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It is significant to develop low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we constructed P-doped NiCo2S4 nanowire arrays on carbon fiber paper (NiCo2S4−xPx/CFP) as a HER electrocatalyst in both acidic and alkaline media. Benefitting from P doping into NiCo2S4, the as-prepared NiCo2S4−xPx/CFP exhibits low HER overpotentials of 80 and 132 mV in acidic and alkaline media at a cathodic current density of 10 mA cm−2, respectively, which are far superior to counterparts of NiCo2S4 nanowire arrays on the carbon fiber paper (NiCo2S4/CFP). Meanwhile, the NiCo2S4−xPx/CFP presents excellent HER stability of 20 hours in acidic and alkaline media. From the results of density functional theory calculations, P doping can not only optimize the hydrogen adsorption energetics on each kind of atomic site of catalysts, but also strengthen the H2O molecule binding ability on the catalyst surface for the alkaline HER and favor kinetics of hydrogen adsorption and H2 formation on the catalyst surface for the acidic HER, eventually improving overall HER performances. The investigation of the HER mechanism modulated by P doping in our work offers novel inspiration to develop highly efficient ternary metal sulfides for the HER. [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]

In this paper, the geometric configuration, electronic properties, and optical characteristics of an InS/GaTe heterojunction have been computed using the foundational principles of density functional theory. The analysis indicates that when the interlayer distance is 3.88 Å, the binding energy is the most negative, indicating that the structure is the most stable. The bandgap of the two monolayers is larger than that of the heterojunction, which makes the photogenerated electrons of the heterojunction more easily excited. The InS/GaTe heterojunction is a type-II heterojunction that enhances the efficient dissociation of electron–hole pairs. In addition, the InS/GaTe heterojunction demonstrates strong absorption of ultraviolet light, rendering it suitable for applications in ultraviolet detectors and related fields. Furthermore, the bandgap electron transfer direction of the InS/GaTe heterojunction can be controlled by applying electrical force and mechanical pressure. The optical absorption coefficient of the InS/GaTe heterojunction can be adjusted to modify its optical properties. Finally, the possible future applications of the InS/GaTe heterojunction are discussed. [ABSTRACT FROM AUTHOR]

This paper evaluates the effect of different synthesis conditions on the structural properties of the porous metal–organic frameworks MIL-53(Al) produced by the microwave method at different reaction temperatures (120, 150, and 180 °C) and times (30, 180 min). The morphologies, chemical contents and crystal structures of the synthesized samples were determined by the SEM-EDS and XRD methods, respectively. The structural properties of MIL-53(Al)s were analysed according to isotherm data obtained from nitrogen gas adsorption by applying the Brunauer–Emmett–Teller (BET), Langmuir, Dubinin–Radushkevich (DR), t-plot, Barrett–Joyner–Halenda (BJH) and quenched solid density functional theory (QSDFT) methods, as well as the new numerical clustering-based adsorption analysis (LBET) method, which is a unique numerical method that provides advanced assessment for porous structures. The LBET analysis showed that the MIL-53(Al) sample at a reaction temperature of 180 °C for 30 min has the best adsorption properties, with the highest volume of the first adsorbed layer and the highest value of the energy parameter for higher layers. Due the LBET method, it was possible to evaluate the porous structure of the MIL-53(Al) samples with high precision and reliability, and thus to determine the precise influence of the conditions of their preparation on the formation of their structure. In turn, based on the shapes of the pore size distributions (PSD), the materials analysed have very similar PSD, with only the MIL-35(AL)S1 sample having a significantly lower PSD height. In conclusion, attention was paid to the necessity of complex evaluation of adsorbent properties, taking into account not only their adsorption properties but also their mechanical and functional properties, as well as production costs and the impact of adsorbent production and utilization on the environment. [ABSTRACT FROM AUTHOR]

The strong metal–support interactions (SMSI) between metal and its support have been regarded as a valid approach to enhance the catalytic performance; however, the extent to which exploration of electronic state regulation affects catalytic performance of alcohol oxidation reactions (AOR) has been rarely reported. In this paper, PdAg nanoparticles loaded on a N-doped carbon substrate with controlled nitrogen content (PdAg@NxC, x representing the nitrogen contents) was synthesized through a seeded synthesis strategy for alkaline AOR. Results show that the electronic state of PdAg nanoparticles was significantly modified after nitrogen doping in the carbon support. Experimental and theoretical results indicate that with increasing nitrogen content, the degree of electronic state regulation becomes increasingly significant. Density functional theory (DFT) calculations suggest that the increased degree of SMSI promotes OH* adsorption on the PdAg surface and weakens the binding between catalyst and CO*. As a result, the PdAg@N15.3C with the highest N content exhibits excellent AOR performance, achieving a MA/SA of 10.8 A mgPd−1/13.2 mA cm−2 and 3.8 A mgPd−1/4.7 mA cm−2 on the EOR and MOR, respectively. Moreover, due to the changes in the adsorption energy of key intermediates on PdAg nanoparticles, the onset oxidation potential of PdAg@N15.3C shows a negative shift of 180 mV compared to PdAg@C as revealed by CO stripping analysis, signifying an increase in the CO tolerance. Our study demonstrates the influence of the SMSI effect between the active center and the support on the catalytic performance for AOR and presents a pathway to achieve high AOR performance through SMSI engineering. [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]

Copper in vegetables can enter the human body, and excessive copper may cause uncomfortable symptoms; thus, it is urgent to test copper ions for safety concerns. Herein, we prepared Zn2GeO4:Mn2+,In3+ (ZGO:Mn,In) persistent luminescent nanoparticles (PLNPs) and then grafted glutathione for the determination of copper ions. ZGO:Mn,In was prepared by doping In3+ in ZGO:Mn to improve the emission at 532 nm under excitation at 258 nm. The doping amount, temperature, time, and pH were carefully optimized for a stronger emission intensity than ZGO:Mn. The fractional densities and energy band gaps were calculated by density functional theory, revealing the excitation enhancement mechanism of ZGO:Mn,In. The surface of ZGO:Mn,In was modified with carboxyl groups for linking glutathione to specially identify Cu2+ ions. The identification resulted in the aggregation-induced quenching of PLNPs' emission. Thus, the sensor exhibited good selectivity for copper ions, and the composite was successfully applied to the detection of copper ions in serum and vegetable samples. [ABSTRACT FROM AUTHOR]

