The synthesis of stable single-metal site catalysts with high catalytic activity and selectivity with a controllable coordination environment is still challenging. Due to the different electronegativity of different coordination atoms (N, P, S, etc.), adjusting the coordination atom type of the active metal center is an effective and wise strategy to break the symmetry of the electron density. We adopted a cation exchange strategy to synthesize two Cu single-atom catalytic materials with different coordination structures. This strategy can change the coordination environment of Cu single atom by changing the different organics wrapped around Cu-CdS. This strategy mainly relies on the anion skeleton of sulfide and the N-rich polymer shell to produce a large number of S and N defects during the high-temperature annealing process, and the precise synthesis of a single-metal Cu site catalyst material with rich edge S and N double modification. In these two materials, one single Cu atom has double coordination of sulfur (S) and nitrogen (N), and the other single Cu atom has only a single S coordination. The first shell coordination number of Cu central atom is 4, the structure of Cu-S/N-C is Cu-S₁N₃, and the structure of Cu-S-C is Cu-S₄. The results show that the catalytic performance of Cu-S/N-C in the hydrogenation of nitrobenzene compounds is much better than that of Cu-S-C, that is, the Cu monoatomic materials with S and N double-modified metal sites has better hydrogenation activity than single S-modified metal sites. After 20 min of reaction, under the catalysis of Cu-S/N-C, the conversion rate of nitrobenzene reached 100%, and the activity did not decrease significantly after being recycled for 5 times. It shows that the Cu-S/N-C catalytic material with a single-atom structure we synthesized has good stability. This discovery not only provides a feasible method for adjusting the coordination environment of the central metal to improve the performance of single-atom catalytic materials, but also provides an understanding of the catalytic performance of heteroatom modification.

Photocatalytic reduction of CO₂ to valuable chemicals is an essential but still remains challenging. Metal-organic frameworks (MOFs) featuring high special surface area, large CO₂ adsorption uptakes, adjustable structures and function, have become a kind of promising porous materials for photocatalytic CO₂ reduction. However, MOFs often suffer from problems like short light harvesting range, rapid recombination of photogenerated carriers, resulting in lower activity. Here, graphene quantum dots (GQD) were supported on the Fe-based nano-sized MOFs, NH₂-MIL-88B(Fe), via electrostatic self-assembly strategy. GQDs were prepared by electrolysis of graphite rod in pure water firstly, and then centrifuged to remove the large species. Transmission electron microscope (TEM) reveals that ultrafine GQDs with 3 nm were obtained. Atomic force microscope (AFM) further demonstrates that the thickness of GQDs is around 0.34—1.5 nm (1—4 stacked layers). The MOFs, NH₂-MIL-88B(Fe), were synthesized with traditional solvothermal method, with a nano spindle shape of 250 nm×40 nm. The amino groups on MOFs provide strong electrostatic force with the carboxylic groups on GQDs, making the composite very stable and efficient electron transfer. High resolution transmission electron microscope (TEM) reveals that the nano MOFs were surrounded by tiny GQDs firmly. The bandgap of composite was determined by solid ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS) and Mott-Schottky measurement, which indicate that it is thermodynamically appropriate for photocatalytic CO₂ reduction. Photocurrent experiments further demonstrate the composite is beneficial for the photogenerated electron-hole separation. Thus, the resulting GQD/NH₂-MIL-88B(Fe) composite showed much enhanced CO production rate (4 times) compared with the parent NH₂-MIL-88B(Fe), reaching 590 μmol/g under 10 h visible light irradiation with triethanolamine (TEOA) as sacrificial agent. The hugely improved photoreduction activity benefits from both the high CO₂ adsorption of MOFs and the enhanced separation of photogenerated electrons and holes. This work provides an avenue for preparation of MOFs based materials with high CO₂ photoreduction activity.

Azulene is a nonalternant and nonbenzenoid hydrocarbon with bright blue color and a dipole moment of 1.08 D, and has received increasing attention due to its unique electronic structure and physicochemical properties. Herein, we report the design and synthesis of two types of azulene-based [4]helicene 1a/1b and 2 that contain isoelectronic B—N and C=C units at the electron-rich 1-position of azulene unit, respectively. Formation of the helical scaffolds is executed by the introduction of boron and alkyne to flexible biaryl precursors, where the Lewis acidic boron and alkyne were employed as “glue” to join two subunits into fully fused scaffolds via electrophilic boronation and platinum-catalyzed cycloisomerization of alkyne at the 1-position of azulene unit, respectively. All of azulene-based helicenes were investigated by ultraviolet visible (UV-vis) absorption spectra, cyclic voltammetry (CV) measurements and density functional theory (DFT) calculations. Additionally, 1a was further characterized by single crystal structure analysis. The results suggest that the introduction of B—N unit changed the electronic structure of the conjugated aromatic framework, leading to a narrow HOMO-LUMO gap. Moreover, the B—N unit also affects the aromaticity of the π-system as revealed by nucleus-independent chemical shift (NICS) via time-dependent density functional theory (TD-DFT) calculation. The single crystal structure analysis demonstrates that 1a has a helically twisted framework and Plus (P)/Minus (M) enantiomers. However, the Gibbs activation energy (ΔG^≠(T)) of the enantiomerization at room temperature is too low to separate two enantiomers by chiral high performance liquid chromatography (HPLC). Furthermore, the B—N unit exhibits partial double bond character and the BN-containing six-membered ring shows weak aromaticity. 1a with a phenyl group exhibits the deboronization upon addition of trifluoroacetic acid (TFA) as well as a specific sensing behavior to fluoride ion. However, 1b shows no deboronization upon addition of TFA and no sensing behavior to fluoride ion due to its steric hindered mesityl (Mes) group, but has a reversible stimuli-responsiveness with acid and base, this proton-responsiveness is similar to all-carbon analogue 2.

The worldwide outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in the infection even death of people all over the world, which has gravely affected our daily life. Globalization of trade and convenient transportation immensely accelerate the propagation of the epidemic, which brings severe difficulties to prevent the epidemic. Therefore, rapid and accurate diagnosis of infected persons and screening of asymptomatic persons play an important role. At present, the most widely used method for the detection of SARS-CoV-2 is reverse transcription-polymerase chain reaction (RT-PCR), which still has some problems including complicated sample storage and transportation, complex operations and so on. These shortcomings cause the hindrances to achieve fast, simple, efficient diagnostic testing under the normalization of the epidemic. In the past few years, with the development of nanotechnology, bio-sensing methods based on nano photonics have become a research hotspot. Label-free optical methods have been widely explored for bio-sensing including virus detection, such as surface plasmon resonance (SPR), surface enhanced Raman scattering (SERS), whispering gallery mode (WGM) and colorimetry. These approaches offer available alternatives to improve the speed, sensitivity, and accuracy of optical bio-sensing, owing to the enhanced interaction between the nanostructure and the biomarkers. This review summarizes these nano photonics-based bio-sensing technologies for the detection of SARS-CoV-2. Moreover, the detection mechanism of biomarkers by nano photonics is explained, and the further development trends are discussed. In view of the difficulties in manufacturing nano photonics structures, a new strategy of large-area preparation of nano photonics structures using nano green printing technology is proposed, which provides theoretical and technical support for accurate and effective prevention and control of the epidemic diseases.

Metallofullerene Sc₃C₂@C₈₀ was synthesized by the arc-discharging method and isolated by multi-stage high performance liquid chromatography. Two Sc₃C₂@C₈₀ azobenzene nitroxide radical derivatives, compound I and II were synthesized through a Prato reaction, respectively. Usually, azobenzene undergoes trans-cis isomerization when irradiated with light tuned to an appropriate wavelength. The reverse cis-trans isomerization can be driven by light or occurs thermally in the dark. Thus, the compound I was excited by UV light, and it exhibited a strong absorption band decrease at around 340 nm and a slight increase at about 470 nm, which belonging to the π→π* and n→π* transition respectively. Similar to the azobenzene molecule in solution, the typical change of the absorption spectrum of compound I can be ascribed to the trans-to-cis transition with UV light irradiation. Similarly, the reverse isomerization of UV-irradiated compound I with visible light (475 nm) resulted in an obvious π→π* band increase, also indicating the reverse isomerization of compound I from cis-to-trans form. Besides, the structure and spin density distributions of compound I were calculated as well. It has two unpaired spins localizing on the Sc₃C₂@C₈₀ moiety and nitroxide radical. The magnetic property of metallofullerene can be manipulated by the spin interactions of the two spin centers. The electron paramagnetic resonance (EPR) signals of the trans isomer of the compound I are almost independent of each other. After UV light irradiation, the distance of the two spin centers decreased to r=0.752 nm, and the strong spin-spin interaction weakened the EPR signals of Sc₃C₂@C₈₀. However, the decreased chain length between Sc₃C₂@C₈₀ and nitroxide radical would result in a weakened spin-lattice interaction, which increased the EPR signals of the nitroxide radical. Moreover, the UV-radiated compound I with visible light treated later for several minutes, and the EPR signals of Sc₃C₂@C₈₀ has a certain degree of recovery with visible light irradiation. Therefore, the compound I has sensitive and reversible spin variation with different light irradiation. The remote nitroxide radical group serves as a magnetic switch for the EPR signal of Sc₃C₂@C₈₀ through the photoisomerization properties of azobenzene bridge. The EPR signals of Sc₃C₂@C₈₀ moiety were decreased by the strong spin-spin interaction, and the EPR signals of Sc₃C₂@C₈₀ would be enhanced by larger space with visible light irradiation. Such magnetic switch for metallofullerenes has potential applications in quantum information processing and molecular devices.

