Sodium catalytic phenylpentazole cracking: a theoretical study.

This work presents an in-depth investigation into the cracking reaction mechanism of phenylpentazole (C6H5N5) under the catalytic influence of sodium metal, utilizing density functional theory. The geometries of the reactants, transition states, intermediates, and products are meticulously optimized employing the GGA/PW91/DNP level of theory. Also, a rigorous analysis is undertaken, encompassing various key factors including configuration parameters, Mulliken charges, densities of states, and reaction energies. Three distinct reaction pathways are comprehensively examined, shedding light on the intricate details and intricacies of each pathway. The results show that a remarkable outcome in which the activation energy of the C6H5N5 cracking reaction releases N2, facilitated by catalytic metal Na, reveals a strikingly reduced value of a mere 5.2 kcal mol-1 compared to the previously reported activation energies ranging from 20 to 30 kcal mol-1. Evidently, this significantly lowered barrier can be readily surpassed at typical room temperatures, exhibiting practical applicability. Notably, the alkali metal Na effectively serves as a catalyst, successfully diminishing the activation energy required for N2 production through the pyrolysis of pentazole compounds. This breakthrough discovery provides a theoretical basis for experimental research on the low-temperature cracking of pentazole compounds. It also offers valuable insights for the development and application of new high energy density materials, contributing to the creation of a green and low-carbon circular economic system.

Density Functional Theory Study on the H2-Acceptorless Dehydrogenative Boration of Alkenes Catalyzed by a Zirconium Complex.

For the synthesis of vinyl boronate esters, the direct catalytic H2-acceptorless dehydrogenative boration of alkenes is one of the promising strategies. In this paper, the density functional theory method was employed to investigate the reaction mechanism of dehydrogenative boration and transfer boration of alkenes catalyzed by a zirconium complex (Cp2ZrH2). There are two possible pathways for this reaction: the alkene insertion followed by the dehydrogenative boration (path A) and the alkene insertion after the dehydrogenative boration (path B). The calculated results showed that path A is more favorable than path B, and that the rate-determining step is the C-B coupling step with an energy barrier of 18.7 kcal/mol. The reaction modes of the C-B coupling assisted dehydrogenative boration and the alkene insertion were also discussed. These analyses reveal a novel hydrogen release behavior in dehydrogenative boration and the alkene insertion modes and sequences were proposed to be of importance in the chemoselectivity of this reaction. In addition, the X ligand effect (X = H, Cl) on the catalytic activity of the zirconium complex was explored, indicating that the H ligand could enhance the catalytic activity of the complex for styrene dehydrogenative boration.

Molecular Thermal Motion Modulated Room-Temperature Phosphorescence for Multilevel Encryption.

The stimulus-responsive room-temperature phosphorescence (RTP) materials have become an increasingly significant topic in the fields of bioimaging, sensing, and anticounterfeiting. However, this kind of materials is scarce to date, especially for the ones with delicate stimulus-responsive behavior. Herein, a universal strategy for multilevel thermal erasure of RTP via chromatographic separation of host-guest doping RTP systems is proposed. The tunable host-guest systems, matrix materials, heating temperature, and time are demonstrated to allow precise six-level data encryption, QR code encryption, and thermochromic phosphorescence encryption. Mechanistic study reveals that the thermal-responsive property might be attributed to molecular thermal motion and the separation effect of the silica gel, which provides expanded applications of host-guest RTP materials such as cold chain break detection. This work offers a simple yet universal way to construct advanced responsive RTP materials.

The Mechanism and Kinetics Model of Degradation of Dicarboxylic Acids by Hydroxyl Radicals under Atmospheric Conditions.

The atmospheric degradation mechanism of dicarboxylic acids (DCAs) initiated by hydroxyl radicals has been theoretically investigated at the DLPNO-CCSD(T)/def2-TZVP//BH&HLYP/6-311++G(d,p) level of theory. In the presence of O2, the degradation of DCAs by hydroxyl radicals takes place through a two-step mechanism: the α-H elimination and the degradation of the peroxyl radical intermediate. The latter degradation mechanism is easy to proceed for the exothermic process of radical recombination. Therefore, the degradation rate of DCAs is determined by an α-H elimination step, which is accelerated in the case of long carbon-chain DCAs with a lower energy barrier. Canonical variational transition state theory has been employed to estimate the rate constants of the H-elimination step of the DCA degradation reaction by hydroxyl radicals over the temperature range of 220-1000 K.

