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Non-enzymatic electrochemical blood glucose sensors often suffer from issues such as requiring an alkaline environment, limited monitoring range, and poor anti-interference properties. Carbon substrates have been demonstrated to improve the performance of non-enzymatic sensors, but complex and energy-consuming manufacturing processes restrict their use. Herein, a simple and green approach for the preparation of 3D porous Au/Au-Pt networks (PAAPNs) is proposed using tissue paper for recycling as the nanomaterial substrate to deposit Au-Pt bimetallic nanoparticles. The unique structure of the PAAPNs sensor allows for low-potential operation (-1.0 V) with a wide monitoring range (-0.25 to 36 mM) in a neutral environment. Moreover, the sensor exhibited excellent selectivity (<10% response of interference) even without the use of an anti-interference outer membrane. Further investigation using density functional theory (DFT) simulation revealed the synergistic effect between Au and Pt in promoting glucose oxidation. Overall, this work provides a simple and low-carbon footprint method for creating carbon substrates from tissue paper for recycling, offering new opportunities for fabricating novel value-added nanomaterials for medical sensing applications. [ABSTRACT FROM AUTHOR]

A new fluorescent probe (T2) containing pyrene-hydrazone furan moieties was developed and synthesized through a two-step process and then coated onto filter paper to form a paper-based sensor for TNT detection. The T2 sensor uses photoinduced electron transfer (PET) induced fluorescence quenching to detect TNT. The sensor properties were studied using fluorescence spectra, 1H-NMR titration and density functional theory (DFT) calculations. The reaction time of the T2 paper-based sensor for TNT detection was only five minutes. A smartphone was used as an alternative instrument to detect fluorescence signals and a typical image J-processing application was employed to evaluate the grayscale values of the smartphone-captured photographs. The sensor showed a linear concentration range for TNT detection of between 30–500 μM and a detection limit of 30 μM. The T2 paper-based sensor was found to have high selectivity and sensitivity, and it can successfully detect and image TNT in actual samples. This research demonstrates that a T2 paper-based sensor is a promising alternative for TNT detection owing to its short reaction time, high selectivity, sensitivity, and easy applicability. [ABSTRACT FROM AUTHOR]

Presently, the use of several pesticides has been continuously rising owing to the increase in the production of food materials to meet the requirements of the growing population of the world. The safety of food materials with regards to pesticides is an important health concern for people. With this aim, we have developed a smartphone-assisted paper-based sensor impregnated with citrate capped Cu@Ag core–shell nanoparticles (NPs) for selective determination of phenthoate pesticides in water and food samples. The mechanism for selective detection is based on the high affinity of phenthoate to interact with silver NPs present on the surface of CuNPs, which results in aggregation and a change in the color of the paper device. Furthermore, the proposed mechanism and interaction of phenthoate with Cu@Ag NPs was theoretically investigated by density functional theory (DFT) using Gaussian 16.0 software. The linear range for the determination of phenthoate was found in the range of 50–1500 μg L−1, with a limit of detection of 15 μg L−1, and a 92.6 to 97.4% recovery, and the interference studies demonstrated the selectivity for the determination of the target analyte from complex sample matrices. Finally, paper impregnated with Cu@Ag was exploited for the monitoring of the phenthoate pesticide in different water and food samples. The advantages of this paper-based sensor, coupled with a smartphone readout system, are that is it is user-friendly, easy-to-use, cost-effective, and can be applied at the sample source compared to sophisticated analytical instruments. [ABSTRACT FROM AUTHOR]

We present in this paper the stability of SWCNT hybrid systems with Py molecules. vdW type interactions are therefore the main interaction mechanism between encapsulated molecules and nanotubes, and the simplest model to describe these interactions is the Lennard-Jones potential. We have therefore performed energy minimization calculations on hybrid SWCNTs in a very wide range of diameters and of all chirality using the Lennard-Jones potential. The structure of the carbon nanotube is obtained from the winding of graphene on itself to form a hollow cylinder described by the pair of integers (n, m) entirely determining its structural characteristics, while the optimization of the geometry of the Py molecule is obtained by SIESTA using the exchange–correlation functional LDA. After minimisation, an approach that combines density functional theory, molecular mechanics, bond polarizability model, and spectral moment's method has been used to compute Raman spectra. Two types of vibration modes of SWCNTs attract our attention. Initially, the modifications of the modes of Py after encapsulation will be analyzed. In the following discussion, we examine how the vibrational properties of single-walled carbon nanotubes (SWCNTs) are affected by encapsulation, specifically in relation to the RBM and tangential modes. Our analysis of the Raman active modes supports the notion that the structural integrity of the SWCNTs remains intact and indicates the occurrence of a charge transfer between the Py molecules and SWCNTs. This charge transfer depends on the geometric position of Py in the SWCNT. [ABSTRACT FROM AUTHOR]

As a promising candidate to replace lithium-ion batteries, rechargeable aqueous zinc ion batteries (AZIB) are receiving increasing attention due their high energy density, high safety, low cost and environmental friendliness. In this study, metal ions may be introduced into the interlayer gap of layered vanadium oxide nanobelts through a one-step hydrothermal process, without changing their original structure. Moreover, we have demonstrated by density functional theory computations that Mn metal ions not only serve as structural pillars but also enhance the conductivity of MnxVO2·0.2H2O, facilitating the migration of Zn ions. As a result, the electrochemical performance of MnxVO2·0.2H2O as an AZIB cathode has significantly improved; after 100 cycles at 0.5 A g−1, it exhibits a high reversible capacity of 350 mA h g−1. With a high current density of 5 A g−1, the initial capacity can still reach 295 mA h g−1. This paper suggests an effective method to maximize the efficiency of AZIB electrode materials. [ABSTRACT FROM AUTHOR]

Diethyl cyanophosphonate (DCNP), a simulant of Tabun, is a common pollutant in pharmaceutical waste and poses a high risk to living organisms. Herein, we demonstrate a compartmental ligand-derived trinuclear zinc(II) cluster [Zn3(LH)2(CH3COO)2] as a probe for the selective detection and degradation of DCNP. It consists of two pentacoordinated Zn(II) [4.4.3.01,5]tridecane cages bridged through a hexacoordinated Zn(II) acetate unit. The structure of the cluster has been elucidated by spectrometric, spectroscopic, and single-crystal X-ray diffraction studies. The cluster shows a two-fold increased emission as compared to the compartmental ligand (at λexc = 370 nm and λem = 463 nm) due to the chelation-enhanced fluorescence effect and acts as a turn-off signal in the presence of DCNP. It can detect DCNP at nano levels up to 186 nM (LOD). The direct bond formation between DCNP and Zn(II) via the –CN group degrades it to inorganic phosphates. The mechanism of the interaction and degradation is supported by spectrofluorimetric experiments, NMR titration (1H and 31P), time of flight mass spectrometry and density functional theory calculations. The applicability of the probe has been further tested by the bio-imaging of zebrafish larvae, analysis of high-protein food products (meat and fish) and vapour phase detection by paper strips. [ABSTRACT FROM AUTHOR]

