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Exosomes have attracted increasing attention in the early diagnosis of tumors due to their participation in physiological and pathological processes. Herein, a novel label-free aptasensor based on the CuNi bimetallic metal–organic frameworks (MOFs) that was decorated with MXene quantum dots (MQDs) was fabricated for exosome sensing. The CuNi-MOFs functionalized with dual specific aptamers, CD63 and MUC1, served as an ideal nanocarrier and catalyst for efficient recognition and capture of target exosomes. Meanwhile, the MQDs with excellent electron transfer can promote the electrochemical catalytic performance of this designed aptasensor. It is noteworthy that the large specific surface area of 2D bimetallic CuNi-MOF nanosheets can offer plenty of exposed active sites and facilitate the connection of aptamers, thereby achieving the goal of specific capture and detection of exosomes. The as-prepared electrochemical aptasensor possesses a wide linear range of 1 × 101 to 1 × 106 particles μL−1 for exosome detection and a low detection limit of 5 particles μL−1 (S/N = 3). Besides, the as-prepared aptasensor exhibited satisfactory electrochemical stability for the detection of exosomes, which can provide new ideas for clinical detection and tumor diagnosis. [ABSTRACT FROM AUTHOR]

Ga-modified CuFeO2 used as an efficient catalyst for CO2 hydrogenation to heavy olefins (C =5+) can achieve a high heavy olefin selectivity of 53.5%, which lies at a high level among reported catalysts, at a single pass CO2 conversion of 41.5%. It also displays an excellent long-term stability over 100 h, exhibiting its promising potential for industrial applications. [ABSTRACT FROM AUTHOR]

Three MnII complexes, named Mn2(HATNA)2(CH3OH)4 (1), {[Mn3(ATNA)2(DMF)2(H2O)2]·0.5DMF·0.5H2O}n (2, DMF = N,N-dimethylformamide), and {[Mn6(ATNA)4(H2O)10]·8DMSO·2.5H2O}n (3, DMSO = dimethyl sulphoxide), were successfully synthesized by the reaction of the ligand azotetrazole-3-hydroxy-2-naphthoic acid (H3ATNA) and Mn(CH3COO)2 in CH3OH, DMF, and DMSO, respectively. A binuclear structure was found for complex 1, with the two Mn(II) ions doubly bridged through N–N linkers from the two tetrazole rings. Both 2 and 3 displayed one-dimensional structures. Magnetic studies show that antiferromagnetic interactions of Mn(II) ions existed in complexes 1–3. All the complexes exhibited luminescence emission peaks at room temperature. [ABSTRACT FROM AUTHOR]

Combining the advantages of energetic heterocycles to achieve high-energy insensitive explosives is a significant challenge. Herein, based on high-energy tetrazole rings and highly stable 1,3,4-oxadiazole rings, a series of novel nitrogen rich energetic compounds 5–9 were successfully constructed. The related compounds were fully characterized by EA, FT-IR, NMR, DSC, and MS, and compounds 6–9 were further confirmed by X-ray single crystal diffraction. Among them, the energetic ion salts 6–8 show high thermal stability (Tdec > 250 °C) and low mechanical sensitivity (IS > 40 J, FS > 360 N), as well as good energy properties (7552–8050 m s−1, 19.4–23.3 GPa). In particular, the azo compound 9 exhibits competent comprehensive performances (Tdec = 226.2 °C, D = 8502 m s−1, P = 28.9 GPa, IS = 32 J, FS = 320 N). These results suggest that the strategy of integrating tetrazole and 1,3,4-oxadiazole and employing an azo structure as a bridging unit are effective approaches to construct high-energy insensitive materials. [ABSTRACT FROM AUTHOR]

The design of heat-resistant energetic compounds generally employs symmetry, planarity, and multi-hydrogen bonds to obtain compounds with high density, good thermal stability, and low sensitivity. In this paper, a heat-resistant hydrazine-bridged compound, 6,6′-(hydrazine-1,2-diyl)bis(5-nitropyrimidine-2,4-diamine) (PHP), was designed and synthesized with the strategy of multi-fused conjugated structure constructed by hydrogen bonds. The compound featured high symmetry, high planarity, and strong conjugation with good thermal stability (364 °C). This strategy provides a basis for the design of heat-resistant energetic compounds. [ABSTRACT FROM AUTHOR]