Generally, thiophene/benzene-fused π-conjugated systems have been the go-to core units for enhancing the electrical conduction and charge transport characteristics of 2D hole-transporting materials (HTMs). However, while thiophene-fused units have been extensively studied, the investigation into benzene-fused π-conjugated cores has been relatively limited. In order to explore the untapped potential of benzene-fused π-conjugated systems in HTMs, we have designed three new molecules utilizing polycyclic triphenylene, pyrene and perylene as core units. These molecules were then simulated using density functional theory in conjunction with the Marcus theory of electron transfer. Our findings reveal that the highest occupied molecular orbital (HOMO) levels of these newly developed HTMs are 0.14–0.29 eV lower compared to Spiro-OMeTAD, a commonly used HTM, potentially leading to an increase in the open circuit voltage of solar cell devices. Additionally, the enhanced electronic interaction between neighboring molecules and lowered reorganization energies contribute to high hole mobilities, measured at 5.08 × 10−3 cm2 V−1 s−1, 7.38 × 10−3 cm2 V−1 s−1 and 9.31 × 10−1 cm2 V−1 s−1, respectively. Furthermore, these new molecules exhibit weak visible light absorption and significant Stokes shifts, both of which are advantageous for HTM performance enhancement. Overall, our calculations suggest that these benzene-fused π-conjugated core molecules are promising as HTM candidates, paving the way for more effective solar cells. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) possess a wide range of functionalities due to their highly tunable chemical, physical, and electronic properties. In this study, we systematically explore the structural, electronic, and phonon characteristics of six TMD systems using density functional theory (DFT) simulations. Our analysis covers both the semiconducting (2H) and metallic (1T) phases of these TMD systems. Specifically, we investigate group-V TMDs (AB2, where A = Nb, Ta, and B = S, Se, Te), examining their structure–property relationships and electronic behaviors to validate the accuracy of various exchange–correlation (XC) functionals, including van der Waals density functionals (vdW-DFs). Our calculations account for both spin–orbit coupling (SOC) and non-SOC (NSOC) scenarios. The results reveal significant impacts on vdW gaps, lattice parameters, and electronic band structures in both the 2H and 1T phases, highlighting their potential for conventional applications. [ABSTRACT FROM AUTHOR]

In this study, red mud (RM), an industrial waste, was used as a raw material to prepare a novel red mud-based Co3O4–Fe2O3–Co2AlO4 (Co–Fe/RM) catalyst using a simple solid-phase method, and lomefloxacin hydrochloride (LOMH) was degraded by using Co–Fe/RM to activate peroxymonosulfate (PMS). The optimum preparation conditions of the mass ratio of Co(NO3)2·6H2O to RM, calcination temperature and calcination time were 1.5 : 1 (1.5 g of Co(NO3)2·6H2O and 1 g of RM), 700 °C, and 2 h, respectively. The characterization results showed that Fe2O3, Co3O4 and Co2AlO4 were the main active components in Co–Fe/RM, and Co–Fe/RM could expose more reaction sites compared with RM. The Co–O–Al bonds that existed on the Co–Fe/RM could facilitate the redox cycle between Co(II) and Co(III), thus improving the Co–Fe/RM catalytic activity. For 10 mg L−1 LOMH solution with a volume of 100 mL, the maximal removal ratio of LOMH (89.3%) was obtained at 20 min under the optimal parameters (0.3 g L−1 Co–Fe/RM dosage, 1 mmol L−1 PMS concentration, initial pH 5.5, and 30 °C of reaction temperature) in a Co–Fe/RM/PMS system. The trapping experiments proved that SO4˙−, 1O2 and O2˙− dominated the degradation of LOMH, and a possible catalytic mechanism of activating PMS using the prepared catalysts was proposed. For LOMH in the Co–Fe/RM/PMS system, degradation pathways were analyzed via density functional theory (DFT) calculations and liquid chromatography–mass spectrometry (LC–MS). A toxicity estimation software tool (TEST) and the Chlorella pyrenoidosa cultivation experiment were used to evaluate the biological toxicity of the treated LOMH solution. The recycling experiments found that the Co–Fe/RM had distinguished reusability and excellent stability. The mineralization assessment showed that organic carbon contents could be effectively diminished in the treated LOMH solution. This study provided a viable way for the beneficial use of RM to activate PMS and offered a low-cost and efficient catalyst for the degradation of pollutants in wastewater. [ABSTRACT FROM AUTHOR]

The helix preferences of cyclopentane-containing β/γ-hybrid oligomers, consisting of alternating βAc5a (2-aminocyclopentanecarboxylic acid) and γ(Et)Ac5a [2-(2-aminocyclopentyl)butanoic acid] residues with homochiral S-configurations, were investigated through conformational searches and density functional theory calculations in chloroform. The β/γ-hybrid dimer exhibited a distinct inclination toward a ribbon-like structure characterized by alternating C8 and C9 H-bonds. However, for β/γ-hybrid oligomers longer than tetramer, a preference for a right-handed (P)-2.413-helical structure emerged. The robust stabilities observed for the H13 helical structures in chloroform were attributed to the favored solvation free energies, which increased with the length of the peptide sequence. Calculations revealed that the mean backbone torsion angles of the H13 helix foldamer in the β/γ-hybrid pentamer closely resembled those observed in X-ray structures of the pentamer consisting of βAc5a and a γ-residue with a cyclohexane substituent. The introduction of cyclopentane substitutions led to distinct conformational preferences and/or handedness of helix foldamers compared to those of the unsubstituted β/γ-hybrid oligomers. Notably, a pyrrolidine-substituted analog of the H13 helical structure for the β/γ-hybrid pentamer, with adjacent amine diads substituted in close proximity, appears to be a promising organic catalyst for organic reactions such as the crossed aldol condensation and the cyclodimerization of dialdehyde in nonpolar solvents, as previously elucidated. [ABSTRACT FROM AUTHOR]

