Enhancing Reverse Intersystem Crossing in Triptycene-TADF Emitters: Theoretical Insights into Reorganization Energy and Heavy Atom Effects.

Thermally activated delayed fluorescence (TADF) emitters based on the triptycene skeleton demonstrate exceptional performance, superior stability, and low efficiency roll-off. Understanding the interplay between the luminescent properties of triptycene-TADF molecules and their assembly environments, along with their excited-state characteristics, necessitates a comprehensive theoretical exploration. Herein, we predict the photophysical properties of triptycene-TADF molecules in a thin film environment using the quantum mechanics/molecular mechanics method and quantify their substantial dependency on the heavy atom effects and reorganization energies using the Marcus-Levich theory. Our calculated photophysical properties for two recently reported molecules closely align with experimental values. We design three novel triptycene-TADF molecules by incorporating chalcogen elements (O, S, and Se) to modify the acceptor units. These newly designed molecules exhibit reduced reorganization energies and enhanced reverse intersystem crossing (RISC) rates. The heavy atom effect amplifies spin-orbit coupling, thereby facilitating the RISC process, particularly at a remarkably high rate of ∼109 s-1.

A Convenient In Situ Preparation of Cu2ZnSnS4-Anatase Hybrid Nanocomposite for Photocatalysis/Photoelectrochemical Water-Splitting Hydrogen Production.

This study details the rational design and synthesis of Cu2ZnSnS4 (CZTS)-doped anatase (A) heterostructures, utilizing earth-abundant elements to enhance the efficiency of solar-driven water splitting. A one-step hydrothermal method was employed to fabricate a series of CZTS-A heterojunctions. As the concentration of titanium dioxide (TiO2) varied, the morphology of CZTS shifted from floral patterns to sheet-like structures. The resulting CZTS-A heterostructures underwent comprehensive characterization through photoelectrochemical response assessments, optical measurements, and electrochemical impedance spectroscopy analyses. Detailed photoelectrochemical (PEC) investigations demonstrated notable enhancements in photocurrent density and incident photon-to-electron conversion efficiency (IPCE). Compared to pure anatase electrodes, the optimized CZTS-A heterostructures exhibited a seven-fold increase in photocurrent density and reached a hydrogen production efficiency of 1.1%. Additionally, the maximum H2 production rate from these heterostructures was 11-times greater than that of pure anatase and 250-times higher than the original CZTS after 2 h of irradiation. These results underscore the enhanced PEC performance of CZTS-A heterostructures, highlighting their potential as highly efficient materials for solar water splitting. Integrating Cu2ZnSnS4 nanoparticles (NPs) within TiO2 (anatase) heterostructures implied new avenues for developing earth-abundant and cost-effective photocatalytic systems for renewable energy applications.

Optoelectronic performance of perovskite Cs2KMI6 (M = Ga, In) based on high-throughput screening and first-principles calculations.

Developing novel lead-free perovskite materials with suitable bandgaps and superior thermal stability is crucial to boost their applications in next-generation photovoltaic technologies. High throughput screening combined with the first principles method can accurately and effectively screen out promising perovskites. Herein, we select two lead-free all-inorganic halide double perovskite materials Cs2KMI6 (M = Ga, In) from 1026 compounds with the criteria including appropriate structure factors, positive decomposition energies, and suitable direct bandgaps. We investigated the thermal and mechanical stability, geometric and electronic structures, photoelectric properties, and defect formation energies for both perovskites Cs2KMI6 (M = Ga, In). They can exhibit excellent structural formability and stability through the analysis of structure factors, elastic constants, and stable chemical potential regions. In addition, we investigate the defect effects of Cs2KMI6 (M = Ga, In) on the photovoltaic performance by evaluating the defect formation energies and transition energy levels. Based on the HSE06 functional, we calculated the energy band structures of these two compounds and demonstrate the direct bandgaps of 1.69 eV (HSE06) and 2.16 eV (HSE06) for Cs2KGaI6 and Cs2KInI6, respectively. Moreover, we predicted excellent spectroscopic limited maximum efficiencies (SLMEs) of these two perovskites with high light absorption coefficients (around 105 cm-1), for instance, the SLME of Cs2KGaI6 can reach as high as 28.39%.

Four New Unusual Pentacyclic Triterpenoids from the Roots of Jasminum sambac (L.) Ait.

Four new unusual pentacyclic triterpenoids (1-4) were isolated from the roots of Jasminum sambac (L.) Ait. Their structures were elucidated by 1D and 2D NMR analysis, single-crystal X-ray diffraction and HRESIMS.

