Monophenyl luminescent material with dual-state emission and pH sensitivity for cell imaging.

Dual-state emission (DSE) luminescent materials are a newly discovered category of luminescent materials that exhibit efficient light emission in multiple states, including dilute solutions, highly concentrated solutions, aggregated states and solid states. These materials effectively address the aggregation-caused quenching (ACQ) observed in traditional organic luminescent materials with large conjugated planes, as well as the limitations of aggregation-induced emission (AIE) materials, which typically do not emit light in dilute solutions. The design and development of DSE luminescent materials for organelle imaging applications has attracted considerable interest. In this context, this study presents the design and synthesis of a novel luminescent compound, DMSS-AM, characterised by intramolecular hydrogen bonding and a D-π-A structure. As a monophenyl luminescent material, DMSS-AM exhibits DSE properties with fluorescence quantum yields of 22.1% in solution and 14.0% in the solid state. In particular, it exhibits unique pH-responsive properties, facilitating the targeted detection of lysosomal pH changes. Confocal laser scanning microscopy imaging of cells demonstrated that DSE emitters at both low and high concentrations do not affect image quality for bio-imaging applications. This advance is expected to significantly broaden the applicability of DSE luminescent materials in future applications.

Three new red neutral and ionic iridium(III) complexes based on the same main ligand and auxiliary ligand but with different counterions for solution-processed organic light-emitting diodes.

Three new neutral and ionic phosphorescent iridium(III) complexes were successfully prepared using 1-(6-methoxynaphthalen-2-yl)isoquinoline as the main ligand, while the auxiliary ligand was 2-(2-1H-imidazolyl)pyridine. Three complexes (Ir1, Ir2, Ir3) showed red emission, peaking at 610, 609, and 615 nm, respectively, and they exhibited good solubility and excellent photophysical properties in different solvents, which is suitable to prepare organic light-emitting diodes (OLEDs) by solution method. Among the three OLEDs prepared by iridium(III) complexes using the solution method, the device based on Ir2 possessed better electroluminescent properties, and its maximum brightness, current efficiency (CE), power efficiency (PE), and the maximum external quantum efficiency (EQE) were 507.2 cd m-2 , 0.14 cd A-1 , 0.06 lm W-1 , and 0.14%. respectively, proving that the three complexes have a certain of potential for OLEDs applications and are expected to expand the applications of iridium(III) complexes for OLEDs.

Clustering-Triggered Emission Liquid Crystalline Polymer Bearing Cholesterol: Tunable Circularly Polarized Luminescence and Room-Temperature Phosphorescence.

Circularly polarized luminescence (CPL) materials with clustering-triggered emission (CTE) characteristic have gradually attracted attention for their unique photophysical properties. However, the majority of reported clusteroluminogens lack chirality and exhibit heterogeneity, making it challenging to achieve a well-defined helical structure necessary for efficient CPL with high dissymmetry factor (glum ). In this paper, chiral liquid crystals are constructed to obtain CTE-based CPL materials with high glum values. Side chain liquid crystal polymer PM6Chol bearing cholesterol clusteroluminogens are designed and synthesized. PM6Chol-coated film and PM6Chol thermal-treated film are also successfully prepared by different film-forming methods. Both the films inherit the CTE characteristic of cholesterol and show excitation wavelength-dependent luminescent behavior. However, the two polymer films exhibit different liquid crystal phase structures, with PM6Chol-coated film being a chiral bilayer smectic C phase and PM6Chol thermal-treated film being an achiral bilayer smectic A phase. Attributed to helical arrangement of cholesterol, PM6Chol-coated film emits efficient CPL with glum values up to 1.0 × 10-1 . For PM6Chol thermal-treated film, no CPL signal is detected due to the absence of helical structure. However, it shows obvious room-temperature phosphorescence with 2.0 s afterglow and 23.9 ms lifetime.

Designing Nonconventional Luminescent Materials with Efficient Emission in Dilute Solutions via Modulation of Dynamic Hydrogen Bonds.