Molecular engineering design is an effective strategy to develop new compounds and optimize the crystal structure by atomic-scale manipulation. In this work, a novel series of fluoride carbonates AMgLi₂(CO₃)₂F (A=K, Rb) are rationally developed by taking Sr₂Be₂B₂O₇ (SBBO) as the parent compound. Their crystal structures are established by single crystal X-ray diffraction. KMgLi₂(CO₃)₂F belongs to centrosymmetric hexagonal system and crystallizes in P6₃/m with a=b=0.4775 nm, c=1.4782 nm. RbMgLi₂(CO₃)₂F crystallizes in the centrosymmetric trigonal space group P3̅1c with a=b=0.4787 nm, c=1.4966 nm. In all of their structures, the a-b plane is the infinite lattice layer [Li₃C₃O₆F₃]_∞ made up of [CO₃] and [LiO₃F] anionic groups. The adjacent layers are further connected with fluorine bridge atoms to form [Li₆C₆O₁₂F₃]_∞ double layers. In the structure of KMgLi₂(CO₃)₂F, all the [CO₃] groups not only parallel to a-b plane but also align in the exactly same orientation in the same double layers. While the [CO₃] groups in RbMgLi₂(CO₃)₂F are parallel to a-b plane but align in the different orientation. But anyway, their structural characteristic is greatly beneficial to improve the layering-growth habit and eliminate polymorphism of a crystal. Since AMgLi₂(CO₃)₂F (A=K, Rb) inherit the beneficial layered structure of SBBO, AMgLi₂(CO₃)₂F (A=K, Rb) should have superior optical properties including short ultraviolet (UV) absorption edges and large birefringences. In order to confirm inference, ultraviolet-visible diffuse reflectance spectroscopy data were recorded at room temperature using a powder sample with BaSO₄ as a standard (100% reflectance) on a PerkinElmer Lambda-950 ultraviolet visible-near infrared spectrophotometer over the scan range 200—2500 nm. The results showed KMgLi₂(CO₃)₂F and RbMgLi₂(CO₃)₂F exhibited a wide transparency window, >80%, from 200 to 2500 nm, indicating that both of them had short UV cutoff edges below 200 nm. The birefringent values of the titled compounds were measured on a Nikon ECLIPSE LV100 POL polarizing microscope, which revealed that KMgLi₂(CO₃)₂F and RbMgLi₂(CO₃)₂F had large birefringences (0.111@546.1 nm for KMgLi₂(CO₃)₂F and 0.113@546.1 nm for RbMgLi₂(CO₃)₂F, respectively). In addition, theoretical cal-culations on electronic structure were carried out to explain the experimental results. Our preliminary results indicate that both compounds have promising applications as deep-UV birefringent materials.

Bacterial infection and resistance have threatened public health and it is necessary to develop a novel and efficient antibacterial agent. Metal-organic frameworks (MOFs) have been widely studied and applied in the antibacterial field. The porous carbon frameworks could provide intrinsic conditions to avoid the agglomeration and avail the stabilization of metal nanoparticles, which may be some synergies. Herein, a novel kind of AgNPs@ZIF-67 composite nanoparticles was prepared by a green, rapid, and cost-effective method, during which zeolitic imidazolate framework-67 (ZIF-67) acted as a template and small silver nanoparticles (AgNPs) could be facilely prepared in situ by the reduction of silver ions with fresh sodium borohydride (NaBH₄). Specifically, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirmed the existence of as-prepared AgNPs with average diameters of (7.05±0.09) nm and the introduction of AgNPs did not alter the size and rhombic dodecahedron-type morphology of ZIF-67. Energy-dispersive X-ray spectroscopy (EDS) elemental mapping revealed that AgNPs@ZIF-67 mainly contained uniformly dispersed C, N, O, Co and Ag elements. And the loading ratio of Ag weight content was 0.98% in it. The X-ray diffraction (XRD) pattern of the AgNPs@ZIF-67 sample showed a series of typical and sharp diffraction peaks in the (011), (002), (112), and (222) planes but no obvious peaks attributed to the AgNPs, which exhibited the formation of phase-pure ZIF-67 and well-dispersed of metallic Ag in ZIF-67. Zeta potentials showed a higher potential of ZIF-67 (+25.6 mV) than AgNPs@ZIF-67 (+17.7 mV), indicating the load of negative charged AgNPs and good stability of the as-obtained AgNPs@ZIF-67. Furthermore, Staphylococcus aureus (S. aureus) (ATCC 6538) was used in the antibacterial assay and the bacterial concentration was regarded as 1×10⁸ CFU• mL^–1 when the OD₆₀₀ value of the suspensions was 0.1. The in vitro minimum inhibitory concentration (MIC) of AgNPs@ZIF-67, ZIF-67 were 300, 350 µg•mL^–1, respectively. The antibacterial efficiency of AgNPs@ZIF-67, ZIF-67, and AgNPs at 24 h were 99.889%, 57.192%, and 26.433%, respectively. It was illustrated that the decoration of AgNPs could significantly improve the antibacterial ability of ZIF-67 nanomaterials. Moreover, SEM images of S. aureus showed that AgNPs@ZIF-67 did more serious damage to the cell membrane than ZIF-67. This work provided a facile method to fabricate the AgNPs@ZIF-67 composite nanoparticles, which was demonstrated as a promising antibacterial material based on the synergistic effect of AgNPs and ZIF-67.

Low-dimensional semiconductors, especially recent emerging two-dimensional halide perovskites, have shown great potential in extensive optoelectronic applications due to their large structural anisotropy, unique quantum well effect and excellent semiconductor properties. Meanwhile, the bulk photovoltaic effect with a highly sensitive angle-resolved photoresponse arising from ferroelectric materials presents a promising approach for highly polarized-sensitive photodetection. Despite the blooming development of two-dimensional halide perovskite ferroelectric materials, it is a great challenge to grow bulk single crystals of two-dimensional halide perovskite ferroelectric, which restricts their further applications in polarized-sensitive optoelectronic devices. This work mainly focuses on the developing of low-dimensional halide perovskite ferroelectric crystals with excellent photoelectric response. Two-dimensional (2D) halide perovskite ferroelectric (iPA)₂EA₂Pb₃I₁₀ (iPA=isopentammonium, EA=ethylammonium) was synthesized by a solution method through the reaction of stoichiometric lead acetate, isoamine and ethylamine in concentrated aqueous hydroiodic acid. Meanwhile, high quality centimeter-size single crystals of ferroelectric (iPA)₂EA₂Pb₃I₁₀ with the max dimensions up to 15 mm×15 mm×3 mm have been grown via temperature cooling method. On the basis of grown bulk single crystals, further investigations on the crystal structure, optical properties measurements and electrical properties characterization were carried out. The photoelectric response performance and polarization photodetection performance of photoelectric detectors based on the compound ferroelectric single crystal assembly. The result indicated that the unique two-dimensional perovskite structure endows (iPA)₂EA₂Pb₃I₁₀ with strong optical anistropy, narrow bandgap (1.80 eV) and fascinating photoelectric features (on/off ratio=10³). Strikingly, the fabricated photodetectors based on ferroelectric crystal (iPA)₂EA₂Pb₃I₁₀ manifest excellent photoelectric features, including large dichroism ratio (2.3), high responsibility (193 mA•W^–1) and photodetectivity (7.0×10¹¹ Jones), better than most photodetector based on intrinsic optical anisotropy of 2D materials. This work will be of great significance to lay a foundation for the exploring of multifunctional halide perovskites and points out the direction for bulk grown of highly anisotropic halide perovskite ferroelectric crystals and promotes their further applications in highly polarized-sensitive photodetection.

