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A novel photocatalytic acylation strategy was developed harnessing tetrabutylammonium decatungstate (TBADT) as a hydrogen atom transfer (HAT) photocatalyst to facilitate the direct coupling of aldehydes with N-heterocycles at ambient temperature. This approach realizes the direct acylation of N-hetrerocycles without the need for noble metals, acids, or external oxidants, thereby marking a significant advance in green chemistry protocols. Utilizing this photocatalyzed method, we successfully synthesized a diverse array of 3-acylated azauracils and quinoxalin-2(1H)-ones, adorned with a variety of functional groups, achieving yields ranging from good to excellent. This research opens avenues for the rapid and efficient modification of heterocyclic compounds, which are foundational structures in medicinal chemistry and materials science. [ABSTRACT FROM AUTHOR]

Theory and experiment have revealed that spin–orbit coupling (SOC) strongly depends on the relativistic effect in topological insulators (TIs), while the influence of orbitals is always ignored. Herein, we provide a direct way of controlling effective SOC with the help of orbital effects, reducing the dependence on elements. Taking 5d W2CO2 and 4d Mo2CO2 MXenes as a specific example, we predict that by decreasing the hybridization strength of W atoms with C or O atoms in 2D W2CO2, the nontrivial bandgaps at the Γ-point are directly enhanced. The weak hybridization of W atoms with ligand elements enhances the electron localization of degenerate d-orbitals of three groups under the triangular prism crystal field, inducing stronger on-site Coulomb repulsion that enhances orbital polarization as well as boosts the SOC effect. Meanwhile, similar results have also been observed in 4d Mo2CO2. This implies that the orbital effects are an efficient and straightforward way to control the nontrivial bandgap in 2D MXene TIs. Our work not only provides an alternative perspective on designing large nontrivial bandgaps but also brings a possibility to control the SOC effect for TI devices. [ABSTRACT FROM AUTHOR]

Alkyl diacyl peroxides were demonstrated to be efficient alkylating reagents for the visible-light-induced 4CzIPN-catalyzed direct C–H alkylation of N-heteroaromatics. With this metal-/base-/additive-free photocatalytic system, 57 examples of alkylated N-heteroaromatics scaffolds including 1,2,4-triazine-3,5(2H,4H)-diones (i.e. azauracils), quinoxalin-2(1H)-ones, 2H-benzo[b][1,4]oxazin-2-ones and quinoxalines were successfully synthesized. [ABSTRACT FROM AUTHOR]

Some two-dimensional (2D) MXene topological insulators (TIs) show a large nontrivial bandgap, which strongly depends on the relativistic effect or electron correlation effects. However, the factors of orbitals are always neglected. Herein, focusing on 5d mono-transition metal MXenes, we demonstrate that the orbital effects of Ta2CF2 monolayers can directly enhance the nontrivial gaps through the changes of thickness (Δh) as a pivot. Compared to the 5d mono-transition metal MXene W2CO2, the surface-functionalized Ta2CF2 monolayers have a larger thickness (Δh) between F and F atoms. Meanwhile, the nontrivial bandgap (0.810 eV) at the Γ-point is significantly enhanced compared to that of W2CO2 (0.472 eV). To emphasize the important role of thickness in regulating the nontrivial bandgaps, we have studied a set of hypothetical Ta2CF2 monolayers, which have different Δh between F and F atoms on the surface of Ta2CF2 monolayers. The results show that the nontrivial gaps can be directly enhanced by increasing the Δh, which originates from the decrease of the orbital overlap between the dz2 and dx2−y2,xy orbitals. In other words, the orbital effects are available for increasing bandgaps in MXene TIs. Our study provides an alternative view of designing large nontrivial bandgaps in 2D MXene TIs. [ABSTRACT FROM AUTHOR]

A photocatalytic strategy for the controllable aroylation or diaroylation of allyl sulfones was established using tetrabutylammonium decatungstate (TBADT) as a hydrogen atom transfer (HAT) photocatalyst and aldehydes as radical precursors. By adjusting the substrate ratio, the selectivity of the reaction could be readily tuned and various aroyl groups were installed on allyl sulfones, which furnished β,γ-unsaturated ketones and 1,5-diketones in moderate to excellent yields, respectively. This methodology featured mild conditions, high step economy, no external additive, readily available resources, and broad substrate scope. [ABSTRACT FROM AUTHOR]

Correction for 'Alkyl radicals from diacyl peroxides: metal-/base-/additive-free photocatalytic alkylation of N-heteroaromatics' by Fukun Cheng et al., Green Chem., 2023, 25, 7971–7977, https://doi.org/10.1039/D3GC02545D. [ABSTRACT FROM AUTHOR]

