Journal of Chemical Sciences最新文献

The role of intermolecular hydrogen bonds in photoinduced electron transfer (PET) between coumarin 153 (C153) and N,N-dimethylaniline (DMA) was investigated using DFT and TDDFT. Calculations revealed that two intermolecular hydrogen bonds significantly strengthen in the excited state (S₂), with hydrogen-bond binding energy increasing from 8.24 kJ/mol to 157.35 kJ/mol, and dipole moment rising from 7.25 D to 23.43 D. Frontier molecular orbital analysis confirmed that the S₁ state is an intermolecular charge transfer (CT) state, facilitated by enhanced hydrogen bond coupling. Spectral shifts in C–H stretching vibrations validated hydrogen bond dynamics. These findings demonstrate that the reinforcement of hydrogen bonds in the excited state accelerates PET, offering valuable insights for the design of efficient photoactive materials.

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This study shows that the S excited state of the C153/DMA complex is a locally excited state on C153 with partial intramolecular charge transfer (CT) from N to the C=O group. The S₁ state, in contrast, is an intermolecular CT state involving photoinduced electron transfer (PET) from DMA to C153 and has low oscillator strength. Hydrogen bonds between molecules are stronger in the S₂ state, supporting this electron transfer.

We have witnessed a recent surge in the development and application of the information-theoretic approach in density functional theory. In this article, by focusing on our own work in recent years, we highlight its theoretical framework, including four representations, three principles and two identities, illustrate four examples of its applications in determining electrophilicity, nucleophilicity, regioselectivity and stereoselectivity, and then overview a few advances in the recent literature such as topological analysis, energetic information, excited states and machine learning. We conclude by providing a few remarks about its future developments and possible applications.

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Strong linear correlations of experimental scales of electriphilicity and nucleophilicity with theoretical quantities such as information gain and Hirshfeld charge from information-theoretic approach were showcases.

Deep eutectic solvents (DESs) offer a sustainable alternative to conventional ionic liquids through their cost-effective synthesis and benign constituents. In this study, we employed all-atom molecular dynamics simulations to investigate how the alkyl chain length of DES constituents influences microscopic diffusion and complexation dynamics in systems composed of lithium perchlorate with acetamide and propanamide. Our analysis identifies distinct diffusion regimes – ranging from ballistic to sub-diffusive and Fickian behaviour – with dynamic heterogeneity becoming more pronounced as the alkyl chain length increases. Importantly, the study reveals that this enhanced dynamical heterogeneity is strongly linked to the stability and extended lifetimes of Li⁺-alkylamide complexes, as evidenced by elevated non-Gaussian parameters, delayed transition to Gaussian dynamics, and reinforced radial distribution peaks. These insights highlight the critical interplay between molecular architecture and complexation dynamics, paving the way for the rational design of DESs for advanced electrochemical and catalytic applications.

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This study reveals that increasing the alkyl chain length in DESs strengthens Li⁺-amide complexation, leading to longer lifetimes. This enhanced complex stability directly induces pronounced dynamical heterogeneity, as evidenced by delayed Fickian diffusion and elevated non-Gaussian behaviour, highlighting the intricate link between complex stability and microscopic transport properties.

In this study, we utilize a promoter, specifically zinc, in varying concentrations to examine its promoting effects. This series of catalysts was prepared using a co-impregnation method involving zinc and platinum on titanium dioxide (TiO₂). The material was then dried at 100 °C and calcinated at 400 °C for 4 hours. The samples were subjected to a prolonged reduction at 300 °C for four hours. The physicochemical characteristics of the x Zn–Pt/TiO₂ P25 samples, each with distinct weight percentages of x Zn, were evaluated using a comprehensive array of analytical techniques. These methods included elemental analysis, X-ray diffraction, nitrogen sorption, hydrogen chemisorption, transmission electron microscopy, and cyclohexane dehydrogenation. This specific reaction has been utilized as a model to evaluate the accessibility of platinum and the degree of zinc coverage. An investigation into the performance and selectivity of the catalysts was conducted during the hydrogenation of citral, which was performed at a temperature of 70 °C and a hydrogen pressure of 7 MPa. The reaction occurred in isopropanol as the solvent and lasted for 120 minutes. A higher concentration of zinc in the materials was correlated with a reduced accessibility of platinum metal within the catalysts. This specific reaction has been utilized as a model to evaluate the accessibility of platinum and the degree of zinc coverage.