The catalytic efficiency of CeO2 in soot oxidation was significantly affected by its grain morphology and calcination temperature. Nanocube-shaped and nanorod-shaped CeO2 catalysts were synthesized via a hydrothermal method with different calcination temperatures. Activity tests revealed that the nanorod-shaped CeO2 exhibited superior catalytic activity compared to the nanocube-shaped catalysts at equivalent calcination temperatures. Furthermore, an inverse relationship between the catalytic activity and the calcination temperature was observed in the nanorod-shaped CeO2 catalysts, with those calcined at 300 °C exhibiting the most effective low-temperature catalytic performance. Combined characterization techniques and density functional theory calculations showed that the improved catalytic performance can be attributed to the increased abundance of oxygen vacancies, enhanced lattice oxygen mobility and higher surface energy due to their unique surface defect structure and electronic structural feature, in addition to the reduction in grain size. [ABSTRACT FROM AUTHOR]

Pesticides are extensively employed worldwide, particularly in less developed countries. These substances, designed to eradicate insects in plantations, permeate the soil, groundwater, and rainwater. As these waters traverse plantations, pesticides are carried into rivers, resulting in contamination of aquatic ecosystems. Consequently, there is a pressing need to detect and eliminate these toxic compounds from the environment. In this study, we employ first principles calculations, utilizing the density functional theory within the Siesta computer program, to analyze the nano-interactions between commonly-used pesticides acephate and glyphosate with graphene. The main theoretical findings indicate that both acephate and glyphosate exhibit a physical interaction with graphene, as evidenced by the assessments of binding energy across all the configurations analyzed. Consequently, we propose that graphene shows potential as an effective filter for eliminating acephate and glyphosate pesticides from aquatic environments, given the observed physical interactions. This research could significantly contributes to the emergent field of computational nanoecotoxicology, anticipating potential toxic effects on human health and promoting efficient bioremediation strategies based on graphene nanomaterials properties. [ABSTRACT FROM AUTHOR]

The present investigation utilizes density functional theory (DFT) to elucidate the influence of iron (Fe) and ruthenium (Ru) as dopants, alongside sulfur (S) co-doping, on the electronic properties and photocatalytic properties of zinc oxide (ZnO) monolayer nanosheets. The findings indicate that the integration of Fe and Ru dopants serves to augment structural stability while concomitantly diminishing the bandgap energy through an elevation of the valence band maximum (VBM). Doping of Fe and Ru along with co-doping up to three sulfur atoms into the ZnO lattice has been observed to result in a compromise of structural stability while concurrently enhancing the specific surface area. The introduction of sulfur expands the bandgap in Fe-doped ZnO nanosheets, enhancing the VBM energy, while for Ru-doped ZnO nanosheets, sulfur doping narrows the bandgap. This effect is especially notable in RuS3 co-doped nanosheets, making them well-suited as a photocatalyst for the overall water splitting process at pH = 7. Furthermore, the increased probability of effective electron–hole pair separation, combined with a bandgap of 3.52 eV, positions FeS-co-doped ZnO as a promising photocatalytic material for the generation of hydrogen via water splitting under near-ultraviolet illumination. [ABSTRACT FROM AUTHOR]

To design highly efficient, low-cost, and stable electrocatalysts for the oxygen evolution reaction (OER), we built a ferromagnetic Fe3GeTe2 (001) basal plane and (100), (110) tellurium iron mixed edge planes, which exhibit good stability owing to the lower surface energy. Density functional theory (DFT) calculation reveals that the edge planes exhibit better OER activity, which is attributed to the synergistic effect between the active site of Fe and Te atoms. For the (100) and (110) edge planes, active site transfer occurs from Te to the Fe atom, and with Te and Fe atoms synergistically acting as the active sites, Fe3GeTe2 exhibits favorable adsorption and desorption of oxygen-containing intermediates during the OER process. These interesting findings may provide important and valuable references for the design of emerging two-dimensional ferromagnetic electrocatalysts. [ABSTRACT FROM AUTHOR]

Due to their high anisotropic behavior, liquid crystals possess strong nonlinear optical properties. The RM734 liquid crystal is famous for having high anisotropic behaviors compared to traditional liquid crystals. The present work focused on the evaluation of electronic, charge-transport, nonlinear optical, electro-optical, and thermochemical properties of the RM734 liquid crystal. Furthermore, the effect of halogenation on the above properties of RM734 was investigated and is discussed in depth as halogen substitution on the liquid crystal molecule can alter the quantum mechanical properties of any liquid crystal molecule. Density functional theory combined with B3LYP and dispersion correction were used to calculate the properties of RM734. The 6-311G** basis set was used for the estimation of these properties, whereas def2-TZVPD was used to evaluate the nonlinear optical parameters. Due to the halogenation of RM734, its electronic properties vary significantly. By halogenation, a better electron-transport molecule can be converted into a hole-transport molecule. The electro-optical properties were calculated with the application of an external electric field for all molecules. With the help of the order parameter, the nematic phase was observed for all reported molecules. The variation in the birefringence with respect to the external electric field was investigated and discussed in detail. Therefore, the present study reveals the significant impact of halogenation in terms of the nonlinear optical and thermochemical properties of RM734. [ABSTRACT FROM AUTHOR]

