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Two emitters based on substituent effects exhibited different and competitive non-radiative decay processes, that was intersystem crossing and thermal deactivation, and excellent phototherapy achievement was realized by the two corresponding processes.

Both molecular conformations and hole–electron distribution impacted by the solvent polarity, can cause an enhanced or reduced emission of TPP structures, which provides a general intramolecular charge transfer rule and guidelines for PEE.

Ultralong organic room-temperature phosphorescence (RTP) materials have attracted tremendous attention recently due to their diverse applications. Several ultralong organic RTP materials mimicking the host-guest architecture of inorganic systems have been exploited successfully. However, complicated synthesis and high expenditure are still inevitable in these studies. Herein, we develop a series of novel host-guest organic phosphorescence systems, in which all luminophores are electron-rich, commercially available and halogen-atom-free. The maximum phosphorescence efficiency and the longest lifetime could reach 23.6% and 362 ms, respectively. Experimental results and theoretical calculation indicate that the host molecules not only play a vital role in providing a rigid environment to suppress non-radiative decay of the guest, but also show a synergistic effect to the guest through Forster resonance energy transfer (FRET). The commercial availability, facile preparation and unique properties also make these new host-guest materials an excellent candidate for the anti-counterfeiting application. This work will inspire researchers to develop new RTP systems with different wavelengths from commercially available luminophores.

Coptis chinensis Franch. (CC), as a commonly used heat-clearing and toxin-resolving traditional Chinese herbal medicine, has gained increased attention for its anti-tumor activity. However, little is known about the anti-tumor angiogenesis effect of CC and its possible bioactive components. Also, it has been shown that temperature affects the quality of CC, albeit whether and how it affects the anti-angiogenic activity of CC is currently unknown.To determine the processing temperatures (40, 60, 80, 120, 140, 150, 160 and 200 °C) at which CC has the strongest anti-angiogenic effect and speculate the possible bioactive components.The q-CAM model was constructed to explore the anti-angiogenesis agents of CC. The angiogenesis inhibition effects of CC samples at different processing temperatures and its seven alkaloids were determined based on morphological observation and vascular area proportion analysis. UPLC-MS/MS was employed to screen the potent active components of CC on anti-angiogenesis.All the intervention by CC at different processing temperatures and its seven alkaloids could inhibit angiogenesis on q-CAM vessels, as evidenced by a poor vasular development in morphological observation and a low vascular area proportion in vascular quantitative analysis, most evident in CC processed at 40 °C and palmatine. LC-MS revealed that palmatine displayed strongest inhibitory effect on q-CAM vessels with a high absorption due to its stable structure. And the maternal nucleus transformation phenomenon of CC alkaloids was found in the quail embryo metabolism.The q-CAM models in conjunction with the UPLC-MS/MS technique could be a useful tool for assessing tumor angiogenesis and screening tumor-targeted medicines. Processing temperature can affect the anti-angiogenesis effect of CC because of its function on the content of alkaloids, and palmatine can be considered as a prospective anti-angiogenic drug.

Pharmacologists usually focus on the structure-activity relationships of drugs, such as antibiotics, to enhance their activity, but often ignore their optical properties. However, investigating their photophysical properties is of great significance because they could be used to in situ visualize their positions and help us to understand their working metabolism. In this work, we identified a class of commercialized antibiotics, such as levofloxacin, norfloxacin, and moxifloxacin (MXF) hydrochloride, featuring the unique aggregation-induced emission (AIE) characteristics. By taking advantage of their AIE feature, antibiotic metabolism in cells could be in situ visualized, which clearly shows that the luminescent aggregates accumulate in the lysosomes. Moreover, after a structure-activity relationship study, we found an ideal site of MXF to be modified with a triphenylphosphonium and an antibiotic derivative MXF-P was prepared, which is able to specifically differentiate bacterial species after only 10 min of treatment. Moreover, MXF-P shows highly effective broad-spectrum antibacterial activity, excellent therapeutic effects and biosafety for S. aureus-infected wound recovery. Thus, this work not only discovers the multifunctionalities of the antibiotics but also provides a feasible strategy to make the commercialized drugs more powerful.