β-Carotene is a natural antioxidant that has an indispensable effect on the growth and immunity of the human body. For intracellular and in vitro detection of β-carotene, N-doped carbon quantum dots (O-CDs) were prepared by co-heating carbonization of 1,5-naphthalenediamine and nitric acid in ethanol solvent for 2 h at 200 °C. O-CDs have longer wavelength orange light emission, with an optimal excitation peak of 470 nm and an optimal emission peak of 590 nm. According to the principle of the internal filtering effect on which the detection system is based, O-CDs present a good linear relationship with β-carotene within a wide range of 0–2000 μM, and the R2 coefficient of the linear regression equation is 0.999. In addition, O-CDs showed targeting of lysosomes in cell imaging and could be used to detect intracellular lysosomal movement. These experiments show that O-CDs can be used for in vivo and in vitro detection of β-carotene and can serve as a potential substitute to commercial lysosome targeting probes. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) with red fluorescence emission are highly desirable for use in bioimaging and trace- substance detection, with potential applications in biotherapy, photothermal therapy, and tumor visualization. Most CDs emit green or blue fluorescence, thus limiting their applicability. We report a novel fluorescent detection platform based on high-brightness red fluorescence emission carbon dots (R-CDs) co-doped with nitrogen and bromine, which exhibit pH and oxidized L -glutathione (GSSG) dual-responsive characteristics. The absolute quantum yield of the R-CDs was as high as 11.93%. We discovered that the R-CDs were able to detect acidic pH in live cells and zebrafish owing to protonation and deprotonation. In addition, GSSG was detected in vitro over a broad linear range (8–200 μM) using the R-CDs with excitation-independent emission. Furthermore, cell imaging and bioimaging experiments demonstrated that the R-CDs were highly cytocompatible and could be used as fluorescent probes to target lysosomes and nucleolus. These studies highlight the promising prospects of R-CDs as biosensing tools for bioimaging and trace-substance detection applications. [ABSTRACT FROM AUTHOR]

Tetranitroethane (TNE), an energetic compound with high-nitrogen (N%, 26.7%) and oxygen (O%, 60.9%) content, is deprotonated by alkali and alkaline earth metal bases to form the corresponding metal salts of TNE which are characterized by FT-IR spectroscopy, elemental analysis, and single crystal X-ray diffraction. All the prepared energetic metal salts show excellent thermal stabilities, and the decomposition temperatures of EP-3, EP-4, and EP-5 are higher than 250 °C, due to the numerous coordination bonds of the complexes. Furthermore, the energy of formation of the nitrogen-rich salts were calculated utilizing heat of combustion. The detonation performances were calculated with the EXPLO5 software, and the impact and friction sensitivities were determined. EP-7 shows excellent energy performance (P = 30.0 GPa, VD = 8436 m s−1). EP-3, EP-4, EP-5, and EP-8 are more sensitive to mechanical stimulation. These alkali and alkaline earth metal salts of TNE show good monochromaticity by atomic emission spectroscopy (visible light), and may be used as potential flame colorants in pyrotechnics. [ABSTRACT FROM AUTHOR]

The direct conversion of CO2 to aromatics with the aid of renewable hydrogen sources is a promising way to mitigate the CO2 emissions and simultaneously replace the dwindling fossil resources for the production of valuable chemicals. Even though some excellent results have been obtained for the direct conversion of CO2 to aromatics via the methanol-mediated or modified Fischer–Tropsch synthesis (FTS) pathway, the low space–time yield (STY) of aromatics and the high selectivity of C1 by-products (CO and CH4) are the main bottlenecks. Herein, we demonstrate that the bifunctional catalyst (CuFeO2/hierarchical HZSM-5) composed of defafossite-CuFeO2 exhibits outstanding catalytic performance for producing olefins from CO2 hydrogenation, and hierarchical HZSM-5 can catalyze the direct CO2 conversion to aromatics with a high efficiency by single pass. Under the optimized reaction conditions, the CuFeO2/hierarchical HZSM-5 bifunctional catalyst can suppress the total selectivity of CO and CH4 to less than 12% with a high aromatics STY of 431.8 mgCH2 gcat−1 h−1 at a CO2 conversion of 52.8% and outperforms previously reported catalysts. In addition, upon the selective elimination of external surface acidity via epitaxial growth of a Silicalite-1 shell on the hierarchical HZSM-5 surface, the fraction of p-xylene in xylenes is improved from 27.8% to 66.9%. Furthermore, H recycling is realized via the intimate synergy between CuFeO2 and hierarchical HZSM-5 and demonstrated to be significantly vital for improving the aromatics formation. The CO2 adsorbed on CuFeO2 also acts as an acceptor for H species produced from the olefin dehydrogenative aromatization in hierarchical HZSM-5, which in turn increases the aromatics STY by shifting the chemical thermodynamic equilibrium. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotube confined CuCo nanoalloy catalysts are fabricated by using ZIF-67 as a sacrificial template for the one-pot selective hydrogenation of levulinic acid (LA) to 1,4-pentanediol (1,4-PDO). The optimal catalyst achieves a high 1,4-PDO yield of 87.8% at full LA conversion. It also exhibits good recycling stability and can be reused at least 5 times. [ABSTRACT FROM AUTHOR]