Preparation of Novel Magnetic Nanomaterials Based on "Facile Coprecipitation" for Developing Latent Fingerprints (LFP) in Crime Scenes.

Recently, the application of novel nanomaterials, especially magnetic nanomaterials in the development of latent fingerprints (LFP), has become the hot focus for forensic scientists and criminal investigators. As a type of recyclable, environment-friendly material, Fe3O4 nanoparticles achieve a wonderful effect in visualization of LFP. We first report the synthesis and encapsulation of nano-Fe3O4 through "facile coprecipitation", (3-mercaptopropyl)triethoxysilane was covalently embedded into Fe3O4 nanoparticles, and the Fe3O4 core was encapsulated by the nanosilver to prepare novel magnetic nanomaterials (P-MNP@Ag) with the core-shell configuration. For comparison, the magnetic nanomaterials (S-MNP@Ag) were prepared by surface modification. Their composition, structure, and properties were characterized by SEM, TEM, XRD, IR, XPS, and VSM. Compared with commercially available gold powder, silver powder, bare magnetic powder, and prepared S-MNP@Ag, the development effect of LFP on different objects by using P-MNP@Ag had better performance, which presented the advantages of low background interference, high sensitivity, and clear secondary details in LFP. In the crime scenes of some influential cases, P-MNP@Ag had been applied to the visualization of LFP. The biometric identification of criminal suspects was confirmed through fingerprint comparison, which was highly affirmed by the public security department.

Thermodynamic and Kinetic Studies on Adsorption of Vanadium with Glutamic Acid.

Many hydrometallurgy methods, including chemical precipitation, ion exchange, solvent extraction, and adsorption, have been used to recover vanadium from vanadium solution, but the final step of these methods involved precipitation with ammonium salts, high concentrations of which are harmful to the environment. The key point is to find a new compound to replace ammonium salts without reducing the vanadium precipitation efficiency. The adsorption process of vanadium with glutamic acid is investigated. The effects of experimental factors, including dosage of glutamic acid, reaction temperature, concentration of H2SO4, and reaction time, on the adsorption process are investigated. The results show that nearly 91.66% vanadium is adsorbed under the following reaction conditions: reaction temperature of 90 °C, H2SO4 concentration of 20 g/L, glutamic acid dosage at n(glu)/n(V) = 3.0:1, and reaction time of 60 min. The response surface methodology is applied to optimize the reaction conditions. The analysis results indicate that the reaction temperature has the greatest effect on the adsorption efficiency of vanadium and the influence of experimental factors follows the order: reaction temperature > dosage of glutamic acid to vanadium > reaction time > concentration of H2SO4. The pseudo-second-order model is selected to describe well the adsorption kinetic behavior, and the thermodynamic analysis results indicate that the adsorption process of vanadium is unspontaneous and exothermic. The results will be useful for further applications of glutamic acid, and they provide a bright future for vanadium recovery.

C(sp3)-H Monoarylation of Methanol Enabled by a Bidentate Auxiliary.

With the assistance of a practical directing group (COAQ), the first catalytic protocol for the palladium-catalyzed C(sp3)-H monoarylation of methanol has been developed, offering an invaluable synthesis means to establish extensive derivatives of crucial arylmethanol functional fragments. Furthermore, the gram-scale reaction, broad substrate scope, excellent functional group compatibility, and even the practical synthesis of medicines further demonstrate the usefulness of this strategy.

Controllably facile design of electrophoretic-induced film-forming of nano tungsten oxide (VI) and their anti-wetting functionalization.