The treatment of cancer has always been a challenging problem in the medical community. In this paper, based on density functional theory (DFT), B12N12 nanocage was studied as delivery carriers of sulforaphane (SF) anticancer drug, and the adsorption properties, electronic properties and topological analysis of complexes were calculated. The adsorption energy, solvation energy, electronic and topological properties were calculated by used M06-2X/6-311+G(2d,p), M05-2X/6-31G(p) and B3LYP/6-311G(d,p) theoretical levels, respectively. In addition, the effects of doping and packaging of alkaline earth metal (Be, Mg, Ca) on the related properties were also studied. Doping and packaging metal can improve the transfer characteristics of nanocages by changing the polarity of systems. All calculation results were performed in Gaussian 09 software. The frontier molecular orbital (FMO) and natural bond orbital (NBO) analysis showed that nanocages acting as charge acceptors and drugs as charge donors during the adsorption process. The atoms-in-molecules (AIM) and interaction region indicator (IRI) analysis showed that there were strong polar covalent bonds between drug and nanocages, which enabled drug to be stably adsorbed on nanocages. The solvation effect results showed that acidic conditions were more conducive to drug transport and release. Compared with the original and encapsulated systems, the doping system has better adsorption properties and solvation effect. Moreover, the charge transfer between drug and nanocages in doping system was more frequent and the interaction was stronger. Therefore, our results indicated that the doping nanocages MB11N12 (M = Be, Mg and Ca) were more suitable as the drug carrier system for SF anticancer drug. [ABSTRACT FROM AUTHOR]

The host–guest complexes formed between [9–11]CPPs and C60 were studied extensively due to their excellent photoelectric conversion properties and photochemistry. The drastically increased electron accepting ability of Li+@C60 with respect to C60 may induce strong intermolecular charge transfer interaction with [9–11]CPP. In this paper, a comprehensive computational analysis of the structure, intermolecular interactions, absorption spectra, charge transfer characteristics and nonlinear optical properties of [9–11]CPP⊂C60 and [9–11]CPP⊂Li+@C60 were studied using density functional theory calculations. It was found that the intermolecular binding energies of [10]CPP⊂C60 and [10]CPP⊂Li+@C60 were −47.76 and −60.08 kcal mol−1, which were larger than those of [9, 11]CPP⊂C60 and [9, 11]CPP⊂Li+@C60. Thus, [10]CPP was found to be the most ideal fullerene encapsulator and most suitable for encapsulating C60. In addition, with the increase of the CPP ring size, the second hyperpolarizability (γ) values of [n]CPP⊂C60 increase gradually. In addition, the γ values of [9–11]CPP⊂Li+@C60 were all greater than those of [9–11]CPP⊂C60, indicating that embedding Li+ into fullerene spheres can effectively improve their third-order nonlinear optical responses. [ABSTRACT FROM AUTHOR]

To understand the mechanism of the dehydrogenation of methanol to CO and H2 catalyzed by a ruthenium pincer complex, a density functional theory (DFT) study has been conducted on two different cycles which differ in the substances entering the cycle (methanol (cycle 1) versus methoxymethanol (cycle 2)). Our calculated results show that both cycles consist of three stages: dehydrogenation of alcohol to aldehyde (stage I); hydrogen formation (stage II); and decarbonylation with the regeneration of the catalyst (stage III). The energy barriers of the rate-determining steps for cycles 1 and 2 are 49.6 and 28.5 kcal mol-1, respectively. Thus cycle 2 is more energetically feasible. For stage III of cycle 2, our results did not support the mechanism proposed in the experiment (CO release occurs prior to decarbonylation). Instead, we suggested and examined an alternative pathway, that is, decarbonylation occurs prior to CO release. The mechanistic insights gained in the present paper could be beneficial for further designing of these kinds of reactions. [ABSTRACT FROM AUTHOR]

Urea electrolysis can be used to treat wastewater containing urea and alleviate the energy crisis, so it is one of the best ways to solve environmental and energy problems. This paper reports the synthesis of M doped NiVS (M = Co, Ce and Cr) composites by a simple hydrothermal process for the first time. What is noteworthy is that the Ce-NiVS material as a catalytic electrode requires only 141 mV overpotential for the hydrogen evolution reaction (HER) and 1.291 V potential for the urea oxidation reaction (UOR) at a current density of 10 mA cm−2 in 1.0 M KOH and 0.5 M urea mixed alkaline solution. Using Ce-NiVS/NF as both the anode and cathode for urea electrolysis, a current density of 10 mA cm−2 is driven by a voltage of only 1.55 V, which is better than most previous catalysts. Experimental results demonstrate that the excellent catalytic activity of Ce-NiVS materials is due to the formation of a large number of active sites and the improvement of conductivity due to doping with Ce. Density functional theory calculation shows that the VS4 material has a small Gibbs free energy of hydrogen adsorption, which plays a major role in the hydrogen production process, and Ce-NiS has a higher density of states (DOS) near the Fermi level, indicating that Ce-NiS has better electronic conductivity. The synergistic catalysis of VS4 and Ce-NiS promoted the hydrogen production performance of the Ce-NiVS material. This work provides guidance for the optimization and design of low-cost electrocatalysts to replace expensive precious metal-based electrocatalysts for overall urea electrolysis. [ABSTRACT FROM AUTHOR]

In this paper, ultra-thin nanofiber PDI was obtained by self-assembly dispersion of commercial PDINH. A novel Co/Ni-MOF-74@PDI Z-scheme heterojunction photocatalyst material was constructed by a simple solvothermal method. XRD, SEM, TEM, FT-IR and other characterization techniques proved the successful preparation of the Co/Ni-MOF-74@PDI Z-scheme heterojunction photocatalyst material. By degrading chlortetracycline hydrochloride, it was found that the photocatalytic activity of Co/Ni-MOF-74@PDI was much higher than that of pure Co/Ni-MOF-74 and PDI. Subsequently, Co/Ni-MOF-74@PDI was used to activate H2O2 to further improve the degradation efficiency of chlortetracycline hydrochloride. It was found that the photocatalytic performance was greatly improved after the addition of 19.6 mM H2O2 to the system, and the degradation rate of chlortetracycline hydrochloride was 87% within 90 min. The electron transfer pathway and H2O2 activation mechanism of the Co/Ni-MOF-74@PDI composite photocatalyst were proved by free radical quenching experiments, electron paramagnetic resonance analysis and X-ray electron spectroscopy. Finally, the easy exfoliation point and degradation pathway of chlortetracycline hydrochloride were studied using density functional theory, UPLC-MS and toxicity evaluation software. It was found that the main active substances were h+, ˙O2, 1O2 and ˙OH, and the toxicity of chlortetracycline hydrochloride and its intermediates was evaluated. [ABSTRACT FROM AUTHOR]

In this paper, the water dissociation abilities of transition metals Cr, Co, Ni, Cu, and surface Cr incorporated into Co, Ni, and Cu matrix were estimated using density functional theory. The calculations indicate that the transition metal matrix can markedly affect the ability of surface Cr to promote H2O dissociation. The barriers of the H2O dissociation step on Cr, Co, Ni, and Cu increase in sequence. After introducing Cr into a transition metal matrix, the H2O dissociation ability of Cr reduces. Compared with pure metals, doping the Co surface with Cr is less favorable for H2O dissociation and introducing Cr onto Ni and Cu surfaces can accelerate the H2O dissociation reaction and Cr–Ni has stronger H2O dissociation ability than Cr–Cu. The electron distribution calculations show that the electron deviation levels from Cr to the metal matrix are a key factor in affecting the H2O dissociation ability of surface Cr, and strong electron deviation is advantageous. The adsorption calculations reveal that the OH-binding energy of catalyst cannot relate to its H2O dissociation ability and follows a rough volcano relationship with its alkaline HER performance. [ABSTRACT FROM AUTHOR]