Hexavalent chromium is highly toxic and regarded as one of the main pollutants in the environment. Sophisticated laboratory instruments are commercially available for the in-field determination of chromium. It is highly desirable to develop affordable, portable, sensitive and reliable methods for on-site Cr(VI) detection. For field analysis, we designed a smartphone-based absorbance device with an ultralong absorption path to improve sensitivity. The intensity of the transmission light was detected by the illumination sensor in the smartphone. The absorption path was enlarged to a maximum of 83.5 cm by 41 reflection cycles. The intensity of the reflected light in an empty colorimetric cell can be serviced as the internal references to correct the possible baseline drift due to light source intensity decay. The absorbance measured by the proposed device obeys the Lambert–Beer law in the range of 0–1.1. This device was used to determine Cr(VI) in water samples on-site by using 1,5-diphenylcarbazide as a colorimetric reagent, with the linear range of 1–18 μg L−1 and limit of detection of 0.26 μg L−1. This simple absorbance device offers the advantages of cost-effectiveness, ease of implementation, portability, sensitivity and reliability for field analysis. [ABSTRACT FROM AUTHOR]

Chlorine is the most common chemical compound used for treatment of water, but the concentration of free chlorine must be strictly controlled. For fast and on-site detection of free chlorine, cost-effective and miniaturized devices are required. Herein, we reported a smartphone-based colorimetric device with improved sensitivity and reliability, equipped with absorbance (total optical path 20 cm) and fluorescence cuvettes. The reaction mixtures of free chlorine and 3,3′,5,5′-tetramethylbenzidine (pH = 1.8) were added into the absorbance cuvette and a methionine stabilized Au nanocluster (Met-Au NC) solution was added into the fluorescence cuvette. A 450 nm laser beam was passed through the fluorescence and absorbance cuvettes and reflected back by a triangular mirror at the end of the absorbance cuvette. The fluorescence images of the Met-Au NC solution in the reference and measuring areas were captured by the camera in a smartphone. The absorbance was obtained by using a ratiometric fluorescence strategy, which is found to be independent of the variations in light source intensity, concentration of fluorescent luminophore, and exposure parameters of the camera. The absorbance measured by the proposed device obeys the Lambert–Beer law in the range of 0–1. The triangular mirror is useful to double the absorption optical path and reduce the distance between the reference and measuring fluorescence areas. The sensitivity of the long-path colorimetric device was one order of magnitude higher than that of a spectrophotometer using a 1 cm cuvette. This simple colorimetric device offers the advantages of portability, sensitivity and reliability for field analysis. [ABSTRACT FROM AUTHOR]

In this work, a novel nanoplatform based on Pd corolla–human serum albumin–indocyanine green (PdCs–HSA–ICG) was developed for cancer photothermal/photodynamic combination therapy. Pd corollas (denoted as PdCs) with good near-infrared photothermal conversion efficiency (η≈ 37%) were first prepared and modified with human serum albumin (HSA) and indocyanine green (ICG) to get the PdCs–HSA–ICG nanocomposite. The prepared PdCs–HSA–ICG not only improves the colloid and thermal stability of ICG, but also shows a higher temperature increase than that of PdCs and free ICG as well as a comparable singlet oxygen (1O2) generation capability to that of free ICG. Upon single 808 nm laser irradiation, the photothermal (PTT)/photodynamic (PDT) combined therapeutic efficacy of PdCs–HSA–ICG at both cellular and animal levels was superior to PdCs–HSA (PTT) or free ICG (PTT and PDT), respectively. Thus, the designed PdCs–HSA–ICG nanocomposite holds great potential as a new class of photosensitive agent for cancer phototherapy. [ABSTRACT FROM AUTHOR]

Direct transformation of a directing group to important synthetic units would provide a high atom efficiency synthetic approach in synthetic chemistry. Herein, a convenient protocol for the synthesis of o-aminobenzaldehyde and benzoxazole derivatives from benzyl alcohols has been developed by employing (N,N-dimethyl)oxamoyl amide as a directing group in a palladium-catalyzed intramolecular amination. Furthermore, the attached directing center may not only be transformed into the product, but may also be further applied to generate synthetically important quinazoline and quinoline units. Finally, a high atom efficiency one-pot, two-step approach to form quinazolines from benzyl alcohol derivatives has been achieved in good yields, thus demonstrating its high utility. [ABSTRACT FROM AUTHOR]

The first bidentate directing group assisted highly selective meta arylation of β-arylethylamine derivatives via palladium/norbornene catalysis is reported, and the range of aryl iodides for the oxalyl amide assisted meta-selective arylation reactions is broadest yet reported. This meta arylation also proceeds well with thiophene derivatives, giving the corresponding products in satisfactory yields. And three-step functionalization of arylethyloxalamide with three different functional groups is successfully performed. [ABSTRACT FROM AUTHOR]