Polarized upconversion luminescence (UCL) of lanthanide (Ln³⁺)-doped micro/nano-crystals has shown great promise in areas such as single-particle tracking and biomedicine. The polarized UCL of Ln³⁺ ions is governed by their localized electronic structures and excited-state dynamics. In this work, β-NaYF₄:Yb³⁺/Er³⁺ microrods with controllable morphologies and sizes were synthesized through a solvothermal method. Based on the customized confocal laser microscopic system, the polarized UCL of a single β-NaYF₄:Yb³⁺/Er³⁺ microrod was systematically investigated. The emission polarization was probed by placing a half-wave plate coupled with a polarizer in front of the detector. As such, the polarized UCL spectra of a single NaYF₄:Yb³⁺/Er³⁺ microrod can be recorded by rotating the half-wave plate under 980-nm excitation. It was observed that the UCL intensity of the microrod exhibited a periodic variation with the emission polarization angle tuning from 0° to 360°, indicating polarization anisotropy of the microrod. Specifically, different crystal-field (CF) transition lines originating from two identical multiplets of Er³⁺ displayed drastically distinct polarization dependence. This results in a higher degree of polarization (DOP) of the UCL intensity for a certain CF transition of Er³⁺ in comparison with that of the integrated UCL intensity of the multiplet. Polar plots of the UCL intensities for the CF transitions of Er³⁺ as a function of polarization angle could provide a qualitative vision of the DOP, with a narrower “neck” indicative of a larger DOP. Moreover, the polar plots of a certain CF transition of Er³⁺ showed a consistent orientation with the corresponding NaYF₄:Yb³⁺/ Er³⁺ microrod and rotated with the rotating of the single microrod. Therefore, by utilizing the polar plots of the highly-polarized CF transition lines of Er³⁺, the spatial orientations of the microrod could be monitored, thus revealing the great potential of NaYF₄:Yb³⁺/Er³⁺ microrods as sensitive anisotropic UCL probes for single-particle tracking.

Metal-organic frameworks (MOFs) are one of the most important crystalline porous materials. In recent years, there has been a strong interest in MOFs based devices with electrochemical activity. MOFs with redox activity are the ideal choice for such devices. 1,1'-Ferrocene dicarboxylic acid (H₂FcDCA) containing ferrocene units is an ideal ligand for constructing MOFs with redox activity. However, due to its uncontrollable coordination mode and torsion angle, there is still a challenge to construct such materials. In this paper, two MOFs were synthesized by the reaction of functional ligand H₂FcDCA with Cd²⁺ under different hydrothermal conditions: [Cd(FcDCA)(bpy)(H₂O)]•(bpy) (1) (bpy=4,4'-bipyridine) and [Cd₂(FcDCA)(bpy)(OX)(H₂O)₂]•2H₂O (2) (H₂OX=oxalic acid). The single crystal structure, fluorescence properties, redox activity of two compounds were characterized and described. In compound 1, Cd center was linked by FcDCA to form a zigzag chain, and it was linked by bpy to form a chain. Both chains linked each other by sharing the Cd center to give birth to a 2D layer with square lattice topology (sql). These layers were packed in AA mode along ac plane. Bpy as guest molecules are filled in the channel of it. By introducing H₂OX in this system under similar condition, compound 2 with 3D framework was obtained. Different to compound 1, two Cd atoms were coordinated by OX ligands to form a binuclear Cd₂ unit. The Cd₂ units were connected by bpy and OX ligands to form a 3D framework with typical 4-connected diamond topology (dia). Each FcDCA ligand linked two Cd₂ units as functional unit and pore partition agent. The whole framework of compound 2 can be simplified as 6-connected sxd topology by treating three kinds of ligands FcDCA, bpy and OX as linkers. Both compounds exhibited strong visible light absorption ability, photocurrent response, and typical redox properties of ferrocene, which may be good candidates for photoelectric catalysts.

Donor-acceptor cyclopropanes as efficient three-carbon synthetic building blocks were widely employed in the synthesis of many natural products and complex drug molecules. However, the ring-opening of aliphatic substituted cyclopropanes, owing to their poor reactivity, usually suffers from the harsh reaction conditions such as strong Lewis acid, large amount of catalyst, high reaction temperature and so on. In this paper, In(NTf₂)₃ was found as a powerful Lewis acid to catalyze the intramolecular nucleophilic ring-opening reaction of donor-acceptor cyclopropane with indole. This reaction could be used to construct the pyrrolo[1,2-a]-indole framework structure in a facile way. This method could be conducted in mild reaction conditions with a broad substrate scope (15 examples), leading to the target products in up to 96% yield. The general procedure is as following: To a dry Schlenk tube in a glove box, was placed In(NTf₂)₃ (0.1 equiv.), 4 Å molecular sieve (50 mg) and a stir bar. The tube was capped and brought out of the glovebox. After connected to argon via a typical Schlenk line system, a solution of 1 (1.0 equiv.) in PhCl (1 mL) was added dropwise until the reaction was completed (monitored by thin-layer chromatography). Et₃N was added to quench the reaction and the reaction mixture was filtered through a thin layer of silica gel and eluted with EtOAc (100 mL). After removal of the volatiles under reduced pressure, the residue was purified by flash chromatography over silica gel to afford the product. When indole substrate contains electron-withdrawing substituents, the reaction temperature needs to be increased to 100 ℃ to obtain the target product.

Nonlinear optical (NLO) crystals can produce tunable lasers due to their second-harmonic generation, sum-frequency generation, difference-frequency generation and optical parametric oscillation. The famous oxide-based NLO materials such as KH₂PO₄ (KDP), β-BaB₂O₄ (BBO) and LiB₃O₅ (LBO) are widely used in ultraviolet-visible (UV-Vis) region. Nevertheless, they are not suitable for the mid- and far-infrared region because of the strong absorption there. Currently, commercially available IR NLO materials are rare, such as chalcogenides AgGaS₂ (AGS), AgGaSe₂ and phosphorus ZnGeP₂, which have the advantages of large NLO coefficient and wide transmission range, but they have drawbacks, like low laser- induced damage threshold (LIDT). Discovering NLO crystals that exhibit simultaneously large NLO and high LIDT is a huge challenge. Here, the introducing electropositive alkali metal ionic K⁺ in chalcopyrite AGS successfully affords a new sulfide KAg₃Ga₈S₁₄ by high temperature solid state reaction. Its crystal structure adopts a three-dimensional honeycomb-like open framework, in which all tetrahedral AgS₄ and GaS₄ units are arranged in a highly oriented manner, thereby producing about a medium phase-matching second harmonic generation (SHG) response of 0.4 times that of the benchmark AGS at the incident laser of 1910 nm. Remarkably, the compound possesses a wide band gap (2.95 eV), thus avoiding two-photon absorption of the incident 1064 nm laser, and exhibits a high LIDT of 4.6 times that of the AGS at the laser of 1064 nm. Moreover, KAg₃Ga₈S₁₄ has a wide transmission range (0.25—25.0 μm) that covers the two important atmospheric windows of 3—5 and 8—12 μm. Furthermore, according to theoretical calculations, the conductive band is mostly composed of Ga-4s and S-3p states, mixing with small amounts of Ga-4p state, whereas the valence band near the Fermi level originates predominately from Ag-4p and S-3p states, mixing with small amounts of Ga-4p state, indicating that tetrahedral GaS₄ and AgS₄ units govern the optical and NLO properties of chalcopyrite KAg₃Ga₈S₁₄.

Indole skeletons are widely used in drug research and development as a “privileged structure”, while spirocyclic scaffold as a common structural unit, usually plays an important role in the bioactivity and physicochemical properties of molecule skeletons. Hence, spiroindoles which incorporate both indole and spirocycle units have great significance and widespread applications in pharmaceutical field, and substantial progress has been made in the field for their construction and modification. C—H Activation via directing group's assistance has emerged as a powerful approach in the field of organic synthesis. To date, various 2- and 3-indolyl-tethered aza-spiro-centres via C—H activation have been successfully achieved. However, due to the inherent reactivity of the pyrrole side of the indole, introduction of spiro-containing systems onto the benzenoid core of indole still remains challenging. Here, by installing an appropriate directing group onto the C(3) position of indole, a mild and efficient method of Rh(III)-catalyzed selectively C(4)—H activation/cyclization of indole with diazo compound was developed. As a result, a series of novel aza-spiro[4,5]indole derivatives were obtained in mild to excellent yields. The protocol showed excellent functional group tolerance. Gram-scale synthesis demonstrated the utility of this protocol, and further modification via click chemistry offered the novel scaffold as a versatile spiro linker. A general procedure for the synthesis of spiroindole derivatives is described as the following: to a solution of N-(pivaloyloxy)-indole- 3-carboxamide (0.1 mmol), [Cp*RhCl₂]₂ (1.6 mg, 2.5 mol%) and NaOAc (1.6 mg, 20 mol%) in CH₃CN (1 mL) was added diazooxindole (0.12 mmol) under air. Then the reaction mixture was stirred at room temperature for 12 h. After completion of the reaction, the resulting mixture was diluted with 25 mL of EtOAc, and filtered through a celite pad. Then the filtrate was concentrated under vacuum to give the crude product, which was purified via silica gel to obtain the corresponding spiroindole product.