Calix[8]arene has been used as a promising type of macrocyclic ligand for the construction of multinuclear metal-oxo clusters (MOCs), but not for zirconium/hafnium-oxo clusters (Zr/HfOCs). In this paper, we report the first series of ZrOCs (HfOCs) based on calix[8]arene: Zr4, Zr8, Hf4, and Hf8. Zr8/Hf8 has a rhombohedral conformation and can be regarded as a derivative of the octahedral Zr6 cluster. Remarkably, I2 adsorption experiments indicate that Zr4 (Zr8) adsorbs much faster than Hf4 (Hf8). Density functional theory (DFT) calculations show that metallic Zr atoms interact more strongly with I2 than metallic Hf atoms. The successful application of calix[8]arene for the synthesis of well-defined ZrOCs (HfOCs) shows a bright future for MOCs protected by macrocyclic ligands. [ABSTRACT FROM AUTHOR]

The development of productive and sustainable bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays an important role in the commercial evolution of metal–air batteries. In this paper, a low-temperature molten salt template method was adopted to synthesize the composite of CoS2 and nitrogen-doped carbon (CoS2/NC) without the protection of inert gas. The structural characterization studies show that the specific surface area (SSA) and crystal growth kinetics are increased and effectively improved, respectively, by the composite of CoS2 and NC. The as-synthesized CoS2/NC composite demonstrates outstanding bifunctional catalytic activity in alkaline electrolytes and exhibits a half-wave potential (E1/2) of 0.854 V (vs. RHE) and an overpotential of only 220 mV for the OER at a current density of 10 mA cm−2 (η10). Simultaneously, CoS2/NC also exhibits excellent electrochemical stability. Additionally, density functional theory (DFT) calculations have manifested that the synergistic effect of CoS2 and NC results in a remarkable enhancement in the bifunctional catalytic performance of the composite materials. This study offers a new pathway and theoretical guidance for the fabrication of efficient bifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

In this paper, a cyclic (CuIpz)3·CH3CN (1) precursor and a mixed-valence pentanuclear complex Cu I3 Cu II2 (OH)pz6·CH3CN (2) have been synthesized and structurally characterized by single-crystal X-ray diffraction, where pzH = 4-chloro-3,5-diphenylpyrazole. The excellent catalytic activity of 2 has been demonstrated in the chemical fixation of CO2 into value-added cyclic carbonates, which can be carried out at ambient pressure and room temperature along with ultra-high yield and perfect steric hindrance tolerance. Based on density functional theory (DFT) calculations and comparison with the catalytic performance of 1, it is proposed that the coordinatively unsaturated CuII atoms of 2 are probably the active sites for this catalytic reaction. [ABSTRACT FROM AUTHOR]

In this paper, the geometric structures and electron-optical properties of AlAs/GaS heterojunctions and Se-doped AlAs/GaS heterojunctions are calculated based on first-principles of density functional theory (DFT). At the same time, the influence of the AlAs layer's 5° rotation stacking method on the AlAs/GaS heterojunction is discussed. The results show that the AlAs/GaS heterojunction is a type-II van der Waals heterojunction (vdWH) with a direct bandgap of 0.974 eV, and the Z-scheme electron transfer mechanism is more conducive to the separation of photogenerated electrons and holes. Both semiconductor-to-metal transitions can be achieved by applying an external electric field and strain. Under the action of an external electric field and uniaxial strain, AlAs/GaS maintains the type-II energy band alignment throughout the process. When biaxial strain is applied, the heterojunction is accompanied by a direct–indirect bandgap transition. It is worth mentioning that the optical absorption of the AlAs/GaS heterojunction is significantly higher than that of the two monolayers, and the absorption range is wider. The above characteristics indicate that the AlAs/GaS heterojunction has wider applications in fields such as photodetectors. [ABSTRACT FROM AUTHOR]

Sensing nitroaromatic explosives has gained significant attention due to both increased terrorist threats and a need for environmental protection. In this regard, a fluorescent chemosensor, 1-benzyl-3,5-di(thiophen-2-yl)pyrazin-1-ium bromide (BTPyz), was synthesized and characterized via spectroscopic methods. The photophysical properties were investigated using absorption and emission spectral analysis. As a fluorescent chemosensor, BTPyz exhibited a selective response towards 2,4,6-trinitrophenol (TNP) with a detection limit of 11.6 nM and quenching constant (KSV) of 3.8 × 104 M−1. The fluorescence quenching mechanism was attributed to ground-state charge-transfer complex formation and resonance energy transfer, as evident from Uv-visible, fluorescence and NMR spectroscopy, single-crystal XRD studies, and density functional theory calculations. BTPyz was also employed for the contact mode detection of TNP on paper strips. The detection of TNP in real water and soil samples demonstrated BTPyz to be a promising detection tool toward environmental specimens. [ABSTRACT FROM AUTHOR]

In this paper, based on density functional theory (DFT), the adsorption and cracking mechanism of CH3OH on the Cu@CnB8 (n = 24, 40, 88) surface is studied. There are three possible paths of C–H, C–O and O–H for the initial cracking of CH3OH on the surface of Cu@CnB8. In this paper, the adsorption energy of CH3OH and intermediates on the Cu@CnB8 surface is calculated, and the related reaction energy and activation energy under the possible cracking path are calculated. The calculation results show that CH3OH is physically adsorbed on the Cu@CnB8 surface. The main path of CH3OH cracking is CH3OH → CH3O → CH2O → CHO → CO. The activity of CH3OH cracking decreases with the increase of Cu@CnB8 size, that is, the small size Cu@CnB8 can be used as an effective catalyst for the cracking of CH3OH. [ABSTRACT FROM AUTHOR]

Calcite is widely used in many fields. The synthesis of calcite is strongly influenced by solvents and additives. In this paper, the adsorption of water and formic acid molecules on the (104) surface of calcite was systematically studied on the atomic scale using the density functional theory (DFT) method. The results show that both molecules can be adsorbed on the calcite surface by occupying the top position of Ca. The results of differential charge density and the projected crystal orbital Hamiltonian population show that the adsorption is controlled by the charge transfer from the oxygen atom to the surface calcium. Formic acid has a carbonyl oxygen and it plays a greater role in stabilizing the surface than water. Moreover, the adsorption of two molecules can be further stabilized by hydrogen bonds formed between the hydrogen atom in the adsorbed molecules and the oxygen in calcite. This work provides a clear understanding of the stabilization of the calcite surface by adsorbing different molecules and also provides the possibility of tuning the synthesis of calcite by choosing a suitable solvent and additives. [ABSTRACT FROM AUTHOR]