There is keen interest for designing promising tungsten oxide (VI, WO3) films or coatings due to their wide applications in fields of energy, engineering, etc. Thus, this paper firstly introduce a novel convenient method of electrophoretic assembly technique (EAT) in an optimal stable suspension of isopropyl alcohol, PEG-1000 and polyethyleneimine for designing the promising anti-wetting functional WO3 (VI) films with relative rough structures and uniform distribution in mild conditions. The product possess a high crystallinity and pureness by x-ray powder diffraction analysis. The EAT dynamic behaviours of WO3 (VI) nanoparticles are investigated in detail. Moreover, obtained films shows excellent anti-wetting properties after suface modification, and the hydrophobic studies results demonstrate that product have a high static water CA of approximate 169° and keep nearly stable even after ultralong exposure time (360 d), and show outstanding properties of anti-soaking, impacting-proof, and moisture resistance even in high relative humidity (90%). These breakthroughs will substantially push forward the convenient processing of other anti-wetting functional coatings with wide potential applications.

Two dimensional CdS/ZnO type-II heterostructure used for photocatalytic water-splitting.

The electronic structures of two dimensional (2D) CdS/ZnO heterostructure (CdZnHT) consisting of CdS singlelayer (SL) and ZnO SL are explored based on hybrid density functional calculation. The negative interface formation energies suggest the formation of CdZnHT is exothermic. The bandgap of CdZnHT is favorable for absorbing visible light, and the decent band edge position makes it thermodynamically feasible for spontaneous generation of oxygen and hydrogen. The formed electric field across the interface induced by charge transfer will reduce photogenerated carrier recombination and promote carrier migration. Particularly, CdZnHT is a type-II heterostructure. Oxygen generation takes place at ZnO layer and hydrogen production occurs at CdS layer, which will also promote the effective separation and migration of phogogenerated carriers and enhance photocatalytic performance. These findings suggest that 2D CdZnHTs are possible candidates as water-splitting photocatalysts.

New Insights into the Stability of Anhydrous 2H-Imidazolium Fluoride and its High Dissolution Capability toward a Strongly Hydrogen-Bonded Compound.

Fluorides have been widely applied in pharmaceutical, medicinal, and materials science as well as in fine chemical manufacturing. The performance of fluorides, however, can be markedly affected by the water content. One previous study (Maiti, A.; et al. Phys. Chem. Chem. Phys. 2008, 10, 5050) suggested that anhydrous 1,3-dimethylimidazolium fluoride ([DMIm]F) was unstable since the fluoride undergoes a self-decomposition reaction. Herein we first show quantum-chemical calculation evidence that although gas-phase [DMIm]F is unstable, the bulk phase of anhydrous [DMIm]F is quite stable. We then demonstrate the successful synthesis of the anhydrous [DMIm]F compound via the reaction between 1,3-dimethylimidazolium iodide and silver fluoride. Importantly, we find that anhydrous [DMIm]F possesses a high dissolution capability toward 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), although it is known that TATB is hardly dissolved in many common organic solvents. Our Born-Oppenheimer molecular dynamics (BOMD) simulations further show that the high dissolving ability of anhydrous [DMIm]F toward TATB can be attributed to the chemical reaction between the F- anion and the TATB molecules, which disrupts the strong hydrogen-bonding interaction among the TATB molecules. Alternatively, water molecules in hydrous [DMIm]F tend to form a hydration layer around the F- anion, thereby preventing F- from reacting with the TATB molecule. This result explains why TATB is barely dissolved in hydrous [DMIm]F.

A two-dimensional CdO/CdS heterostructure used for visible light photocatalysis.

Based on hybrid density functional calculations, the geometrical and electronic structures of a two-dimensional (2D) CdO/CdS heterostructure (HT) formed by a CdO monolayer (ML) and a CdS ML are investigated. The formation of the CdO/CdS HT is exothermic, and the CdO/CdS HT shows excellent ability for visible light absorption. The CdO/CdS HT with a rotation angle of 0° possesses the characteristics of type-II band alignment and strong built-in electric field across the interface, which boost the photogenerated carrier separation. Besides, the band edge positions of the CdO/CdS HT of 0° are energetically favorable for overall water-splitting processes with the pH scope of 0-3.6. Therefore, the CdO/CdS HT is a promising photocatalyst to split water.

Strain-Tunable Visible-Light-Responsive Photocatalytic Properties of Two-Dimensional CdS/g-C3N4: A Hybrid Density Functional Study.