High-Contrast Visualization Chemiluminescence Based on AIE-Active and Base-Sensitive Emitters.

Peroxyoxalate chemiluminescence (PO-CL) is one of the most popular cold light sources, yet the drawback of aggregation-caused quenching limits their use. Here, we report a new kind of efficient bifunctional emitter derived from salicylic acid, which not only exhibits typical aggregation-induced emission (AIE) character but also has the ability to catalyze the CL process under basic conditions based on base sensitivity. By taking advantage of these unique features, we successfully confine the CL process on the surface of solid bases and provide a high-contrast visualization of CL emission. This method allows most of the common basic salts like sodium carbonate to be invisible encryption information ink and PO-CL solution to be a decryption tool to visualize the hidden information. The current study opens up an appealing way for the development of multifunction CL emitters for information encryption and decryption applications.

Tröger's Base-Derived Thermally Activated Delayed Fluorescence Dopant for Efficient Deep-Blue Organic Light-Emitting Diodes.

The development of efficient deep-blue emitters with thermally activated delayed fluorescence (TADF) properties is a highly significant but challenging task in the field of organic light-emitting diode (OLED) applications. Herein, we report the design and synthesis of two new 4,10-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (TB)-derived TADF emitters, TB-BP-DMAC and TB-DMAC, which feature distinct benzophenone (BP)-derived acceptors but share the same dimethylacridin (DMAC) donors. Our comparative study reveals that the amide acceptor in TB-DMAC exhibits a significantly weaker electron-withdrawing ability in comparison to that of the typical benzophenone acceptor employed in TB-BP-DMAC. This disparity not only causes a noticeable blue shift in the emission from green to deep blue but also enhances the emission efficiency and the reverse intersystem crossing (RISC) process. As a result, TB-DMAC emits efficient deep-blue delay fluorescence with a photoluminescence quantum yield (PLQY) of 50.4% and a short lifetime of 2.28 µs in doped film. The doped and non-doped OLEDs based on TB-DMAC display efficient deep-blue electroluminescence with spectral peaks at 449 and 453 nm and maximum external quantum efficiencies (EQEs) of 6.1% and 5.7%, respectively. These findings indicate that substituted amide acceptors are a viable option for the design of high-performance deep-blue TADF materials.

Cerium Synchronous Doping in Anatase for Enhanced Photocatalytic Hydrogen Production from Ethanol-Water Mixtures.

Cerium element with a unique electric structure can be used to modify semiconductor photocatalysts to enhance their photocatalytic performances. In this work, Ce-doped TiO2 (Ce/TiO2) was successfully achieved using the sol-gel method. The structural characterization methods confirm that Ce was doped in the lattice of anatase TiO2, which led to a smaller grain size. The performance test results show that the Ce doped in anatase TiO2 significantly enhances the charge transport efficiency and broadens the light absorption range, resulting in higher photocatalytic performance. The Ce/TiO2 exhibited a photocurrent density of 10.9 µA/cm2 at 1.0 V vs. Ag/AgCl, 2.5 times higher than that of pure TiO2 (4.3 µA/cm2) under AM 1.5 G light. The hydrogen (H2) production rate of the Ce/TiO2 was approximately 0.33 µmol/h/g, which is more than twice as much as that of the pure anatase TiO2 (0.12 µmol/h/g). This work demonstrates the effect of Ce doping in the lattice of TiO2 for enhanced photocatalytic hydrogen production.

N-Acylethanolamine acid amidase (NAAA) exacerbates psoriasis inflammation by enhancing dendritic cell (DCs) maturation.

Psoriasis is an incurable autoimmune disease that affects 2-3% of the world's population. Limited understanding of its pathogenesis hinders the development of therapies for the disease. Herein, we reported that N-acylethanolamine acid amidase (NAAA), a cysteine enzyme that catalyzes the hydrolysis of fatty acid ethanolamides (FAEs), was upregulated in psoriasis patients and imiquimod (IMQ)-induced mouse model of psoriasis. The upregulated NAAA contributes to the progression of psoriasis via enhancing dendritic cell (DCs) maturation. Transgenic expression of NAAA in mice accelerated the development of psoriasis, whereas genetic ablation of NAAA or local administration of NAAA inhibitor F96 ameliorated psoriasis. NAAA expressed in dendritic cells (DCs), but not in macrophages, T cells, or keratinocytes plays a critical role in psoriasis development. In addition, the results showed that NAAA degrades palmitoylethanolamide (PEA) and reduces PEA-PPARα-mediated dissociation of NF-κB p65 from Sirtuin 1 (SIRT1), subsequently, repressing the acetylation of p65 and down-regulating IL10 production. The decreased IL10 then leads to the maturation of DCs, thus promoting the development of psoriasis. These results provide new insights into the pathophysiological mechanism of psoriasis and identify NAAA as a novel target for the treatment of psoriasis.