Nonconventional luminescent materials (NLMs) which do not contain traditional aromatic chromophores are of great interest due to their unique chemical structures, optical properties, and their potential applications in various areas, such as cellular imaging and chemical sensing. However, most reported NLMs show weak or no emission in dilute solutions, which severely limits their applications. In this work, dynamic hydrogen bonds were utilized to design NLMs with efficient emission in dilute solutions. To further validate the results, polymers P1 and P2 were successfully prepared and investigated. It was found that the luminescence quantum efficiency of P1 and P2 at a concentration of 0.1 mg/mL in water solution was 8.9 and 0.6%, respectively. The high efficiency can be attributed to the fact that polymer P1 has more intra- or intermolecular dynamic hydrogen bonds and other short interactions than P2 in dilute solutions, allowing P1 to achieve the through-space conjugation effect to increase the degree of system conjugation, restrict molecular motion, and decrease nonradiative transitions, which can effectively improve luminescence. In addition, polymer P2 exhibits the characteristics of clustering-triggered emission, excitation wavelength-dependent and concentration-dependent fluorescence properties, excellent photobleaching resistance, low cytotoxicity, and selective recognition of Fe3+. The present study investigates the manipulation of luminescence properties of NLMs in dilute solutions through the modulation of dynamic hydrogen bonds. This approach can serve as a semi-empirical technique for designing and building innovative NLMs in the times ahead.

Two Novel Neutral Cyclometalated Iridium(III) Complexes Based on 10,11,12,13-Tetrahydrodibenzo[a,c]phenazine for Efficient Red Electroluminescence.

Two novel neutral phosphorescent iridium(III) complexes (Ir1 and Ir2) were rationally designed and synthesized with high yields using 10,11,12,13-tetrahydrodibenzo[a,c]phenazine as the main ligand. The two complexes showed bright-red phosphorescence (625 nm for Ir1, and 620 nm for Ir2, in CH2Cl2), high-luminescence quantum efficiency (0.32 for Ir1, and 0.35 for Ir2), obvious solvatochromism and good thermostability. Then, they were used to fabricate high-efficiency red OLEDs via vacuum evaporation; the maximum current efficiency, power efficiency, and external quantum efficiency of the red devices based on Ir1 and Ir2 are 13.47/15.22 cd/A, 10.35/12.26 lm/W, and 10.08/7.48%, respectively.

Preparation and Characterization of Carbazole-Based Luminogen with Efficient Emission in Solid and Solution States.

Organic luminescent materials with high luminescence efficiency in both solution and solid states, namely dual-state emission (DSE), have attracted considerable attention due to their promising applications in various fields. In order to enrich the variety of DSE materials, carbazole, similar to triphenylamine (TPA), was utilized to construct a novel DSE luminogen named 2-(4-(9H-carbazol-9-yl)phenyl)benzo[d]thiazole (CZ-BT). CZ-BT exhibited DSE characteristics with fluorescence quantum yields of 70, 38 and 75% in solution, amorphous and crystalline states, respectively. CZ-BT shows thermochromic and mechanochromic properties in solution and solids, respectively. Theoretical calculations show that there is a small conformational difference between the ground state and the lowest singly excited state of CZ-BT and that it exhibits a low non-radiative transition characteristic. The oscillator strength during the transition from the single excited state to the ground state reaches 1.0442. CZ-BT adopts a distorted molecular conformation with intramolecular hindrance effects. The excellent DSE properties of CZ-BT can be explained well using theoretical calculations and experimental results. In terms of application, the CZ-BT has a detection limit for the hazardous substance picric acid of 2.81 × 10-7 mol/L.

Poly-L-aspartic acid based nonconventional luminescent biomacromolecules with efficient emission in dilute solutions for Al3+ detection.