By means of a hybrid density functional, we comprehensively investigate the energetic, electronic, optical properties, and band edge alignments of two-dimensional (2D) CdS/g-C 3 N 4 heterostructures by considering the effect of biaxial strain and pH value, so as to improve the photocatalytic activity. The results reveal that a CdS monolayer weakly contacts with g-C 3 N 4 , forming a type II van der Waals (vdW) heterostructure. The narrow bandgap makes CdS/g-C 3 N 4 suitable for absorbing visible light and the induced built-in electric field between the interface promotes the effective separation of photogenerated carriers. Through applying the biaxial strain, the interface adhesion energy, bandgap, and band edge positions, in contrast with water, redox levels of CdS/g-C 3 N 4 can be obviously adjusted. Especially, the pH of electrolyte also significantly influences the photocatalytic performance of CdS/g-C 3 N 4 . When pH is smaller than 6.5, the band edge alignments of CdS/g-C 3 N 4 are thermodynamically beneficial for oxygen and hydrogen generation. Our findings offer a theoretical basis to develop g-C 3 N 4 -based water-splitting photocatalysts.

Microwave-assisted iodine-catalyzed oxidative coupling of dibenzyl(difurfuryl)disulfides with amines: a rapid and efficient protocol for thioamides.

An efficient protocol for synthesis of thioamides was developed via the microwave-assisted iodine-catalyzed oxidative coupling of dibenzyl(difurfuryl)disulfides with amines. This process is scalable and tolerates a wide spectrum of amines to deliver the corresponding products in moderate to excellent yields in 10 minutes, providing a cheap and rapid approach to thioamides.

Mitochondria-targeting single-layered graphene quantum dots with dual recognition sites for ATP imaging in living cells.

As a molecular unit of intracellular energy transfer, adenosine triphosphate (ATP) is significant for maintaining the energy balance in living cells and thus monitoring cellular ATP is important to assess cellular physiological functions. However, effective monitoring of cellular ATP still faces challenges owing to the similarity of ATP to other nucleoside polyphosphates. Herein, yellow emissive single-layered graphene quantum dots (s-GQDs) with dual recognition sites including π-conjugated single sheets and positively charged sites were developed. The s-GQDs exhibit a good mitochondria targeting ability and respond only to purine nucleotides and show good selectivity in discriminating tri-, di- and monophosphate nucleotides. The good selectivity should be attributed to the concurrent effect of π-π stacking and electrostatic interactions between filmy layered positive s-GQDs and negative purine nucleotides. Owing to the mitochondria targeting ability and dual recognition sites of the s-GQDs, the mitochondrial ATP fluctuation resulting from the activation and suppression of ATP in living cells has been successfully monitored.

Boron and nitrogen co-doped single-layered graphene quantum dots: a high-affinity platform for visualizing the dynamic invasion of HIV DNA into living cells through fluorescence resonance energy transfer.

High-affinity binding of carbon nanomaterials with nucleobases, which is still a challenge, is the basis for DNA directed assembly and sensing. In this work, boron and nitrogen co-doped single-layered graphene quantum dots (BN-SGQDs) are designed as a high-affinity platform for nucleic acid detection and imaging in living cells, which has been confirmed by density functional theory (DFT) simulation and experiments. Owing to their excellent absorption and photoluminescence ability, the high quantum yield (QY 36.5%) yellow fluorescent BN-SGQDs could act as an energy donor in the fluorescence resonance energy transfer (FRET) process for nucleic acid detection. Furthermore, this BN-SGQD based sensing platform has been successfully adopted to visualize the dynamic invasion of human immunodeficiency virus (HIV) DNA into HeLa cells. The high-affinity platform has shown potential for biosensing in complicated biological samples.

Fluorescence enhancement on silver nanoplates at the single- and sub-nanoparticle level.