Supermolecule Cucurbituril Subnanoporous Carbon Supercapacitor (SCSCS).

It is quite challenging to prepare subnanometer porous materials from traditional porous precursors, and use of supramolecules as carbon sources was seldom reported due to the complex preparation and purification processes. We explore a facile one-pot method to fabricate supramolecular coordination compounds as carbon sources. The resultant CB[6]-derived carbons (CBC) have a high N content of 7.0-22.0%, surface area of 552-861 m2 g-1, and subnano/mesopores. The CBC electrodes have a narrow size distribution at 5.9 Å, and the supercapacitor exhibits an energy density of 117.1 Wh kg-1 and a potential window of over 3.8 V in a two-electrode system in the ionic liquid (MMIMBF4) electrolyte with appropriate cationic (5.8 Å) and anionic (2.3 Å) diameter. This work presents the facile fabrication of novel supermolecule cucurbituril subnanoporous carbon materials and the smart design of "pores and balls" for high-performance energy storage systems.

Cerium-Doped Iron Oxide Nanorod Arrays for Photoelectrochemical Water Splitting.

In this work, a simple one-step hydrothermal method was employed to prepare the Ce-doped Fe2O3 ordered nanorod arrays (CFT). The Ce doping successfully narrowed the band gap of Fe2O3, which improved the visible light absorption performance. In addition, with the help of Ce doping, the recombination of electron/hole pairs was significantly inhibited. The external voltage will make the performance of the Ce-doped sample better. Therefore, the Ce-doped Fe2O3 has reached superior photoelectrochemical (PEC) performance with a high photocurrent density of 1.47 mA/cm2 at 1.6 V vs. RHE (Reversible Hydrogen Electrode), which is 7.3 times higher than that of pristine Fe2O3 nanorod arrays (FT). The Hydrogen (H2) production from PEC water splitting of Fe2O3 was highly improved by Ce doping to achieve an evolution rate of 21 µmol/cm2/h.

Substoichiometric 3D Covalent Organic Frameworks Based on Hexagonal Linkers.

Covalent organic frameworks (COFs), a fast-growing field in crystalline porous materials, have achieved tremendous success in structure development and application exploration over the past decade. The vast majority of COFs reported to date are designed according to the basic concept of reticular chemistry, which is rooted in the idea that building blocks are fully connected within the frameworks. We demonstrate here that sub-stoichiometric construction of 2D/3D COFs can be accomplished by the condensation of a hexagonal linker with 4-connected building units. It is worth noting that the partially connected frameworks were successfully reticulated for 3D COFs for the first time, representing the highest BET surface area among imine-linked 3D COFs to data. The unreacted benzaldehydes in COF frameworks can enhance C2H2 and CO2 adsorption capacity and selectivities between C2H2/CH4 and C2H2/CO2 for sub-stoichiometric 2D COFs, while the reserved benzaldehydes control the interpenetrated architectures for the 3D case, achieving a rare non-interpenetrated pts topology for 3D COFs. This work not only paves a new avenue to build new COFs and endows residual function groups with further applications but also prompts redetermination of reticular frameworks in highly connected and symmetrical COFs.

Thermally activated delayed fluorescence materials with aggregation-induced emission properties: a QM/MM study.

Organic molecules with thermally activated delayed fluorescence (TADF) and aggregation induced emission (AIE) properties have attracted increasing research interest due to their great potential applications in organic light emitting diodes (OLEDs), especially for those with multicolor mechanochromic luminescence (MCL) features. Theoretical research on the luminescence characteristics of organic TADF emitters based on the aggregation states is highly desired to quantify the relationship between the TADF properties and aggregation states. In this work, we study the 4,4'-(6-(9,9-dimethylacridine-10(9H)-yl)quinoline-2,3-dibenzonitrile (DMAC-CNQ) emitter with TADF and AIE properties, and calculate the photophysical properties in gas, solid and amorphous states by using the quantum mechanics and molecular mechanics (QM/MM) method. Our simulations demonstrate that the aggregation states enhance obviously the reverse intersystem crossing rates and transition dipole moments of the DMAC-CNQ emitter, and suppress the non-radiative rates from the lowest excited singlet state (S1) to ground state (S0). Specifically, the molecular stacking of DMAC-CNQ in solid phases can mainly restrict the geometric torsion of the DMAC moiety for decreasing non-radiative decay rates, and the torsion of the CNQ moiety for increasing the reverse intersystem crossing rates. As a result, the calculated fluorescence efficiencies of the DMAC-CNQ emitter in the crystal and amorphous states are 67% and 26% respectively, and in good agreement with the experimental results.