11-Chloro-1,1'-di-n-propyl-3,3,3',3'-tetramethyl-10,12-trimethyleneindatricarbocyanine iodide (IR-780) is a near infrared (NIR) photosensitizer for cancer treatment. Under NIR irradiation, IR-780 efficiently generates singlet oxygen or other reactive oxygen species (ROS) in lesion position that ultimately cause cell apoptosis and necrosis. However, biomedical application of IR-780 was limited by its poor water solubility. In this work, we designed a water-soluble IR-780 polymer (Poly-IR) for mitochondria-targeted photodynamic therapy via condensation polymerization. The results of dynamic light scattering (DLS) and transmission electron microscope (TEM) displayed that Poly-IR was self-assembled into nanoparticles in water. And ROS detection experiments demonstrated that Poly-IR quickly and efficiently generated ROS under NIR irradiation in solution and cells. The cellular distribution of the Poly-IR was monitored by confocal laser scanning microscopy (CLSM). Colocalization experiments with mitochondrial stain revealed a high degree of colocalization between Poly-IR and mitochondria, which illustrated that Poly-IR selectively accumulated in mitochondria. Furthermore, we explored the photodamages of Poly-IR to mitochondria through monitoring the change of mitochondrial membrane potential that was stained by JC-1 probe. In the dark, red fluorescence emerged with Poly-IR treated A549 cells. Under NIR irradiation, the red fluorescence was disappeared and green fluorescence was generated in Poly-IR treated cells, which confirmed the photodamage of Poly-IR to mitochondria. The cytotoxicity of Poly-IR was measured by MTT assay (MTT=3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide). The IC₅₀ values of Poly-IR for A549 cells and MCF-7 cells were 9.13 and 10.98 μg/mL respectively in the dark. At the same time, the IC₅₀ values of Poly-IR for A549 cells and MCF-7 cells were 4.57 and 0.22 μg/mL respectively under NIR irradiation. The cytotoxicity of Poly-IR for MCF-7 cells treated with NIR exposure was significantly increased 50 times compared to without irradiation. Live/dead cell staining experiments also verified that Poly-IR had more phototoxicity. Meanwhile, cytotoxicity on tumor cells was also detected by flow cytometry apoptosis assay according to the typical Annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) double staining principle. These results suggested that Poly-IR promoted tumor cells apoptosis under near-IR irradiation, which expanded ideas in mi-tochondria-targeted photodynamic therapy in cancer treatment.

Self-seeding route of living crystallization-driven self-assembly with merits of easily-handling and excellent compatibility with various block copolymers (BCPs) has been considered as one of the most important strategies to generate uniform nanofibers of controlled length and composition. Polyoxometalates with unique structure and shape are usually endowed with attractive electric/magnetic/optical properties. Herein, the influence of phosphotungstic acid (H₃O₄₀PW₁₂) on the self-seeding of oligo(p-phenylenevinylene)-b-poly(2-vinylpyridine) (OPV₅-b-P2VP₄₂, the subscripts represent the number of repeat unit of each block) was systematically examined aiming to get more insight on the effect of polyoxometalates on living crystallization-driven self-assembly. Uniform fiber-like micelles of OPV₅-b-P2VP₄₂ are formed with addition of different molar ratios of phosphotungstic acid to pyridyls of P2VP, α_acid/v, from 0 to 0.20. The percentage of surviving seed micelles decreased exponentially with increasing annealing temperature regardless of α_acid/v from 0 to 0.10, demonstrating the typical characteristics of self-seeding behaviors. The most striking finding of this work is that the resistance of seed micelles toward the dissolution upon annealing is enhanced significantly with the increasing of α_acid/v, leading to the formation of shorter fiber-like micelles with a higher α_acid/v. For example, fiber-like micelles with average length of 1325, 232, 137 and 73 nm were formed with α_acid/v of 0, 0.01, 0.05 and 0.10, respectively, upon the heating of seed micelles of OPV₅-b-P2VP₄₂ with average length of 22 nm at 60 ℃ for 45 min, followed by cooling/aging at 30 ℃ for 24 h. It is likely that the coordination, instead of hydrogen bonding interaction, between phosphotungstic acid and pyridyls, contributes to the enhancement of resistance of seed micelles toward the dissolution. The tight and multi-dentate coordination between phosphotungstic acid and pyridyls of P2VP chains would make the P2VP chain crosslink. The crosslinking would weaken the repulsion within P2VP chains and increase the energy for the dissolution of micelles. This work not only provides more information to deepen our understanding on the influence of nature of corona chains on living crystallization-driven self-assembly (CDSA), especially self-seeding process, but also presents a new platform to generate uniform hybrid polyoxometalate/polymer nanofibers of controlled length.

Magnesium hydride is a promising hydrogen storage material due to its high hydrogen storage capacity, low cost and abundance. The gravimetric and volumetric hydrogen capacities of MgH₂ are about 7.6% and 110 g/L, respectively. However, its sluggish de/re-hydrogenation rates and high operating temperatures ranging between 300~400 ℃ restrict it in practical applications. Catalyzing has been proved to be an effective method to improve its hydrogen storage performance. In this work, V₂O₅ has been chosen as a catalyst for improving the de/re-hydrogenation kinetics of MgH₂. Experimental results show that MgH₂ doping with V₂O₅ (w=5%) has the best hydrogen storage properties among the doping amounts (w) of 2.5% to 10%. Comparing with the pristine MgH₂, the addition of V₂O₅ (w=5%) significantly improves the ab/desorption behaviors of MgH₂. V₂O₅ (w=5%) doped MgH₂ starts releasing hydrogen from 175 ℃ which is 89 ℃ lower than the additive-free as-milled MgH₂. It should be noted that the dehydrogenated V₂O₅ (w=5%) doped MgH₂, is able to absorb 2.1% and 3.8% in the mass fraction of H₂ respectivity, within 30 and 180 min at room temperature and 3 MPa hydrogen pressure. Under the same hydrogen pressure, when the temperature is increased to 300 ℃, the mass fraction of H₂ absorbed by the sample is as high as 6.7% within 1 min. In addition, the catalyzed system shows a good reversibility, after 20 cycles, the hydrogen capacity maintains above 6.0%. Compared with the pure MgH₂, the dehydrogenation apparent activation energy of V₂O₅ catalyzed sample decreased from 108 to 56 kJ•mol^–1. X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) have been employed to investigate its reaction mechanism. It shows that the formation of metallic vanadium and low-oxidation vanadium during ball milling and dehydrogenation process play important roles in improving the de/re-hydrogenation kinetics of MgH₂/Mg system.

The development of modern automobile industry and the increasingly strict environmental protection regulations continuously drive the development of automobile lubricating oil. Friction modifiers play an important role in improving the friction reduction and fuel economy of the engine oil. Organic molybdenum compounds are the most widely used friction modifiers, the metal elements of which will increase the thermal oxidation deposits, and further affect the ternary catalytic converter system. Additionally, the friction reduction performance will decrease with the oxidation of oil. In view of the problems existing in friction modifiers such as harmful elements, ash content and limited active adsorption sites, two bis/triaza crown ethers were designed and synthesized in this paper. Active nitrogen atoms and long-chain alkyl groups were introduced into the structure of crown ether to provide adsorption sites and oil solubility. UMT-tribolab and 3D profilometer were applied to study the friction-reducing and anti-wear properties of the synthesized azacrown ethers under boundary lubrication regime. The adsorption properties of additive molecules on metal surface were analyzed by using steel surface contact angle measurement. And the composition of lubrication film on metal friction pair surface was analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, in order to clarify the lubrication mechanism of the azacrown ethers. The results show that both bis/triaza crown ethers can effectively reduce the friction coefficient and wear rate of base oil. The triaza-crown ether containing pyridine structure unit shows superior tribological properties, which can reduce the friction coefficient and wear rates by up to 8.8% and 42%, respectively. It can be indicated from the mechanism analysis that azacrown ethers can be adsorbed on the surface of steel in varying degrees. Under the shear stress of friction pairs, the compounds adsorbed on the surface further undergo tribochemical reaction to form lubricating protective film. The lubricant layer with ferric oxide and carbon film will prevent the sliding surface from direct contact to improve tribology performance.

Organic light-emitting transistor (OLET) is a kind of revolutionary miniaturized optoelectronic device which integrates the functions of an organic field-effect transistor and an organic light-emitting diode in a single device. This unique integrated architecture of OLET makes it show great potential for studies of fundamental properties of organic materials, applications in fields of novel organic flexible display/lighting technology, organic electrically-pumped lasers as well as on-chip optoelectronic systems. To realize the full potential of these technologies, the development of key materials and optimization of device fabrication techniques including device structures and processing conditions are highly required. Based on the comprehensive study of the development and basic scientific problems in the OLET field, in the past five years, the authors' research group and collaborators carried out systematical exploratory researches with focuses on the development of high mobility emissive organic semiconductors and construction of high performance OLETs with line- and area-feature emission. Up to now, a series of achievements have been obtained. For instance, we developed a series of anthracene- and fluorene-based high mobility emissive organic semiconductors from the origin of molecular design innovation, which overcomes the science bottleneck of impossibility for integrating high charge carrier mobility and strong emission in the same molecule. Furthermore, this molecular design concept also shows a certain feasibility for the development of other small molecular systems and high mobility emissive conjugated polymers. Moreover, with the mind of integrating the advantages of area-emission of vertical OLET and good gate-tunability and stability of planar OLET, we propose a new area-emission planar OLET architecture, which exhibits a large aperture ratio of over 80% due to the arbitrary tunability of device structure. These preliminary experimental researches and results will provide valuable guidelines for future research of OLETs and their related fields.