The fluorescence intensity of a fluorescent molecule can be strongly enhanced when the molecule is near a metal nanoparticle. Hence, fluorescence enhancement has a lot of applications in the fields of biology and medical science. It is necessary to understand the mechanism for such an attractive effect, if we intend to develop better materials to improve the enhancement. In this paper, we directly image the diverse patterns of fluorescence enhancement on single Ag nanoplates by super-resolution microscopy. The research reveals that the edges or tips of the Ag nanoplate usually show a much higher ability of fluorescence enhancement than the mid part. The spatial distribution of fluorescence enhancement strongly depends on the size of the Ag nanoplate as well as the angle between the Ag nanoplate and the incident light. The experimental results above are essentially consistent with the simulated electric field by the theory of localized surface plasmon resonance (LSPR), but some irregularities still exist. We also find that fluorescence enhancement on small Ag nanoplates is mainly due to in-plane dipole plasmon resonance, while the enhancement on large Ag nanoplates is mainly due to in-plane quadrupole plasmon resonance. Furthermore, in-plane quadrupole resonance of large plates has a higher ability to enhance the fluorescence signal than the in-plane dipole plasmon resonance. This research provides many valuable insights into the fluorescence enhancement at the single- and sub-nanoparticle level, and will be very helpful in developing better relevant materials.

Mechanistic Insights into the Cu(I)- and Cu(II)-Catalyzed Cyclization of o-Alkynylbenzaldehydes: The Solvent DMF and Oxidation State of Copper Affect the Reaction Mechanism.

A computational study with the BhandHLYP density functional is conducted to elucidate the mechanisms of Cu(I)- and Cu(II)-catalyzed reactions of o-alkynylbenzaldehydes with a nucleophile (MeOH). Our calculations suggest the following. (a) The use of CuCl as a catalyst deceases significantly the energy barrier and promotes intramolecular cyclization. (b) Solvent DMF is critical in the stepwise hydrogen-transport process involved in an intermolecular nucleophilic addition because it can greatly reduce the free energy barrier of the hydrogen-transfer process as a proton shuttle. In addition, we find that substrate MeOH also plays a role similar to that of DMF in the hydrogen-transport reaction. (c) The 6-endo product P1 is formed exclusively using a catalytic system consisting of CuCl and DMF, whereas a mixture of 6-endo product P1 and 5-exo product P2 in a ratio of ∼1:1 is produced using CuCl2 and DMF as a catalytic system. Our theoretical calculations reproduce the experimental results very well. This study is expected to improve our understanding of Cu(I)- and Cu(II)-catalyzed reactions involving Lewis base solvents and to provide guidance for the future design of new catalysts and new reactions.

Thermally induced isomerization of linoleic acid in soybean oil.

The molecular mechanisms of the thermally induced cis/trans isomerization of the non-conjugated linoleic acids (C18:2) were investigated in a combined experimental and computational study of C18:2 isomers. C18:2 isomers in soybean oil heated at two temperatures (180 and 220 ° C) were analyzed by GC method. C18:2-9c, 12t and C18:2-9t,12c were both the main trans isomers in heated soybean oil. Two alternative isomerization schemes via the proton transfer paths were developed. The geometries in ground states, transition states, and intermediates were optimised using the density functional theory (DFT) at B3LYP/6-31G* level. The formation of C18:2-9t, 12t had two barriers; the first of which was the formation of C18:2-9c, 12t or C18:2-9t, 12c. Zero-point energy corrections of each isomer was calculated at B3LYP/6-311++G** level. The intrinsic reaction coordinates (IRCs) were obtained to examine the transition states and intermediates. The activation energy differences between the cis and trans isomers of C18:2 possibly contributed to the distribution of the final ratio of the isomers. The DFT calculations indicated that the obtained experiment data was well explained by the isomerization mechanism developed.

Description and validation of coupling high performance liquid chromatography with resonance Rayleigh scattering in aminoglycosides determination.

In view of the fact that many substances generally exhibit very little ultraviolet absorbance and the absence of native fluorescence, a new strategy with simple instrumentation and excellent analytical performance combining high performance liquid chromatography (HPLC) with resonance Rayleigh scattering (RRS) was developed. It was validated for the quantification of aminoglycosides (AGs). This fact was also carefully calculated by quantum chemistry. However, the sensitivity was probably limited by the volume of flow-through cell. Therefore, the result calls for a suitable one to ensure optimal RRS signal. Interestingly, when serum or urine samples of analytes were analyzed by this method, they were all well resolved without any interference, which would hold a new perspective to be applied in the determination of substances in biological matrix.