Luminescence Tunable Europium and Samarium Complexes: Reversible On/Off Switching and White-Light Emission.

Single-molecule functional materials with luminescence tunable by external stimuli are of increasing interest due to their application in sensors, display devices, biomarkers, and switches. Herein, new europium and samarium complexes with ligands having triphenylamine (TPA) groups as the redox center and 2,2'-bipyridine (bpy) as the coordinating groups and diketonate (tta) as the second ligand have been constructed. The complexes show white-light emission in selected solvents for proper mixtures of the emission from Ln3+ ions and the ligands. Meanwhile, they exhibit reversible luminescence switching on/off properties by controlling the external potential owing to intramolecular energy transfer from the Ln3+ ions to the electrochemically generated radical cation of TPA•+. Time-dependent density functional theory (TD-DFT) calculations have been performed to study the electronic spectra. The proposed intramolecular energy transfer processes have been verified by density functional theory (DFT) studies.

Synergistic Intra- and Intermolecular Noncovalent Interactions for Ultralong Organic Phosphorescence.

Metal-free ultralong organic phosphorescence (UOP) materials have attracted significant attention owing to their anomalous photophysical properties and potential applications in various fields. Here, three pyrimidine-based organic luminogens, 9-(pyrimidin-2-yl)-9H-carbazole, 9-(4,6-dimethylpyrimidin-2-yl)-9H-carbazole, and 9-(5-bromopyrimidin-2-yl)-9H-carbazole are designed and synthesized, which show efficient yellow UOP with the longest lifetimes up to 1.37 s and the highest absolute phosphorescence quantum yields up to 23.6% under ambient conditions. Theoretical calculations, crystal structures, and photophysical properties of these compounds reveal that intramolecular hydrogen bonding, intermolecular π-π interactions, and intermolecular electronic coupling are responsible for forming dimers and generating highly efficient UOP. Their efficacy as solid materials for data encryption is demonstrated.

N-Acylethanolamine acid amidase (NAAA) inhibitor F215 as a novel therapeutic agent for osteoarthritis.

Osteoarthritis (OA), characterized by cartilage damage, synovitis inflammation and chronic pain, is a common degenerative joint disease that may lead to physical disability. In the present study, we first explored the association between N-Acylethanolamine acid amidase (NAAA) and OA progression, and then examined the capability of the NAAA inhibitor F215 to attenuate osteoarthritis. Increased NAAA expressions and decreased PEA levels in synovial membrane and lumbar spinal cord were observed in MIA induced osteoarthritic rats. F215 (i.a., and i.p.) significantly protected against cartilage damage and synovial inflammation by directly increasing PEA levels in joints, or normalization of PEA levels and resolution of inflammation in spinal cord. Moreover, F215 also markedly alleviated osteoarthritic pain in rats, and the therapeutic effects of F215 were blocked by the PPAR-α antagonist MK886. The results revealed that NAAA may has been implicated in OA progression, and treatment with NAAA inhibitor F215 alleviated OA development by preventing cartilage damage, reducing inflammation, and alleviating pain. Our study suggested that NAAA inhibitor might be a novel therapeutic agent for OA treatment.

Moisture-Resistant Mn4+ -Doped Core-Shell-Structured Fluoride Red Phosphor Exhibiting High Luminous Efficacy for Warm White Light-Emitting Diodes.

K2 TiF6 :Mn4+ is a highly efficient narrow-band emission red phosphor with promising applications in white light-emitting diodes (LEDs) and wide-gamut displays. Nevertheless, the poor moisture-resistant properties of this material hinder commercialization. A convenient reverse cation-exchange strategy is introduced for constructing a core-shell-structured K2 TiF6 :Mn4+ @K2 TiF6 phosphor. The outer K2 TiF6 shell acts as a shield for preventing moisture in the air from hydrolyzing the internal MnF6 2- group, while effectively cutting off the path of energy migration to surface defects, thereby increasing the emission efficiency (especially for the phosphors doped with high concentrations of Mn4+ ). Employed as a red phosphor, the packaged white LED exhibits an extraordinarily high luminous efficacy of 162 lm W-1 , a correlated color temperature (CCT) of 3510 K, and a color rendering index of 93 (Ra ). Aging tests performed on this device at 85 °C and 85 % humidity for 480 h retain up to 89 % luminous efficacy. The findings could facilitate commercial application of K2 TiF6 :Mn4+ @K2 TiF6 phosphor.