The development of high-efficiency, green and energy-saving material separation and purification technology is of great significance, and gas separation has a wide range of applications in the fields of industry, energy, medical treatment and technology. Since traditional polymer membranes still face many challenges in achieving high-efficient gas separation, the development of new separation membrane materials has become the current hotspot and difficult issue. As an emerging porous coordination polymer, metal-organic frameworks (MOFs) materials have attracted great attention due to their unique, designable topological structures and tunable functionalities. In order to overcome the problem that bulk or powder MOFs are difficult to be used for gas separation efficiently, it is of great significance and a challenging task to develop MOFs membranes for separation. As a representative MOF material, MOF HKUST-1 is widely used to prepare membranes for gas separation due to its advantages of high stability, economic raw material and hierarchical pore structure. The preparation methods and gas separation performances of the HKUST-1 membrane in the past ten years are summarized, and some viewpoints and the research prospect on this research area are described.

Light-responsive drug delivery systems (DDS) exhibit the advantages of non-invasive, high controllability and spatio-temporal precision. However, DDS triggered by near-infrared (NIR) light are few and inefficient. In this work, we designed a novel NIR-responsive upconversion nanoplatform for drug delivery. In this nanoplatform, core-shell upconversion nanoparticle (UCNP) NaYF₄:Yb,Er@NaYF₄ was coated by mesoporous silica, and then successively coupled with NIR dye cypate, amantadine (AD) and β-cyclodextrin (β-CD) to block the pores and entrap the drugs. The cypate molecules with the feature of auto-sensitized photooxidation under 808 nm irradiation were, for the first time, employed as light-responsive moieties in DDS. The obtained nanoplatform was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption/desorption, dynamic light scattering (DLS) and zeta potential analysis. Mechanism of photocleavage of cypate by singlet oxygen (¹O₂) was also investigated by electron spin resonance (ESR) measurement. The nanoplatform loaded with antibiotic ofloxacin (OFL) showed a low drug leakage (6.9%) in the dark condition and a rapid release (50.9%) upon 808 nm irradiation with a relatively low power density of 0.5 W•cm^-2 for 40 min. Moreover, on-demand release of OFL can be achieved by adjusting the irradiation time (0~40 min). In vitro antibacterial experiments showed that the nanoplatform had a much better antibacterial effect against Staphylococcus aureus after 808 nm irradiation as compared with the group without irradiation. These results further verified the excellent NIR-responsive performance for the designed nanoplatform. In addition, the nanoplatform exhibited strong and stable upconversion luminescence (UCL) under 980 nm excitation, which can be applied for DDS tracing and bioimaging. The cytocompatibility of the nanoplatform was evaluated by methyl thiazolyl tetrazolium (MTT) assay, showing that the nanoplatform had no cytotoxic effect on human embryonic liver cell line (LO2) and exhibited great potentials in versatile bioapplications. Our work may open up a new avenue for the exploration of multi-functional NIR-responsive DDS.

Organogermanium compounds have been gaining more attention for their unique properties compared to silicon or tin. Among which, tetraalkylgermanes, especially alkyltrimethylgermanes that have been confirmed to be active in photoredox radical reactions, are still lack of efficient and simple synthesis methods. Herein, we report a new protocol using commercially available trimethylgermanium bromide and alkyl bromides as substrates and cheap copper(II) sulfate as catalyst. When using magnesium powder as the reductant, a series of alkyltrimethylgermanes could be generated in moderate to good yield. Mechanism studies suggested a probable in-situ Grignard reaction pathway. The copper salt added could significantly accelerate the reaction between organohalogermanes and Grignard reagents so that the formation of Ge-Ge byproduct from the reduction of organohalogermanes by magnesium could be inhibited. Compared to the traditional method using Grignard reagent and organohalogermanes, this new protocol has better compatibility towards functional groups like esters and amides. The protocol could also be expanded to the synthesis of various tetraalkylgermanes or germacycloalkanes using dichlorodimethylgermane and alkyl bromides. General procedure for the synthesis of alkyltrimethylgermane is: To an oven-dried 25 mL screw-capped tube equipped with a stir bar was charge with 48 mg (2 mmol) magnesium powder and 8.0 mg (0.05 mmol) CuSO₄. The tube was vacuumed and backfilled with argon for three cycles. 6 mL freshly distilled THF was added followed by the addition of 128 μL (1 mmol) trimethylgermanium bromide and 1.5 mmol alkyl bromide. The mixture was sealed with a Teflon stopper, warmed to 60 ℃ and stirred for 10 h. After cooled to room temperature, the resulted mixture was quenched with saturated NH₄Cl solution, extracted with diethyl ether and washed with brine. Combined organic layer was dried over Na₂SO₄ and concentrated under reduced pressure. The residue was purified by flash column chromatography on silica gel or distillation to give the desired alkyltrimethylgermane.

Icosahedral carboranes are carbon-boron molecular clusters, sharing many features with benzene such as aromaticity, high thermal and chemical stability. On the other hand, carboranes have their own unique characteristics like spherical geometry and three-dimensional electronic delocalization. These properties render carboranes unique building blocks for various applications ranging from versatile ligands to functional materials to medicine. In this regard, functionalization of carboranes, particularly regioselective functionalization of cage B-vertexes has recently received much attention. Based on our recently developed Pd-catalyzed iodine-migration on o-carborane cage, a Pd-catalyzed regioselective difunctionalization of 3-iodo-o-carborane in a one-pot manner has been achieved to afford a series of 3-alkenyl-4-Nu-o-carboranes (Nu=arylamino, alkoxyl, alkyl and arylthio) in 47%~99% yields. This protocol combines the sequential activation of cage B(3)—I and B(4)—H bonds by Pd migration, as well as further Pd-catalyzed transformation of B(4)—I bond, leading to the construction of B—C and B—Heteroatom bonds. A general procedure for the synthesis of 3-alkenyl-4-Nu-o-carboranes is described as follows: to a tetrahydrofuran (THF) solution (1 mL) of NuH (1.0 mmol) was added base (1.0 mmol) at 0 ℃ under an atmosphere of dry nitrogen. The reaction mixture was stirred for another 10 min to obtain the NuM solution (NuM=ArNHMgBr, base=EtMgBr; NuM=Ar₂NLi, base=ⁿBuLi). Another oven-dried Schlenk flask equipped with a stir bar was charged with 3-iodo-o-carborane (1, 27 mg, 0.1 mmol), Pd(PPh₃)₄ (12 mg, 0.01 mmol), diphenylacetylene (89 mg, 0.5 mmol) and dry toluene (1 mL) under an atmosphere of dry nitrogen. The flask was closed, and stirred at 80 ℃ for 72 h. Then, the resulting solution was cooled to 0 ℃, to which was slowly added NuM (0.15 mmol) (NuM=ArNHMgBr, Ar₂NLi, ^tBuONa and RSNa). The reaction mixture was warmed to room temperature, and stirred at 80 ℃ for 24 h. After quenching with water (1 mL) and extraction with ethyl acetate (5 mL×3), the organic portions were combined and concentrated to dryness in vacuo. The residue was subjected to flash column chromatography on silica gel (300~400 mesh) using n-hexane as eluent to give the product.

Dimethoxymethane (DMM) has wide application in resin, solvent, and fuel fields as a fundamental organic chemical. The traditional route to synthesize DMM using methanol and formaldehyde as reactants via condensation reaction has poor efficiency. Methyl nitrite (MN), which is obtained by the reaction of methanol, oxygen and nitrite monoxide without catalysts, could be used as raw material to produce DMM through catalytic decomposition. The current work systematically investigated the catalytic activity and selectivity to DMM of several molecular sieves in MN decomposition reaction. The results show that the activity trend is NaY (97%)=HY (97%)>HZSM-5 (90%)>Hβ (89%)>NaZSM-5 (18%)>Naβ (6%), and the DMM selectivity trend is NaY (53%)>HY (12%)=Naβ (12%)>NaZSM-5 (7%)>Hβ (4%)>HZSM-5 (3%). X-ray diffraction (XRD), Brunner-Emmet-Teller measurements (BET), scanning electron microscope (SEM) and Pyridine-IR (Py-IR) experiments have been employed to reveal the structure-activity relationship of these molecular sieves. Combining the temperature-programmed desorption of CO₂ experiments (CO₂-TPD) data with the evaluation results of the catalytic performance of the zeolite catalyst, the basic sites of the zeolite have no direct connection to the catalytic MN decomposition process. Meanwhile, the calcination temperature experiment of NH₄-zeolite and the catalytic performance test experiment of NaY-tetraethoxysilane (TEOS) further proved that the acid site played an essential role in promoting the decomposition of MN, and the results show that the Lewis acidity sites of Na⁺ and low-coordinated Al metal center are key factors to catalyze MN to DMM high selectively. We have proposed the MN decomposition mechanism. In the process of MN decomposition, there are both proton generation and proton consumption processes. Intermediates in the decomposition process are easily protonated by Brönsted acid sites to form by-products. The Lewis acid site of zeolite is generally a low-coordinated Al metal center, which can effectively adsorb and stabilize the oxygen-containing intermediates generated during the decomposition of MN, especially the methoxy and formaldehyde intermediates involved in the production of DMM, which is very beneficial to

the decomposition of MN to DMM. We believe that the research in this paper can provide a new and efficient synthetic route for DMM.