Nonconventional luminescent macromolecules exhibiting bright fluorescence or phosphorescence emission at high concentrations and solid-state have attracted significant attention due to their promising application in different fields. However, most reported nonconventional luminescent macromolecules show weak or no emission in dilute solutions, limiting their large-scale applications. Herein, nonconventional luminescent biomacromolecules with hydrophobic rigid chains, hydrophilic flexibility and inter- or intra-molecular hydrogen bonding interactions were proposed to achieve effective luminescence in dilute solutions. Poly-L-aspartic acid (PASA) with a fluorescence quantum yield of 4.6 % in a dilute solution (0.8 mg/mL) was synthesized to validate this design strategy. The fluorescence intensity of PASA solution increased with the increase of the concentration, demonstrating a clustering-triggered emission (CTE) effect. Furthermore, the fluorescence intensity significantly enhanced when adding Al3+ into PASA aqueous solution via the Al3+ recognition effect. The detection limits for Al3+ (1.71 × 10-6 mol/L) meet the World Health Organization (WHO) requirements for food detection. At last, PASA solid-state samples exhibit room temperature phosphorescence emission.

Ionic Rigid Organic Dual-State Emission Compound With Rod-Shaped and Conjugated Structure for Sensitive Al3+ Detection.

Dual-state emission (DSE) luminogens, a type of luminescent material which can effectively emit light in both dilute solution and solid states, have attracted tremendous attention, due to their widespread applications in chemical sensing, biological imaging, organic electronic devices, and so on. They overcome the shortcomings of aggregation-induced emission (AIE)-type compounds that do not emit light in dilute solutions and aggregation-caused quenching (ACQ)-type compounds that do not emit light in a concentrated or aggregated state. This work reports a novel ionic DSE material based on rigid rod-shaped organic conjugated structure using 4,4'-bis(2-sulfonatostyryl) biphenyl disodium salt (BSBDS); the ion repulsion effect can reduce the strong π-π interaction in aggregation and achieve high-efficiency luminescence in solution and solid states. In addition to excellent DSE characteristics, BSBDS also exhibits a mechanochromic nature and sensitive detection performance for aluminum ion (Al3+).

-808 nm-activated Ca2+doped up-conversion nanoparticles that release no inducing liver cancer cell (HepG2) apoptosis.

A near-infrared (NIR) light-triggered release method for nitric oxide (NO) was developed utilizing core/shell NaYF4: Tm/Yb/Ca@NaGdF4: Nd/Yb up-conversion nanoparticles (UCNPs) bearing a mesoporous silica (mSiO2) shell loaded with the NO donor S-nitroso-N-acetyl-DL-penicillamine (SNAP). To avoid overheating in biological samples, Nd3+was chosen as a sensitizer, Yb3+ions as the bridging sensitizer, and Tm3+ions as UV-emissive activator while co-doping with Ca2+was done to enhance the luminescence of the activator Tm3+. NO release from SNAP was triggered by an NIR-UV up-conversion process, initiated by 808 nm light absorbed by the Nd3+ions. NO release was confirmed by the Griess method. Under 808 nm irradiation, the viability of the liver cancer cell line HepG2 significantly decreased with increasing UCNPs@mSiO2-SNAP concentration. For a UCNPs@mSiO2-SNAP concentration of 200µg ml-1, the cell survival probability was 47%. These results demonstrate that UCNPs@mSiO2-SNAP can induce the release of apoptosis-inducing NO by NIR irradiation.

Room Temperature Phosphorescence Emission From Multi-States.

Organic room temperature phosphorescence (RTP) materials have received considerable attention due to their fascinating photophysical properties. During the past decade, various organic luminogens exhibiting RTP emission in solid states were reported. However, the phosphorescence emission of organic compounds can hardly be observed in their solutions at room temperature. Herein, we reported two fluorene derivatives that can emit RTP in degassed organic solvents, polymer doped film, and crystalline states. Furthermore, those RTP luminogens emitted different colors with different phosphorescence lifetimes in multi-states. These results indicated that the phosphorescence performance can be adjusted flexibly in different condensed states. To our knowledge, this is the first example possessing diverse organic RTP at multi-states, including solution state.