In this work, a novel bactericidal agent based on two-dimensional Pd@Ag nanosheets (Pd@Ag NSs) that is responsive to near-infrared (NIR) light has been developed. These Pd@Ag NSs were prepared by reducing silver ions on the surface of Pd nanosheets (Pd NSs) seeds by formaldehyde, and displayed excellent NIR absorption and photothermal conversion properties. In addition, the NIR irradiation triggers the release of more Ag+ from the Pd@Ag NSs. Upon exposure to a NIR laser at a low power density (0.5 W cm−2), Pd@Ag NSs kill both Gram-negative (Escherichia coli, E. coli) and Gram-positive (Staphylococcus aureus, S. aureus) bacteria effectively by the synergistic effect of plasmonic heating and Ag+ release, which is much higher than either plasmonic heating or Ag+ alone. Such a novel nanomaterial is promising as an adjuvant therapeutic method for the treatment of patients suffering from severe bacterial infections. [ABSTRACT FROM AUTHOR]

Correction for 'A self-activated cascade nanoreactor based on Pd–Ru/GOx for bacterial infection treatment' by Tianbao Zhu et al., J. Mater. Chem. B, 2022, https://doi.org/10.1039/d2tb01416e. [ABSTRACT FROM AUTHOR]

The preparation, characterization and application of NaYF4:Yb3+, Tm3+–NaYF4:Yb3+, Er3+ core–shell upconversion nanocrystals (UCNPs) with multiple emission peaks (e.g. 539, 654 and 802 nm) have been demonstrated in this work. The monodisperse nanocrystals were prepared via a modified thermal decomposition synthesis. The resulting UCNPs were ∼31 nm in diameter with the lanthanide ions Tm3+ and Er3+ doped in the core and the shell, respectively. Under the laser diode excitation at 980 nm, these core–shell nanocrystals give strong upconversion emissions from the visible to near-infrared (NIR) region. By coating a PEG–phospholipid (PP) layer on the surface of the nanocrystals, the as-prepared UCNPs were favorably endowed with good water solubility for the potential biological applications. Here, a photosensitizer drug of Chlorin e6 (Ce6), which has maximum absorption that overlaps with the red emission of UCNPs, was loaded on these PP-coated UCNPs (UCNP@PP) by physical adsorption. The activity of the Ce6-loaded UCNP@PP (UCNP@PP–Ce6) in photodynamic therapy of cancer cells in vitro has been fully investigated in this work. Our results indicated that these multifunctional UCNP@PP–Ce6 nanoparticles have efficient NIR-to-NIR upconversion luminescence and photodynamic therapy capabilities, which could be potentially employed as a theranostic platform for cancer treatment. [ABSTRACT FROM AUTHOR]

A synthetic method to prepare novel multifunctional core-shell-structured mesoporous silica nanoparticles for simultaneous magnetic resonance (MR) and fluorescence imaging, cell targeting and photosensitization treatment has been developed. Superparamagnetic magnetite nanoparticles and fluorescent dyes are co-encapsulated inside nonporous silica nanoparticles as the core to provide dual-imaging capabilities (MR and optical). The photosensitizer molecules, tetra-substituted carboxyl aluminum phthalocyanine (AlC4Pc), are covalently linked to the mesoporous silica shell and exhibit excellent photo-oxidation efficiency. The surface modification of the core-shell silica nanoparticles with folic acid enhances the delivery of photosensitizers to the targeting cancer cells that overexpress the folate receptor, and thereby decreases their toxicity to the surrounding normal tissues. These unique advantages make the prepared multifunctional core-shell silica nanoparticles promising for cancer diagnosis and therapy. [ABSTRACT FROM AUTHOR]

Here we report the synthesis and crystallization of a -COOH-capped N -heterocyclic carbene (NHC)-protected Au 13 cluster. The single-crystal structure of the -COOH-capped NHC-Au 13 cluster reveals a classic icosahedral core with one Au atom in its center. The icosahedral core is surrounded by five NHC ligands with pseudo C5 symmetry and exposed carboxyls in a pentagonal antiprism fashion. The detailed formula of the Au cluster was identified as Au 13 (bi-NHC carboxyl) 5 Cl 2 (hereafter abbreviated as Au 13 -c). The density functional theory (DFT) calculations confirm that Au 13 -c is an electronically stable eight-electron super-atom cluster and elucidate its optical transitions in the UV-Vis range. The Au 13 -c cluster exhibits excellent thermal and chemical stability under bio-relevant conditions. Additionally, this cluster shows a strong red emission in DMF and H 2 O with an excellent quantum yield (QY) of 40% and 12.6%, respectively. The high QY of Au 13 -c enables its use in cell imaging on both cancer and noncancerous cells., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