The development of stable and durable oil/water separation materials with photocatalytic activity holds great significance for the purification of complex oily wastewater containing refractory organic pollutants. Herein, a multifunctional Ag@Cu2O decorated copper mesh was designed and prepared via a two-step hydrothermal method. The material possesses outstanding superwettability, photocatalytic activity, and antibacterial properties towards Escherichia coli and Staphylococcus aureus. The mesh demonstrates remarkable and durable superhydrophilic properties while maintaining underwater superoleophobic characteristics, enabling excellent separation efficiency and high permeability flux involving various oil/water mixtures in gravity-driven separation processes. Under visible light, the Ag@Cu2O anchored mesh serves as an effective photocatalyst in the removal of dyes and tetracycline antibiotics from aqueous solution. The catalyst shows high stability and reusability and exhibits high performance after 5 cycles of photocatalytic tests. Density functional theory calculations reveal that the improved photocatalytic performance is attributed to the narrowed indirect band gap after Ag anchoring. The silver atoms induce the shifting up of the energy level of the Cu 3d orbital, enhancing the photocatalytic activity of Cu2O. The outstanding performance of the Ag@Cu2O anchored mesh endows this material with great application potential in the removal of refractory pollutants from oily wastewater. [ABSTRACT FROM AUTHOR]

Two new pyrazolidine-3,5-dione derivatives namely (Z)-4-(2-(4-bromophenyl)hydrazono)-1-phenylpyrazolidine-3,5-dione (2) and (E)-1-phenyl-4-((pyridin-2-ylamino)methylene)pyrazolidine-3,5-dione (3) were synthesized and their structures were elucidated by single-crystal X-ray analysis along with spectroscopic techniques. Density functional theory (DFT) studies were carried out to examine the distribution of charge, and natural bond orbital (NBO) analysis and frontier molecular orbital (FMO) analysis were carried out. Hirshfeld surface analysis was carried out to examine the intermolecular interactions, revealing a prevalence of H⋯H interactions in the crystals of both molecules. NBO analysis was carried out to investigate the stabilization energy, while MEP analysis was conducted to explore regions susceptible to nucleophilic and electrophilic attacks. The molecules were screened for their medicinal potential based on physiochemical and pharmacokinetics including (gastrointestinal) GI absorption, blood brain barrier (BBB) permeation, skin permeation capability, Caco-2 permeability, Madin–Darby canine kidney (MDCK) permeability, drug metabolism by the cytochrome P450 (CYP) family of liver enzymes, and toxicity evaluations. The expected metabolic reactions in the real cell system and the resulting metabolites along with their polarities for the determination of the probability of excretion from the body and drug-likeness were studied. To investigate the anticancer potency of 2 and 3, both were docked with three enzymes as drug targets for anticancer studies including HER2 (PDB ID: 3WSQ), EGFR (PDB ID: 5WB7), and the extracellular domain of the Tdp enzyme (PDB ID: 6N0D). From the calculated binding energies and inhibition constants, 2 is a better inhibitor of the target substrates than 3. [ABSTRACT FROM AUTHOR]

The Cu⋯Cu interactions, known as cuprophilicity, play a significant role in copper–chalcogenide functional materials. Three dinuclear copper chalcogenone complexes, [(L1CuI)2] (1), [(L2CuI)2] (2) and [Cu2(L3)4]PF6 (3), have been isolated and characterized. L1 = 1-(9-methyl anthracene)-2-isopropyl-benzimidazole-2-thione; L2 = 1-(9-methyl anthracene)-2-isopropyl-benzimidazole-2-selenone and L3 = 1-pyridine-2-isopropyl-imidazole-2-selenone, ligands and 1–3 were characterized by 1H NMR, 13C NMR, FT-IR, and SCXRD. Complexes 1 and 2 compress a four-membered strained ring system bridged by iodine, whereas 3 consists of a similar-four-membered ring core bridged by a selenium ligand. The Cu⋯Cu interactions in the crystal structures are observed (2.591 Å for 1, 2.576 Å for 2, and 2.523 Å for 3). The bridging ligand shows a key contribution to the Cu⋯Cu interactions. The density functional theory calculations also confirm the presence of d10⋯d10 interactions, which are predominantly covalent in nature. The computational study also shows the effect of the bridged ligands on the d10⋯d10 interactions and overall stability of the complexes, where complex 2 is the most stable followed by 1, and after that 3, although the d10⋯d10 interactions were the strongest in the case of 3. [ABSTRACT FROM AUTHOR]

Developing a facile and effective assay method is crucial due to the potential harm of metronidazole (MNZ) antibiotics to both human health and the environment. Herein, snowflake-shaped poly(3-thiophenemalonic acid, 3-TPA) combined with a carbonized core–shell-type ZIF-8@ZIF-67 (C-ZIF-8@ZIF-67) hollow polyhedra modified glassy carbon electrode (GCE), denoted as C-ZIF-8@ZIF-67/P3TPA/GCE, was fabricated by electropolymerization followed by the electrodeposition strategy. The resulting sensor demonstrates a significant electrocatalysis effect for the reduction reaction of MNZ, exhibiting a broad linear range (0.1–20, 20–800 μM) with a low limit of detection (LOD, 3S/N) of 0.024 μM. Furthermore, it has been successfully applied to determine MNZ in tablets and lake water. A synergistic effect between P3TPA and C-ZIF-8@ZIF-67 is elucidated through density functional theory (DFT) calculations. Consequently, this research introduces a sensitive and effective method for monitoring MNZ in real samples. [ABSTRACT FROM AUTHOR]