Crystallization-Induced Red Phosphorescence and Grinding-Induced Blue-Shifted Emission of a Benzobis(1,2,5-thiadiazole)-Thiophene Conjugate.

Mechanochromic luminogens are of significant importance in both academic and technical aspects. Thus far, most mechanochromic compounds exhibit bathochromically shifted emission upon grinding; the examples of those that exhibit blue-shifted emission still remain limited. Herein, a donor-acceptor-donor (D-A-D)-structured conjugate, namely 4,7-di(2-thienyl)-2,1,3-benzothiadiazole (DTBT), comprising benzobis(1,2,5-thiadiazole) and thiophene units, has been carefully synthesized and investigated. DTBT exhibits typical intramolecular charge transfer (ICT) characteristics, crystallization-induced phosphorescence (CIP), and remarkable mechanochromism. Although it merely emits fluorescence in solutions with distinct ICT features, its crystals demonstrate bright-red room-temperature phosphorescence (616 nm) with efficiency up to 25.0% and generate yellow excimer fluorescence (578 nm) upon mechanical grinding, accompanying decreased lifetimes from 10.9 µs to 3.5 ns and a blue-shifted emission of 38 nm. These results highly indicate the feasibility to fabricate novel CIP luminogens with blue-shifted mechanochromism.

Preparation and Properties of a High-Performance EOEOEA-Based Gel-Polymer-Electrolyte Lithium Battery.

Gel polymer electrolyte (GPE) is a promising candidate for lithium-ion batteries due to its adhesion property (like a solid), diffusion property (like a liquid), and inhibition of the growth of lithium dendrite. In this paper, 2-(2-ethoxyethoxy)ethyl acrylate (EOEOEA) and LiBF4 electrolyte were mixed as precursors of gel polymer electrolytes. Through thermal curing, a thermally stable GPE with high ionic conductivity (5.60 × 10-4 s/cm at 30 °C) and wide room temperature electrochemical window (4.65 V) was prepared, and the properties of the GPE were measured by linear sweep voltammetry (LSV), AC impedance spectroscopy, Thermogravimetric analysis (TG), and X-ray diffraction (XRD) techniques. On the basis of the in-situ deep polymerization on a LiFePO4 electrode and cellulose membrane in a battery case, EOEOEA-based GPE could be derived on both LiFePO4 electrode and cellulose membrane. Meanwhile, the contact between GPE, LiFePO4 electrode, and lithium electrode was promoted. The capacity retention rate of the as-prepared LiBF4-EOEOEA 30% gel lithium battery reached 100% under the condition of 0.1 °C after 50 cycles, and the Coulombic efficiency was over 99%. Meanwhile, the growth of lithium dendrite could be effectively inhibited. GPE can be applied in high-performance lithium batteries.

High-Voltage Sulfolane Plasticized UV-Curable Gel Polymer Electrolyte.

A high-voltage electrolyte can match high-voltage positive electrode material to fully exert its capacity. In this research, a sulfolane plasticized polymer electrolyte was prepared by in situ photocuring. First, the effect of the sulfolane content on the ionic conductivity of the gel polymer electrolyte was investigated. Results showed that the ionic conductivity variation trend was in good agreement with the exponential function model for curve fitting. Second, the activation energy was calculated from the results of the variable temperature conductivity tests. The activation energy was inversely proportional to the sulfolane content. For the sulfolane content of 80 wt. % in gel polymer electrolyte (GPE)-80 (19.5 kJ/mol), the activation energy was close to conventional liquid electrolyte (9.5 kJ/mol), and the conductivity and electrochemical window were 0.64 mS/cm and 5.86 V, respectively. The battery cycle performance test showed that the initial specific discharge capacities of GPE-80 and liquid electrolyte were 176.8 and 148.3 mAh/g, respectively. After 80 cycles, the discharge capacities of GPE-80 and liquid electrolyte were 115.8 and 41.1 mAh/g, and the capacity retention rates were 65.5% and 27.7%, respectively; indicating that GPE-80 has a better specific discharge capacity and cycling performance than the liquid electrolyte. SEM images indicated that GPE-80 can suppress the growth of lithium dendrites. The EDS test showed that GPE-80 can inhibit the dissolution of metal ions in the cathode material.

