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Manipulation of long-lived triplet excitons in organic molecules is key to applications including next-generation optoelectronics, background-free bioimaging, information encryption, and photodynamic therapy. However, for organic room-temperature phosphorescence (RTP), which stems from triplet excitons, it is still difficult to simultaneously achieve efficiency and lifetime enhancement on account of weak spin-orbit coupling and rapid nonradiative transitions, especially in the red and near-infrared region. Herein, we report that a series of fluorescent naphthalimides-which did not originally show observable phosphorescence in solution, as aggregates, in polymer films, or in any other tested host material, including heavy-atom matrices at cryogenic temperatures-can now efficiently produce ultralong RTP (ϕ=0.17, τ=243 ms) in phthalimide hosts. Notably, red RTP (λRTP =628 nm) is realized at a molar ratio of less than 10 parts per billion, demonstrating an unprecedentedly low guest-to-host ratio where efficient RTP can take place in molecular solids.

Thermally activated delayed fluorescence (TADF) materials utilizing purely organic compounds have become a promising and more eco-friendly alternative to phosphorescent organometallic emitters in organic light-emitting diode (OLED) devices. However, the modulation of luminescence properties for molecules with a high degree of structural complexity remains challenging. Herein, by combining the aromatic electrophilic directing (AED) and intramolecular charge transfer (ICT) effects, two OLED emitters containing an electron donor (triphenylamine, TPA) and acceptor (benzophenone) covalently linked via a carbazole ring were synthesized and compared. The design concomitantly allows for spatial separation of origin/destination orbitals involved in the lowest singlet excited state and increased density of charge carriers in contrast to a non-conjugated linker. More conveniently, we demonstrate that increased acceptor strength by cyano-substitution results in a significant decrease of the singlet–triplet energy gap from 0.23 to 0.09 eV. The latter exhibits a TADF photoluminescence quantum yield of up to 63% with a lifetime of 7.67 μs in the OLED matrix. Notably, the OLED device using the cyano-TADF molecules as the emitting layer possesses an enhanced external quantum efficiency of 15.6%, compared to 10.3% efficiency obtained from the non-substituted version, and small efficiency roll-off, demonstrating the modulation versatility of purely organic molecule-based OLED devices.

A new strategy was devised for estimating and screening pKa values among different carbon acids under ambient conditions by using the UV/Vis absorption spectrum of persistent radical pairs (PRPs), which are generated from an N-substituted naphthalimide (NNI) derivative in the presence of various carbanions in organic solutions. The electron paramagnetic resonance (EPR) spectroscopy was used to examine the presence of radicals. Unexpectedly, it was discovered that the UV/Vis spectrum of PRPs reveals a distinct linear relationship between the PRP absorption and the pKa value of a corresponding carbon acid, which is likely due to the energy difference among different RPRs. The finding may offer organic chemists an alternative reference to conduct carbanion-mediated reactions in various organic solutions.

Organic luminogens with persistent room-temperature phosphorescence (RTP) have found a wide range of applications. However, many RTP luminogens are prone to severe quenching in the crystalline state. Herein, we report a strategy to construct a donor-sp3 -acceptor type luminogen that exhibits aggregation-induced emission (AIE) while the donor-sp2 -acceptor counterpart structure exhibits a non-emissive solid state. Unexpectedly, it was discovered that a trace amount (0.01 %) of the structurally similar derivative, produced by a side reaction with the DMF solvent, could induce strong RTP with an absolute RTP yield up to 25.4 % and a lifetime of 48 ms, although the substance does not show RTP by itself. Single-crystal XRD-based calculations suggest that n-σ* orbital interactions as a result of structural similarity may be responsible for the strong RTP in the bicomponent system. This study provides a new insight into the design of multi-component, solid-state RTP materials from organic molecular systems.