Near-infrared (NIR) spectroscopy technique plays an important role in night-vision surveillance, food analysis, bioimaging and agriculture fields, and the development of compact and efficient NIR light source is a precondition for their massive commercial applications. Phosphor-converted light emitting diodes (pc-LED) have the advantages of compactness, low-cost, and long operating lifetime, thus have attracted considerable attentions in recent years. The key point is to exploit high performance NIR phosphors which can be excited efficiently by blue diode chips. A number of Cr³⁺-activated phosphors have been investigated aiming at NIR pc-LED applications. Nevertheless, most of the NIR phosphors show relatively short peak wavelength and narrow full width at half maximum (FWHM), resulting in spectral deficiency in the range 900~1100 nm. The phosphors with ultrabroad bandwidth are more desirable for spectroscopic applications. In this work, a novel broadband NIR light emitting phosphor In₂BP₃O₁₂:Cr³⁺ is synthesized by solid state reaction method. The structure, concentration and temperature dependent luminescence properties, electron-phonon coupling as well as the NIR LED performances and applications of the In₂BP₃O₁₂:Cr³⁺ have been investigated. Upon 480 nm excitation, the In₂BP₃O₁₂:Cr³⁺ phosphor shows a broad emission band peaked at 950 nm and covering 750~1350 nm (bandwidth of ~210 nm), which is owing to the ⁴T₂ → ⁴A₂ transition of Cr³⁺ ions. It is found that the emission intensity of the phosphor at 373 K keep 40% of that at room temperature. A NIR pc-LED is packaged by combining the In₂BP₃O₁₂:Cr³⁺ phosphor and a commercial blue InGaN chip, which generates broad NIR light emissions with an output power of ~5 mW at 60 mA drive current. When this NIR pc-LED is used to illuminate the human palm, the blood vessels in the palm are clearly imaged by a NIR charge coupled device (CCD) camera. These results suggest that the In₂BP₃O₁₂:Cr³⁺ is a promising phosphor for fabricating NIR pc-LEDs, which are potential for non-destructive analysis in the fields of biology and medicine.

Inorganic-organic hybrid perovskite-like materials have attracted widespread attention due to their tunable structure and unique optoelectronic properties. By simply changing the size of the organic cations, the structural dimensions of inorganic-organic hybrid perovskite-like materials can be adjusted. However, most of the research were carried out by selecting different types of organic cationic ligands, which is not conducive to the study of structure-activity relationship. Herein, by choosing different alkylation solvents, the control of dimensions and performance of inorganic-organic hybrid perovskite-like materials was realized when the reaction precursors were consistent. Two new inorganic-organic hybrid materials were synthesized in situ by a simple one-step hydrothermal method, that were two-dimensional (2D) [(Me₃)ODA(Me₃)]₃Pb₅I₁₆ (1) and one-dimensional (1D) [H(Et₂)ODA(Et₂)H]Pb₂I₆•H₂O (2) (ODA=4,4-diaminodiphenyl ether). Compound 1 is consisted by 2D inorganic perovskite-like network layers and [(Me₃)ODA(Me₃)]²⁺ organic dications, while compound 2 is composed by 1D inorganic perovskite-like chains, [H(Et₂)ODA(Et₂)H]²⁺ and water molecules. Compound 1 and 2 showed different structures and exhibited different stability, optoelectronics, and humidity sensitivity. The methylated compound 1 showed an obvious photoelectric response under visible light illumination (400~790 nm), and the ethylated compound 2 exhibited no photoelectric response. Compound 2 presented better stability to water and organic solvents compared to compound 1, which can be as an ideal candidate in fabricating smart and efficient sensors for humidity detection. The chemiresistive humidity sensor based on compound 2 showed an investigated response in the wide relative humidity (RH) (10%~100%) at room temperature. The sensor showed a high sensitivity in the range of 10%~100% RH and good cycle stability. It displayed 10⁵-fold increase toward 100% RH. The sensing mechanism of the compound 2 based humidity sensor was further studied by direct current (DC) instantaneous reverse polarity method, which proved that the moisture responsiveness was dominated by electronic conduction, and the free transmission of electrons dominated the change of material's conductivity.

Selective hydrogenation of quinoline toward 1,2,3,4-tetrahydroquinoline shows great application potential in the production of medicine, pesticides and fine chemicals. However, the hydrogenation of quinoline is usually carried out under harsh reaction conditions such as high temperature and high pressure, and thus, it is a great challenge to achieve selective hydrogenation of quinoline under mild conditions. In this work, we construct platinum nanoparticles (Pt NPs) sandwiched in an inner core and an outer shell composed of a metal-organic framework synthesized by zirconium chloride and 2,2'-bipyridine-5,5'-dicarboxylic acid (known as UiO-67N). Different sandwich structures with shell thickness of 11, 28 and 42 nm are precisely prepared. The obtained catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma emission spectrometer (ICP-OES), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption and desorption. Impressively, the selective hydrogenation of quinoline over Pt NPs is significantly enhanced by using UiO-67N as support in respect with UiO-67. Moreover, UiO-67N@Pt@UiO-67N exhibits the selective hydrogenation of quinoline with high conversion rate (>99%) and high selectivity of 1,2,3,4-tetrahydroisoquinoline (>99%) at room temperature. The shell thickness has significant influence on the catalytic activity of Pt NPs, and with increasing the shell thickness from 11 to 42 nm, the conversion rate decreases from 99% to 53.5% under the identical conditions, while the selectivity of 1,2,3,4-tetrahydroisoquinoline is well kept. When other derivatives of quinoline are used as substrates, the excellent activity and selectivity are also achieved over sandwich catalysts. Besides, the UiO-67N@Pt@UiO-67N catalyst could be used at least 5 times without obvious deactivation, but the significant deactivation happens over supported UiO-67N@Pt catalyst. XPS and FTIR measurements show that the excellent catalytic performance mainly originates from the electron transfer between UiO-67N and Pt NPs, and the strong interfacial interaction between UiO-67N and quinoline.

Jarosite is a common iron-containing mineral. Researchers have studied its application for removing aqueous pollutants, such as Cr(VI) and As(V). Surprisingly, it shows adsorption for arsenates, but little for the structurally similar phosphate ions. In this study, we prepare cerium doped jarosite and prove the successful doping of cerium at the K⁺ site by X-ray diffraction (XRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Phosphorus adsorption experiments show that the small amount of cerium doping (Ce content: 8.75×10^-5 mol/g) significantly improves the phosphate adsorption of jarosite, from 1.69 mg/g to 29.33 mg/g (pH=7, 24 h). The phosphate adsorption of Ce-doped jarosite exhibits good pH stability (from pH=3 to pH=11) and excellent selectivity, which is capable of maintaining more than 91% of its adsorption capacity in the presence of various competing anions, such as HCO₃^-, CO₃^2-, humic acid anion, SO₄^2-, NO₃^-, and SiO₃^2-. Further analysis reveals that the adsorption process obeys the pseudo-second order kinetic model while the adsorption isotherms represent the Freundlich isotherm. The analysis indicates that the adsorption may be a chemical adsorption process that is easy to proceed. To explore the mechanism of adsorption enhancement, we first characterize the Zeta-potential of the pure jarosite and Ce-doped jarosite. The result indicates similarity of the surface potential between the two samples, which rules out the electrostatic adsorption mechanism. Next, based on the result of anion exchange chromatography, we confirm that the cerium doping greatly increases the exchange between the sulfate groups in jarosite and the phosphate groups in solution, from 2.85 mg/g to 24.90 mg/g. Finally, XPS high-resolution spectroscopy reveals that the chemical environment of Ce changes after the phosphate adsorption, likely indicating the formation of Ce—O—P chemical bonds to achieve specific chemisorption. These results may provide insights for the modification and application of jarosite, as a new adsorbent material for treating phosphorus rich wastewater.

Ion-molecule reaction is one of the most fundamental processes in the Earth and other planets' atmosphere, interstellar space and combustion. Basic physical chemistry processes such as charge transfer and energy transfer are frequently involved in the low-energy (several eV) ion-molecule reactions. In recent decades, the experimental study of low-energy ion-molecule reaction dynamics is highly benefit from the introduction of velocity map imaging method, but some dynamics mechanisms remain to be validated. Based on our own cross-beam ion velocity imaging apparatus, we have recently realized an efficient measurement of three-dimensional ion velocity images for multiple products by using a delay line anode detector, indicating the much higher efficiency. Upon above technique improvement, more details about the charge transfer reactions between Ar⁺ and small molecules have been revealed. Here we summarize and emphasize the dynamics differences among this process, photoionization and Marcus theoretical model. Meanwhile, we obtained stereodynamic characteristics of the dissociative charge transfer reactions of Ar⁺ with O₂ and CO. Moreover, comparison between the charge transfer only and dissociative charge transfer reaction indicates that the latter is not a subsequent even of the former, namely, these two processes may have completely different pathways. We also present a perspective about the experimental techniques those are potentially applicable and some interesting topics in the future.