Reevaluating Protein Photoluminescence: Remarkable Visible Luminescence upon Concentration and Insight into the Emission Mechanism.

It is a textbook knowledge that protein photoluminescence stems from the three aromatic amino acid residues of tryptophan(Trp), tyrosine (Tyr), and phenylalanine (Phe), with predominant contributions from Trp. Recently, inspired by the intrinsic emission of nonaromatic amino acids and poly(amino acids) in concentrated solutions and solids, we revisited protein light emission using bovine serum albumin (BSA) as a model. BSA is virtually nonemissive in dilute solutions (≤0.1 mg mL-1 ), but highly luminescent upon concentration or aggregation, showing unique concentration-enhanced emission and aggregation-induced emission (AIE) characteristics. Notably, apart from well-documented UV luminescence, bright blue emission is clearly observed. Furthermore, persistent room-temperature phosphorescence (p-RTP) is achieved even in the amorphous solids under ambient conditions. This visible emission can be rationalized by the clustering-triggered emission (CTE) mechanism. These findings not only provide an in-depth understanding of the emissive properties of proteins, but also hold strong implications for further elucidating the basis of tissue autofluorescence.

Mechanical and Water-Resistant Properties of Eco-Friendly Chitosan Membrane Reinforced with Cellulose Nanocrystals.

Environmentally benign and biodegradable chitosan (CS) membranes have disadvantages such as low mechanical strength, high brittleness, poor heat resistance and poor water resistance, which limit their applications. In this paper, home-made cellulose nanocrystals (CNC) were added to CS to prepare CNC/CS composite membranes through mechanical mixing and solution casting approaches. The effects of CNC dispersion patterns and CNC contents on the properties of composite membranes were studied. The analysis of the surface and cross-section morphology of the membranes showed that the dispersion performance of the composite membrane was better in the case that CNC was dissolved in an acetic acid solution and then mixed with chitosan by a homogenizer (Method 2). CNC had a great length-diameter ratio and CNC intensely interacted with CS. The mechanical properties of the composite membrane prepared with Method 2 were better. With a CNC content of 3%, the tensile strength of the composite membrane reached 43.0 MPa, 13.2% higher than that of the CNC-free membrane. The elongation at break was 41.6%, 56.4% higher than that of the CNC-free membrane. Thermogravimetric, contact angle and swelling analysis results showed that the addition of CNC could improve the heat and water resistance of the chitosan membrane.

Room-temperature phosphorescent polymers with excitation-wavelength and delay-time emission dependencies.

Novel room-temperature phosphorescent materials based on commercialized poly(4-styrenesulfonic acid-co-maleic acid) salt have been identified with aggregation-induced emission and room temperature phosphorescence emission characteristics. We systematically investigated their excitation-wavelength and delay-time dependencies to provide new insight into the potentiality of these materials for multiple industrial applications, such as optical storage and anti-counterfeit labelling.

AIE-active polyanetholesulfonic acid sodium salts with room-temperature phosphorescence characteristics for Fe3+ detection.

Room-temperature phosphorescent materials have been a major focus of research and development during the past decades, due to their applications in OLEDs, photovoltaic cells, chemical sensors, and bioimaging. However, achieving polymeric phosphorescent materials without heavy-metal atoms and halogens under ambient conditions remains a major challenge. Here, we report a polymeric phosphor, namely polyanetholesulfonic acid sodium salt, which not only has room temperature phosphorescence characteristic but also aggregation-induced emission and dependence on the excitation wavelength characteristics. Moreover, it can recognize Fe3+ effectively.

A novel triphenylacrylonitrile based AIEgen for high contrast mechanchromism and bicolor electroluminescence.

