such as thermos-, vapo-, and mechanochromism, have been discovered. Based mainly on results from recent studies, we illustrate these mechanisms as well as unique luminescent behaviors of o-carborane derivatives.     

D-A-D type dinitriles with vapor-dependent luminescence in the solid state

D-A-D (Donor-Acceptor-Donor) type dinitriles linked by a styryl or phenylethynyl group have been prepared. These groups were introduced to increase the flexibility and the size of the π-conjugation in the chromophores. Both compounds showed strong emission in the solid state, AIE (aggregation-induced emission) behavior, and mechanochromism. The fluorescence color of ground powder changed by organic solvent vapor (vapochromism). Especially, the emission color of the styryl dinitrile after exposures depends on the solvent, while that of the phenylethynyl dinitrile is the same after exposure to different solvents. These results were explained by single crystal and powder XRD measurements, which revealed that the flexible styryl linker leads to a loose crystal packing, resulting in a dinitrile with multi-state microcrystalline structures. This methodology based on the flexible linker allows for the detection of small organic molecules without transition metals.     

Synthesis and Characterization of Diketopyrrolopyrrole-Based Aggregation-Induced Emission Nanoparticles for Bioimaging

Conventional fluorescent dyes have the property of decreasing fluorescence due to aggregation-caused quenching effects at high concentrations, whereas aggregation-induced emission dyes have the property of increasing fluorescence as they aggregate with each other. In this study, diketopyrrolopyrrole-based long-wavelength aggregation-induced emission dyes were used to prepare biocompatible nanoparticles suitable for bioimaging. Aggregation-induced emission nanoparticles with the best morphology and photoluminescence intensity were obtained through a fast, simple preparation method using an ultrasonicator. The optimally prepared nanoparticles from 3,6-bis(4-((E)-4-(bis(40-(1,2,2-triphenylvinyl)-[1,10-biphenyl]-4-yl)amino)styryl)phenyl)-2,5-dihexyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DP-R2) with two functional groups having aggregation-induced emission properties and additional donating groups at the end of the triphenylamine groups were considered to have the greatest potential as a fluorescent probe for bioimaging. Furthermore, it was found that the tendency for aggregation-induced emission, which was apparent for the dye itself, became much more marked after the dyes were incorporated within nanoparticles. While the photoluminescence intensities of the dyes were observed to decrease rapidly over time, the prepared nanoparticles encapsulated within the biocompatible polymers maintained their initial optical properties very well. Lastly, when the cell viability test was conducted, excellent biocompatibility was demonstrated for each of the prepared nanoparticles.     

Aggregation emission properties and self-assembly of conjugated oligocarbazoles

Conjugated oligocarbazoles with a 9,10-divinylanthracene core have been synthesized, and exhibit the transition from aggregation-induced emission (AIE) to aggregation-induced emission enhancement (AIEE) behaviour with extending conjugation length; self-assembly of the Cz4 molecule affords nanorings with high fluorescent efficiency.     

Synthesis of Tetraarylethene Luminogens by C−H Vinylation of Aromatic Compounds with Triazenes

Tetraarylethenes are obtained by acid-induced coupling of vinyl triazenes with aromatic compounds. This new C−H activation route for the synthesis of aggregation-induced emission luminogens is simple, fast, and versatile. It allows the direct grafting of triarylethenyl groups onto a variety of aromatic compounds, including heterocycles, supramolecular hosts, biologically relevant molecules, and commercial polymers.     

Tetrapyridyl tetraphenylethylenes: supramolecular building blocks with aggregation-induced emission properties

Two tetrapyridyl-substituted tetraphenylethylenes have been prepared via Suzuki coupling between tetrabromo tetraphenylethylene and 3- or 4-pyridine boronic acid. Both compounds exhibit aggregation-induced emission as determined by solid state fluorescence spectroscopy and solution phase fluorescence measurements performed in aqueous/organic solvent mixtures. Solution phase fluorescence was also found to be switchable as a function of pH. 3-Pyridyl-substituted tetraphenylethylene has been structurally characterized by X-ray crystallography.