Phyllobilins, derived from the breakdown of chlorophyll in plants, are acyclic tetrapyrroles that bear the signature ring E of the parent macrocycle. Few synthetic studies have concerned members of this emergent class of natural products, which now number >70. A prior synthesis of southern rim structures relied on Knoevenagel and Nazarov reactions to construct a dipyrromethane bearing the annulated ring E. Here, the synthesis has been extended to linear tetrapyrroles containing ring E as well as an appended dicyanovinyl unit. The latter serves as an optical marker with clearly observable absorption near 400 nm, rendering all compounds yellow, orange or red, thereby facilitating isolation and reaction monitoring. Knoevenagel condensation was carried out with a DC half (gem-dimethyl-substituted dihydrodipyrrin-1-carboxaldehyde bearing a 9-carboethoxy group) and an AB half (dipyrromethane equipped with a β-ketoester at the 8-position and the dicyanovinyl group at the 1-position). The resulting propenone is blocked by the ester and dicyanovinyl groups from reactions at the respective pyrrolic termini. Subsequent Yb(OTf)3-catalyzed Nazarov reaction accompanied by unexpected prototropic rearrangement afforded the isolated phyllobilin (8) wherein conjugation shifted from the DC dihydrodipyrrin moiety to the CB southern rim, thereby resembling the conjugation of a native phyllolumibilin. The expected direct products of Nazarov cyclization, the cis and trans products (pre-8-cis , pre-8-trans) due to the configuration of substituents in ring E, were not observed. Calculations by density functional theory showed the stability order as 8 > pre-8-trans > pre-8-cis. Access to phyllobilin analogues may open opportunities for fundamental studies pertaining to the native constituents, which are germane to plant sciences, nutrition, and ecology. [ABSTRACT FROM AUTHOR]

In the present study, a series of 2-amino-3-cyanopyridine-based enaminoates 2 were synthesized from substituted 2-amino-3-cyanopyridines 3 and ethyl cyclopentanone-2-carboxylate 4 in acetic acid. The synthesized compounds were characterized by using various techniques such as 1H NMR, 13C NMR, Mass, HRMS and FTIR. The photophysical properties of all the derivatives were investigated, including their absorption maxima, emission maxima and Stokes shift. Among these, compound 2e was investigated as a fluorimetric "turn-off" sensor for the selective detection of Fe3+. The interaction between 2e and Fe3+ was confirmed through Job's plot analysis and density functional theory (DFT) studies. The fluorimetric detection limit for Fe3+ reached up to 9.2 μM. Photostability and response time studies were also conducted to evaluate the analytical performance of 2e. Additionally, 2e was successfully applied for analyzing Fe3+ in real water samples such as lake water (Sukhna Lake, Chandigarh, India), distilled water and tap water using the standard addition method. Furthermore, 2e was employed to develop fluorimetric test strips for practical applications. [ABSTRACT FROM AUTHOR]

The chemical synthesis of 5-(4-azidophenyl)-10,15,20-tris(2-furyl/2-thienyl)porphyrins and their utilization in a Cu(I) catalyzed alkyne-azide 'click' reaction (CuAAC) with ethynylferrocene to obtain the hitherto unknown meso-tris(2-furyl/2-thienyl) substituted porphyrin–ferrocene 'click' conjugates are reported. These new 'click' conjugates were studied along with the reference 'click' conjugates containing all-meso-aryl substituted porphyrins by experimental and computational methods. Compared to the reference, the new conjugates displayed red-shifted absorption/emission bands, easier porphyrin ring reduction, and an efficient photoinduced electron transfer (PET) process from ferrocene to a porphyrin unit. Density functional theory (DFT) calculations performed on these conjugates revealed a good correlation with the experimental results. [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]

Heteroatom doping, especially with elements of lower electronegativity and smaller atomic radius, can effectively modulate the electronic structure and surface properties of electron materials, facilitating the electrochemical performance of supercapacitors. Herein, we have designed boron-doped NiCoP nanoarrays grown on carbon cloth (B-NCP-CC) for supercapacitor cathode materials using a simple process method combining hydrothermal, calcined phosphating and boronation processes. The introduction of boron, with lower electronegativity (2.04) and smaller atomic radius (0.85 Å) than phosphorus (2.19 and 1.00 Å), induces electron redistribution and shortens the Ni/Co–B bonds, enhancing their redox activity and charge transfer kinetics. The boron doping greatly enables the B-NiCoP-CC-18 (NiCoP-CC borated for 18 h) cathode material to provide a high capacity of 801 C g−1. The assembled B-NiCoP-CC-18‖‖AC hybrid supercapacitor achieves a high energy density of 73.22 W h kg−1 at a power density of 963.8 W kg−1 and retains 90% capacity after 5000 cycles, significantly improving the stability of nickel-based materials. Besides, density functional theory (DFT) calculations further elucidate that the introduction of boron increases the d-band centers of Ni and Co in NiCoP, promoting the conductivity and enhancing the electrochemical properties. [ABSTRACT FROM AUTHOR]

The redox-active electrolyte materials are critical components in redox flow batteries (RFBs). Quaternary bipyridinium derivatives, such as viologens (4,4′-bipyridine double quaternary salts), represent an important class of organic anolyte materials that can be well-matched with cheap and non-corrosive pH-neutral aqueous electrolytes in RFB applications. Herein, to search for promising quaternary bipyridinium compounds, we investigated the redox potentials and kinetic rate constants of 228 C-substituted quaternary bipyridinium derivatives that either contain paraquat or diquat parent structures by applying density functional theory (DFT) calculations. The analysis of the results reveals the effects of the terminal functional groups, number of methylene units, substitution sites and parent structure on the electrochemical properties. On this basis, we identify several promising candidates for the anolyte materials of neutral aqueous organic RFBs and further assess their aqueous solubility and structural stability through DFT theoretical calculations. [ABSTRACT FROM AUTHOR]

