Emission Enhancement Properties Research Articles

Alkoxy substituted D-π-A dimethyl-4-pyrone derivatives: Aggregation induced emission enhancement, mechanochromic and solvatochromic properties

Three series of D-π-A 2,6-dimethyl-4-pyrone-cored derivatives were designed and synthesized. Evaluation by spectroscopic methods indicated that all the compounds exhibited aggregation-induced emission enhancement (AIEE) effect and solvatochromism. The experimental results revealed that the restriction of intramolecular rotation is the key element for showcasing the AIEE phenomenon. Moreover, all of the compounds presented red-shifted mechanochromic behavior, the extent of the red-shift was mainly dependent on the position and length of alkoxyl group. The PXRD and DSC profiles demonstrated a transformation from crystalline to amorphous state upon grinding. The D-A strategy introduced in this work could facilitate the development and application of ingenious mechanochromic materials.

The selective detection of chloroform using an organic molecule with aggregation-induced emission properties in the solid state as a fluorescent sensor

An one-step synthesized 1,2,4,5-tetraphenyl-1,4-dihydropyrrolo [3,2-b]pyrrole (DPPTP) exhibits aggregation-induced emission enhancement properties. The solid film prepared by spin-coating a DPPTP solution in THF onto a quartz glass showed rapid response and excellent selectivity to chloroform when fumed with different organic solvents. Experimental results show that hydrochloric gas produced from the photodecomposition of chloroform is the main reason for the fluorescent response of the DPPTP film to chloroform. The DPPTP solid films have good reversibility and also can be used as a quantitative analysis sensor for the detection of chloroform as low as 100ppm.

Electron rich triphenylamine derivatives (D-π-D) for selective sensing of picric acid in aqueous media

A series of dimethyl substituted triphenylamine derivatives (D-π-D) having linear, V-shaped and star-like molecules have been synthesised by Wittig-Horner reaction. All the molecules exhibit blue light emission and shows fluorescent nano-aggregates in aqueous media due to its aggregation induced emission enhancement property. The three chemosensors undergo highly selective fluorescence quenching with picric acid and also all the fluorescent aggregates serve as potent chemosensors for electron deficient nitro aromatics.

Aggregation-induced emission enhancement and mechanofluorochromic properties of α-cyanostilbene functionalized tetraphenyl imidazole derivatives

Twisted tetraphenyl imidazole derivatives functionalized by α-cyanostilbene possess aggregation-induced emission enhancement and mechanochromic luminescence properties.

Aggregation-induced emission enhancement and living cell imaging of novel diarylanthracene conjugated dyes

Diarylanthracene conjugated dyes with good aggregation-induced emission enhancement (AIEE) properties were synthesized and their BSA nanoparticles were successfully used in HeLa cell imaging.

Carbon dots with aggregation induced emission enhancement for visual permittivity detection

Photoluminescent carbon dots (CDs), hydrothermally prepared using tannic acid (TA), show visual aggregation induced emission enhancement (AIEE) properties at 455 nm when excited at 350 nm owing to the rotational hindering of the surface groups on CDs such as aromatic rings and phenolic hydroxyl ones, causing exponential decay between the ratio of the photoluminescence intensity in organic solvents to that in water and the permittivity of the solvent, and thus dazzling emissions of the CDs in the presence of solvents with small permittivity, tetrahydrofuran (THF), for instance, could be visually observed.

A macrocyclic 1,4-bis(4-pyridylethynyl)benzene showing unique aggregation-induced emission properties.

A box-like macrocycle based on 1,4-bis(4-pyridylethynyl)benzene was derived in high yield. The macrocyclic fluorogen shows unique aggregation-induced emission properties.

Glutathione modified carbon-dots: from aggregation-induced emission enhancement properties to a “turn-on” sensing of temperature/Fe3+ ions in cells

Glutathione stabilized carbon dots show good dispersion, high fluorescence and aggregation-induced emission enhancement properties which could be used as a “turn-on” chemosensor for detecting temperature and Fe3+ in aqueous solution and cells.