A new compound of azotetrazole-3-hydroxy-2-naphthoic acid (H3ATNA) has been successfully synthesized and characterized. By controlling the ratio of metal ions to the ligand and the pH value of solution, mononuclear, dinuclear and tetranuclear dysprosium(III) complexes [Et3NH]3[Dy(HATNA)3]·5H2O (1), [Dy2(HATNA)3(DMF)(H2O)]·2DMF·CH3OH·2H2O (2) and [Et3NH]6[Dy4(ATNA)6(H2O)2]·DMF·2CH3CN·8H2O (3) were synthesized and characterized by X-ray diffraction crystallography (DMF = N,N-dimethylformamide). Crystallographic data demonstrate that the neutral H3ATNA exists as a hydrazone tautomer. Complex 1 is a mononuclear structure, in which the Dy(III) ion is a nine-coordinated ion surrounded by three tridentate HATNA− ligands. Complex 2 shows a dinuclear structure, which is bridged by three μ1,1-hydroxyl groups of three HATNA− ligands. In complex 2, the Dy(III)1 ion is a nine-coordinated ion surrounded by three tridentate HATNA− ligands, while Dy(III)2 is an eight coordinated atom with three tridentate HATNA− ligands, one DMF and one water molecule. Complex 3 displays a tetranuclear structure, which can be approximately considered as two μ1,3-carboxyl groups of ATNA3− ligands linking complex 2. The magnetic properties of 1–3 were investigated. Complexes 2 and 3 display slow magnetic relaxation in a zero dc field. [ABSTRACT FROM AUTHOR]

Two mixed-valence Co(II)/Co(III) complexes of [CoII(phen)3][CoIII(HATD)2]2·3DMA·3.5H2O (1), and [CoII(terpy)2][CoIII(HATD)2]2·4DMA·H2O (2), (phen = 1,10-phenanthroline, terpy = 2,2′:6′,2′′-terpyridine, H3ATD = azotetrazolyl-2,7-dihydroxynaphthalene, DMA = N,N-dimethylacetamide) were synthesized and their crystal structures were characterized. Crystal structure analyses reveal that complexes 1 and 2 consist of CoIII and CoII ions in an octahedral environment where the CoII ion is coordinated by three phen ligands and two terpy ligands, respectively. Magnetic measurements show that complex 1 displays field induced single-molecule magnet behavior, whereas 2 undergoes a gradual thermal spin crossover (SCO). [ABSTRACT FROM AUTHOR]

Energetic metal organic frameworks (EMOFs) are increasingly developed and have proven to be candidates for novel high energy density materials (HEDM). Here, two energetic metal complexes based on 3,5-diaminopyrazolone-4-oxime (DAPO) ligands were synthesized by simple steps and fully characterized by NMR and IR spectroscopy, X-ray single-crystal diffraction, and DSC-TG. The detonation performance was calculated using the Kamlet–Jacobs formula. The crystal densities of these complexes (C6H14N12O10Co (2) and C6H14N12O10Cd (3) are as high as 1.945 g cm−3 at 163 K and 2.072 g cm−3 at 298 K, respectively. Thermal analysis by the DSC-TG test shows that they all have good thermal stability with the highest decomposition temperatures of 287 °C and 344 °C, respectively. These two as-synthesized complexes exhibit excellent detonation performance; 2 (D = 8682 m s−1, P = 34.98 GPa) and 3 (D = 8383 m s−1, P = 33.78 GPa) have good detonation velocity and detonation pressure that are superior to those of TNT, which is widely used today. Thus, they show great promise for potential applications as thermally stable energetic materials. [ABSTRACT FROM AUTHOR]

The design, synthesis, physical properties, and calculated detonation performances of two skeleton isomeric energetic compounds containing tetrazole were introduced. By changing the chemical modification sites of the original fused-pyrimidine skeleton, a new pyrazolo[5,1-c][1,2,4]triazine framework was designed to compensate for the inability to functionalize CH sites in the original backbone. The potential energetic molecule 4-amino-8-nitro-3-(1H-tetrazol-5-yl)pyrazolo[5,1-c][1,2,4]triazin-7(6H)-one (PTT) was synthesized and characterized, which exhibits a moderate thermal decomposition temperature of 278.8 °C, good detonation velocity of 8620 m s−1, and desirable mechanical sensitivity. A comprehensive comparison between original 2-nitro-6-(1H-tetrazol-5-yl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine (NPT) and PTT suggests that positional isomerism modulation holds broad prospects in the design of energetic materials. [ABSTRACT FROM AUTHOR]

Two bimetallic complexes of 4-hydroxy-3,5-dinitropyrazole, [K2Mn(DNPO)2(H2O)4]n·2H2O (BMEP-1) and [K2Zn(DNPO)2(H2O)6]n (BMEP-2), were synthesized and characterized by IR spectroscopy and elemental analysis. The crystal structures of BMEP-1 and BMEP-2 were determined by single-crystal X-ray diffraction. It is noteworthy that these complexes presented different metal–organic frameworks. The thermal behaviors of BMEP-1 and BMEP-2 were investigated by differential scanning calorimetry and thermogravimetric analysis measurements. These bimetallic complexes exhibited high thermal stability (348.0 °C and 331.0 °C) due to their large coordination bonds and three-dimensional interconnected structure. The catalytic performances of BMEP-1 and BMEP-2 on the thermal decomposition of ammonium perchlorate were investigated by TGA-DSC, TGA-FTIR, and non-isothermal kinetic analyses. The results showed that BMEP-1 and BMEP-2 exhibited excellent catalytic performance in the thermal decomposition of ammonium perchlorate. Notably, there was only a single exothermic peak at 302.6 °C and 318.6 °C, and the activation energy values of ammonium perchlorate decreased to 123.88 kJ mol−1 and 128.43 kJ mol−1, respectively. TGA-FTIR results showed that BMEP-1 and BMEP-2, as effective components of catalysis, will promote the production of H2O, N2O, NO2, and HCl in advance, during the thermal decomposition of ammonium perchlorate. BMEP-1 and BMEP-2 are expected to be two candidate additives for the catalytic decomposition of ammonium perchlorate in composite solid propellants. [ABSTRACT FROM AUTHOR]