In this paper, Mn2+-doped Rb4CdCl6 metal halide single crystals were prepared by a hydrothermal method. The Rb4CdCl6:Mn2+ metal halide exhibits yellow emission with photoluminescence quantum yields (PLQY) as high as 88%. Due to the thermally induced electron detrapping, Rb4CdCl6:Mn2+ also displays good anti-thermal quenching (ATQ) behavior with thermal quenching resistance (131% at 220 °C). The increase in the photoionization and the detrapping of the captured electrons from the shallow trap states were appropriately attributed to this exceptional phenomenon based on thermoluminescence (TL) analysis and density functional theory (DFT) calculations. The relationship between the fluorescence intensity ratio (FIR) of the material and temperature change was further explored using the temperature-dependent fluorescence spectrum. It was used as a temperature measuring probe based on absolute sensitivity (Sa) and relative sensitivity (Sb) with the change in temperature. The phosphor-converted white light emitting diodes (pc-WLEDs) were fabricated using a 460 nm blue chip with a yellow phosphor, which has a color rendering index (CRI = 83.5) and a low correlated color temperature (CCT = 3531 K). Because of this, finding new metal halides with ATQ behavior for high-power optoelectronic applications may be made possible by our findings. [ABSTRACT FROM AUTHOR]

Homo-valent diruthenium(II , II) carbonates have been underexplored hitherto. This paper reports the synthesis and crystal structure of a diruthenium(II , II) compound, Na4Ru2(CO3)4·10H2O (1). It has a two-dimensional structure in which the paddle-wheel diruthenium units of Ru2(CO3)44− are cross-linked through the carbonate groups. The investigation of the primary magnetic properties and theoretical studies with density functional theory (DFT) reveal that weak antiferromagnetic interactions are propagated between the Ru2 units which contain two unpaired electrons in an electron configuration σ2π4δ2π*2δ*2 with a ground state S = 1. According to Raman spectrum measurements combined with theoretical calculations, the strong peak at 356 cm−1 in the small-wavenumber region was assigned to the stretching of the Ru–Ru double bonds. [ABSTRACT FROM AUTHOR]

This paper reports fluorescein-linked calixarene-based columnar liquid crystals with a broad temperature range of mesophases. The photophysical and density functional theory (DFT) study suggested good electronic behaviour and reactivity of supramesogens. All the synthesized materials (4a–4d) were characterized by FT-IR, 1HNMR, 13C NMR, MALDI-TOF, and elemental analysis and displayed yellow to orange light emission in the solution, thin films, and solid state. Further, all materials showed aggregation-induced emission (AIE) effect with higher quantum yields. The fluorescein-linked supramolecules broadly stabilized the columnar hexagonal phase and formed self-assembly with higher thermal stability. The substituted alkoxy side chains on the terminal position influenced the mesophase temperature range and thermal stability. All the compounds adopted cone conformation, which was confirmed by experimental and computational studies. Further, these fluorescent materials were used to stain model organism nematodes in solution-state aggregation. [ABSTRACT FROM AUTHOR]

The use of industrial solid waste to produce a cement clinker can not only effectively reduce the consumption of natural resources, but also reduce the pollution of waste. In this paper, the solidification trend of Cr ions in the clinker phases of ordinary Portland cement (OPC) was studied by combining experiments with theoretical simulations. The results from energy dispersive spectrometry, X-ray diffraction, and density functional theory (DFT) simulations suggests that Cr ions will preferentially enter the mineral C4AF by displacing Fe ions. Further analysis of the bond length and bond order, electron density differences and partial density of states suggests that this phenomenon is mainly due to the similar electronic contributions of the host and guest ions. These insights will provide important fundamental guidance for understanding the doping behaviour of chromium ions in an OPC clinker and the utilization of Cr-containing industrial solid waste, thus paving an efficient way for the treatment of Cr-bearing industrial solid waste. [ABSTRACT FROM AUTHOR]

Cocatalysts are usually applied in the photocatalytic water splitting process to accelerate the kinetics of the hydrogen evolution reaction (HER). Specifically, the transition metal nitride (Mo2N) featuring a unique local surface plasmon resonance (LSPR) effect has exhibited great potential to function as a HER cocatalyst. However, the low metallicity of Mo2N hampers its ability to improve charge separation. To address this issue, transition metal atom doping (Co and Cu) engineering was used to modulate the electronic structure of Mo2N nanosheets to achieve a higher electrical conductivity and a lower hydrogen adsorption free energy (‖ΔGH*‖), thereby favoring the HER kinetics. Density functional theory (DFT) calculations and experimental results showed that Co-doping and Cu-doping mainly take place at Mo sites in the crystal structure of Mo2N to form stable structures of Co doped Mo2N (Co–Mo2N) and Cu doped Mo2N (Cu–Mo2N). Compared with pristine Mo2N, both Cu–Mo2N and Co–Mo2N demonstrated a much improved cocatalytic effect over g-C3N4 in promoting charge separation, accelerating HER kinetics and enhancing light absorption. The Co–Mo2N with the highest conductivity and lowest ‖ΔGH*‖ illustrated the best cocatalytic effect, and the H2 production performance (367.8 μmol g−1 h−1) of Co–Mo2N/g-C3N4 achieved was 10 and 5 times higher than those of Mo2N/g-C3N4 and Cu–Mo2N/g-C3N4. This paper provides significant guidance in the design and development of efficient cocatalysts for the HER application. [ABSTRACT FROM AUTHOR]

Carbazole-substituted N-heterocyclic carbene (NHC)–gold complexes have exhibited diverse structural features and interesting thermal properties. The role of the remotely linked carbazole group to mesoionic carbene in gold(I)–NHC complexes has been addressed in this paper. Thus, we have synthesized and characterized neutral gold–mesoionic carbene monomers tagged with carbazole groups. The mononuclear gold(I)–carbene complexes [(L1)AuCl] (1) and [(L2)AuCl] (2), where L1.HI = 1-(naphth-1-yl)-3-methyl-4-(carbazolylmethyl)-1,2,3-triazolium iodide and L2.HI = 1-(mesityl)-3-methyl-4-(carbazolylmethyl)-1,2,3-triazolium iodide, were synthesized and characterized. This new class of complexes exhibited interesting gold–hydrogen bonding. In addition, the thermal properties of 1 and 2 were investigated. Density functional theory (DFT) calculations and natural bond orbital (NBO) analysis were carried out on a model system, [(L′)AuCl] (1A), where L′ = 1-phenyl-4-methyl-carbazole-1,2,3-triazol-ylidene, to realize the bonding situations. The calculated metrics agreed reasonably well with the experimental observations. [ABSTRACT FROM AUTHOR]

The study of the carbon cycle is profound to the global ecosystem. In this paper, isotopic spectroscopy based on laser-induced breakdown spectroscopy (LIBS) was applied to the online detection of carbon isotopes and the study of atmospheric carbon cycle. The emission of carbon dioxide in the atmosphere was simulated by using a laser beam to ablate the coal, wood and paper samples. The emission spectra of smoke showed that carbon dioxide in the smoke could be detected online by the analysis of the molecular spectrum of the CN radicals. Then, taking urea as a carbon isotope sample, the isotopic shifts in the CN molecular spectra were clearly observed. The emission band of the (1,0) transition occurs red-shift of about 0.6 nm, while the emission band of the (0,1) transition appears blue-shift of about 0.8 nm. Furthermore, gaseous 13CO2 was directly detected by LIBS and the isotopic shifts in the CN bands from CO2 were also measured. Moreover, the energy differences in the isotopic shifts of the CN emission bands were calculated based on the density functional theory with the B3PW91/6-31+G(d) basis set, and the calculation results were basically consistent with the experimental values. Finally, the wavelength shifts for all the six different combinations of carbon and nitrogen isotopes were calculated. All the results indicate that the LIBS technique combined with an isotope spectrum is a promising and effective online detection method of gaseous carbon isotopes. [ABSTRACT FROM AUTHOR]