Tetraphenylpyrazine (TPP), as a multi-rotor type AIE building block with a better electron-withdrawing ability, has attracted much attention due to the unique photoelectric properties and wide applications of its derivatives. However, how to predict and amplify the AIE effect of its derivatives through structural control is an urgent problem to be solved. In this work, we develop a theoretical model for predicting the luminescence performance of TPP derivatives where the hole–electron overlap on the TPP unit is employed as a criterion with discussion based on in-depth theoretical calculations. The theoretical model indicates that the larger hole–electron overlap percentage on the TPP unit and the higher transition density matrix value of {TPP, TPP} will cause weaker emission in solution and a notable AIE process. Further expanding its universality to triphenylpyrazine-based derivatives, the experimental data and theoretical prediction are also very consistent, implying that this model based on hole–electron overlap could be expanded to more multi-rotor AIE luminogens.

Aggregation-induced/enhanced emission (AIE/AEE) materials have aroused wide attention for their potential applications in optoelectronic devices and biosensors. In this paper, the working mechanism of a new kind of AEE-active luminogen, tetraphenylpyrazine (TPP) and its derivatives, is studied by first-principles calculations contrasting their pyrazine core with an inherent n → π* transition. Our results indicate that the attachment of phenyl rings to the pyrazine core can change the n → π* transition component to π → π* via the electronic conjugated effect and evoke restriction of intramolecular motion (RIM) that is responsible for the AEE characteristics. Decoration of the TPP peripheries with electron-withdrawing CF3 groups hardly affects the electronic transition properties and barely improves the solid-state luminescence. Substitution of the peripheral phenyls with electron-donating OCH3 groups thoroughly opens up the radiative channel and greatly enhances the emission quantum efficiency. Moreover, CF3 and OCH3 substituents can respectively generate extra CH⋯F/F⋯F/CF⋯π and CH⋯O interactions, which could promote RIM and slow down the non-radiative decay process. The experimental results confirm the theoretical predictions well. The above modulation guideline can be summarized from a molecular picture: the phenyl attachment reduces the n → π* transition component and evokes RIM, while the substituent decoration imparts altered electronic conjugation and promotes RIM. Our work not only offers valuable insight into AEE phenomena, but also provides a strategy for the rational design of efficient heterocycle-containing emitters.

By combining aggregation-induced emission (AIE) effect and a triplet–triplet upconversion (TTU) process, a blue emitter with excellent photoluminescence quantum efficiency and high upconversion efficiency in the film state is developed, from which a highly efficient non-doped blue TTU organic light-emitting diode (TTU-OLED) was realized.

Excellent luminescence and transportation are the most essential features of organic light-emitting diodes (OLEDs); however, many D–A type materials usually facilitate charge transport but have poor luminescence properties. Herein, we designed two triphenylamine-pyrazine compounds, namely 25-TPA2P and 26-TPA2P, with planarized intramolecular charge transfer character to overcome this problem. Both single crystal XRD and computational analysis show an asymmetric configuration for 26-TPA2P, which furnishes 26-TPA2P with relatively strong ICT and better charge transport balance, as compared with the symmetric 25-TPA2P. A non-doped device containing 25-TPA2P displays sky-blue electroluminescence with a maximum external quantum efficiency (ηext) of 6.09%, by virtue of its strong emission in the solid state and its orientation; for 26-TPA2P, a deep blue OLED with a CIEy of 0.07 and ηext of 4.88% is achieved. Thanks to the balanced transport ability of 26-TPA2P, a series of high efficiency orange/red phosphorescent OLEDs and two-color hybrid WOLEDs are obtained based on 26-TPA2P as the host material. The ηext of the orange OLED exceeds 28%, and the warm-white OLED exhibits a total ηext of 30.11%. These results suggest that PLICT materials could satisfy both conditions of good charge transportation and luminescence, which could bring about bright prospects for displays and illuminations.