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The synthesis of x% Zn–Pt/TiO₂ catalysts (x between 0 and 0.3 wt%), for further application in the selective hydrogenation of citral in the liquid phase. The catalytic systems were deeply characterized by several physico-chemical techniques. We clearly evidenced the existence of an interaction between Pt and Zn with the formation problem of alloy, leading to an inhibition of the Pt hydrogenating activity but contributing to a remarkable increase in the selectivity to unsaturated alcohols due to a better activation of the C=O bond of citral. A maximum value of 81% for the unsaturated alcohols selectivity was reached with the bimetallic 0.3% Zn–Pt/TiO₂ catalyst.

Self-driving or autonomous labs are platforms that integrate artificial intelligence (AI)/machine learning (ML), robotics and high-throughput experiments, and are capable of designing, synthesizing, testing and optimizing materials for specific purposes with minimal human intervention. Crucial components are algorithms and methods that are capable of generating new materials with desired properties. A recent study by Zeni et al. has reported a material generative model, MatterGen that is fine-tuned to propose new materials conditioned on user-specific mechanical, electronic and magnetic properties.

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Fully autonomous chemistry laboratories bring together advanced generative AI algorithms, robotic systems and high-throughput experiments that can computationally design, and experimentally synthesize and characterize molecules/materials. In this news story, we discuss the importance of methods such as recently proposed MatterGen in making self-driving laboratories a reality.

An eco-friendly method for synthesizing naphthalene diazonium salts and azo dyes has been developed, offering a sustainable alternative to the traditional techniques requiring strong acids and extensive cooling. Aryldiazonium ions derived from nitroanilines are effective for vivid color labeling and precursors for durable azo dyes. In this method, naphthylamines (1-naphthylamine, 4-nitro-1-naphthylamine, and 2,4-dinitro-1-naphthylamine) undergo diazotization using tert-butyl nitrite and p-toluenesulfonic acid in an organic solvent at room temperature. The products obtained are bench-stable for several months and have been utilized as intermediates for azo dye formation by coupling with 2-naphthol at room temperature. A complete spectroscopic technique using 1D and 2D NMR with the mass spectrometric characterization of the dyes reveals that they exist as azo-hydrazone tautomers. The percentage hydrazone tautomer was calculated using the ¹⁵N chemical shift, ¹J_NH coupling constant, as well as the predicted ¹³C chemical shift. The result obtained shows that the synthesized dyes are predominantly present in hydrazone form (71%, 90%, and 94% for compounds 1c, 2c, and 3c, respectively). The electrospray ionization mass spectrometry analysis confirmed the mass of the dyes at m/z 298, 343, and 388, respectively. The environment-friendly and thermostable diazonium salts have been synthesized and also successfully employed as intermediates in synthesizing azo dyes with precise structural elucidation.

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An eco-friendly synthesis of naphthalene diazonium salts and azo dyes was developed using tert-butyl nitrite and p-toluenesulfonic acid. 1D and 2D NMR spectroscopy revealed dominant azo-hydrazone tautomerism, with hydrazone content reaching up to 94%. This method offers sustainable alternatives for stable dye synthesis with precise structural elucidation.

This study presents a novel approach for synthesizing various regio-selective 3,5-disubstituted isoxazoles using inexpensive CuI catalysis. Moderate to good yields of the target compounds were achieved through this method. Based on the experimental results and literature insights, a plausible mechanism involving two consecutive Cu-catalytic cycles, Sonogashira coupling, and intramolecular cyclization was proposed. Notably, opposite regio-selectivity was observed between products obtained from uncatalyzed and CuI-catalyzed reactions. The outcomes of this CuI-catalyzed one-pot protocol represent an improvement over previous methods, offering a promising avenue for diverse isoxazole derivative synthesis. The proposed process involves homogeneous CuI-promoted one-pot three-component regio-selective synthesis of 3,5-disubstituted isoxazoles, with key in situ α,β-unsaturated ynone intermediates crucial for subsequent reactions. This approach streamlines synthesis, allowing simultaneous assembly of multiple chemical components in a single reaction vessel, while minimizing the need for complex steps and costly reagents. Overall, this strategy holds promise for rapid and economical production of diverse 3,5-disubstituted isoxazoles, with potential applications in medicinal chemistry and materials science.