Aggregation-induced emission enhancement in halochalcones

Decorating the periphery of chalcones with halogen atoms increased their aggregation-induced emission enhancement properties, even if their optoelectronic properties are dominated by the other substituents.

Multi-Stimulus-Responsive Fluorescent Properties of Donor-π-Acceptor Indene-1,3-dionemethylene-1,4-dihydropyridine Derivatives

Three donor (D)-π-acceptor (πA) indene-1,3-dionemethylene-1,4-dihydropyridine (IDM-DHP) derivatives with triphenylamine (TPA)/bis(diphenylamino)triphenylamine (BDPA-TPA) end groups were designed and synthesized. These target compounds with highly twisted conformations showed aggregation-induced emission enhancement properties in their THF/water mixtures due to the restriction of intramolecular rotation, and distinct piezofluorochromic (PFC) properties in the solid state. Interestingly, solvent-induced emission changes similar to those resulting from PFC properties can be achieved by a simple dissolution–desolvation process in different solvent systems, such as chloroform, THF, and dichloromethane. X-ray diffraction experiments revealed that the transformations between crystalline and amorphous states were responsible for the PFC properties and solvent-induced emission changes. Moreover, these compounds exhibited remarkable and reversible acid/base-induced fluorescence switching properties in both solution...

Effect of ionic interaction on the mechanochromic properties of pyridinium modified tetraphenylethene.

A pyridinium modified tetraphenylethene-based salt shows aggregation-induced emission enhancement properties and irreversible mechanochromic behaviours.

The aggregation-induced emission enhancement properties of BF2 complex isatin-phenylhydrazone: Synthesis and fluorescence characteristics

Isatin-phenylhydrazone derivatives and their corresponding BF2 complexes were efficiently synthesised by a three-step reaction starting from isatin and phenylhydrazine hydrochloride. The fluorescence properties of the isatin-phenylhydrazone derivatives and derived BF2 complexes were investigated in different organic solvents, in the solid state and in mixed solvent solutions of THF and H2O. These fluorescent dyes exhibited low fluorescent intensity in solution but a high fluorescent intensity as aggregates and in their solid state due to the interesting aggregation-induced emission enhancement characteristics which were caused by the inhibition of intramolecular rotation in the single molecule state. Information supporting this inference was supported by single crystal X-ray analysis.

Design and synthesis of a highly sensitive “Turn-On” fluorescent organic nanoprobe for iron(iii) detection and imaging

Novel naphthalimide fluorescent organic nanoparticles with aggregation-induced emission enhancement properties were designed and synthesized, which were used as a highly selective and sensitive “turn-on” fluorescent probe for Fe3+ detection in water. Fluorescence imaging experiments of Fe3+ ions in living cells demonstrated the value of this probe for practical applications in biological systems.

Synthesis of unsymmetric bipyridine-Pt(II) -alkynyl complexes through post-click reaction with emission enhancement characteristics and their applications as phosphorescent organic light-emitting diodes.

Two unsymmetric bipyridine-platinum(II)-alkynyl complexes have been synthesised by a post-click reaction. These metal complexes are found to exhibit emission enhancement properties. The photoluminescence quantum yield can be significantly increased from 0.03 in solution to 0.72 in solid-state thin films. Efficient solution-processable organic light-emitting diodes have been fabricated by utilizing these complexes as phosphorescent dopants. A high external quantum efficiency of up to 5.8% has been achieved.

Practical and convenient synthesis of 1,6-di- or 1,2,5,6-tetra-arylhexa-1,3,5-trienes by the dimerization of Pd(0)-complexed alkenylcarbenes generated from π-allylpalladium intermediates.