Aggregation-induced emission (AIE) has drawn considerable attention owing to its interesting phenomenon, and the AIE mechanisms of different molecule systems have been gradually revealed. Here, we investigated the difference in 3-carbazole-pyrazine-based isomers and explored the effects of three substituted phenyl groups (ortho, meta and para) on the tetraphenylpyrazine derivatives (TPPs). The meta- and para-phenyl groups could slightly and significantly adjust their emission properties, respectively. The ortho-phenyl group could distort the pyrazine plane owing to the large steric hinderance of the two moieties; this triggered many molecular motions and led to the wastage of excited state energy, stimulating the AIE characteristics of TPPs. This result is demonstrated for other pyrazine derivatives and can serve as a design strategy of AIE molecules.

Planarized intramolecular charge transfer(PLICT) state can facilitate the fluorescence process thanks to the relative excellent planarity. Recently, we have discovered that the excited state quinone-conformation induced planarization(ESQIP) occurring on tetraphenylpyrazine(TPP) based derivatives could furnish them with PLICT feature. Unlike to the well-known intramolecular charge transfer, strengthening the electron-donating nature on the donor(D) moiety did not impair the PLICT. The calculation results showed that planarization of the TPP based compounds scarcely accompanied with energy wastage while amount of energy was required for the torsion on geometries. In the polar solvents, the energy consumption for planarization could further decrease, but that for twisting structure would increase. To take advantage of the transformation of the frontier orbitals’ distribution, the PLICT type materials would perform a potential application on organic light-emitting diodes(OLEDs).

Triplet-triplet upconversion (TTU), where two low-energy triplet excitons are converted to one higher energy singlet exciton, is excellent approach to break through the theoretical limit of the pure fluorescent organic light-emitting diodes (OLEDs) by 5%. To data, however, the reported emitters with high emission efficiency and efficiently TTU in film state are rare. Herein, we design the blue aggregation-induced emission luminogens (AIEgens) and investigate their upconversion efficiency. TPA-An-mPhCz can not only achieve high emission efficiency in the film state, but also show high upconversion efficiency of close to 50% even though the calculated energy level of the triplet excitons (T2) is lower than 2T1. A possible upconversion mechanism is proposed according to the transient electroluminescence spectra and theoretical calculation. This strategy may provide a new platform for the construction of highly efficient non-doped blue OLEDs based on TTU and AIEgens.

With the advent of the big data era, information storage and security are becoming increasingly important. However, high capacity information storage and multilevel anti-counterfeiting are typically difficult to achieve simultaneously. To address this challenge, herein, two electrochromic and electrofluorochromic dual-functional polymers with aggregation-induced emission (AIE) characteristics were rationally designed and facilely prepared. Upon applying voltages, the absorption and fluorescence spectra of the AIE polymers can undergo reversible changes, accompanied by variation of their color and emission. By utilizing the controllable characteristics of the polymers, dual-mode display devices were fabricated via a simple spraying technique. More interestingly, a four-dimensional color code device was constructed by adding color change multiplexing to the two-dimensional space, thereby achieving high capacity information storage. Moreover, the color code device can also be applied in the multilevel anti-counterfeiting area. The encrypted information can be dynamically converted under different voltages. Thus, the AIE polymers show great promise for applications in multidimensional information storage and dynamic anti-counterfeiting, and the design strategy may provide a new avenue for advanced information storage and high security technology., By using electrical stimuli-responsive AIE polymers, dual-mode display devices, multidimensional information storage and anti-counterfeiting devices were constructed.

Ultralong organic room-temperature phosphorescence (RTP) materials have attracted great attention recently due to its diverse application potentials. Several ultralong organic RTP materials mimicking the host-guest architecture of inorganic systems have been exploited successfully. However, complicated synthesis and high expenditure are still inevitable in these cases. Herein, we develop a series of novel host–guest organic phosphore systems, in which all chromophores are electron-rich, commercially available and halogen atom free. The maximum phosphorescence efficiency and the longest lifetime reach at 23.6% and 362 ms, respectively. Most importantly, experimental results and theoretical calculation indicate that the host molecules not only play a vital role in providing a rigid environment to suppress non-radiative decay of the guest, but also show a synergistic effect to the guest through Förster energy transfer (FERT). The commercial availability, facile preparation and unique properties also make these new host-guest materials an excellent candidate for anti-counterfeiting devices.