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Apart from tri-iso-amyl phosphate (TiAP), which has been used in fast reactor fuel reprocessing, several studies have focused on various derivatives of amyl phosphates for their potential application in the extraction of U and Pu. For effective decontamination of heavy metals, it is crucial that the uptake of fission products be minimized by target ligands. In this study, we explore the primary interaction, i.e., the molecular level interaction of Zr [in the form of Zr(NO₃)₄], a troublesome fission product, with four amyl phosphates using computational chemistry techniques. The four ligands studied are tri-sec-amyl-phosphate (TsAP), tris (2-methylbutyl) phosphate (T2MBP), tri-iso-amyl-phosphate (TiAP), and tri-n-amyl-phosphate (TAP). Calculations indicate that, for the single-step 1:2 complex formation, all four ligands exhibit almost the same binding affinity towards zirconium nitrate, with a marginally higher propensity for TsAP and TAP. The stepwise formation of 1:2 complex was also studied starting from Zr(NO₃)₄.2H₂O, in which the formation of the 1:2 complex was attributed via the respective 1:1 complexes, i.e., Zr(NO₃)₄·H₂O·L. Here the 1:1 complexes of TsAP, TiAP and TAP ligands were found to be more stable compared to the T2MBP complex and the higher stability is attributed to the presence of intra-molecular hydrogen bond present between the H atom of water and the O atom of the nitrate. Interestingly, it was observed that the zirconium nitrate moiety is highly sensitive to the external ligand environment, as evident from the very high strain or deformation energy of the metal nitrate upon complexation.

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Zirconium Amyl Phosphate Complexes: The interaction of zirconium nitrate [Zr(NO₃)₄] with four amyl phosphates (TsAP, T2MBP, TiAP, and TAP) indicates a higher affinity for the TsAP and TAP ligands. The study also highlights the sensitivity of zirconium nitrate to external ligand environments, as evidenced by significant deformation energy upon complexation.

The ever-increasing global energy demand has necessitated alternate sources of energy. Photoelectrochemical water splitting proved to be a viable method of green hydrogen production. In the present study, four different one-dimensional titanium dioxide nanotube arrays (TNAs) were fabricated by varying the time duration of the second anodization. The highly ordered TNAs proved to be potential photoanodes for photoelectrochemical water splitting, for production of hydrogen. The fabricated TNAs were confirmed as stable anatase crystal structures using X-ray diffraction and Raman spectroscopy analysis. The TNAs showed an increase in length with an increase in anodization time. The morphological studies revealed the formation of the one-dimensional tube-like morphology of TNAs with lengths varying from 1.41 μm to 6.35 μm. The increased length and one-dimensional nanotube formation implied an increased number of active sites and an increased surface-to-volume ratio. The observed increase in photocurrent may be attributed to increased electrode–electrolyte interfacial area, where charge and mass transport occured. The band-gap of the TNAs showed a minimal progressive decrease with an increase in anodization time. The oxidation states of the constituent elements were confirmed using X-ray photoelectron spectroscopy. Contact angle measurement indicated a transition from slight hydrophobicity to slight hydrophilicity with an increase in the anodization time of the TNAs. Electrochemical studies of TNAs exhibited increased photo-response with an increase in anodization time. The influence of anodization time on the characteristics of TNAs is explored in this study.

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TiO₂ Nanotube Arrays (TNAs) were synthesized by two – step anodization method, by varying second anodization time. The TNAs were tested for their efficacy as photo-anode, following exhaustive characterization techniques. The activity of the potential photoanodes for PEC water splitting was analyzed using LSV, CA, EIS and Tafel plots

Microhydration of neutral and anionic nitromethane molecules was investigated up to (n =10) water molecules using dispersion-corrected density functional B2PLYPD with aug-cc-pVDZ basis sets. The calculated interaction energies of both anion and neutral nitromethane–water clusters were extrapolated to the complete basis set (CBS) limit. It was observed that the water molecules interact with the methyl group of the nitromethane in the case of a neutral molecule, whereas in anionic nitromethane hydration, water molecules build a hydrogen bond network strongly around the nitro group of the nitromethane. The SAPT analysis and MED critical point calculations have revealed that the anionic nitromethane–water cluster is more stable as compared to the neutral one. Further, the SAPT analysis showed that an increase in stability in case of the interaction in an anionic nitromethane–water complex is because of a higher attractive contribution from the electrostatic and dispersion components. The vertical detachment energy (VDE) and electron affinity (EA) values of nitromethane were also calculated, and the VDE values were found to be in good agreement with the experimental values.

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Anionic Nitromethane-(H₂O)_n clusters investigated using Dispersion Corrected Density Functional Theory and compared with neutral counterparts. The calculated VDE values show good agreement with Experimental values.