The reaction characteristics of FOX-7 and NH2/NO2-substituted oxazole compounds in the Diels–Alder reaction were studied, based on which six series of novel bridge-ring energetic compounds were designed. The reaction feasibility, energetic properties and stability of the designed compounds were extensively evaluated based on density functional theory. The preferred dienes tend to undergo normal or inverse Diels–Alder reactions with FOX-7. And, the formation of the most designed bridge-ring energetic compounds tends to follow a two-step reaction mechanism rather than the common one-step concerted cycloaddition mechanism. All the designed bridge-ring energetic compounds exhibited excellent detonation performance, except for P1 and P2 series compounds. In a comprehensive evaluation of detonation performance and stability, compounds P6-1 and P6-3 (ρ > 2.08 g cm−3, D > 9800 m s−1, P > 44 GPa, h50 values are comparable to that of CL-20) and compounds P4-1, P4-4, P5-1, and P5-4 (ρ: 1.952–1.976 g cm−3, D: 9474–9508 m s−1, P: 40.5–41.5 GPa, h50 values are superior to that of CL-20) are the most promising high-energy-density compounds. This study can provide some guidance for the extension of the derivative reaction of FOX-7, as well as the design and experimental synthesis of these novel bridge-ring energetic compounds. [ABSTRACT FROM AUTHOR]

In the present work, the barrier energies (Eb) of CH4 formation and C–C coupling and the mechanism of Fischer–Tropsch synthesis (FTS) on different cluster sizes of cobalt were investigated. Three cobalt clusters with 10, 18, and 30 atoms (Co-10, Co-18, and Co-30) were used for comparison of the results. The Eb, transition state, and reaction energy (ΔEr) were analyzed by using density functional theory (DFT) calculations. The results showed that CH4 was produced more easily on the small cluster (Co-10) than on the other two clusters. The Eb values for the Co-10, Co-18, and Co-30 clusters were 1.62, 2.53, and 2.44 eV, respectively. The Eb values for dissociation of CO on the three clusters Co-10, Co-18, and Co-30 were 1.64, 0.93, and 1.81 eV, respectively, and the minimum Eb was related to the Co-18 cluster. Also, the tendency towards chain growth increased with increasing cobalt cluster size. The results showed that the mechanism of the FTS reaction was dependent on the particle size of the cobalt clusters. It can be concluded that the Co-10 cluster followed the CO insertion mechanism and the Co-18 cluster followed the carbide mechanism in the FTS reaction. Also, the Co-30 cluster followed both mechanisms (CO insertion and carbide mechanisms) in the FTS reaction. DFT results showed that as the cobalt cluster size increased, the olefin/paraffin ratio in the FTS reaction products enhanced. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations were carried out to investigate the absorption spectra and photoelectric properties of new metal-free dyes integrating an acene group positioned proximal to the donor moiety, exemplified by the 2-amino pyrrole. A linear carbon chain (LCC) with varying lengths serves as the link between the donor group and two distinct electron-attracting groups: cyanoacrylate and a derivative of pyridinium salt. Molecular orbital analysis reveals strategically positioned energy levels for efficient electron recovery, ensuring favorable thermodynamics for injection. UV-VIS absorption properties underscore superior outcomes for dyes with longer π–spacers, particularly those with pentacene showcase a panchromatic effect extending beyond 920 nm. Furthermore, the study explores the electron transfer process at the dye–semiconductor interface, emphasizing stable adsorption modes and favorable interactions. Photovoltaic property estimations, considering electron injection and recombination rates, indicate that dyes with pyridinium salt as the withdrawing group, specifically, P-Pen-4-A2 and P-Ant-4-A2, exhibit excellent values for both open-circuit voltage (Voc) and short-circuit photocurrent density (Jsc), thus demonstrating superior photovoltaic outcomes. The investigation of J–V curves predicts outstanding photoelectric conversion efficiency values of 29.72% and 27.90% for these dyes. Moreover, derivatives incorporating cyanoacrylate yields commendable PCE values of 20.30% and 25.01% for P-Ant-4-A2 and P-Pen-4-A2. Classical molecular dynamics simulations (MD) demonstrate that, over the course of 200 ns simulation time, the dyes maintain a vertical adsorption configuration. These results underscore the potential of the designed dyes for both standalone and co-sensitizing applications, presenting a promising avenue for the development of efficient and panchromatic DSSCs. [ABSTRACT FROM AUTHOR]

Designing and discovering negative thermal expansion (NTE) materials is important in precisely controlled thermal expansion devices. In this work, the NTE of a cubic metal fluoride, ReO3-type VF3, was predicted by density functional theory within the quasi-harmonic approximation. These results reveal that cubic VF3 displays a negative thermal expansion behavior below 200 K, and the predicted minimum negative thermal expansion coefficient is approximately −6.4 × 10−6 K−1 at 80 K. The negative thermal expansion was mainly dominated by the prominently negative Grüneisen parameter situated at M(0.5,0.5,0) and R(0.5,0.5,0.5). The underlying mechanism was attributed to the anisotropic F atom vibration, where the amplitude of transverse vibration perpendicular to the V–F–V connection was much larger than that of the vibration along the parallel V–F–V direction. This research provides a good understanding of the relationship between NTE and crystal structure. [ABSTRACT FROM AUTHOR]

We report an unexpected direct transfer hydrogenation (TH) from 8-alkoxyjulolidine as a strong electron donor to tricyanofuran-based hemicyanines and tandem condensation for the synthesis of push–pull chromophores. Density functional theory calculations identify the α-hydride transfer of julolidine derivatives, instead of nucleophilic addition, as the key initial step of reaction cascades, followed by efficient β-deprotonation to generate a nucleophilic enamine of isojuloline that condenses in situ with a second equivalent of hemicyanines as electrophiles. The scheme represents an exceptional example of TH reactions from 8-alkoxyjulolidine to highly polarizable hemicyanines, notably under simple reaction conditions without using potent catalysts of metal complexes or Lewis acids. The resulting products of isojuloline-based merocyanines exhibit strong near-infrared (NIR) absorption and large first hyperpolarizabilities. The study suggests that direct TH can be exploited to construct new NIR merocyanines by following rational, regioselective condensation pathways for photonic applications. [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]

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]

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 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]

