Enhancing corannulene chemiluminescence, electrochemiluminescence and photoluminescence by means of an azabora-helicene to slow down its bowl inversion.

Aromatic system extension of corannulene (Cor) is a synthetic challenge to access non-planar polyaromatic hydrocarbons (PAHs). Herein, we report the design and synthesis of azaborahelicene corannulene 1 through hybridization of an azabora[5] helical structure and subsequent luminescence studies. Significant enhancement in chemiluminescence (CL), electroluminescence (ECL) and photoluminescence (PL) is achieved compared to those of pristine Cor. Specifically, hybrid 1 shows a notable augmentation in absolute luminescence quantum efficiencies: 25-fold for CL, up to 23-fold for ECL with BPO as a coreactant, and 30-fold for PL, respectively, compared to those of pristine Cor. Intriguingly, the blue light emission observed in all three luminescence types suggests the presence of a single excited state. As revealed by variable-temperature (VT) 1H NMR experiments, the bowl inversion frequency apparently decelerates by the steric effect of the helix motif in 1, which could contribute to the enhanced luminescent properties by reducing excited energy losses non-radiatively through fewer molecular motions; these enhanced luminescence observations could be categorized alongside the aggregation induced emission (AIE) and crystallization-induced emission (CIE) phenomena. This work not only provides fundamental insights into improved luminescence quantum efficiencies via strategic modulation of the molecular structure and geometry, but the work also reveals Cor's inherent potential to build efficient blue-light emitting materials and devices.

Stable Interfacial Ruthenium Species for Highly Efficient Polyolefin Upcycling.

The present polyolefin hydrogenolysis recycling cases acknowledge that zerovalent Ru exhibits high catalytic activity. A pivotal rationale behind this assertion lies in the propensity of the majority of Ru species to undergo reduction to zerovalent Ru within the hydrogenolysis milieu. Nonetheless, the suitability of zerovalent Ru as an optimal structural configuration for accommodating multiple elementary reactions remains ambiguous. Here, we have constructed stable Ru0-Ruδ+ complex species, even under reaction conditions, through surface ligand engineering of commercially available Ru/C catalysts. Our findings unequivocally demonstrate that surface-ligated Ru species can be stabilized in the form of a Ruδ+ state, which, in turn, engenders a perturbation of the σ bond electron distribution within the polyolefin carbon chain, ultimately boosting the rate-determining step of C-C scission. The optimized catalysts reach a solid conversion rate of 609 g·gRu-1·h-1 for polyethylene. This achievement represents a 4.18-fold enhancement relative to the pristine Ru/C catalyst while concurrently preserving a remarkable 94% selectivity toward valued liquid alkanes. Of utmost significance, this surface ligand engineering can be extended to the gentle mixing of catalysts in ligand solution at room temperature, thus rendering it amenable for swift integration into industrial processes involving polyolefin degradation.

Spectroscopy and absolute quantum efficiency of near-infrared electrochemiluminescence for a macrocyclic palladium complex.

Electrochemiluminescence (ECL) is widely applied as a reliable tool in clinical diagnosis, including immunoassays, cancer biomarker detection, etc. Metal complexes with emission in the near-infrared (NIR) range possess distinct features such as high transmission and minimal tissue auto-absorption, making them versatile for applications in biosensing and other fields. Through ECL spectral studies of an O-linked nonaromatic benzitripyrrin (C^N^N^N) macrocyclic palladium complex (Pd1) with multiple pyrrole structures, we observed emission peaks from the Qx(0,0) and its vibronic Qx(0,1) bands during both photoluminescence (PL) and ECL. Notably, the emission from the Qx(0,1) band was significantly enhanced in the ECL spectrum, demonstrating higher selectivity for near-infrared light at 743 nm. In the ECL annihilation pathway, the appearance of ECL signals showed a strong correlation with the redox processes of the tri-pyrrin structure, revealing a cyclic tri-pyrrin ligand-centered nature with contributions from the metal center. Upon the introduction of tripropylamine (TPrA) and benzoyl peroxide (BPO) coreactants, the ECL signals exhibited enhancements ranging from several hundred to tens of times. Various reaction routes within different coreactant systems are extensively discussed. Additionally, the absolute quantum efficiencies of the Pd1/TPrA coreactant system were determined, showing efficiencies of 0.0032% ± 0.0005% and 0.000074% ± 0.000016% during pulsing and CV scan processes, respectively. This work addresses gaps in the study of palladacycle complexes in ECL and provides insights into the design of NIR luminescent structures that contribute to the fast screening and deep tissue penetration bioimaging techniques.