Cellular imaging using carbon dots is an important research method in several fields. Herein, green-emissive carbon quantum dots (G-CDs) with a pretty high absolute quantum yield (QY) were fabricated via a one-step solvothermal method by using m-phenylenediamine and concentrated hydrochloric acid. G-CDs displayed strong green fluorescence with excitation/emission peaks at 460/500 nm, and their absolute quantum yield was as high as 58.65%. Further experiments suggested that the G-CDs we prepared have good solubility, excellent biocompatibility, and the capacity of rapidly imaging HeLa and 4T1 cells. Over expectations, the G-CDs could penetrate cells in only 10 s and the confocal images showed that the G-CDs could target the nucleus of cells. Moreover, by using 920 nm as the excitation wavelength, two-photon imaging has been successfully applied to 4T1 cells, overcoming the inherent limitations of single-photon imaging. The extremely high absolute quantum efficiency, ultra-fast imaging speed, and two-photon imaging capability make the G-CDs have good application potential in biomedical analysis and the clinical diagnostic field. [ABSTRACT FROM AUTHOR]

Determining the surface structure and morphology under working conditions is essential to obtain facet-dependent catalytic performance. However, the evolution of the morphology and exposed surfaces of nanocatalysts is sensitive to experimental conditions such as temperature and gaseous pressure, which brings about a great experimental challenge to obtain this information. Herein, ab initio thermodynamics, density functional theory and Wulff morphology were employed to investigate the surface structure and morphology evolution of HCP-Co under hydrogen-relevant conditions. From the stepwise adsorption on each facet of HCP-Co, hydrogen prefers to adsorb on threefold hollow sites. The morphology of HCP-cobalt presents a quasi-spherical shape and the main exposed surfaces of HCP-Co are (0001), (10-10), (10-11) and (10-12) under different temperatures and hydrogen partial pressures. This work provides complementary information to experimental studies for knowing the microstructures of cobalt nanocatalysts in hydrogen-involved reactions. [ABSTRACT FROM AUTHOR]

Recently, Se cathodes have caught growing attention owing to their higher electronic conductivity, better compatibility with the carbonate electrolyte and comparable theoretical volumetric capacity to S cathodes. However, large volume variation, shuttle effect and sluggish redox kinetics have hindered the development of Li–Se batteries. Herein, we report chain-mail Co@C nanoparticles (Co@C NPs) embedded in macro-meso-microporous carbon nanofibers (CPCFs) with the characteristics of generalized Murray's law as a flexible Se host for advanced Li–Se batteries. The chain-mail Co@C structure protects Co from both active species and electrolyte, and then strengthens the adsorption-catalytic functions for active Se and Li2Se, thus improving the one-step solid-phase redox. In addition, the hierarchical porous structure enhances mass transfer and relieves volume expansion. Accordingly, the Se@CPCFs cathode demonstrates a high capacity of ∼500 mA h g−1 at 0.2C (1C = 675 mA g−1) after 500 cycles and exhibits high-capacity retention of 97.4%, 97.6%, and 99.1% between 1 and 100, 100 and 300, and 300 and 500 cycles. An excellent rate capability at 10C with a reversible specific capacity of 438 mA h g−1 is also realized. This work pioneered the utilization of chain-mail metal NPs as electrocatalysts to accelerate the solid-phase redox kinetics of Se cathodes for advanced Li–Se batteries. [ABSTRACT FROM AUTHOR]

Guided by synthetic chemistry, coordination chemistry and crystallization chemistry, a novel synthesis and crystallization strategy for laser complex energetic materials has been established in this study. In this study, a method with milder reaction conditions was adopted to design the steps and successfully synthesize urazine (H2ur). At the same time, using H2ur as the ligand, the "acid-controlled dissolution-crystallization" method was used to successfully prepare the crystalline coordination polymer Ag(H2ur)NO3 (5), and its 1D structure was confirmed by X-ray single crystal diffraction. The physicochemical property evaluation revealed that 5 has the best performance: insensitive to light, noncorrosive properties to metal shells, excellent tolerance to moisture, good thermal stability, and insensitive to mechanical stimulation. Theoretical calculations show that the compound has acceptable detonation properties (D = 7.6 km s−1, P = 31.83 GPa). In addition, hot-needle experiments show that 5 has a good DDT effect. More importantly, it has great potential for application in laser energetic materials (τ = 300 ms, E = 800 mJ). [ABSTRACT FROM AUTHOR]