The development of new ionic compounds with aggregation-induced emission (AIE) has been widely noticed. They can not only effectively solve the problem of aggregation-caused quenching (ACQ) encountered in conventional fluorescent dyes, but also exhibit promising applications in biological imaging, diagnosis and therapy, etc. However, such AIE system should be further developed. In this work, a series of novel cationic AIE luminogens (AIEgens) of tricyclic 2-aminopyridinium derivatives with seven-membered rings were designed and synthesized via a simple multi-component reaction, which exhibit the ability to specifically stain gram-positive bacteria. Meanwhile, they also possess excellent bacteriostatic ability for S. aureus in liquid medium and solid agar plates, of which the minimum inhibitory concentration (MIC) value is between 4 and 8 µg/mL. In addition, these molecules showed mitochondria-targeting capability in hydrophilic AIEgens and specific staining lysosomes in lipophilic AIEgens by wash-free process in living cells. These AIEgens with bacteriostatic activity hold great promise for distinguishing bacteria and inhibiting bacterial infection in clinical trial.

Aggregation-induced emission luminogens (AIEgens) have been widely used in organic light-emitting diodes (OLEDs), but few works have reported on utilizing AIEgens as hosts in doped OLEDs. In this work, a new AIEgen of TPP-mCP was designed and synthesized by integrating a typical AIE moiety of tetraphenylpyrazine (TPP) with a conventional host of 1,3-di(9H-carbazol-9-yl)benzene (mCP). TPP-mCP exhibits better thermal and conformational stability and carrier capacity, and higher emission efficiency in the film state than those of mCP. More importantly, the OLEDs fabricated with TPP-mCP as the host show much higher electroluminescent performance than those with mCP. Thus, this work not only generates a new AIE-active host of TPP-mCP with high device performance, but also provides a strategy to construct more effective hosts by decorating conventional ones with AIE units, which will potentially promote the development of OLEDs.

Based on our deep comprehension of the unique excited state decay process of tetraphenylpyrazine derivatives, triphenylpyrazine-3-carbazole (TrPP-3C) was designed by replacing the phenyl group with a methyl group at the 3-position of pyrazine. Compared to the values for its model tetraphenylpyrazine-3-carbazole (TPP-3C), the Commission International de l’Eclairage (CIE) coordinates of TrPP-3C shifted to the more valuable deep-blue region in the non-doped device, demonstrating that the in-depth study of the excited state distribution was of great significance for the development of a new aggregation-induced emission (AIE) building block.

The reported organic light-emitting diodes (OLEDs) based on hybridized local and charge-transfer (HLCT) state emitters mostly exhibit low photoluminescence quantum yields (PLQYs) in aggregates, failing to achieve optimal device efficiency although they exhibit good exciton utilization efficiencies (EUEs). In this work, by introducing an aggregation-induced emission (AIE) moiety (tetraphenylethene, TPE) and a cyano group (CN) to the HLCT-typed core, phenanthroimidazole (PI), six luminescent compounds with different conjugation patterns at the C2 and N1 substituent positions were obtained, and their excited states were regulated effectively. Based on systematic photophysical analysis, the impacts of molecular conjugation patterns on the regulation of the locally excited (LE) and charge-transfer (CT) components are disclosed, and their AIE characteristics that ensure the high PLQYs of these compounds in aggregates were observed. Exciton conversion channels from triplets to singlets via the tuning of excited states were proposed based on theoretical calculations. The non-doped OLED based on ppCTPI compounds exhibited excellent performance with a maximum luminance, current efficiency, and external quantum efficiency of up to 31 070 cd m−2, 18.46 cd A−1, and 7.16%, respectively, and a very small efficiency roll-off of 4.0% at 1000 cd m−2 luminance. The successful design of these HLCT-based AIEgens not only provides more optimization choices for OLED emitters, but also demonstrates that the strategy of reasonably superposing the AIE unit onto HLCT emitters is feasible in materials design.