Polyaniline materials are widely utilized as electrodes for supercapacitors because of low cost, facile synthesis, high mechanical flexibility and theoretical high specific capacitance. However, the poor cycle stability and low rate capability restrict their practical applications. Integration of polyaniline with carbon materials is an effective strategy to solve the aforementioned limitations. In this review, polyaniline electrode materials, especially in the forms of different nanostructures, are firstly summarized to demonstrate the general merits of polyaniline-carbon composites for supercapacitors. Subsequent emphasis focuses on the rational design of the composites with various carbon materials, including activated carbon, porous carbon, carbon nanotubes, carbon fibers, graphene or their hybrids. The importance of the compositions, desired architectures and synergistic interactions on the enhanced electrochemical properties is emphasized. In particular, the research trends in the configurational design of unconventional devices, such as flexible, stretchable, compressible and asymmetric supercapacitors with excellent performance at different states (bending, stretching, compressing and/or folding). The review ends with a summary and discusses the perspectives and challenging issues regarding the rational design of flexible supercapacitors in future studies, along with the current outlook for the integrated electronic devices.

Bacterial cellulose/polyaniline (BC/PANI) nanocomposites display many potential applications in various fields. However, the conductivity and mechanical properties remain a challenge. Here, we developed a novel method to prepare BC/PANI nanocomposites via the chemical grafting of PANI onto epoxy modified BC (EBC), followed by the grafting of polyacrylamide (PAM). For comparison, an in situ BC/PANI sample was also prepared. The grafting reaction between PANI and EBC and the retention of PANI on EBC were confirmed by FTIR, X-ray photoelectron spectroscopy, and elemental analysis. The cross-section morphology of BC transformed into a three-dimensional and continuous network structure with the incorporation of PANI. The effects of epoxy and PAM contents on the morphology, conductivity, and mechanical properties of PANI-g-EBC and PANI-g-EBC3/PAM nanocomposites were investigated. Compared with those of the in situ BC/PANI sample, the conductivity of PANI-g-EBC increased from 0.12 to 1.08 S/cm, while the stress ...

Room-temperature phosphorescent (RTP) materials have been widely used in sensing, imaging and display technology. The ability to predict and modulate RTP properties, such as emission color and lifetime, is particularly important for the design of rational materials. Here, we show that by incorporating three different types of acceptor moieties into a polylactide (PLA)-substituted carbazole donor, RTP with different emission colors and lifetimes (with an absolute quantum yield of up to 39.4%) could be generated. Specifically, the chemical conjugation between an n–π* type of luminophore and a π–π* one most likely results in dual RTP while the conjugation between two π–π* types of luminophores produces fluorescence-RTP (F-RTP) dual emission. The consistency between the experimental results and theoretical calculations further validates the observation. To demonstrate the versatility and application potential of these purely organic, biocompatible materials, aqueous nanoparticles were fabricated and used as high-contrast cell imaging agents, given the large Stokes shift of RTP materials.

Purely organic phosphors have important applications in imaging, sensing, informatics and illumination. Methoxy-substituted difluoroboron dibenzoylmethane (BF2dbm) complexes exhibit intense fluorescence with an almost unity quantum yield. Here we show that by simply introducing an sp3 oxygen-bridged methoxylphenyl group as a pendant to BF2dbm, the boron complex exhibits a triplet quantum yield of 0.16, a more than 100-fold increase compared to that of BF2dbm.

Pyridinium ylides are usually considered nucleophiles that can undergo various reactions involving electron pairs. However, it was found that ylides resulting from deprotonation of N-alkyl-substituted pyridinium salts exhibit radical characters, with no discernable NMR signals but decent EPR spectra in both solution and the solid state. An observed correlation between lowered π* energy level of the pyridinium ring and increased EPR activity indicates that thermally induced electron-transfer processes could be involved, where the variable-temperature EPR spectrum indicates a singlet ground state and a thermally activated triplet state for the ylide. The fact that the high-resolution mass spectrum confirms the presence of oligomers of a less sterically hindered pyridinium ylide further points to a radical mechanism.

A novel photochromic metal-organic framework ([Zn(L)0.5(bpy)(H2O)]·3.5H2O, FJU-34) based on Zn(II), carboxylate-based naphthalene diimides derivatives (H4L) and 4,4′-bipyridine (bpy) has been prepared, which exhibits a unique doubly interpenetrated 3D open framework with a rare mog topological net. In addition, the excellent chemical stability and reversible photochromic performances have been observed in this compound.