Compared with traditional fluorescent biological imaging, the second near-infrared (NIR-II) fluorescent biological imaging technology has the advantages of high spatial resolution, excellent signal-to-background ratio, large imaging depth, low autofluorescence, and less biological damage, which is widely used in disease diagnosis, non-invasive treatment and other fields. Among diverse NIR-II fluorescent nanomaterials, NIR-II emitting lanthanide based nanoprobes (NIR-II Ln-NPs) have received extensive attention owing to their exceptional merits like good photochemical-stability, narrow emission band, tunable emission colors and long-lived lifetime. In this review, we provide a comprehensive survey of the latest advances in developing lanthanide-based NIR-II emitting nanoprobes as deep-tissue-penetration fluorescent diagnostic and therapeutic agents, which cover from their design strategy, controllable synthesis, surface functionalization, optical properties as well as their biomedical applications, with an emphasis on heterogeneous and homogeneous in-vitro biodetection of tumor markers and multimodal bioimaging of various tumor tissues. Some future prospects and challenges in this rapidly growing field are finally summarized.

During the past 170 years, organic small molecular fluorescent dyes had been widely applied in fluorescence labeling, fluorescence probes and bioimaging. And their structures and performances continually evolved with development of synthetic method and application. However, the emerging super-resolution imaging put forward higher requirements at brightness, stability and switching performance of organic small molecular fluorescent dyes, which also offers new opportunity for developing novel dyes at the same time. So, chemists presently pay more attentions on brightness and photostability. Twisted intramolecular charge transfer (TICT), the major nonradiative decay channel in organic small molecular fluorescent dyes, seriously decrease brightness and photostability. Therefore, inhibiting TICT has became the crucial strategy to develop organic small molecular fluorescent dyes towards super-resolution imaging. This review will firstly demonstrate mechanism and development of TICT and emphatically introduce the progress in improving organic small molecular fluorescent dyes based on inhibiting TICT.

Drugs can be roughly divided into small molecule drugs (naturally extracted or chemically synthesized) and macromolecular drugs (biologics) according to molecular weight. Although small molecule drugs are still the mainstay of drug research and development (R&D) at present, the slow update rate of small molecule libraries has retained their R&D speed, thus highlighting the increasingly important position of macromolecular drugs in the future pharmaceutical market. In addition to macromolecular biologics, chemically synthesized macromolecular drugs prepared by combining small molecule drugs with natural or synthetic macromolecules have received more and more attention in recent years. Due to the unique characteristic of abundant backbone architectures and spatial framework of macromolecules, including their distinctive backbone effect and multivalent effect, as well as aggregation effect and targeting effect produced by molecular assembly, many new possibilities will be introduced into the design of medicinal chemistry. In view of this, this review will briefly introduce macromolecular effects in medicinal chemistry design, with an emphasis on new performances and functions introduced in drug design based on the backbone effects, multivalent effects, aggregation effects, and targeting effects of synthetic macromolecules. We hope this review could promote the development of chemically synthesized macromolecular drugs and provide new horizons for medicinal chemistry design.

Organic solar cells (OSCs) are among the most promising photovoltaic technologies to solve energy and environmental problems. To achieve highly efficient OSCs, controlling over electrode interfacial layers is greatly important for improving charge transportation and collection. Here, ternary metal oxide semiconductor films of Mg-doped NiO (NiMgO) have been prepared via a sol-gel method, and further optimized by several post-treatment strategies. The structures, properties and energy levels of different NiMgO films have been investigated to explore the influence of various post-treatment strategies. Incorporating the ternary NiMgO films as a novel type of hole transport layers (HTLs), non-fullerene OSCs have been fabricated based on a promising bulk-heterojunction of PM6:M36. Their photovoltaic performances and mechanisms of device physics are also investigated. When the sol-gel derived NiMgO film without post-treatment is used as an HTL, the OSCs show a relatively low power conversion efficiency (PCE) of 5.90%. By contrast, after simple ultraviolet-ozone (UVO) post-treatment on the NiMgO HTL, the resulted OSCs exhibit greatly enhanced photovoltaic performances, with an increased open-circuit voltage (V_OC) of 0.87 V and an improved PCE of 12.67%. More importantly, a new dual post-treatment combining surface rinse with UVO treatment has been demonstrated to further optimize NiMgO HTLs and improve device performances. The rinse process can remove excess impurities and flatten the surface of NiMgO films as well as increase the transmittance, while the UVO treatment process is beneficial for reducing surface defects of the ternary oxide films. Benefit-ing from such an efficient dual post-treatment on NiMgO HTLs, the OSCs afford a high PCE of 13.17% with a retained V_OC of 0.87 V, an increased short-circuit current density of 23.48 mA•cm^–2, and an improved fill factor of 64.29%. These results provide an effective way for surface post-treatment and property optimization of semiconducting metal oxide films, and contribute to the development of high-performance optoelectronic devices.

HMOR zeolites has an excellent performance similar to enzyme catalysis in the carbonylation of dimethyl ether (DME). The distribution of framework aluminum and the identification of the active site of the reaction are the key issues in the study of the reaction mechanism. The early work was based on theoretical calculation to study the active site of DME carbonylation, but lacked direct experimental evidence. In this work, a series of HMOR catalysts were prepared by calcination of NH₄MOR at various temperatures. The stability and location of framework aluminum were studied by a variety of spectroscopic characterization methods. Moreover, the evidence of reaction mechanism was obtained by the carbonylation reaction activity of dimethyl ether related to the acidity of MOR zeolite and aluminum distribution. Firstly, it was found that the crystallinity and morphology of MOR zeolites did not change significantly after calcination at different temperatures by XRD (X-Ray diffraction) and SEM (Scanning electron microscope). However, it was found by ²⁹Si, ²⁷Al and ¹H Magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) that the local environment of HMORs was dealuminated, which resulted in obvious defect hydroxyl groups and the decrease of Brönsted acid sites (BASs) content. In addition, the calcination temperature has a great influence on the stability of framework Al of HMORs. Increase of calcination temperature will accelerate the occurrence of dealumination. Quantitative ¹H MAS NMR combined with Fourier transform infrared spectra (FTIR) provided the distribution of BASs content in different channels of HMOR zeolites. By using 2D ²⁷Al multiple quantum (MQ) MAS NMR method combined with the representative slices parallel to the F2 dimension of MQMAS NMR spectra at selected F1 chemical shift to distinguish the framework Al sites, it was found that when the temperature was lower than 600 ℃, framework Al atoms located in the different T-sites had the similar dealumination rate. But when the calcination temperature was increased to 600 ℃, the removal rate of Al atom at T3 site was accelerated. Furthermore, the relationship between the carbonylation performance of dimethyl ether and the distribution of Brønsted acid and aluminum was studied, and the definitive spectral evidence of the carbonylation activity center was obtained, that is, the Al site at T3-O33 was the active site of the carbonylation reaction.

Due to their low density in atmosphere, theoretical simulations of the nucleation of gas-phase molecules are computationally very expensive. In this study, neural network potential (NNP) is combined with enhanced sampling techniques to effectively investigate the nucleation of water clusters in gas phase. The neural network potential is trained based on water-cluster energies and forces from density functional theory (DFT). The problem that the binding between water molecules is too weak in the previous empirical force field model has been solved in the NNP. This NNP potential is then applied to Monte Carlo simulations in grand canonical ensemble with enhanced sampling methods such as aggregation-volume-bias Monte Carlo (AVBMC) and transition-matrix Monte Carlo (TMMC) to realize a random walk among different cluster sizes. Probability distribution of water cluster sizes and the corresponding Gibbs free energies can then be obtained. Subsequently, the evaporation rates of water clusters can be calculated via umbrella sampling Monte Carlo simulations in canonical ensemble combined with variational transition state theory (VTST). We observe a big change of free energy and evaporation rate from tetramer to pentamer. A statistical analysis of the number of hydrogen bonds suggests that more hydrogen bonds are required to be broken in the evaporation reaction of tetramer compared to that of trimer and pentamer. Structure analysis indicates that, although the ground state of the pentamer has a two-dimensional ring structure, three-dimensional hydrogen bond network begins to form in pentamer at finite temperature. Therefore, it is a two-dimensional to three-dimensional transition from tetramer to pentamer. The fact that the most probable configuration of pentamer is different from the lowest energy configuration demonstrates the importance of molecular simulations. Simply finding the lowest energy configuration via global geometry optimization and then calculating the free energy within a harmonic approximation of vibrations are not a universal protocol for cluster systems. Methods used in this study are expected to be applicable for more complicated multicomponent systems, which opens an avenue for the research of particulate matter formation in atmosphere.