Herein, a colorimetric sensor (L) based on a naphthyl derivative bearing hydrazone receptors was synthesized via a one-step reaction process, and its recognition properties towards biologically important anions in an acetonitrile–water mixture were investigated by naked-eye observation and UV-Vis and 1H NMR spectroscopy. The molar addition of anions, such as TBAF−, TBAOH−, TBACN− and TBAAcO−, induced a significant red shift in the charge transfer band (Δλ = 73 nm, from 337 nm to 410 nm), in agreement with visible "naked eye" detectable colorimetric activities; in addition, soaked-in-L paper strips were prepared, which could significantly discriminate cyanide (KCN) and hydroxide (NaOH) ions dissolved in tap water via the litmus test method. This study was complemented by density functional theory computations to gain more insight into the interaction between L and anions. [ABSTRACT FROM AUTHOR]

In this paper, a novel Schiff base ligand NaHL (NaHL = sodium (S,E)-2-((4-chloro-2-hydroxybenzylidene) amino) propanoate) was designed and synthesized, and three novel complexes with Zn(II) were obtained by a solvent evaporation technique. Single crystal X-ray diffraction indicated that [Zn(L)(H2O)]n1 and [Zn(L)(H2O)]n2 were one-dimensional coordination polymers (CPs) with a helix structure, while [Zn2(L)2(bipy)] 3 was a two-dimensional CP with the participation of an auxiliary ligand. Fluorescence spectra exhibited that 1 and 2 had good fluorescence properties in both solution and solid states, but 3 was basically quenched due to the addition of ancillary ligands in the solid state. Density functional theory (DFT) calculations have been performed to further reveal the intrinsic fluorescence properties and mechanisms of 1 and 2, which demonstrated the chelate fluorescence enhancement effect (CHEF). Moreover, 1 and 2 show selective recognition of NH4+ and HPO42− accompanied by an efficient fluorescence "turn off" phenomenon, and a series of related experiments demonstrate that 1 and 2 were fully quenched through the removal of Zn2+ from the complex and the protonation of the ligand. [ABSTRACT FROM AUTHOR]

In this paper, eight complexes M-1, M-2, M-3 and M-4 (M = Ir or Rh) in the general formula [M(C^N)2(N^N)] (C^N = cyclometalated ligands and N^N = ancillary ligands) are systematically investigated by density functional theory (DFT) and time-dependent DFT methods. With the aim to study the influence of metal centers for nonlinear optical (NLO) responses, the geometrical and electronic structures, first hyperpolarizabilities (βtot) and UV-Vis absorption spectra are investigated in detail. It is found that the βtot values increase 1.8–3.7 times as the metal atom changes from Rh to Ir. Among all the studied complexes, Ir-3 (C^N = 4-chloro-2-phenylquinoline with N^N = 2,9-dimethyl-1,10-phenanthroline) shows the highest βtot value with an amplitude of 2415.4 a.u. computed at the ωB97XD/6-31G+(d)/SDD level, which can be seen as a promising candidate for second-order NLO materials. In addition, the HOMO energy levels increase upon increasing the size of the metal atom, which contributes to a significant reduction in HOMO–LUMO gaps. The βtot values and HOMO–LUMO gaps are in an inverse relationship. Furthermore, tuning the center metals Ir/Rh can be seen as an effective method to modulate the charge transfer degree. We anticipate that this study may serve as a new strategy for the rational design and synthesis of second-order NLO materials. [ABSTRACT FROM AUTHOR]

Hypochlorous acid (HOCl) is widely used in daily production and life because of its green and strongly oxidizing properties. Additionally, as a vital reactive oxygen species (ROS), it is an innate immune system weapon and performs a critical function in many pathophysiology processes. In this paper, a novel water-soluble fluorescent probe, BMH, with excellent performance is designed and synthesized by simple condensation of benzocoumarin and 2-mercaptoethanol. BMH has specific selectivity, excellent sensitivity, ultra-fast response (<3 s), and a wide pH detection range. The fluorescence intensity of BMH has an excellent linear correlation with the concentration of HOCl in the scope of 0–10 μM, and the calculated detection limit (DL) is 2.45 nM. The intramolecular charge transfer (ICT) sensing mechanism of BL has been verified by fluorescence, UV, and MS studies as well as density functional theory (DFT) calculations. Furthermore, BMH can be incorporated into a solid-state visual sensor to detect HOCl conveniently. BMH was applied to detect HOCl-spiked actual water samples and achieved satisfying recovery rates. Also, the low-toxicity BMH can be successfully used to track changes in endogenous/exogenous HOCl in living cells. In short, BL provides a robust and reliable monitoring tool to reveal the biological functions of HOCl and ensure its safe use. [ABSTRACT FROM AUTHOR]

In this paper, the mechanism of the deoxygenation of lignite model compounds in the aqueous phase under a CO atmosphere catalyzed by OH− ions was investigated at the M06-2X/6-311++G(d, p) level. The results revealed that for the deoxygenation of phenol, the activity of the H species follows H˙ > H− > H+, and the reaction of CO with OH− ions under aqueous conditions confirmed that H− is the dominating active species. The study of H− attacking carbon atoms at different positions on phenol indicated that deoxygenation via substitution to form benzene is preferred over hydrogenation via addition. The effect of the active species H− on the deoxygenation of the lignite model compounds phenol, benzenediols, and benzenetriols was also examined. This study provides valuable information for future research on lignite deoxygenation. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) was used to investigate the adsorption of twenty-four gases (SiH4, H2, Cl2, F2, CF4, CH4, CF2Cl2, N2, CHF3, OCS, N2O, AsH3, CH3Cl, COCl2, C2H2, C2H4, H2Se, H2S, PH3, COF2, CH3F, HCHO, (CH3)2O, and CH3NH2) on B12N12 and Al12N12 nanocages. Most of the studied gases are weakly (strongly) adsorbed on the B12N12 (Al12N12) nanocage. However, AsH3, H2Se, H2S, PH3, CH3F, HCHO, (CH3)2O, and CH3NH2 are strongly adsorbed on the B12N12 nanocage and H2, F2, CF4, CH4, and CF2Cl2 are weakly adsorbed on the Al12N12 nanocage. The most negative-valued molecular electrostatic potential (MESP) minimum (Vmin) corresponds to the electron-rich region (e.g., lone pair and π-bond) in the molecule. An important observation is that the adsorption energies of the gases on the B12N12 and Al12N12 nanocages are well correlated with the MESP Vmin values of the gases. Substantial changes are found in the DFT reactivity indices like chemical potential and hardness of the B12N12 and Al12N12 nanocages, mainly due to the strong gas adsorption. The quantum theory of atoms in molecules analysis suggests the covalent nature of interactions only in the AsH3/B12N12, H2Se/B12N12, H2S/B12N12, and PH3/B12N12 systems. [ABSTRACT FROM AUTHOR]