Synergetic effects and inhibition mechanisms of the polysaccharide-selenium nanoparticle complex in human hepatocarcinoma cell proliferation.

BACKGROUND: Active components from natural fungal products have shown promising potential as anti-tumor therapeutic agents. In the search for anti-tumor agents, research to overcome the drawbacks of high molecular weight and low bioavailability of pure polysaccharides, polysaccharide-conjugated selenium nanoparticles (SeNPs) has attracted much attention. RESULTS: A novel polysaccharide-selenium nanoparticle complex was produced, in which SeNPs were decorated with polysaccharide obtained from fermented mycelia broth of Lactarius deliciosus (FLDP). Transmission electron microscope, dynamic light scattering, and X-ray photoelectron spectroscopy were utilized to characterize the FLDP-SeNPs; and human hepatocarcinoma cell line (HepG2) was used to assess growth inhibition efficacy. The FLDP-SeNPs that were prepared had a spherical shape with the smallest mean diameter of 32 nm. The FLDP-SeNPs showed satisfactory dispersibility and stability after combination, demonstrating that a reliable consolidated structure had formed. The results revealed that FLDP-SeNPs had notable growth inhibition effects on HepG2 cells. They reduced the membrane potential of mitochondria significantly, increased the generation of reactive oxygen species, enhanced levels of both Caspase-3 and Caspase-9, and led to the nucleus in a wrinkled form. CONCLUSION: The FLDP-SeNPs could exert a synergetic toxicity reduction and inhibition enhancement effect on HepG2 cells by inducing early apoptosis, through mitochondria-mediated cytochrome C-Caspases and reactive oxygen species-induced DNA damage pathways. These results indicate that FLDP-SeNP treatment of HepG2 cells induced early apoptosis with synergetic efficacy, showing that FLDP-SeNPs can be useful as natural anti-tumor agents. © 2024 Society of Chemical Industry.

Patterns and drivers of avian taxonomic and phylogenetic beta diversity in China vary across geographical backgrounds and dispersal abilities.

Geographical background and dispersal ability may strongly influence assemblage dissimilarity; however, these aspects have generally been overlooked in previous large-scale beta diversity studies. Here, we examined whether the patterns and drivers of taxonomic beta diversity (TBD) and phylogenetic beta diversity (PBD) of breeding birds in China vary across (1) regions on both sides of the Hu Line, which demarcates China's topographical, climatic, economic, and social patterns, and (2) species with different dispersal ability. TBD and PBD were calculated and partitioned into turnover and nestedness components using a moving window approach. Variables representing climate, habitat heterogeneity, and habitat quality were employed to evaluate the effects of environmental filtering. Spatial distance was considered to assess the impact of dispersal limitation. Variance partitioning analysis was applied to assess the relative roles of these variables. In general, the values of TBD and PBD were high in mountainous areas and were largely determined by environmental filtering. However, different dominant environmental filters on either side of the Hu Line led to divergent beta diversity patterns. Specifically, climate-driven species turnover and habitat heterogeneity-related species nestedness dominated the regions east and west of the line, respectively. Additionally, bird species with stronger dispersal ability were more susceptible to environmental filtering, resulting in more homogeneous assemblages. Our results indicated that regions with distinctive geographical backgrounds may present different ecological factors that lead to divergent assemblage dissimilarity patterns, and dispersal ability determines the response of assemblages to these ecological factors. Identifying a single universal explanation for the observed pattern without considering these aspects may lead to simplistic or incomplete conclusions. Consequently, a comprehensive understanding of large-scale beta diversity patterns and effective planning of conservation strategies necessitate the consideration of both geographical background and species dispersal ability.

Amelioration of Acute Alcoholic Liver Injury via Attenuating Oxidative Damage and Modulating Inflammation by Means of Ursodeoxycholic Acid-Zein Nanoparticles.