In this work, density-functional theory (DFT) was used to investigate the geometry and electronic structure of Run(n = 1–6,10) supported on CeO2(110) (Run(n = 1–6,10)/CeO2(110)) and their electrocatalytic properties for the N2 reduction reaction (NRR). The results indicated that there is a strong metal–support interaction between Run and CeO2(110), which leads to large surface distortion and stabilized Run. On Run(n = 1–6,10)/CeO2(110), N2 captured in the end-on mode is thermodynamically more favorable than that captured in the side-on mode; however, the side-on mode can lead to stronger activation of N2 which promotes the following protonation step of N2. For Run(n = 3,5,6)/CeO2(110), the electrochemical NRR prefers to occur via an enzymatic mechanism with limiting potentials of −0.31, −0.53 and −0.66 V. The electrocatalytic activity of Run(n = 1–6,10)/CeO2(110) for the NRR shows a strong size dependence. For Ru3/CeO2(110), it has the lowest absolute value of limiting potential, and with the increase in n (n > 3), the limiting potential becomes more negative. Moreover, Ru3/CeO2(110) shows high selectivity and stability. This study gives valuable insights for designing effective catalysts for the NRR. [ABSTRACT FROM AUTHOR]

Non-acidic hydrogen evolution systems have a low concentration of hydrogen ions, and the H2 evolution reaction (HER) is often limited by the water dissociation step. Preparing catalysts that can accelerate water dissociation is a common method for achieving high-efficiency evolution of hydrogen. In the current work, the performance of a hydrogen evolution system was first improved by introducing CO2 to transform the presence status of H2O. According to density functional theory (DFT) calculations, water reacts with CO2 to produce carbonic acid which can reduce the barrier of adsorbed H generation. Subsequently, under same pH conditions, a constructed dye-sensitized Ni–CO2 system shows an H2 evolution rate 1.5 times higher than that shown by dye-sensitized Ni. This result indicates that transforming the presence status of H2O may be a new strategy for further improving H2 evolution efficiency. [ABSTRACT FROM AUTHOR]

Mastery with regard to the evolution of the chemical form of fission products in the primary circuit is essential for the development and improvement of models, which can predict the release of fission products into the primary loop under normal or accidental operating conditions and analyze the consequences of severe accidents. Here, the chemical forms of fission products in the primary loop of the HTR-PM are predicted by the thermodynamic database method. Furthermore, the microscopic mechanisms of the reactions between radionuclides Cs and I with steam are systematically investigated using density functional theory. The predominant reaction products of Cs + H2O and I + H2O include CsO, CsOH, IO, IOH, and HI. The bond evolution properties are analyzed using the electron localization function, quantum theory of atoms in molecules, bond order density, and mayer bond order. The reaction rate constants are determined utilizing the variational transition state theory. Within the temperature range of the HTR-PM primary circuit (250–750 °C), the reaction rate constant of OIH2 is effectively zero, and the reaction rate constant of HI is higher than that of IOH. The results of the above microscopic calculations are consistent with the macroscopic thermodynamic calculations, and these data serve as valuable ESI for the experiments. [ABSTRACT FROM AUTHOR]

Inhibition of intraerythrocytic iron uptake by plasmodium parasites is a viable alternative antimalarial mode of action to that adopted by artemisinins, since microorganisms require iron for growth and replication, but this has received less research attention. Against this backdrop, an in silico study on bis-thiosemicarbazones (TSCs) with significant antiplasmodial properties as Fe(III)-selective chelators and inhibitors of hemozoin formation is undertaken herein using density functional theory (DFT), molecular docking and molecular dynamics (MD) simulations. From the large contrasts in calculated binding energies for Fe(III) and Fe(II) sequestration in aqueous solution at DSD-BLYP/def2-TZVPD level of theory (−1162.99 to −1187.64 kcal mol−1 and −671.75 to −687.60 kcal mol−1, respectively), the TSCs are potential Fe(III)-selective chelators as desired for chelation therapy. Based on their satisfactory oral bioavailability profiles, the TSCs are found to be adequately drug-like. They are therefore expected to easily penetrate parasitized erythrocytes and inhibit the growth/development of plasmodium parasites by scavenging and externalizing intraerythrocytic ferric iron. Moreover, docking and adsorption studies of these TSCs onto the (001) face of the β-hematin crystal have yielded favorable binding free energies (−9.874 to −11.83 kcal mol−1) and negative adsorption energies (−84.61 to −109.80 kcal mol−1), respectively. The adsorption energies obtained herein are either comparable or more negative than those obtained in previous studies for well-known antimalarial drugs. Therefore, besides Fe(III)–chelation, the antiplasmodial activities of the TSCs studied are also attributable to inhibition of β-hematin/hemozoin formation, which has a cascade effect on plasmodium parasite survival. From our findings, in vitro β-hematin inhibition assays on these TSCs are recommended. [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]

Porphyrins have been widely used in designing photocatalyst systems. However, finding an effective strategy to improve the intrinsic photocatalytic activity of porphyrin molecules remains a challenge. Here, two new porphyrins, meso-tetra(5-carboxyfuryl)porphyrin (H2TCFP) and meso-tetra(5-carboxythienyl)porphyrin (H2TCTP), were successfully synthesized and compared with meso-tetra(m-carboxyphenyl)porphyrin (H2TmCPP), to clarify the influence of the organic unit bridging the carboxyl acid group with the porphine ring on the photocatalytic activity of porphyrin for H2 evolution from water splitting. The H2 evolution rates of 10.8 mmol g−1 h−1 observed for H2TCFP and 9.7 mmol g−1 h−1 for H2TCTP are both larger than 8.0 mmol g−1 h−1 observed for H2TmCTP under optimal conditions. The best photocatalytic activity observed for H2TCFP was investigated through experiments and density functional theory (DFT) calculations and was interpreted in terms of the combined effect of several key factors of the entire photocatalytic process, including the high absorptivity of UV light, high separation efficiency of photogenerated carriers, and low Gibbs energy required for associated water splitting. Meanwhile, the concentration-dependent performance of photocatalytic activity was analyzed and attributed to the aggregation and light-bleaching effect exerted on porphyrins. [ABSTRACT FROM AUTHOR]