AgInSe₂ (AISe) quantum dots (QDs) exhibit large Stokes shift, composition-dependent photoluminescence (PL), long PL lifetimes and low toxicity, making them exceptional candidates in a wide variety of bioapplications. However, it remains notoriously challenging to precisely control both the morphology and composition to optimize the PL performance of AISe QDs via conventional direct synthesis. Herein, we develop the unique low-temperature (75 ℃) template-based synthesis of highly efficient near-infrared (NIR) luminescent AISe QDs from In₂Se₃ QDs via a facile cation exchange method. The brief synthesis AISe QDs process was as follows: firstly, indium acetate was dissolved in non-coordinating solvent octadecene. Selenium precursor was injected into the above mixture at 200 ℃, followed by nucleation and growth within a few minutes. Thereafter, In₂Se₃ template QDs can be acquired, and the dispersity of the as-prepared QDs can be improved by adding zinc. Secondly, silver acetate was added to the In₂Se₃:Zn²⁺ QDs solution with stirring for 15 min at 75 ℃. Finally, AgInSe₂:Zn²⁺ QDs were obtained. The proposed method enables the as-prepared AISe QDs to inherit the size and morphology of the template QDs. The extent of cation exchange can be controlled by rationally manipulating the Ag/In precursor molar ratio. We successfully regulate the stoichiometry of Ag/In ratio from 0.26 to 1.09. As a result, highly efficient luminescence of AISe QDs with the maximum absolute quantum yield of 42.5% has been achieved, which is higher than that of the AISe counterparts synthesized via the direct method. Moreover, we survey the luminescence mechanism of AISe QDs by means of the steady-state, transient and temperature-dependent spectroscopies. AISe nanoprobes were prepared by coating the hydrophobic QDs with a layer of 1,2-distearoyl-sn-glycero-3-phosphoethanol-amine-N-[biotin(polyethyleneglycol)- 2000] (DSPE-PEG-Biotin) phospholipids through hydrophobic interaction. By virtue of the excellent biocompatibility and intense NIR emission, we exemplify the application of AISe nanoprobes in the targeted cancer cell imaging, thus revealing their promising bioapplications including disease diagnosis and imaging-guided surgery.

Infrared nonlinear (IR NLO) optical crystals have an essential position in military and civilian fields because of their ability to convert lasers from near infrared (NIR) to mid/far infrared (MIR/FIR). In this work, two alkali-metal chalcogenides, Rb₂MGe₃S₈ [M=Zn (1), Cd (2)], were successfully synthesized by high-temperature solid-state reactions. Both compounds feature a two-dimensional layered structure and have a large optical band-gap, the experimental band-gap of 1 and 2 are 3.24 eV and 3.16 eV, respectively. Compound 1 belongs to the centrosymmetric group P-1, while 2 belongs to the non-centrosymmetric space group P2(1)2(1)2(1) and exhibits obvious NLO effect, which is comparable to that of KH₂PO₄ (KDP) (@1064 nm) at the particle size of 50~75 μm. Particle-size dependent NLO response measurements indicated that 2 is non-phase-matchable. Compound 2 exhibits a high laser-induced damage threshold of 16.6×AGS at 1064 nm. Through the analysis of the crystal structures of these two compounds, the reason why their formulas have the same stoichiometric ratio but symmetries are different is the structure change of basic building unit [MGe₃S₈]^2– in 1 and 2. All M atoms in both compounds are coordinated by four S atoms to form MS₄ tetrahedra. In each [CdGe₃S₈]^2– unit of 2, three S atoms bonded to the Cd atom are also bonded to all Ge atoms in that unit, that is to say, each CdS₄ tetrahedron is connected to the other three GeS₄ tetrahedra by sharing S vertices. Unlike the coordination manner in the [CdGe₃S₈]^2– unit of 2, there are only two S atoms bonded to both Zn and Ge atoms in [ZnGe₃S₈]^2– unit of 1. This structure change of [MGe₃S₈]^2– unit eventually led to the non-centrosymmetric transformation. What’s more, to get insight into the origin of NLO effect of 2, theoretical calculations of electronic band structure and NLO susceptibility were performed based on density functional theory.

¹³⁷Cs has the strong radioactivity and long half-life. In the event of leaking, it will pose a great danger to human health and the environment. The effective removal of ¹³⁷Cs⁺ from complex radioactive waste streams remains a challenge due to its high solubility, easy migration and the influence of interfering ions in the waste streams. In this study, two new three-dimensional microporous lanthanide metal-organic framework compounds (Me₂NH₂)_0.5(H₃O)_0.25Na_0.25Ln(OH)(stp)• 0.25H₂O (FJSM-LnMOF; Ln=Eu, Tb; H₃stp=2-sulfonic acid terephthalic acid) are synthesized by the solvothermal method, which have the good water stability and acid-base resistance. The adsorption performance of FJSM-LnMOFs for Cs⁺ are tested with solid-liquid ratio of 1∶1 under stirring at room temperature for 8 h. The adsorption kinetics of FJSM-EuMOF for Cs⁺ are tested with low-concentration Cs⁺ solution. FJSM-LnMOFs show fast kinetics and high adsorption capacities of Cs⁺ ions (the maximum adsorption capacities q_m^Cs of FJSM-EuMOF and FJSM-TbMOF are 229.25 and 211.28 mg/g, respectively). They have good selectivity for Cs⁺ ions (K_d^Cs value up to 2.18×10³ mL/g). Even in the presence of interfering Na⁺, K⁺, Mg²⁺, Ca²⁺ ions, they still show selective adsorption performance for Cs⁺ ions. Impressively, we successfully obtain the single crystal structure of Cs⁺-absorbed product by soaking FJSM-EuMOF crystals in 20,000 mg/L Cs⁺ solution, which confirms that the adsorption mechanism of Cs⁺ ions is ion exchange by the means of single crystal structure analysis combined with various characterization methods including X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), energy dispersion spectrum (EDS), elemental analysis (EA). The results indicate that the highly efficient Cs⁺ adsorption of FJSM-LnMOF mainly originates from the strong interactions between COO^– and $\text{SO}_{3}^{}$ functional groups from organic ligands and Cs⁺ ions, and the presence of easily exchangeable [Me₂NH₂]⁺ cations and [H₃O]⁺ located in the channels. This work indicates the potential application of lanthanide metal-organic frameworks in the remediation of radioactive cesium.

Nowadays, nanotechnology has been widely used in many fields such as medicine, catalysis, food and agriculture. With the rapid growth of the production amounts of anthropogenic nanoparticles (NPs), they will inevitably enter the natural environment after use and disposal. As a result, their potential risks to the environment and human health have caused significant concerns. Tracing the sources and environmental transformation of NPs is the prerequisite for the accurate evaluation of toxicity effects and pollution control. The recent progress in the area of source tracing technologies for NPs, including multi- chemical fingerprinting technology, non-traditional stable isotope tracing technology, isotope labeling technology, and DNA labeling technology is outlined. Furthermore, the future development of tracing technologies of NPs is also prospected.

Sepsis is a life-threatening disease caused by a dysregulated host response to infection. Its pathogenesis is complex, and despite some advances in recent years, the mortality rate is still 25% to 30%. Sepsis treatment based on nanomaterials can be constructed for the purpose of eliminating infection sources and eliminating inflammation, which is an effective tool to fight sepsis. In this paper, the latest progress in the treatment of sepsis based on nanomaterials is reviewed. From the perspective of its pathogenesis, the nanomaterials for the treatment of sepsis based on antibacterial, scavenging of reactive oxygen species, and scavenging of dangerous molecules is reviewed in detail. And the problems and challenges facing the potential treatment in the future are discussed. The new challenges facing the treatment of sepsis using nanomaterials are also discussed in the hope to provide new ideas and solutions for sepsis treatment.

The sensitive and specific detection of key molecules and biological micro/nanoparticles in complex biological systems is of great significance for understanding biological processes at multiple levels and scales, uncovering the mechanisms of disease onset and development, and exploring novel biomarkers. Microfluidic biosensors with advantages of microfluidics and biosensing have made significant progress in the precise detection of biological samples with small volumes. Recent years, thermomicrofluidic biosensing that combines thermophoretic migration in a temperature gradient and homogenous signal amplification strategies has realized rapid, sensitive, in situ detection of biomolecules and biological micro/ nanoparticles in complex biological systems. Different thermomicrofluidic biosensing strategies, including microscale thermophoresis (MST), thermophoresis-convection coupling, thermophoresis-diffusiophoresis coupling, and thermophoresis-electrophoresis coupling were presented. The fundamentals, features, and applications of these strategies in detecting biomolecules (protein, nucleic acids, etc.) and biological micro/nanoparticles (extracellular vesicles, viral particles, cells, etc.) were summarized. The challenge and future directions for the application of thermomicrofluidic sensing in biomedical detection were discussed.