Ursodeoxycholic acid (UDCA) has been broadly adopted for the clinical treatment of hepatic and biliary diseases; however, its poor water-solubility becomes an obstacle in wide applications. To overcome these challenges, herein, a two-tier UDCA-embedded system of zein nanoparticles (NPs) along with a polyelectrolyte complex was designed under facile conditions. Both the UDCA-zein NPs and their inclusion microcapsules showed a spherical shape with a uniform size. A typical wall plus capsule/core structure was formed in which UDCA-zein NPs distributed evenly in the interior. The UDCA inclusion microcapsules had an encapsulation rate of 67% and were released in a non-Fickian or anomalous transport manner. The bioavailability and efficacy of UDCA-zein NPs were assessed in vivo through the alcoholic liver disease (ALD) mouse model via intragastric administration. UDCA-zein NPs ameliorated the symptoms of ALD mice remarkably, which were mainly exerted through attenuation of antioxidant stress levels. Meanwhile, it notably upregulated the intestinal tight junction protein expression and improved and maintained the integrity of the mucosal barrier effectively. Collectively, with the improvement of bioavailability, the UDCA-zein NPs prominently alleviated the oxidative damage induced by alcohol, modulating the inflammation so as to restore ALD. It is anticipated that UDCA-zein NPs have great therapeutic potential as sustained-nanovesicles in ALD treatment.

Integrated Photochromic-Photothermal Processes for Catalytic Plastic Upcycling.

Incorporating high-energy ultraviolet (UV) photons into photothermal catalytic processes may enable photothermal-photochemical synergistic catalysis, which represents a transformative technology for waste plastic recycling. The major challenge is avoiding side reactions and by-products caused by these energetic photons. Here, we break through the limitation of the existing photothermal conversion mechanism and propose a photochromic-photothermal catalytic system based on polyol-ligated TiO2 nanocrystals. Upon UV or sunlight irradiation, the chemically bonded polyols can rapidly capture holes generated by TiO2 , enabling photogenerated electrons to reduce Ti4+ to Ti3+ and produce oxygen vacancies. The resulting abundant defect energy levels boost sunlight-to-heat conversion efficiency, and simultaneously the oxygen vacancies facilitate polyester glycolysis by activating the nucleophilic addition-elimination process. As a result, compared to commercial TiO2 (P25), we achieve 6-fold and 12.2-fold performance enhancements under thermal and photothermal conditions, respectively, while maintaining high selectivity to high-valued monomers. This paradigm-shift strategy directs energetic UV photons for activating catalysts and avoids their interaction with reactants, opening the possibility of substantially elevating the efficiency of more solar-driven catalysis.

Materials for Electrochemiluminescence: TADF, Hydrogen-Bonding, and Aggregation- and Crystallization-Induced Emission Luminophores.

Electrochemiluminescence (ECL) is a rapidly growing discipline with many analytical applications from immunoassays to single-molecule detection. At the forefront of ECL research is materials chemistry, which looks at engineering new materials and compounds exhibiting enhanced ECL efficiencies compared to conventional fluorescent materials. In this review, we summarize recent molecular design strategies that lead to high efficiency ECL. In particular, we feature recent advances in the use of thermally activated delayed fluorescence (TADF) emitters to produce enhanced electrochemiluminescence. We also document how hydrogen bonding, aggregation, and crystallization can each be recruited in the design of materials showing enhanced electrochemiluminescence.

Elucidation of an Aggregate Excited State in the Electrochemiluminescence and Chemiluminescence of a Thermally Activated Delayed Fluorescence (TADF) Emitter.

The electrochemistry, electrochemiluminescence (ECL), and chemiluminescence (CL) properties of a thermally activated delayed fluorescence (TADF) emitter 4,4'-(1,2-dihydroacenaphthylene-5,6-diyl)bis(N,N-diphenylaniline) (TPA-ace-TRZ) and three of its analogues were investigated. TPA-ace-TRZ exhibits both (a) delayed onset of ECL and (b) long-persistent luminescence, which we have attributed to the formation of an aggregate excited state in excimer or exciplex form. The evidence of this aggregate excited state was consistent across ECL annihilation and coreactant pathways as well as in CL. The absolute ECL efficiency of TPA-ace-TRZ using benzoyl peroxide (BPO) as a coreactant was found to be 0.028%, which was 9-fold stronger than the [Ru(bpy)3]2+/BPO reference coereactant system. Furthermore, the absolute CL quantum efficiency of TPA-ace-TRZ was determined to be 0.92%. The performance and flexibility of the TADF emitter TPA-ace-TRZ under these various emissive pathways are highly desirable toward applications in sensing, imaging, and light-emitting devices.