A bifunctional NiMoFe/Cu NW core–shell catalyst assembled into a practical solar-driven overall water splitting system leads to an unprecedented solar-to-hydrogen (STH) efficiency of 10.99% in neutral electrolytes, attributed to the synergic combination of a unique 3D self-supported core–shell architecture and rapid electron/mass transfer properties. [ABSTRACT FROM AUTHOR]

Based on tetraphenylethylene as the skeleton, two novel salamo-type fluorescent probes (TPES1 = 2-hydroxy-1-naphthaldehyde O-(3-(((-2-hydroxy-5-(1,2,2-triphenylvinyl)benzylidene)amino)oxy)propyl) oxime and TPES2 = bis(2-hydroxy-1-naphthaldehyde O-(3-(((2-hydroxy-5-(1,2,2-triphenylvinyl)benzylidene)amino)oxy)propyl) dioxime) were designed and synthesized. Through the colorimetric and fluorescence dual-channel modes, cyanide ions could be specifically recognized by the two probe molecules. Interestingly, the probes TPES1 and TPES2 exhibited completely different spectral behaviors during the recognition process. Of the two, the TPES1 molecule is a ratio-type fluorescent probe, and double fluorescence emission peaks appeared during the titration process. The reason for this phenomenon is due to the rotation of the C–C single bond in tetraphenylethylene, causing the solution system to contain molecules in two states. On the other hand, the TPES2 molecule is a fluorescence-enhanced probe that has undergone two reaction processes of deprotonation and addition reaction successively, causing the fluorescence intensity to increase continuously. Theoretical calculations indicated that the configuration of probe TPES1 is reversed after interacting with cyanide ions (CN−). By calculating the minimum detection limits of TPES1 and TPES2 to CN−, the LOD values were 8.56 × 10−8 M and 5.37 × 10−8 M, respectively. In addition, probe-based test strips have been prepared for quick and simple detection of cyanide ions. [ABSTRACT FROM AUTHOR]

Three mononuclear, dinuclear and one-dimensional dysprosium(III) complexes based on 3-azotriazolyl-2,6-dihydroxybenzoic acid (H4ATB) of [Dy(H3ATB)3]·3H2O (1), [Dy2(H2ATB)2(H2DHB)2(H2O)4]·2CH3CN·5H2O (2), and [Dy2(H2ATB)2(DCB)(DMF)2(H2O)2]·4DMF (3) were synthesized and structurally characterized by X-ray single crystal diffraction (H3DHB = 2,6-dihydroxybenzoic acid, H2DCB = 1,4-dicarboxybenzene). Complex 1 was used as a precursor to synthesize complexes 2 and 3, and 2 was further used to synthesize 3. Complex 1 is a mononuclear complex, in which the Dy(III) ion is in a nine-coordinated structure surrounded by three tridentate chelate H3ATB− ligands. Complex 2 displays a dinuclear structure bridged by two μ2 carboxyl groups of two H2DHB− ligands and two μ1,1-O atoms from the phenolic hydroxyl groups of two H2ATB2− ligands. Complex 3 shows a one-dimensional structure formed by two bridging DCB2− ligands. The magnetic measurements were performed on three complexes 1–3, and they showed different magnetic behavior. Complex 1 shows a field-induced slow magnetic relaxation. Complexes 2 and 3 display distinct slow magnetic relaxation under zero dc field with energy barriers (Ueff) of 26(2) cm−1 and 11(1) cm−1, respectively. The magnetic behavior of three complexes 1–3 was investigated by ab initio calculations. [ABSTRACT FROM AUTHOR]

Photodynamic therapy, as an effective treatment for superficial tumors, has attracted more and more attention. The development of safe, biocompatible and in vivo photosensitive materials is helpful to promote photodynamic therapy. Here we report green fluorescent carbon quantum dots prepared from a natural vitamin, riboflavin (VB2), as a photosensitizer. The VB2-based carbon dots have excellent water solubility and biocompatibility, and their singlet oxygen generation ability is much stronger than that of riboflavin itself. Through endocytosis, the carbon dots can easily enter the cells and show bright green fluorescence. In vivo experiments show that after photodynamic therapy the carbon dots can significantly inhibit the growth of tumors, and will not have toxic and side effects on other organs. [ABSTRACT FROM AUTHOR]

A new salamo-type bisoxime compound H3L has been synthesized and exploited as a highly efficient chemosensor with multiple responses to Cu2+ and S2−. Chemosensor H3L exhibits highly selective and sensitive detection of Cu2+ and S2− simultaneously. The LODs of Cu2+ and S2− were calculated to be 1.5398 × 10−7 and 1.7274 × 10−7 M in DMF-water (9 : 1, v/v) solution, respectively. The color of the chemosensor H3L solution changed from light green to dark green after adding S2− under a 365 nm UV-lamp. The sensing mechanism of the chemosensor H3L was characterized using several methods, including ultraviolet spectroscopy, ESI-mass spectrometry, 1H-NMR and FT-IR spectroscopy. Meanwhile, the crystal structure of the Cu(II) complex, [Cu2(L)]ClO4·2CH3OH, has been determined by X-ray crystallographic analysis. Density Functional Theory (DFT) was employed to further understand the obtained experimental results. [ABSTRACT FROM AUTHOR]