Because of their unique physicochemical integration mode, energetic host–guest solvates provide a balanced method to expand CL-20 high explosives. CL-20/hydrogen peroxide (H2O2) energetic solvates maintain their detonation performance by combining H2O2 molecules into a lattice akin to hydrate CL-20/H2O solvate (α-CL-20). Herein, using periodic density functional theory (DFT) calculation and molecular dynamics simulation, the structural evolution and intermolecular interaction mechanism of orthorhombic CL-20/H2O2 (o-CL-20/H2O2), monoclinic CL-20/H2O2 (m-CL-20/H2O2) and CL-20/H2O solvates were monitored by the vibrational spectrum and vibrational density of states (VDOS) in the THz region when the temperature was increased from 298 K to 558 K. There was greater similarity in the vibrational characteristics of THz spectra for o-CL-20/H2O2 and CL-20/H2O solvates that was supported by the thermal expansion anisotropy of lattice parameters and that of difference for the m-CL-20/H2O2 solvate. With increased temperature, spectral signals in the power spectrum of VDOS reflected the conformational evolution of CL-20 molecules in o-CL-20/H2O2 solvate and structural insensitivity of m-CL-20/H2O2 solvate. THz peaks of CL-20/H2O revealed the weakening of intermolecular interactions of CL-20 and H2O molecules, which were in agreement with the fact that H2O molecules more easily escape from host–guest solvates, whereas the H2O2 molecule was restricted in a cage of CL-20 molecules for the m-CL-20/H2O2 solvate. RDF and hydrogen bond (H-bond) interaction analyses were performed to further clarify stronger intermolecular H-bond interactions in the o-CL-20/H2O2 solvate as compared to that of the other two combined with H2O2 or H2O solvates. This finding introduces new insights into clarifying the formation mechanism of hydroxide with CL-20-based energetic host–guest solvates. [ABSTRACT FROM AUTHOR]

A novel, one-pot, three-component coupling (3-CCR) reaction of aromatic aldehydes, β-naphthol, and 6-amino-1,3-dimethyl uracil in a deep eutectic solvent (DES) has been developed as a highly efficient and selective method for the expedient synthesis of the densely functionalized 8,10-dimethyl-12-phenyl-8,12-dihydro-9H-benzo[5,6]chromeno[2,3-d]pyrimidine-9,11(10H)-dione framework in synthetically pleasing yield. The devised protocol adeptly harnesses the versatility of DESs, resulting in a straightforward, cost-effective, resilient, and environmentally sustainable synthetic approach. The resulting cascade adduct exhibits noteworthy antiproliferative activity against a variety of cancer cell lines, thereby showing promise as a potential anticancer drug candidate for breast and hepatocellular carcinoma with moderate to good IC50 values. The most potent compounds in the synthesized library, 4m and 4l, exhibit highly potent cytotoxicity against HepG2 and MCF7 cancer cell lines, with notable IC50 values of 46.39 and 28.21 μM, respectively. The present findings are corroborated by computational and molecular docking studies. The density functional theory (DFT) calculations underscore the pivotal role of the naphthyl ring in orchestrating the success of this intricate domino process in delivering the anticipated scaffolds in reasonable yields. [ABSTRACT FROM AUTHOR]

Potassium europium molybdate, KEu(MoO4)2, is an intriguing material known for its efficient luminescence properties attributed to Eu3+ ions and its polymorphic nature. Despite its significance, research on the metastable γ-phase has been limited, with no prior reports on its structure, particle morphology, and luminescence characteristics. In this study, both the stable α-phase and the metastable γ-phase of KEu(MoO4)2 were synthesized using solid-state and hydrothermal reaction methods, and their crystal structures, particle morphologies, and luminescence properties were comprehensively investigated. X-Ray diffraction analysis confirmed the formation of the triclinic α-phase and the orthorhombic γ-phase, with factor analysis results consistent with theoretically optimized structures, facilitating accurate structural determination. Both phases exhibited typical photoluminescence (PL) spectra of Eu3+ ions. However, in the γ-phase, the 5D0 → 7F2 transition appeared as a non-split peak with minimal Stark effect, attributed to differences in structural symmetry between the phases. A red-shift in the PL excitation edge was observed in the α-phase, which was attributed to a narrowed band gap resulting from the broadening of the O-p orbital in the valence band, as indicated by density functional theory (DFT) calculations. Additionally, KEu(MoO4)2 was doped with Y3+ ions to form K(Eu,Y)(MoO4)2, revealing a solid solubility limit of 40% in the α-phase, while the γ-phase displayed no solid solution limit. The estimated critical distance of Eu3+ ions suggested that Eu–Eu interactions contributing to concentration quenching are minimal in the stacking direction but significant in the in-plane direction, operating in the second shell. [ABSTRACT FROM AUTHOR]

A combined density functional theory (DFT) and microkinetic model (MKM) based approach is applied to design Pd-based A3B type bimetallic alloys – Pd3Cu, Pd3Ag and Pd3Au for hydrodechlorination (HDC) reaction of 4-chlorophenol (4-CP). The DFT results predict that the binding energy trend of 4-CP is Pd3Cu (111) [−257 kJ mol−1] > Pd (111) [−165 kJ mol−1] > Pd3Au (111) [−151 kJ mol−1] ≈ Pd3Ag (111) [−151 kJ mol−1]. The adsorbed 4-CP then undergoes C–Cl bond dissociation followed by hydrogenation to form phenol. Of all the surfaces, Pd3Ag (111) exhibits the least activation barrier for Cl dissociation from 4-CP (44 kJ mol−1), followed by Pd3Au (111) (66 kJ mol−1), Pd (111) (71 kJ mol−1) and Pd3Cu (111) (76 kJ mol−1) surfaces. The DFT generated data are utilized to construct an ab initio microkinetic model to calculate the turnover frequencies (TOFs) of 4-CP HDC. The Pd3Ag (111) surface displays the highest TOF, which could be attributed to the ease of Cl dissociation from the 4-CP molecule. However, the low TOF over the Pd3Cu (111) surface could be due to surface poisoning as a result of high 4-CP binding energy on the surface. For the C–Cl bond dissociation step, a positive degree of rate control is observed, which suggests that this step is crucial in ascertaining the HDC rate. [ABSTRACT FROM AUTHOR]

The frustrated Lewis pair (FLP) adducts PB{ECl2} (PB = iPr2P(C6H4)BCy2; Cy = cyclohexyl; E = Si, Ge) were used to access a bis(alkynyl)-functionalized silylene and a germylene; the goal behind preparing these species was to obtain new unsaturated main group polymers [E(C≡CSiMe3)2]n upon heating. While the silylene adduct PB{Si(C≡CSiMe3)2} was stable up to 150 °C, the heavier element congener PB{Ge(C≡CSiMe3)2} underwent a complicated rearrangement process accompanied by Cy-group migration and Ge(II)-alkyne coordination. Density functional theory computations were performed to understand the mechanistic pathway for the unusual rearrangement of PB{Ge(C≡CSiMe3)2}. [ABSTRACT FROM AUTHOR]