Nitrogen- and sulfur-doped graphene quantum dots for chemiluminescence.

Graphene quantum dots (GQDs), as one of the most promising luminescent nanomaterials, have been receiving increasing attention in various applications. However, it is still a challenge to improve their chemiluminescence (CL) quantum efficiency. Herein, the CL emissions of nitrogen- and sulfur-doped GQDs (NS-GQDs), nitrogen-doped GQDs (N-GQDs) and undoped GQDs synthesized through one-pot high-temperature pyrolysis are investigated in their chemical reactions with bis(2-carbopentyloxy-3,5,6-trichlorophenyl) oxalate (CPPO) and hydrogen peroxide (H2O2). A bright blue emission, and yellowish green and yellowish white light from NS-GQDs, N-GQDs and GQDs can be observed, respectively, in the mixture solutions with CPPO and H2O2. For the first time, spooling CL spectroscopy was used to investigate the CL reaction mechanisms, illuminant decays and the absolute CL efficiencies of these three GQD systems. Compared with the same system of undoped GQDs, it has been found that the NS-GQDs not only present slower illuminant decay, but also display an absolute CL quantum efficiency of 0.01%, 5-fold enhancement, due to the increase in N and S doping for a well-defined band gap energy. Moreover, three peak wavelengths attributed to intrinsic emission at 425 nm, aggregation-induced emission (AIE) at 575 nm and S-doped emissive surface states at 820 nm are observed for the first time in the NS-GQD system. The CL spectrum of N-GQDs displays two emission peaks at 395 and 575 nm attributed to intrinsic emission and AIE, whereas the CL spectrum of undoped GQDs demonstrates 500 nm and 600 nm peak wavelengths attributed to core emission and AIE. Absolute CL quantum efficiencies from these emissions at these various peaks can be determined quantitatively. This study provides guidance on tuning the surface states of GQD for more conducive injection of electrons and holes, facilitating the production of CL emission, which is beneficial for promoting the development of optical, bioassay and energy conversion applications.

Profiling H2O2 from single COS-7 cells by means of scanning electrochemical microscopy.

We report quantitative determination of extracellular H2O2 released from single COS-7 cells with high spatial resolution, using scanning electrochemical microscopy (SECM). Our strategy of depth scan imaging in vertical x-z plane was conveniently utilized to a single cell for obtaining probe approach curves (PACs) to any positions on the membrane of a live cell by simply drawing a vertical line on one depth SECM image. This SECM mode provides an efficient way to record a batch of PACs, and visualize cell topography simultaneously. The H2O2 concentration at the membrane surface in the center of an intact COS-7 cell was deconvoluted from apparent O2, and determined to be 0.020 mM by overlapping the experimental PAC with the simulated one having a known H2O2 release value. The H2O2 profile determined in this way gives insight into physiological activity of single live cells. In addition, intracellular H2O2 profile was demonstrated using confocal microscopy by labelling the cells with a luminomphore, 2',7'-dichlorodihydrofluorescein diacetate. The two methodologies have illustrated complementary experimental results of H2O2 detection, indicating that H2O2 generation is centered at endoplasmic reticula.

Leveraging Deep Neural Networks for Estimating Vickers Hardness from Nanoindentation Hardness.

This research presents a comprehensive analysis of deep neural network models (DNNs) for the precise prediction of Vickers hardness (HV) in nitrided and carburized M50NiL steel samples, with hardness values spanning from 400 to 1000 HV. By conducting rigorous experimentation and obtaining corresponding nanoindentation data, we evaluated the performance of four distinct neural network architectures: Multilayer Perceptron (MLP), Convolutional Neural Network (CNN), Long Short-Term Memory network (LSTM), and Transformer. Our findings reveal that MLP and LSTM models excel in predictive accuracy and efficiency, with MLP showing exceptional iteration efficiency and predictive precision. The study validates models for broad application in various steel types and confirms nanoindentation as an effective direct measure for HV hardness in thin films and gradient-variable regions. This work contributes a validated and versatile approach to the hardness assessment of thin-film materials and those with intricate microstructures, enhancing material characterization and potential application in advanced material engineering.