TiO2-graphene (P25-GR, PG) nanocomposite was fabricated from P25 titania and graphite oxide by hydrothermal method, and then Cu nanoparticles (Cu NPs) were assembled in P25-GR composite (Cu- P25-GR, CPG) under microwave-assisted chemical reduction. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV–Vis absorption (UV–Vis) and Raman spectroscopies. Cu NPs were well dispersed on the surface of PG and are in metallic state. The ternary Cu-P25-GR (CPG) nanocomposites show an extended light absorption range and more efficient charge separation properties compared to binary P25-GR (PG) composite. Methylene blue photodegradation experiment proved that surface plasmon resonance (SPR) phenomenon had an effect on photoreaction efficiency. The corresponding hydrogen evolution rate for CPG prepared using 0.002 M Cu(NO3)2 solution was 10 times higher than with pure P25, and 2.3 times higher than with PG in the same test conditions. The improved photocatalytic performance can be attributed to the presence of GR in the prepared composite and to the SPR effect, leading to the longer lifetime of photogenerated electronhole pairs and faster interfacial charge transfer rate. We expect that our work would be useful for the further exploration of GR-based nanocomposites.

The luminescent metal–organic frameworks (LMOFs) have been widely used as sensors for toxic organic compounds or heavy metals due to their functional sites and accessible pores. About this work, a new luminescent metal–organic framework, {[Cd3(L)2(H2O)4]·4H2O}n (1) has been synthesized through the spontaneous self-assembly of V-shaped asymmetrical tricarboxylate ligand (H3L = 2-(4-carboxylphenoxy)terephthalic acid) and Cd(NO3)2·4H2O under hydrothermal condition. Single crystal X-ray diffraction analysis H3L is completely deprotonated and connects Cd(II) to exhibit a 3D microporous structure. Furthermore, the complex shows a strong fluorescence emission, and can act as a potential multifunctional fluorescent probe for detection of nitroaromatic, Fe3+, Cr2O72− and CrO42− anions with high stability, selectivity and sensitivity. Secondly, the complex can effectively sensitize visible-light-emitting Tb3+ ions as an antenna and rapidly remove harmful organic dye Methylene Blue (MB) as an adsorbent. Thus, the multifunctional complex 1 combines optical-sensing, adsorption, and sensitization properties, which is very useful in many potential applications.

N-Substituted naphthalene diimides (NDIs) were explored as purely organic room temperature phosphorescence (RTP) materials based on the strategy of intramolecular charge-transfer (ICT) mediation. A series of NDIs were designed and investigated for their luminescence properties. All emissive NDIs exhibited similar red RTP (emission range from ~600 to ~800 nm) in solid state media; the quantum yield (QY) of the obtained RTP relies heavily on the N-substitution. From poor to moderate to strong donor moieties, the QY increases but suddenly disappears. First-principle calculations reveal that a “sweet spot” for strong NDI RTP exists: while a suitable charge-transfer state can enhance RTP, a strong donor may cause total triplet quenching through the photo-induced electron transfer (PET) mechanism. Furthermore, combining NDI aggregation effects, we realized the reddest RTP ever reported for purely organic materials (Max emission = 675 nm, QY = 21.7%). Given the red emission, respectable QY and oxygen sensitive properties for some of the NDIs, they were tested as imaging agents for in vivo imaging studies.