A series of charge transfer cocrystals with fluorescence properties involving 1,2,4,5-tetracyanobenzene (TCNB, C10H2N4) as acceptor, fluorene (FR, C13H10) and its bromide 2-bromofluorene (2-BrFR, C13H9Br), carbazole (CZ, C12H9N) and its bromide 2-bromocarbazole (2-BrCZ, C12H8BrN) as donor were synthesized via cocrystal design strategies. The formation mechanism of the crystal structure was explored by density functional theory at the molecular level. The stacking structure of the cocrystal was formed by the combination of charge transfer interactions, π–π interactions and hydrogen bonding. The N atom of donors in TCNB–CZ and TCNB–2-BrCZ could enhance the charge transfer, appearing as a red shift of the fluorescence emission wavelength. Conversely, the Br atom in TCNB–2-BrFR and TCNB–2-BrCZ weakens the charge transfer, giving a blue shift in the fluorescence emission spectrum. The four new cocrystals exhibit tunable luminescence from green (529 nm) to yellow (552 nm) and to red (604 nm and 614 nm). It was found that the introduction of N and Br atoms in the assembly units can not only regulate the luminescence range of the cocrystals, but also adjust the luminescence efficiency, which provides a strategy for the development of promising organic luminescent materials. [ABSTRACT FROM AUTHOR]

The global market of fossil carbon-derived adipic acid (AA) was over 3 million tons in 2022, emitting 3.1 million tons of the potent greenhouse gas N2O. Alternative biomass-derived feedstocks offer a sustainable option to replace fossil carbon, but alternative pathways for AA synthesis are also required to curb the substantial emissions associated with the process. A novel and sustainable approach to synthesize AA is by coupling biomanufacturing and electrocatalysis. Biologically-produced cis,cis-muconic acid (ccMA) from sugars and lignin monomers has recently gained significant attention as a precursor to AA, as it can be electrochemically hydrogenated to AA using water-derived (instead of fossil-derived) hydrogen and electricity generated from wind energy. For the first time in literature, we demonstrate appreciable electrochemical production of AA using supported palladium nanoparticles. The performance of this system contrasts with that of palladium foil or platinum-based catalysts, which produced little AA. Density functional theory calculations on model surfaces of palladium and platinum suggest that the reduction of ccMA to trans-3-hexenedioic acid occurs through an outer sphere proton-coupled electron transfer mechanism, while subsequent reduction to AA preferentially occurs on surface terrace sites. Our calculations also explain the exceptional performance of palladium nanoparticles compared to palladium- and platinum-based foils, attributing the more favorable activation energy barriers found on palladium terraces to the relatively moderate binding strength of adsorbed species. These results suggest structure-sensitive catalyst design strategies that maximize the exposure of terrace atoms for further improvement of the ccMA electrochemical hydrogenation process. [ABSTRACT FROM AUTHOR]

To overcome the limitations of the Fe(II)-activated percarbonate process for ACT removal, this study introduced cysteine as a complexing agent into the Fe(II)/SPC system and enhanced the degradation efficiency of ACT. Investigations were conducted on the effects of pH, temperature, common anions (Cl−, HCO3− and NO3−) in the water column, and humic acid (HA) on the degrading efficiency of the Cys/Fe(II)/SPC system. The results showed that under ideal conditions, 99.9% removal of ACT at 0.05 mM could be achieved. Alkaline environments inhibited ACT degradation, whereas acidic environments promoted it. Electron paramagnetic resonance (EPR) successfully detected ˙OH and O2˙−, but no 1O2 radical signal was detected. Further research was carried out to determine how much ˙OH and O2˙− contributed to the oxidation process. The results showed that both ˙OH and O2˙− contributed to the degradation of the ACT, with ˙OH's contribution being particularly significant. Mass spectrometry analysis was used to determine the structure of the oxidation products. Vulnerable sites in ACT were predicted using density functional theory. Using LC-MS/MS analysis, seven intermediates of the Cys/Fe(II)/SPC degradation of ACT were individually identified. The results showed that the acetylamino group on ACT and the C–N bond on the benzene ring are susceptible to attack by ˙OH. The T.E.S.T. toxicity prediction model was used to predict the toxicity of ACT and its intermediates. The results showed a trend towards reduced acute toxicity and overall developmental toxicity. [ABSTRACT FROM AUTHOR]

The structural and conductive properties of the synthetic tychite Na6Mg2(CO3)4SO4 (space group: Fd3¯) were explored. Optimal synthesis parameters were selected by varying the molar ratio of reagents, synthesis temperature and time. For structural descriptions, we carried out scanning electron microscopy, thermal analysis, and Raman and Fourier-transform infrared spectroscopy. We carried out theoretical and experimental studies of conductivity. Theoretical calculations were obtained using geometrical-topological analysis based on Voronoi partitioning (the evaluation of geometrical sizes of voids and channels), the bond valence site energy (BVSE) method (the fast calculation of migration energies, Em), kinetic Monte Carlo simulation (the estimation of ionic conductivity at different temperatures), and density functional theory (the precise assessment of Em and vacancy formation energies). The experimental techniques included electrochemical impedance spectroscopy EIS (total conductivity determination) and direct current DC polarization (electronic conductivity assessment) measurements. Na6Mg2(CO3)4SO4 was found to have a three-periodic Na+-ion migration map with an Em of 0.37 eV and 0.18 eV from BVSE and DFT results, respectively. The theoretical value of cationic conductivity was 2.6 × 10−7 S cm−1 at 100 °C. The experimental total conductivity was equal to 6.0 × 10−7 S cm−1 at 100 °C, which is close to theoretical results. Using additional DC polarization, the electronic contribution to the total conductivity was characterized as insignificant. [ABSTRACT FROM AUTHOR]

Metalloviologens, as emerging electron-transfer photochromic compounds, have shown intriguing properties such as radiochromism, photochromism and photoconductance. However, only a limited number of them have been reported so far. Exploration of new metalloviologens is strongly desired. Herein, we report a new solvothermally synthesized metalloviologen complex [CdCl2(ND)2]n (1, ND = 1,5-naphthalenes) that exhibits photochromic and intrinsic white light emission properties. Density functional theory calculation results reveal that the photochromism could be assigned to photoinduced electron transfer from chlorine atoms to ND molecules. The photoinduced charge-separated states are heat/air stable, attributed to the delocalization of ND and strong intermolecular π–π interactions. Besides, complex 1 consistently emits intrinsic white light when excited with 340–370 nm UV light, achieving high color rendering index (CRI) values (82.54–94.04). By adjusting the excitation wavelength, both "warm" and "cold" white light emission can be produced, making it suitable for the application of a white light emitting diode (WLED). Thus, this work demonstrates that the ND-based metalloviologen is not only helpful in producing photochromism, but also beneficial for creating white-light emission. [ABSTRACT FROM AUTHOR]

Lead-free inorganic perovskites have attracted intensive attention in the field of photodetectors owing to their high stability, non-toxicity, and remarkable photoelectric characteristics. Herein, we designed and developed a series of thus-far unreported lead-free all inorganic perovskite single crystals, K7Bi3X16 (X = Cl, Br). In particular, we resorted to cooling crystallization and intercalated K+ to inorganic Bi–Br and Bi–Cl frameworks as inorganic A-site cations, obtaining zero-dimensional (0D) K7Bi3X16 (X = Cl, Br) perovskite single crystals, which display suitable bandgaps, excellent electron mobility and low trap-state density, as analysed by experimental characterization and density functional theory (DFT) calculations. Accordingly, the vertical structure K7Bi3Br16 photodetector can achieve a fast ON/OFF switch under the irradiation of 395 nm light. When the light intensity is 5 mW cm−2 and the voltage is 3 V, the responsivity is calculated to be 0.052 mA W−1. The above characteristics make K7Bi3Br16 a promising material for fabricating ultraviolet photodetectors. [ABSTRACT FROM AUTHOR]