MoSe2 as one graphene-like 2D transition metal selenide has attracted great attention. However, its application for the hydrogen evolution reaction (HER) is still restricted by the poor electrical conductivity and structural restacking. In this work, an excellent electrocatalyst for hydrogen production is developed based on the in situ synthesis of V-doped MoSe2 confined on carbon black nanoparticles (denoted as V-MoSe2/CB) via a sol–gel process. The characterization results show that the carbon black nanoparticles can protect the V-MoSe2 nanosheets from agglomeration, resulting in ultra-thin thickness and short vertical lattice arrays. Meanwhile, density functional theory (DFT) calculations indicate that vanadium doping can optimize the electronic structure of MoSe2. Accordingly, compared to the pure MoSe2, V-MoSe2 and MoSe2/CB electrocatalysts, V-MoSe2/CB exhibits improved electrocatalytic activity with a small overpotential of 166 mV at −10 mA cm−2 and a small Tafel slope of 65 mV dec−1. This work paves a new way for improving the HER performance through synergistic morphology, structure and electronic regulation. [ABSTRACT FROM AUTHOR]

Encouraged by the promising performance of C60-graphene single-molecule transistors observed in experiments, two types of Fen/C60-GNR (n = 2 and 4 and GNR = graphene nanoribbon) molecules with Fe atoms sandwiched between the upper and lower GNR layers were designed and their electronic and transport properties were investigated by employing density functional theory (DFT) and nonequilibrium Green's function (NEGF) methods. Adding the Fe atoms induces high spin magnetism in the systems. Within the considered bias, almost all Fe2/C60-GNR devices generate double NDR peaks, and some of the Fen/C60-GNR devices (n = 2 and 4) possess a large peak-to-valley current ratio R = Ipeak/Ivalley (>400), implying potential applications in developing on–off–on/off–on–off current switches. The NDR character originates from the crossing of the frontier molecular orbitals. In addition, these systems show distinct spin-polarized transport characteristics, with up-spin channels displaying higher conductivity than down-spin pathways. The spin filter efficiency (SFE) oscillates up and down as bias is scanned for almost all devices, suggesting the possibility of designing on–off–on/off–on–off current switches as well as up–down spin switches. All these findings provide guidance for exploring single molecular devices with promising properties combined with graphene, fullerenes, and transition metals. [ABSTRACT FROM AUTHOR]

This work explores the characteristics of two-dimensional (2D) titanium carbide (Ti3C2 MXene) and utilizes first-principles study to weigh its potential for supercapacitor applications. Scanning electron microscopy images confirm the layered morphology of the MXene, and energy-dispersive X-ray spectroscopy (EDX) analysis supports the extraction of aluminum from the MAX phase. Fourier-transform infrared (FTIR) spectroscopy confirms the presence of oxygen-based functional groups on the surface of the MXene and X-ray diffraction (XRD) patterns validate its hexagonal crystalline structure. Cyclic voltammetry (CV) analysis reveals the presence of redox peaks, indicating the pseudocapacitive behaviour of the fabricated electrode. Additionally, galvanostatic charge–discharge (GCD) measurements yield a calculated specific capacitance of 370 F g−1. Electrochemical impedance spectroscopy (EIS) substantiates the low impedance resulting from the layered structure via the adequate adsorption/desorption of cations. The utilization of first-principles density functional theory (DFT) calculations reveals the merging of conduction and valence bands, signifying effective conductivity. Both the total and partial density of states cross the Fermi level, indicating a highly efficient charge mobility process. The combination of prominent surface redox reactions and excellent conductivity contributes to the superior specific capacitance of the fabricated electrode. Overall, these results highlight the excellent electrochemical properties of the Ti3C2 MXene electrode, declaring it as a promising candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

In this work, the interfacial self-assembly behavior of [1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylic acid (TDA) and the regulation of the introduced guest molecules (trimesic acid (TMA) and coronene (COR)) on TDA's mono-component system were investigated by scanning tunneling microscopy (STM), and the formation mechanism was investigated by density functional theory (DFT). Newly added TMA molecules destroyed the single-row structure formed by TDA self-assembly and formed a new hexagonal co-assembly structure with TDA molecules. When COR was introduced into this system, the co-assembly structure collapsed and the resulting structure was dependent on the concentration of the COR solution. [ABSTRACT FROM AUTHOR]

With the current food demand, pesticides have become some of the most important compounds to maintain food quality; however, this requires the development of methodologies that allow fast, sensitive, and low-cost screening for these contaminants. Surface-enhanced Raman spectroscopy is an emerging solution since the interaction between the analyte and metallic nanostructures increases the Raman signals, enabling trace detection and a chemical-specific measurement. In this way, the fast detection of contaminants is possible, and further advances may enable portable assays. In this work, SERS substrates with silver nanosheets (AgNSs) on a copper surface were synthesized, producing a strong SERS effect and a reproducible signal intensity from methylene blue probe molecules at an optimal reaction time of 1 min. A quantitative analysis of the pesticide imidacloprid was then performed by applying a PLSR chemometric model, revealing a high linear correlation between the reference values and the predicted values of the pesticide (Rcv2 = 0.9732 and RMSECV = 0.1239). AgNS substrates were used to determine the feasibility of using this methodology for screening imidacloprid in real bee honey samples obtained through QuEChERS extraction, and an average recovery of 75.5% ± 0.08 was obtained. In addition, density functional theory simulations were carried out to elucidate the possible molecular interaction with the SERS surface and to assign the observed vibrational modes of imidacloprid. SERS is thus demonstrated to be an alternative to conventional pesticide detection techniques. [ABSTRACT FROM AUTHOR]