Nanocluster Transformation Induced by SbF6- Anions toward Boosting Photochemical Activities.

The interactions between SbF6- and metal nanoclusters are of significance for customizing clusters from both structure and property aspects; however, the whole-segment monitoring of this customization remains challenging. In this work, by controlling the amount of introduced SbF6- anions, the step-by-step nanocluster evolutions from [Pt1Ag28(S-Adm)18(PPh3)4]Cl2 (Pt1Ag28-Cl) to [Pt1Ag28(S-Adm)18(PPh3)4](SbF6)2 (Pt1Ag28-SbF6) and then to [Pt1Ag30Cl1(S-Adm)18(PPh3)3](SbF6)3 (Pt1Ag30-SbF6) have been mapped out with X-ray crystallography, with which atomic-level SbF6- counterion effects in reconstructing and rearranging nanoclusters are determined. The structure-dependent optical properties, including optical absorption, photoluminescence, and electrochemiluminescence (ECL), of these nanoclusters are then explored. Notably, the Pt1Ag30-SbF6 nanocluster was ultrabright with a high phosphorescence quantum yield of 85% in N2-purged solutions, while Pt1Ag28 nanoclusters were fluorescent with weaker emission intensities. Furthermore, Pt1Ag30-SbF6 displayed superior ECL efficiency over Pt1Ag28-SbF6, which was rationalized by its increased effectively exposed reactive facets. Both Pt1Ag30-SbF6 and Pt1Ag28-SbF6 demonstrated unprecedented high absolute ECL quantum efficiencies at sub-micromolar concentrations. This work is of great significance for revealing the SbF6- counterion effects on the control of both structures and luminescent properties.

Enhanced Electrochemiluminescence of A Macrocyclic Tetradentate Chelate Pt(II) Molecule through Its Collisional Interactions with the Electrode.

A macrocyclic tetradentate chelate Pt(II) molecule (Pt1) served as an excellent luminophore in electrochemiluminescence (ECL) processes. The blue ECL of Pt1/S2 O8 2- coreactant system in N,N'-dimethylformamide was found to be 46 times higher than that of the Ru(bpy)2+ /S2 O8 2- system or 30 times higher than that of the 9,10-diphenylanthracene/S2 O8 2- system. The unprecedented high ECL quantum efficiencies were caused by the cyclic generation of monomer excited states through collisional interactions of Pt1 molecules with the electrode at an elevated frequency. The ECL is tunable from bright blue to pure white by simply changing the solvent from N,N'-dimethylformamide to dichloromethane. The white ECL of Pt(II) molecule was reported for the first time and the mechanism was proposed to be the simultaneous emissions from the monomer excited state (blue) and excimer (red).

Favorable Bonding and Band Structures of Cu2ZnSnS4 and CdS Films and Their Photovoltaic Interfaces.

Thin-film photovoltaic cells using Cu2ZnSnS4 (CZTS, p-type) have many advantages, such as high photoconversion, low cost, and great tunability with earth-abundant, nontoxic elements, all of which are necessary to be long-term contributors to next-generation solar energy harvesting. Accurate measurements of bonding and band structures of both the thin-film materials and their interfaces are paramount to designing the solar devices layer-by-layer. Here, finely tuned 1 µm thick CZTS films, 50 nm thick CdS layers (n-type), and their 1 µm/2 nm p-n junction were fabricated inexpensively using our previously studied methods and investigated extensively for maximizing the key interface in the CZTS solar devices. Synthesized bulk CZTS and CdS were analyzed for structural deviations and crystal defects using synchrotron-based (SR) X-ray absorption fine structure (XAFS) along with simulated XAFS patterns. The structural properties of the two materials were designed to favor photovoltaic activity. Interface valence band structures of the CZTS/CdS p-n junction were measured through SR X-ray photoelectron spectroscopy (SR-XPS) and compared with the ones simulated using density functional theory. A full band diagram was constructed from XPS of the bulk films and SR-XPS of the interface, providing guidelines in optimizing charge-carrier extraction from the CZTS absorber to CdS buffer layer. It turns out that a small spike-like interface in the conduction band overlap was formed, maintaining a strong internal bias, while favoring a small energy barrier to prevent large-scale recombination from occurring. A large open-circuit voltage was obtained in the preliminary solar cell devices built on the small spike-like interface.