Anion-π Interaction-Induced Room-Temperature Phosphorescence of a Polyoxometalate-Based Charge-Transfer Hybrid Material.

Room-temperature phosphorescence (RTP) was realized for the first time in a polyoxometalate-based charge-transfer (CT) hybrid material bearing polyoxometalates (POMs) as electron-donors (D) and rigid naphthalene diimides (NDIs) as electron-acceptors (A), meanwhile, this hybrid material displayed photochromism as well. The significant D-A anion-π interaction induced an additional through-space charge-transfer pathway. The resulting suitable D-A CT states can efficiently bridge the relatively large energy gap between the NDI-localized 1 π-π* and 3 π-π* states and thus trigger the ligand-localized phosphorescence (3 π-π*).

Inflammation-restricted anti-inflammatory activities of a N-acylethanolamine acid amidase (NAAA) inhibitor F215.

N-Acylethanolamine acid amidase (NAAA) is a cysteine enzyme that catalyzes the hydrolysis of palmitoylethanolamide (PEA). Pharmacological blockage of NAAA elevates PEA levels and exerts powerful anti-inflammatory activities. We have recently identified a highly potent NAAA inhibitor F215. Here, we demonstrated that F215 was an unusual inflammation-restricted NAAA inhibitor. In lipopolysaccharides (LPS) induced acute lung injury (ALI) model, F215 markedly accelerated inflammation resolution, promoted clearance of neutrophils infiltration and alveolar repair in the lungs. F215 efficiently inhibited NAAA and protected endogenous PEA from degradation in ALI model, but it cannot readily suppress the NAAA activity in naïve mice. The inflammation-restricted effect of F215 was further confirmed in the alveolar macrophage, F215 only increased PEA levels and exerted anti-inflammatory effects in activated macrophages, but not in unstimulated macrophages. Moreover, we also showed that the pharmacological effects of F215 were restricted to the local inflamed skin elicited by 12-o-tetradecanoylphorbol-13-acetate (TPA), but not the normal tissues. We believe that F215 could be a useful probe to investigate the function of NAAA, as well as a potent anti-inflammatory agent, and its inflammation-restricted feature might offer a new approach to prevent potential side effects of systemic enzyme inhibition.

Syntheses, Photoluminescence, and Electroluminescence of a Series of Sublimable Bipolar Cationic Cuprous Complexes with Thermally Activated Delayed Fluorescence.

Three thermally activated delayed fluorescence cationic cuprous complexes [Cu(POP) (ECAF)]PF6 (1, POP = bis(2-diphenylphosphinophenyl)ether, ECAF = 9,9-bis(9-ethylcarbazol-3-yl)-4,5-diazafluorene), [Cu(POP) (EHCAF)]PF6 (2, EHCAF = 9,9-bis(9-ethylhexylcarbazol-3-yl)-4,5-diazafluorene), and [Cu(POP) (PCAF)]PF6 (3, PCAF = 9,9-bis(9-phenylcarbazaol-3-yl)-4,5-diazafluorene) with bipolar 4,5-diazafluorene ligand substituted by bis-carbazole have been successfully prepared, and their UV absorption, photoluminescent properties, and electrochemical behaviors were investigated. At room temperature, complexes 1, 2, and 3 exhibit efficient yellowish-green emission with peak maxima of 550, 549, and 556 nm, respectively, and lifetimes of 5.7 µs. In powder states, the quantum yields (ϕPL) of 22.4% for 1, 18.5% for 2, and 20.0% for 3, respectively, are found. These metal phosphors can be vacuum-evaporated and applied in the organic light-emitting diodes (OLEDs) of indium tin oxide/poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (40 nm)/4,4',4″-tri(9-carbazoyl)triphenylamine (15 nm)/cuprous complexes (10 wt %): 1,3-bis(9-carbazolyl)benzene (30 nm)/1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (50 nm)/LiF (0.5 nm)/Al (100 nm). Complex 1-based device D1 achieved a maximum luminance of 11 010 cd m-2, a current efficiency of 47.03 cd A-1, and an external quantum efficiency of 14.81%. The high electroluminescence efficiencies of these complexes are assumed to be due to their good thermal stabilities and capture of both singlet and triplet excitons. The research presented here provides a powerful tool toward highly efficient and cheap OLED devices.