On account of the fascinating surface plasmon resonance (SPR) properties, the ability of passively targeting tumors and remarkable biocompatibility, two-dimensional (2D) Pd-based nanomaterials have demonstrated wide application prospects in cancer theranostics. However, the used animal models for exploring the bioapplications and biosafety of 2D Pd-based nanomaterials were usually limited to mice. To further widen their biomedical applications and promote future clinical transformation, it is necessary to make a breakthrough in animal models. In this work, Sprague Dawley (SD) rats and New Zealand rabbits were used as the experimental animals and orthotopic liver tumors or subcutaneous tumors were induced in these animals. Taking ≈5 nm small Pd nanosheets (SPNS) and 30 nm Pd@Au nanoplates (Pd@Au) as the representative 2D Pd-based nanomaterials, we investigated their biobehaviors and biosafety in rat liver & subcutaneous tumor models and rabbit liver tumors. The results indicated that SPNS and Pd@Au could still effectively accumulate on the tumor sites of these bigger animal models by the enhanced permeability and retention (EPR) effect, and the accumulation effects were closely related to their sizes. Metabolism studies confirmed that SPNS could be excreted out of rats through urine. Moreover, based on the sufficient uptake by cancer cells and passive accumulation of SPNS and Pd@Au in subcutaneous tumors in rats, we performed photothermal therapy (PTT) in vitro and in vivo . Significant tumor growth inhibition illustrated that even though the animal model was dozens of times bigger than the mouse model, the 2D Pd-based nanomaterials satisfied the requirements of being an outstanding photothermal reagent. Finally, the hematological and histological examination results suggested that SPNS and Pd@Au had favorable biocompatibility in rats and rabbits at a given dose. We hope this work will drive the development of 2D Pd-based nanomaterials towards practical clinical applications and provide a guide for other theranostic nanoplatforms that will be applied in bigger animal tumor models in the future.

In this work, a novel bactericidal agent based on two-dimensional Pd@Ag nanosheets (Pd@Ag NSs) that is responsive to near-infrared (NIR) light has been developed. These Pd@Ag NSs were prepared by reducing silver ions on the surface of Pd nanosheets (Pd NSs) seeds by formaldehyde, and displayed excellent NIR absorption and photothermal conversion properties. In addition, the NIR irradiation triggers the release of more Ag + from the Pd@Ag NSs. Upon exposure to a NIR laser at a low power density (0.5 W cm -2 ), Pd@Ag NSs kill both Gram-negative (Escherichia coli, E. coli) and Gram-positive (Staphylococcus aureus, S. aureus) bacteria effectively by the synergistic effect of plasmonic heating and Ag + release, which is much higher than either plasmonic heating or Ag + alone. Such a novel nanomaterial is promising as an adjuvant therapeutic method for the treatment of patients suffering from severe bacterial infections.

Herein we report a drug delivery system based on hollow iron silicate nanospheres. Fe 3+ on the nanospheres' surface can effectively bind with doxorubicin (DOX), an anticancer drug, through coordination bonds. The bonds are fairly stable in a neutral environment but could easily break up in an acid environment. The release of DOX from hollow iron silicate nanospheres into cancer cells can be therefore triggered by a pH drop caused by endocytosis. The iron silicate shell allows a DOX loading content of up to 50.2% in weight, which is significantly higher than most drug delivery systems reported. Cell experiments show that DOX-loaded hollow iron silicate nanospheres exhibit a higher efficiency in killing cancer cells than free DOX, and a higher cytotoxicity for human hepatoma cells than hepatocyte cells at the same DOX-loaded nanospheres' concentration. Confocal laser scanning microscopy (CLSM) experiments show the releasing and transportation process of DOX, and confirm the enrichment of DOX in cell nuclei.

In this work, we have demonstrated that mesoporous silica-coated Pd@Ag nanoparticles (Pd@Ag@mSiO 2 ) can be used as an excellent nanoplatform for photodynamic therapy (PDT) drug delivery. Photosensitizer molecules, Chlorin e6 (Ce6), are covalently linked to the mesoporous shell and the prepared Pd@Ag@mSiO 2 -Ce6 nanoparticles exhibit excellent water solubility, good stability against leaching and high efficiency in photo-generating cytotoxic singlet oxygen. More importantly, the photothermal effect of Pd@Ag nanoplates under the irradiation of a NIR laser can enhance the uptake of Pd@Ag@mSiO 2 -Ce6 nanoparticles by cells, further increasing the PDT efficiency toward cancer cells. The photothermally enhanced PDT effects were demonstrated both in vitro and in vivo. When the Pd@Ag@mSiO 2 -Ce6 nanoparticles were injected intratumorally into the S180 tumor-bearing mice, the tumors were completely destroyed without recurrence of tumors upon irradiation with both 808 nm and 660 nm lasers, while the irradiation with 808 nm or 660 nm alone did not. These results indicate that the Pd@Ag@mSiO 2 nanoparticles may be a valuable new tool for application in cancer phototherapy.