Two electroactive polyoxometalates (POMs)-based metal-organic frameworks (MOFs) films (POMOFs) in situ grown on carbon cloth (NENU-3/CC and NENU-5/CC) were synthesized by a facile one-step solvothermal method containing Cu(NO3)2, 1,3,5-benzentricarboxylate (H3BTC) and POMs (PMo12 and PW12), in which the POMs were wrapped into MOFs to increase stability. The analysis of electrochemical behavior of the NENU-3/CC and NENU-5/CC films reveals that they can serve as conductive electrode materials. Subsequently, two kinds of film electrodes exhibit enhanced electrocatalytic activity toward bromate reduction in acidic solution. Thus, they can act as electrochemical sensors to detect bromate. Amperometric detection results of NENU-3/CC to bromate show a high sensitivity of 45.11 μA cm −2 mM−1 and a low detection limit of 0.55 μM. Furthermore, NENU-5/CC can exhibit a detection limit of 1.18 μM, and a high sensitivity of 18.83 μA cm−2 mM−1. Experimental results show that two POMOFs films have high electrochemical stability as working electrode materials and good selectivity for detecting bromate as sensor materials. Novelty statement Up to now, electrochemical methods to detect bromated have attracted considerable attention due to their simplicity, rapidity, high sensitivity, excellent selectivity and environmentally friendliness with low-cost equipment compared with other techniques. Polyoxometalates (POMs) have been widely used for the electrocatalytic reduction of bromate because of their high redox properties. However, when POMs are used as conductive electrodes materials, they dissolve easily in the electrolyte, and the instability of POMs can increase performance degradation. For solving the above-mentioned problem, POMs are encapsulated into MOFs to generate POM-based MOFs (POMOFs), it combine the merits of POMs and MOFs and increase the stability of skeleton. However, POMOFs materials can increase the reversible electrochemical capacity, the leaching and dispersity of POMOFs in the electrocatalytic measurement can make them unstable, and it hinders the conductivity in electrochemical behaviors. Thus, Proper POMOFs films have been developed to overcome the aforementioned difficulties by packing POMOFs on the conductive substrates uniformly to increase the stability and performance in electrochemical catalysis. In this paper, two electroactive polyoxometalates (POMs)-based metal-organic frameworks (MOFs) films (NENU-3 and NENU-5) were chosen as target materials in the synthesis of POMOFs film. And they were located on the surface of the carbon cloth through a facile in situ one-step solvothermal method as conductive electrode materials. According to report, NENU-3 and NENU-5 were coated on the substrate using hot-pressing and electrochemical method, we firstly prepared NENU-3/CC and NENU-5/CC films by in situ one-step solvothermal method, and the as-synthesized POMOFs materials using this method are more uniform, facile, and stable than other methods. The results of amperometric detection of NENU-3/CC to bromate show a wide linear range of 5–560 μM with a high sensitivity of 45.11 μA cm−2 mM−1 and a low detection limit of 0.55 μM. Furthermore, NENU-5/CC can exhibit a good linearity range of 15–380 μM, a detection limit of 1.18 μM, and a high sensitivity of 18.83 μA cm−2 mM−1. As a result, the amperometric determination demonstrates that two as-synthesized POMOFs/CC films as working electrode materials exhibit good sensitivity, selectivity, and stability to detect bromate as sensor materials.

The canonical Wnt signaling pathway controls normal embryonic development, cellular proliferation and growth, and its aberrant activity results in human carcinogenesis. The core component in regulation of this pathway is β-catenin, but molecular regulation mechanisms of β-catenin stability are not completely known. Here, our recent studies have shown that KCTD1 strongly inhibits TCF/LEF reporter activity. Moreover, KCTD1 interacted with β-catenin both in vivo by co-immunoprecipitation as well as in vitro through GST pull-down assays. We further mapped the interaction regions to the 1-9 armadillo repeats of β-catenin and the BTB domain of KCTD1, especially Position Ala-30 and His-33. Immunofluorescence analysis indicated that KCTD1 promotes the cytoplasmic accumulation of β-catenin. Furthermore, protein stability assays revealed that KCTD1 enhances the ubiquitination/degradation of β-catenin in a concentration-dependent manner in HeLa cells. And the degradation of β-catenin mediated by KCTD1 was alleviated by the proteasome inhibitor, MG132. In addition, KCTD1-mediated β-catenin degradation was dependent on casein kinase 1 (CK1)- and glycogen synthase kinase-3β (GSK-3β)-mediated phosphorylation and enhanced by the E3 ubiquitin ligase β-transducin repeat-containing protein (β-TrCP). Moreover, KCTD1 suppressed the expression of endogenous Wnt downstream genes and transcription factor AP-2α. Finally, we found that Wnt pathway member APC and tumor suppressor p53 influence KCTD1-mediated downregulation of β-catenin. These results suggest that KCTD1 functions as a novel inhibitor of Wnt signaling pathway.