Aggregation-induced emission (AIE) has become a hot research topic. The generation of new AIE luminogens (AIEgens) will further promote the development of the AIE area. Currently, AIEgens with different emission colours have been reported. However, full-colour emissive luminogens based on a single AIE core and the structure–property relationship are rarely reported. To tackle this challenge, in this work, six tetraphenylpyrazine (TPP)-based luminogens DTPP, DTPP-Ph, DTPP-BT, DTPP-T, DTPP-TO and DTPP-TBTT are rationally designed by varying the effective conjugation and donor–acceptor units and facilely prepared under mild reaction conditions. The photophysical property investigation shows that they exhibit bright blue to red emission in the film states, covering the whole visible light range. Through systematic experimental investigations and theoretical calculations, their structure–photophysical property, and the competition of restriction of intramolecular motion and intramolecular charge-transfer are unambiguously elaborated. Moreover, DTPP-BT can be used as a reversible mechanochromic material and an indicator to show the exciton recombination area in OLEDs. This work provides guidance for further design of AIEgens with high efficiency and full-colour emission from a single AIE core.

Acridone (ADO) is an anthracene-based derivative that plays an important role in the construction of organic light-emitting diode emitters. However, ADO suffers from an aggregation-caused quenching (ACQ) effect because of its strong intermolecular stacking and tendency to form excimers. In this work, we appended some electron-donating moieties with different rotors and substitution patterns on ADO to prepare six ADO-based derivatives. In addition, a benzonitrile group was introduced onto the nitrogen atom of the ADO unit to fabricate a high-energy charge-transfer (CT) state that formed a reverse intersystem crossing (RISC) channel. Systematic spectral measurements revealed that the rotors effectively suppressed the ACQ effect. In addition, aggregation-enhanced emission (AEE) was observed for the ADO derivatives modified with triphenylamine (TPA) because of the existence of multiple rotors and propeller-like conformation in TPA block. Theoretical calculations and the performance of electroluminescent devices containing the derivatives confirmed that the exciton conversion channel was constructed at the high-energy level and activated during device operation. Although the performance of these ADO-based derivatives was not ideal in terms of efficiency, the results confirmed the feasibility of this structure modification strategy to simultaneously inhibit the ACQ effect and construct excitons conversion channels.

Rhizoma Chuanxiong (CX) and Radix Angelica sinensis (DG) are very important Traditional Chinese Medicine (TCM) and usually used in clinic. They both are from the Umbelliferae family, and have almost similar chemical constituents with each other. It is complicated, time-consuming and laborious to discriminate them by using the chromatographic methods such as high performance liquid chromatography (HPLC) and gas chromatography (GC). Therefore, to find a fast, applicable and effective identification method for two herbs is urged in quality research of TCM. In this paper, by using a three-stage infrared spectroscopy (Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2D-IR)), we analyzed and discriminated CX, DG and their different extracts (aqueous extract, alcoholic extract and petroleum ether extract). In FT-IR, all the CX and DG samples' spectra seemed similar, but they had their own unique macroscopic fingerprints to identify. Through comparing with the spectra of sucrose and the similarity calculation, we found the content of sucrose in DG raw materials was higher than in CX raw materials. The significant differences in alcoholic extract appeared that in CX alcoholic extract, the peaks at 1743 cm−1 was obviously stronger than the peak at same position in DG alcoholic extract. Besides in petroleum ether extract, we concluded CX contained much more ligustilide than DG by the similarity calculation. With the function of SD-IR, some tiny differences were amplified and overlapped peaks were also unfolded in FT-IR. In the range of 1100–1175 cm−1, there were six peaks in the SD-IR spectra of DG and the intensity, shape and location of those six peaks were similar to that of sucrose, while only two peaks could be observed in that of CX and those two peaks were totally different from sucrose in shape and relative intensity. This result was consistent with that of the FT-IR. Several undetected characteristic fingerprints in FT-IR and SD-IR spectra were further disclosed by 2D-IR spectra. In the range of 1120–1500 cm−1, the FT-IR spectra and the SD-IR spectra of aqueous extract of CX and DG were almost similar and hard to be discriminated, but the 2D-IR spectra were markedly different. These findings indicated that the three-stage infrared spectroscopy can identify not only the main compositions in these two medicinal materials and their different extracts, but also can compare the differences of categories and quantities of chemical constituents between the similar samples. In conclusion, the three-stage infrared spectroscopy could identify the two similar TCM (CX and DG) quickly and effectively.