The quantitative structure-property relationship (QSPR) of constrained geometry catalysts (CGCs) has been analyzed by combining density functional theory (DFT) and multivariate linear regression (MLR). QSPR models for determining the reaction energy barriers of ethylene and 1-octene and molecular descriptors were established and validated with a testing set. At the initiation stage, the quaternary QSPR models for ethylene and 1-octene feature R² values of 0.90 and 0.82, respectively, while the corresponding leave-one-out Q² values for ethylene and 1-octene are determined to be 0.82 and 0.69. Using the generated QSPR models, the electronic effect was proven to be more critical for determining the energy barriers of ethylene and 1-octene insertion processes. At the propagation stage, the quaternary QSPR models for ethylene and 1-octene feature R² values of 0.97 and 0.96, respectively, while the corresponding leave-one-out Q² values for ethylene and 1-octene are determined to be 0.93. Particularly, the impact of the steric effect on the energy barriers of ethylene and 1-octene insertion is more pronounced. Furthermore, the correlation between the corresponding energy barriers and experimental activities with three series of CGCs was discussed, which revealed that theoretical calculations are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

A metal-free one-pot cascade process involving reduction of nitroarenes, cyclization, and sequential hydrogenation of imines with B2cat2 and water was developed to construct dihydroquinoxalinones and tetrahydroquinoxalines directly from readily available 2-nitroanilines or o-dinitrobenzenes with α-ketoesters and a-diketones. This strategy provides various dihydroquinoxalinones and tetrahydroquinoxalines in good to excellent yields and tolerance to many functional groups. Mechanism studies by control experiments and density functional theory (DFT) calculations show that this cascade procedure involves the deoxygenative reduction of nitroarenes, the Maillard reaction, and hydrogenation to produce dihydroquinoxalinones and tetrahydroquinoxalines. This method aims to reduce the environmental impact while maintaining high yields and selectivity for both nitroarene reduction and the synthesis of dihydroquinoxalinones and tetrahydroquinoxalines. [ABSTRACT FROM AUTHOR]

Density functional theory plus Hubbard U (DFT+U) methodology was used to calculate the structures and energetic landscapes of CeSiO4, including its stetindite and scheelite phases from ambient pressure to ~24 GPa. To ensure accurate simulations of the high-pressure structures, assessments of strain-stress methods and stress-strain methods were conducted in prior, with the former found to have a better agreement with the experimental result. From DFT calculations the equation of states (EOS) of both stetindite and scheelite were further obtained, with the fitted bulk moduli being 182(2) GPa and 190.0(12) GPa, respectively. These results were found to be consistent with the experimental values of 177(5) GPa and 222(40) GPa. Furthermore, the calculated energetics suggest that the stetindite structure is more thermodynamically stable than the scheelite structure at a pressure lower than 8.35 GPa. However, the stetindite → scheelite phase transition was observed experimentally at a much higher pressure of ~15 GPa. A further phonon spectra investigation by the density functional perturbation theory (DFPT) indicated the Eg¹ mode is being softened with pressure and becomes imaginary after 12 GPa, which is a sign of the lattice instability. Consequently, it was concluded that the stetindite → scheelite transition is predominantly initiated by the lattice instability under high-pressure. [ABSTRACT FROM AUTHOR]

The electrochemical selective oxidative transformation of lignin feedstocks into valuable oxygenated aromatics is essential to establish a sustainable biorefinery. In this study, we used a rhombohedral ZnIn2S4 (R-ZIS) electrocatalyst to realise the efficient anodic cleavage of C-O bonds in benzyl phenyl ether (BPE), an a-O-4 lignin model compound, to a series of industrially relevant oxygenated mono-aromatics. The reaction occurred at +2 VAg/AgCl, 65 °C, and atmospheric pressure. In optimised conditions, the reaction achieved over 99% conversion rate with a Faraday efficiency of 51.6% at 91.3% conversion of BPE, that is greater than most known electrocatalytic oxidative cleavage examples. The ZnIn2S4 electrocatalyst was deposited on a carbon cloth support, and its structural properties and surface morphology were extensively investigated. Systematic potential controlled electrolysis coupled with 18O isotopic labelling confirmed that C-O scission occurred exclusively between the benzylic carbon and phenolic oxygen. Furthermore, substrate competition studies were conducted to compare the electrocatalytic performance of the R-ZIS catalyst with that of its structural analogue, hexagonal ZnIn2S4, in terms of BPE and monoaromatics conversion. The experimental results were supported by density functional theory calculations. The substrate scoping study revealed the suitability of the R-ZIS induced electrocatalytic system for a variety of substituted a-O-4/ß-O-4 model dimers. Overall, this work demonstrates an efficient anodic process that can enable the atom-efficient valorisation of lignin to produce oxygenated aromatics. The proposed approach can complement the numerous existing reductive lignin cleavage methods. [ABSTRACT FROM AUTHOR]

Halogenated nitroarenes' hydrogenation on metal-based catalysts without dehalogenation to synthesize halogenated amines is a research challenge. Herein, using a covalent organic framework (COF) as a support and benefiting from strong metal-support interactions (SMSIs), ultrafine Pt nanoparticles were successfully anchored on a polyimide-based covalent triazine framework, to construct an electron-rich Pt active site-based catalyst (Pt/TAPT-COF). The electronic regulation from the COF contributed to both the selective hydrogenation of halogenated nitrobenzenes and the tandem hydrogenation-coupling reaction of halogenated nitrobenzenes with aldehyde compounds to synthesize halogenated amines with high selectivity under mild reaction conditions. According to density functional theory calculations, the hydrogenation of halogenated nitrobenzene is exothermic with strengthened absorption, confirming the existence of SMSIs to explain the high activity of Pt/TAPT-COF in hydrogenation reactions. Thus, this work provides a facile strategy to fabricate an electron-rich Pt-based catalyst enabled by SMSIs to selectively catalyze the synthesis of halogenated anilines and halogenated secondary amines. [ABSTRACT FROM AUTHOR]

The development of highly efficient and environment friendly methods for arsenic pollution treatment has attracted special attention. Herein, a new polyoxometalate-thiacalix[4]arene-based metal-organic complex [Ag2L(HL)][PW12O40]·2C2H5OH·2CH3CN (1) (L = thiacalix[4]arene-based ligand) was synthesized and applied for BiVO4 (BVO) surface modification to efficiently enhance the simulated sunlight-driven photoelectrocatalytic oxidation of arsenic(III). Compared with the pristine BVO, the removal efficiency of arsenic(III) was drastically increased to 312% at 0.6 V with the optimized 1@BVO photoanode (B1-20) versus the saturated calomel electrode (SCE) under the simulated sunlight (100 mW cm-2). The removal efficiency of arsenic(III) (25 mg L-1) with B1-20 was up to 100% within 40 min with a faradaic efficiency of 45%. More importantly, electron spin resonance measurements and reactive species trapping experiments demonstrated that the Z-scheme heterojunction formation of 1 plays a key role in the enhanced photoelectrocatalytic performance of 1@BVO. Furthermore, density functional theory (DFT) calculations were used to investigate the relationship between the photoelectrocatalytic properties and the structure of 1. This work developed a new photoelectrocatalytic application for the polyoxometalate-thiacalix[4]arenebased metal-organic complexes by their efficient combination with BVO. [ABSTRACT FROM AUTHOR]