A novel thermally stable and aggregation-induced emission (AIE) active compound, 2,2'-(([1,1'-biphenyl]-4,4'-diylbis(phenylazanediyl))bis(4,1-phenylene))bis(3,3-diphenylacrylonitrile) (BP2TPAN) was synthesized through a C-N coupling reaction between 2-(4-bromophenyl)-3,3-diphenylacrylonitrile (Br-TPAN) and N,N'-diphenyl-1,4-phenylenediamine, under mild conditions using Pd(OAc)2 and P(t-Bu)3 as a catalyst. The BP2TPAN was characterized by nuclear magnetic resonance spectroscopy, high resolution mass spectrometry and elemental analysis. The thermal analysis showed that the glass transition and decomposition temperatures (5% weight loss) are 96 and 414 °C, respectively. The fluorescent emission peaks changes at 540 and 580 nm upon grinding were attributed to a transformation from crystal to amorphous occurring by altering the condensed state. The photoluminescence quantum yield and fluorescence lifetime of the as prepared and ground samples were 74.3 and 8.4%, 3.4 and 5.1 ns, respectively. The difference of the luminous efficiency of before and after grinding samples indicates BP2TPAN has a high contrast more importantly, both doped and nondoped OLED devices emit different color, the doped one is highly efficient and its L max, CEmax, PEmax and EQE are up to 15 070 cd m-2, 11.0 cd A-1, 7.5 lm W-1, and 3.1%, respectively.

Superhydrophobic Melamine Sponge Coated with Striped Polydimethylsiloxane by Thiol-Ene Click Reaction for Efficient Oil/Water Separation.

Superhydrophobic and oleophilic sponges have been demonstrated as promising candidates for oil/water separation. However, there are still challenges in large-scale fabrication of superhydrophobic sponges with low cost and feasible method for industrial applications. Herein, we report a superhydrophobic and oleophilic melamine sponge functionalized by a uniform polydimethylsiloxane (PDMS) film that can be easily coated onto the sponge skeleton through UV-assisted thiol-ene click reactions. The PDMS films are characterized by a hierarchically striped microstructure with an average distance less than 2 µm. Because of the striped microstructure and the hydrophobic property of silicone, a high contact angle of 156.2° was achieved. Importantly, the interconnected open-cell structure of the melamine sponge was preserved by adapting the thickness of the PDMS film. The PDMS-coated melamine sponge exhibited a desirable absorption capacity of 103-179 times its own weight with oils and organic solvents. The excellent mechanical properties of melamine and the flexibility of PDMS enable the PDMS-coated melamine sponges to be squeezed repeatedly without collapsing. This study offers a robust and effective approach in large-scale preparation of a superhydrophobic sponge for large-scale oil spill containment and environmental remediation by the inexpensive commercial polymethylvinylsilicone and facile dip-coating/UV-curing method.

Clustering-Triggered Emission of Nonconjugated Polyacrylonitrile.

Intrinsic emission from nonconjugated polymers has attracted considerable attention owing to its fundamental importance and intensive applications in diverse fields. The emission mechanism, however, is still in debate. Herein, nonconjugated polyacrylonitrile (PAN) molecules are found to be virtually nonluminescent in dilute solutions, while being highly emissive when concentrated or aggregated as nanosuspensions, solid powders, and films, exhibiting distinct aggregation-induced emission (AIE) characteristics. Moreover, triplet emissions of delayed fluorescence and room temperature phosphorescence are detected from the solid powders. Such unique emission of nonconjugated PAN is ascribed to the formation of cyano clusters, which act as the exact chromophores. In these clusters, through space electronic interactions, namely overlap of π and lone pair (n) electrons among cyano groups extend the conjugation and meanwhile rigidify the molecular conformations, thus offering remarkable emission upon irradiation. The AIE phenomenon can also be well rationalized by the formation of cyano clusters together with conformation rigidification. And the triplet emissions shall be originated from the n-π* transition owing to the presence of lone pairs. It is believed that such clustering-triggered emission mechanism is instructive for further development of unorthodox luminogens.