Iron, nitrogen-co-doped carbon quantum dots (Fe,N-CDs) were prepared via a simple one-step hydrothermal method. The quantum yield of fluorescence reached about 27.6% and the blue-emissive Fe,N-CDs had a mean size of 3.76 nm. The as-prepared carbon quantum dots showed good solubility, a high quantum yield, good biocompatibility, low cytotoxicity, and high photostability. Interestingly, the as-prepared Fe,N-CDs exhibited good selectivity and sensitivity toward both hematin and ferric ions, and the limit of detection for hematin and ferric ions was calculated to be about 0.024 μM and 0.64 μM, respectively. At the same time, Fe,N-CDs were used for imaging HeLa cells and showed that most Fe,N-CDs were detained in the lysosome. Thus, this fluorescent probe has potential application in the quantitative detection of hematin or Fe3+ in a complex environment and for determining Fe3+ at the cellular level. [ABSTRACT FROM AUTHOR]

Two ion-pair Fe(III) complexes (PPh4)[FeIII(HATD)2]·2H2O (1, H3ATD = azotetrazolyl-2,7-dihydroxynaphthalene) and [FeII(phen)3][FeIII(HATD)2]2·3DMA·3.5H2O (2, phen = 1,10-phenanthroline, DMA = N,N-dimethylformamide) were synthesized by employing the tridentate ligand H3ATD. Crystal structure analyses reveal that complexes 1 and 2 consist of FeIII ions in an octahedral environment where a FeIII ion is coordinated by two HATD2− ligands forming the [FeIII(HATD)2]− core. The shortest cation⋯anion distance between the phosphorus ion of the (PPh4)+ cation and the ferric ion of the [FeIII(HATD)2]− anion is 13.190 Å in complex 1, whereas that between the ferrous ion of the [FeII(Phen)3]2+ cation and the ferric ion of the [FeIII(HATD)2]− anion is 7.821 Å in complex 2. C–H⋯C and C–H⋯O hydrogen interactions between the [FeII(phen)3]2+ cation and the [FeIII(HATD)2]− anion are observed in 2. Face-to-face π-π stacking interactions between naphthalene rings with the separated interplanar center to center distances of 3.421–3.680 Å were observed, which result in a one-dimensional supramolecular chain in complexes 1 and 2. Magnetic measurements show that complex 1 is in the low-spin (LS) state below 500 K, whereas 2 undergoes a high temperature spin crossover (SCO) between 360 and 500 K. Magneto-structural relationship studies reveal that π-stacking, hydrogen interactions and Coulomb interactions between the [FeIII(HATD)2]− anion and the [FeII(phen)3]2+ cation play a crucial role in the high temperature Fe(III) SCO behaviour of complex 2. [ABSTRACT FROM AUTHOR]

Herein, a novel and fluorescent zinc-organic framework sensor [Zn3(μ3-Hbptc)2(μ2-4,4′-bpy)2(H2O)4]n·2nH2O (1) (H4bptc = 2,3,3′,4′-biphenyl tetracarboxylic acid, 4,4′-bpy = 4,4′-bipyridine) is synthesized and characterized, demonstrating its excellent fluorescence performance for Cu2+ detection and the enrichment of Cu2+ in aqueous media. The fluorescence intensity of 1 can be selectively quenched by Cu2+ in a linear range of Cu2+ concentrations of 0–0.7 μM. The limit of detection (LOD) value is as low as 32.4 nM, which is superior to those of most of the fluorescent sensors based on metal–organic frameworks (MOFs). It is also far below the maximum allowable concentration of Cu2+ in drinking water as defined by the U.S. Environmental Protection Agency (EPA) and the World Health Organization (WHO), so it is employed for the detection of Cu2+ in actual water samples. More importantly, the nature of the interaction between the active coordination site (COO−) of 1 and Cu2+ determines the quenching mechanism, that is Cu2+ in the analyte is captured by MOF 1, which has been investigated by ICP, luminescence, UV-vis, XPS, and lifetime studies. Besides, the chemosensor shows regeneration performance without the loss of performance in five consecutive cycles. So MOF 1 is a simple and convenient probe used not only for the rapid detection but also for the enrichment of trace amounts of Cu2+ in aqueous media, and the application can be further extended to a variety of environmental and biological analysis processes. [ABSTRACT FROM AUTHOR]