Controlling the Structure, Properties and Surface Reactivity of Clickable Azide-Functionalized Au25 (SR)18 Nanocluster Platforms Through Regioisomeric Ligand Modifications.

To fine-tune structure-property correlations of thiolate-protected gold nanoclusters through post-assembly surface modifications, we report the synthesis of the o, m, and p regioisomeric forms of the anionic azide-functionalized [Au25 (SCH2 CH2 -C6 H4 -N3 )18 ]1- platform. They can undergo cluster-surface strain-promoted alkyne-azide cycloaddition (CS-SPAAC) chemistry with complementary strained-alkynes. Although their optical properties are similar, the electrochemical properties appear to correlate with the position of the azido group. The ability to conduct CS-SPAAC chemistry without altering the parent nanocluster structure is different as the isomeric form of the surface ligand is changed, with the [Au25 (SCH2 CH2 -p-C6 H4 -N3 )18 ]1- isomer having the highest reaction rates, while the [Au25 (SCH2 CH2 -o-C6 H4 -N3 )18 ]1- isomer is not stable following CS-SPAAC. Single-crystal X-ray diffraction provide the molecular structure of the neutral forms of the three regioisomeric clusters, [Au25 (SCH2 CH2 -o/m/p-C6 H4 -N3 ]0 , which illustrates correlated structural features of the central core as the position of the azido moiety is changed.

Microencapsulation of functional ovalbumin and bovine serum albumin with polylysine-alginate complex for sustained protein vehicle's development.

Overcoming harsh gastric environment is still a challenging to bioactive proteins, microencapsulation provides one strategy in designing this protection barrier. In this work, bovine serum albumin and ovalbumin were chosen as model proteins, while polylysine-alginate complex was fabricated for microencapsulation purpose. Both of the protein-loaded microcapsules had regular internal microstructures. The model protein's embedding increased the thermal stability of the microcapsules. Both of the protein-loaded microcapsules had a slow release rate in simulated gastric fluids (pH 3.0), while a sustained release profile in simulated intestinal fluids (pH 6.4), indicating an excellent tolerance to the acidic gastric environment. The microencapsulation process was mild and had no influence on the protein's molecular weight, while a slight peak shifting occurred in the secondary structure of the released proteins. The developed microcapsules could be explored as a kind of vehicle for bioactive proteins applied in functional foods, health care products and medical formulations.

Monitoring single Au38 nanocluster reactions via electrochemiluminescence.

Herein, we report for the first time single Au38 nanocluster reaction events of highly efficient electrochemiluminescence (ECL) with tri-n-propylamine radicals as a reductive co-reactant at the surface of an ultramicroelectrode (UME). The statistical analyses of individual reactions confirm stochastic single ones influenced by the applied potential.

Identifying Highly Photoelectrochemical Active Sites of Two Au21 Nanocluster Isomers toward Bright Near-Infrared Electrochemiluminescence.

Thus far, no correlation between nanocluster structures and their electrochemiluminescence (ECL) has been identified. Herein, we report how face-centered-cubic and hexagonal close-packed structures of two Au21(SR)15 nanocluster isomers determine their chemical reactivity. The relationships were explored by means of ECL and photoluminescence spectroscopy. Both isomers reveal unprecedented ECL efficiencies in the near-infrared region, which are >10- and 270-fold higher than that of standard Ru(bpy)32+, respectively. Photoelectrochemical reactivity as well as ECL mechanisms were elucidated based on electrochemistry, spooling photoluminescence, and ECL spectroscopy, unfolding the three emission enhancement origins: (i) effectively exposed reactive facets available to undergo electron transfer reactions; (ii) individual excited-state regeneration loops; (iii) cascade generations of various exited states. Indeed, these discoveries will have immediate impacts on various applications including but not limited to single molecular detection as well as photochemistry and electrocatalysis toward clean photon-electron conversion processes such as light-harvesting and light-emitting technologies.