Two heavy atom-free white-light emitting luminophores exhibit fluorescence–phosphorescence dual-emission and are multi-stimuli responsive at room temperature., Two heavy atom-free luminophores (SHB2t and SDB2t) with simple molecular structures have been synthesized via Suzuki coupling reactions in which both display white-light emission with prompt fluorescence and room temperature phosphorescence (RTP) in the solid state. The impressive RTP of the luminophores is produced by a synergistic effect of the strong intermolecular hydrogen bonding in addition to the spin–orbit coupling of the sulfonyl oxygen atoms and the moderate singlet-triplet energy gaps (ΔE ST). These factors facilitate the intersystem crossing (ISC) process to generate triplet excitons in which the molecular conformations become immobilized to effectively suppress radiationless decay. Under the stimuli of mechanical force and solvent vapor, the RTP of SHB2t and SDB2t can be simply turned off and on by breaking and reforming the robust hydrogen bonding, which leads to remarkable and reversible mechanochromism between white and deep-blue emission. Moreover, two different thermochromic processes have been observed for the pristine and ground samples of SDB2t, in which a tricolor switching system between white, deep-blue and blue emission has been successfully achieved through the sequential control of grinding, heating and fuming. From detailed studies we have determined that the mechanism for the thermochromism of SDB2t is correlated with the rearrangement of the white-light emitting molecules to a new packing mode without RTP emission.

The excited-state properties of the “free” and “locked” pyrazine derivatives are investigated in solution. DCFP with “free” phenyls is theoretically calculated to be non-emissive due to the non-radiative energy dissipation through strong Duschinsky rotation effect, in agreement with the available experimental result. Surprisingly, DCBP with “bi-locked” phenyls is also calculated to be nonluminous. The emission of DCAP with “conjoined” architecture is predicted to be weaker than DCPP with “single-locked” phenyls, quite contrary to our intuition but further validated by the experimental measurement. The construction of four-, five- and six-membered ring respectively in DCBP, DCAP and DCPP is found to be the major structural origin for the descending relaxation energy in these “locked” systems, thus giving rise to the ascending luminescence order. Our work not only provides strategy for the molecular design of efficient organic light-emitting materials, but also offers valuable insight into the aggregation-induced emission phenomena.

Polyhedral oligomeric silsesquioxanes (POSS) anchored to poly(2-methoxy-5-(2-ethylhexyloxy)-1.4-phenylenevinylene) (MEH-PPV) (MEH-PPV–POSS), and to poly(9,9-dihexylfluorenyl-2,7-diyl) (PFO) (PFO–POSS) were synthesized. Compared with the corresponding parent polymers, MEH-PPV and PFO, MEH-PPV–POSS and PFO–POSS have better thermal stability. MEH-PPV–POSS and MEH-PPV have identical absorption and photoluminescent (PL) spectra, both in solution and as thin films. They also have identical electroluminescent (EL) spectra. Devices made from MEH-PPV–POSS exhibit higher brightness (1320 cd m–2 at 3.5 V) and higher external quantum efficiency (ηext = 2.2 % photons per electron) compared to MEH-PPV (230 cd m–2 at 3.5 V and ηext = 1.5 % ph el–1). Compared with PFO in the same device configuration, PFO–POSS has improved blue EL emission and higher ηext.

OBJECTIVE To distinguish the ginseng and American ginseng pieces accurately and rapidly by electronic nose technology and principal component analysis (PCA) method. METHOD The optimum conditions of electronic nose for ginseng and American ginseng pieces, such as sample size and volume, headspace volume, incubation time and temperature were determined by the orthogonal test, the data were processed by the normalization method and the preprocessed data were analyzed PCA. RESULT The detection methods of ginseng and American ginseng pieces was established by electronic nose, and the odor fingerprint figures of ginseng and American ginseng pieces were obtained, and ginseng and American ginseng pieces were distinguished by PCA recognition pattern. CONCLUSION A new accurate and rapid method to distinguish ginseng and American ginseng pieces was established by electronic nose detection.