The presence of excessive ROS can cause much harm to the human body and can even cause diseases. Therefore, it is important to detect and remove ROS, but there is no ideal method available for this at present. In this research, using procyanidins, a type of plant extract with strong reducibility, as raw materials, fluorescent carbon dots (CDs) were prepared by a hydrothermal method. The proanthocyanidin-based carbon dots (PCDs) emit a light-green colored light under UV irradiation. The PCDs retain the strong reducibility of procyanidins and are highly water-soluble compared with procyanidins. The PCDs, in addition to having good biocompatibility, also have the superior properties of radical scavenging activity and cell imaging. In in vitro experiments, 1,1-diphenyl-2-picrylhydrazyl (DPPH; 100 μM) was reduced by 30% when PCDs were added up to a concentration of 87.5 μg mL−1. At the same time, the fluorescence quenching correlates with the concentration of hypochlorite and hydrogen peroxide and has a good linearity in the range of 250–2250 nM and 60–180 μM with a detection limit of 3.676 nM and 0.602 μM, respectively. Based on the previously described advantages, PCDs have potential as a biomedicine. [ABSTRACT FROM AUTHOR]

Integrating the merits of different components to construct heterostructures for energy storage and conversion has attracted intensive attention. Herein, taking advantage of bimetallic MOFs and transition bimetal hydroxide, we have successfully used nanoflower-like Ni1−xCox(OH)2 as both the precursor and template to in situ construct three dimensional (3D) NiCo-MOF@Ni1−xCox(OH)2 (denoted as MOF@TMH) hierarchical heterostructures. Benefiting from the optimized composition with hierarchical heterostructures assembled by ultrathin nanosheets, MOF@TMH-2 possesses rich effective active sites and high electrochemical reactivity, delivering superior pseudocapacitor performance with a specific capacitance of 1855.3 F g−1 at 2 A g−1 and good rate performance. Besides, MOF@TMH-2 also exhibits excellent OER activity with small overpotentials of 193 mV and 310 mV at 10 and 100 mA cm−2, respectively. [ABSTRACT FROM AUTHOR]

A new, simple and easy-to-manufacture highly selective and sensitive dual-mode sensor A1, is used for CN− colorimetric and fluorescence detection. Interestingly, the solid powder of sensor A1 emits a strong green fluorescence, and has aggregation-induced emission properties. Single crystal diffraction analysis results prove that the generation of AIE properties is based on the J-aggregation mechanism. Simultaneously, A1 showed high selectivity and sensitivity to CN− in many interfering anions. The sensing mechanism of cyanide is carried out by deprotonation of the –OH group by the cyanide ion, and has been confirmed by spectroscopic studies, 1H NMR spectroscopy, Job's plot analyses and DFT calculation. The practicality of the sensor has been well proven by filter paper strips and small molecule smart fluorescent display materials. In addition, the sensor is used to detect cyanide in food materials (such as germinated potatoes, cassava and bitter almonds) with satisfactory results. The most important thing is considering the colorimetric and fluorescent dual modes, the ultra-fast response, excellent selectivity and recyclability that demonstrate its excellent value in practical applications. [ABSTRACT FROM AUTHOR]

By employing the ligand azotetrazolyl-2,7-dihydroxynaphthalene (H3ATD), two linear trinuclear mixed-valence cobalt complexes [CoIICo III2 (HATD)4(H2O)4]·4DMA·3H2O (1, DMA = N,N-dimethylacetamide) and [CoIICo III2 (HATD)4(DMF)2(H2O)2]·2DMF·2H2O (2, DMF = N,N-dimethylformamide) were synthesized. Two [2 × 2] grid-like tetranuclear ion-pair complexes [Co II2 Co III2 (HATD)4(bpp)2(H2O)2][CoIII(HATD)2]2·8DMF·6H2O (3, bpp = 2,6-di(pyrazol-1-yl)pyridine) and [Co II2 Co III2 (HATD)4(bpp)2(H2O)2][CoIII(HATD)2]2·8DMSO·4MeOH (4, DMSO = dimethyl sulphoxide) were obtained by the reaction of complex 1/2 with tridentate-chelating bpp in DMF and DMSO, respectively. The single-crystal X-ray diffraction analysis indicated that complexes 1 and 2 have a similar core, in which the DMA in 1 acts as a guest molecule, and the DMF in 2 acts as a coordinated molecule and guest molecule. Complexes 3 and 4 are isostructural. All the Co(II) ions in 1–4 are present in a distorted octahedral geometry. The ac susceptibility measurements show that all complexes display frequency-dependent peaks in the out-of-phase (χm′′) component of the alternating-current (ac) magnetic susceptibility data, which is the characteristic behavior of single molecule magnets (SMMs). [ABSTRACT FROM AUTHOR]