Pd(0)-complexed 3-aryl or 2,3-diaryl propenylcarbenes generated from α-silyl-, α-germyl-, or α-boryl-σ-allylpalladium intermediates undergo self-dimerization to provide 1,6-di- or 1,2,5,6-tetraarylhexa-1,3,5-trienes in good to high yields. This method allows the use of a π-allylpalladium intermediate for a carbenoid precursor. Furthermore, the obtained 1,2,5,6-tetraarylhexa-1,3,5-trienes exhibit aggregation-induced emission enhancement property.

Bulky group functionalized porphyrin and its Zn (II) complex with high emission in aggregation

A novel porphyrin derivative 5,10,15,20-tetra-4′-(tert-butylthio)phenylporphyrin (abbreviated as TSPP) and its Zn (II) complex (Zn-TSPP) have been synthesized and characterized, which possess aggregation-induced emission enhancement (AIEE) properties. The bulky groups increase the intermolecular steric effects which impede the π–π stacking interactions inducing J-aggregates of the two compounds in the THF-H2O mixed solution. DFT calculation was used to understand the relationship of molecular structure and luminescence.

A novel tetraphenylethene–carbazole type compound containing the dimesitylboron moiety: aggregation-induced emission enhancement and electroluminescence properties

A novel tetraphenylethene–carbazole type compound containing the dimesitylboron moiety with aggregation-induced emission enhancement properties was synthesized and utilised as a blue light-emitting material in OLED devices.

A large dipole moment to promote gelation for 4-nitrophenylacrylonitrile derivatives with gelation-induced emission enhancement properties.

A series of 4-nitrophenylacrylonitrile and phenylacrylonitrile derivatives consisting of a carbazole moiety was synthesized. Some of these derivatives with longer alkyl chains and a nitro group could gelatinize some organic solvents, such as ethanol, n-butanol, ethyl acetate, and DMSO. By contrast, phenylacrylonitrile derivatives did not form gels in measured solvents. This result proved that the electron-withdrawing nitro moiety was important for gel formation because it conferred the molecules with large dipole moments, which enhanced the intermolecular interaction. Analyses by UV-vis absorption, X-ray diffraction, and scanning electron microscopy showed that the gelator molecules could self-assemble into one-dimensional nanofibers with layer packing, which further twisted into thicker fibers and formed three-dimensional networks in the gel phase. The single crystal structure of C4CNPA implied that the gelators might adopt an anti-parallel molecular stacking because of their larger ground-state dipole moment. Interestingly, the organogels had enhanced fluorescence relative to solutions at the same concentrations.

Small molecules based on diphenylamine and carbazole with large two-photon absorption cross sections and extraordinary AIEE properties

Two simple small molecules based on diphenylamine (T1) and carbazole (T2) have been synthesized and characterized. Both dyes exhibit extraordinary aggregation-induced emission enhancement properties and high corresponding quantum efficiencies of 11.5% and 16.0%. The value of the two-photon absorption cross-section for T1 is 1240 GM.

Temperature-induced fluorescence enhancement of GFP chromophore containing copolymers for detection of Bacillus thermophilus

Green fluorescent protein (GFP) chromophore based copolymers with temperature-induced emission enhancement properties were successfully prepared and applied for biodetection. First, diblock copolymers (PEG-b-PNIPAM-c) with different poly(N-isopropylacrylamide) (PNIPAM) chain lengths were synthesized by atom transfer radical polymerization (ATRP) employing a poly(ethylene glycol) (PEG) macroinitiator and then modified with a GFP chromophore at one chain end through a click reaction. Owing to the different PNIPAM chain lengths, the block copolymers exhibited thermoresponsive phase transitions with adjustable lower critical solution temperature (LCST). Above the LCST, the fluorescence intensity of PEG-b-PNIPAM-c was enhanced dramatically, which could be attributed to the chromophore's conformational restriction by the collapse of PNIPAM blocks. Moreover, the emission intensity of PEG-b-PNIPAM-c increased with the PNIPAM chain length. Correspondingly, the temperature-dependent fluorescence enhancement properties of PEG-b-PNIPAM-c were successfully applied in the highly sensitive detection of Bacillus thermophilus with a 102 cfu per mL detection limit.