Two heteropolynuclear complexes, namely [Cu2(L)Ce(NO3)3] and [{Cu2(L)Y(NO3)2(μ-AcO)}{Cu2(L)Y(NO3)2(μ-NO3)(CH3OH)}]·4CH3OH, were synthesized through the reaction of a newly synthesized bis(salamo)-based ligand (H4L), Cu(OAc)2·H2O and Ln(NO3)3·6H2O (Ln = Ce and Y), respectively. Single crystal structure analyses showed that the [CuII2CeIII] and [CuII4YIII2] complexes contained similar trinuclear [CuII2LnIII] structures. The difference was that the [CuII4YIII2] complex consisted of two crystallographically independent and chemically different trinuclear complexes with coordination and free solvent molecules. Among the two heteropolynuclear metal complexes, only the [CuII2CeIII] complex showed catecholase activity and benzoxazinone synthase activity under normal temperature and aerobic conditions. For catecholase activity, the calculated Kcat of the [CuII2CeIII] complex was 346.5 h−1, and the Kcat of p-benzoxazinone synthase activity was 9.73 h−1. Compared with the [CuII4YIII2] complex, we speculated that the main reason for the high catalytic function of the [CuII2CeIII] complex is the presence of three nitrate groups coordinated with the central CeIII atom. Evidence from mass spectrometry and cyclic voltammetry curves indicated that there may be heterometallic cooperation, in which CeIII binds to the substrate, while the metallic copper transformed between CuII and CuI through redox reactions. In addition, the catalytic mechanism was inferred through electrospray mass spectrometry and cyclic voltammetry, and fluorescence properties were studied and Hirshfeld surface analyses were also conducted. [ABSTRACT FROM AUTHOR]

A series of Au catalysts supported on Cu–Al composite oxides were prepared and applied for the selective catalytic oxidation of glycerol to 1,3-dihydroxyacetone (DHA) in base-free conditions. The optimal Au/CuAlO-3 catalyst (the molar ratio of Cu/Al was 5 : 1) exhibited the best performance, and reached the glycerol conditions of 76.7% and DHA selectivity of 97.3% under the optimized reaction conditions. The high catalytic activity of the Au/CuAlO-3 catalyst correlated to the large concentration of surface-active oxygen species, the low reduction temperature of the support, the small size of Au nanoparticles (NPs) and the interactions between Au NPs and the support. This work demonstrates that Cu–Al composite oxides are promising supports for selective catalytic oxidation of glycerol to DHA, and may offer guidelines for designing efficient support for the selective conversion of glycerol to other high value-added products. [ABSTRACT FROM AUTHOR]

Immunomagnetic beads are important tools for the isolation and detection of circulating tumor cells (CTCs). However, the current immunomagnetic bead technique provides poor CTC separation purity due to nonspecific binding of background cells. Furthermore, immunomagnetic beads have not been appropriately functionalized for enabling CTC analysis and quantification. In this work, bimetallic magnetic gold nanoparticles were prepared and coated with leukocyte membranes to form leukocyte membrane-camouflaged nanoparticles. After conjugation with the antibody of epithelial cell adhesion molecule (EpCAM), the biomimetic immunomagnetic gold nanoparticles (CM-Fe3O4@Au-Ab) showed a high specific recognition ability on mock (EpCAM-positive) CTCs and a reduced interaction with leukocytes. We subsequently optimized the conditions for CTC separation, including the concentration of nanoparticles and the incubation time. Under the optimized conditions, CM-Fe3O4@Au-Ab exhibited high CTC capture efficiency with negligible background cell binding in mock clinical blood samples. More importantly, gold probes were tagged on the surface of these separated CTCs. When coupled with ICP-MS analysis, the number of CTCs and gold signals exhibited a good linear relationship, and a low limit of detection was obtained, enabling us to estimate the number of CTCs in blood samples. Hence, we expected that CM-Fe3O4@Au-Ab could provide an opportunity to surmount the limitations of current CTC detection. [ABSTRACT FROM AUTHOR]

One-dimensional zig-zag chain and two-dimensional network dysprosium(III) single-molecule toroics with anisotropy barriers of about 5 and 31 cm−1 under a zero dc field are reported. These are the first one- and two- dimensional homometallic single-molecule toroics reported to date. Furthermore, the two complexes also display white-light emission under UV-light irradiation. [ABSTRACT FROM AUTHOR]

Copper ions (Cu2+) and L- cysteine (L- Cys) in the human body always play critical roles in various physiological processes, while abnormal Cu2+ and L- Cys concentrations in the biological system lead to many diseases. In this manuscript, Si-doped carbon dots (Si-CDs) with near-infrared fluorescence were designed for the detection of Cu2+ and L- Cys through the fluorescence "on–off–on" mode. The carbon dots exhibited not only excellent optical merits including good stability against photobleaching and high chemical stability, but also superior biological compatibility. Interestingly, due to the abundant amino groups distributed on the surface of Si-CDs, they could bind to copper ions to form cupric amine complexes and then quench the fluorescence of Si-CDs due to an electron transfer process. In addition, upon the addition of L- Cys, the FL intensity of Si-CDs could be effectively recovered accompanied with complexation between Cu2+ and the functional groups in L- Cys, due to which Cu2+ was removed from the surface of Si-CDs. Notably, as far as we know, these are the first red-emitting carbon dots for copper ion and L- Cys assays in water samples and human plasma samples. Furthermore, this strategy was successfully applied to the determination of Cu2+ and L- Cys in living systems, demonstrating great practicability in biomedical applications. [ABSTRACT FROM AUTHOR]