Density Functional Theory Research Articles

Unraveling the Synergistic Role of Sm3+ Doped NiFe-LDH as High-Performance Electrocatalysts for Improved Anion Exchange Membrane and Water Splitting Applications.

Effective first-row transition metal-based electrocatalysts are crucial for large-scale hydrogen energy generation and anion exchange membrane (AEM) devices in water splitting. The present work describes that SmNi0.02Fe-LDH nanosheets on nickel foam are used as a bifunctional electrocatalyst for water splitting and AEM water electrolyzer study. Tuning the Ni-to-Fe ratios in NiFe-LDH and doping with Sm ions improves the electrical structure and intrinsic activity. SmNi0.02Fe-LDH has higher oxygen evolution reaction (OER), HER, and TWS activity, achieving 10 mAcm⁻2 current density at lower overpotentials (230 mV, 95 mV, and 1.62 V, respectively). In AEMWE cells, SmNi0.02Fe-LDH as a cathode and anode pair exhibits outstanding activity (0.9 Acm⁻2 at 2 V) and stability over 120 h. Density Functional Theory (DFT) investigations reveal that the Sm doping in NiFe-LDH surface enhances its bifunctional activity toward OER and HER. These findings emphasize the potential of non-noble composites for long-term water electrolysis in total water splitting and AEMWE applications.

Ab Initio Investigation of the Mechanics and Thermodynamics of the Cubic EuAlO3 and GdAlO3 Perovskites for Optoelectronic Applications

Perovskites are currently becoming common in the field of optoelectronics, owing to their promising properties such as electrical, optical, thermoelectric, and electronic. Although mechanical and thermal properties also play a crucial part in the functioning of the optoelectronic devices, they have scarcely been explored. The present work performed an ab initio study of the mechanical and thermal properties of the cubic EuAlO3 and GdAlO3 perovskites for the first time using density functional theory. Quantum Espresso and Themo_pw codes were utilized by employing the generalized gradient approximation. Although the results showed that both materials have good mechanical and thermal properties that are ideal for the above–mentioned applications, EuAlO3 possessed better structural and thermal stability, bulk modulus, Poisson ratio, thermal expansion coefficient, and thermal stress; while GdAlO3 possessed better Young’s modulus and shear modulus. Moreover, the mechanical properties of the two materials turned out to be much better than those of the common materials for optoelectronic applications, while their thermal properties were comparable to that of sapphire glass. Since this study was computational, an experimental verification of the computed properties of the two materials needs to be carried out before they can be commercialized.

Toxicity of anthraquinone derivatives in relation to non-linear optical properties and electron correlation.

1,4-Dialkylamino -5,8-dihydroxy anthraquinones are investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) for their growth inhibitory potential. The frontier molecular orbital shows that the electron density is located at the anthraquinone core and at the substituents NH and OH in both HOMO as well as in LUMO. The chemical potential and electrophilicity index showed a direct relation, while hardness and hyperhardness had an inverse association with an energy gap. The results of the molecular docking analysis revealed that the anthraquinone molecules have a high affinity for the primary targets of the DNA topoisomerase IIα enzyme. The docking results showed good binding ability with extremely energetically stable scores ranging from -8.9 to -7.6 kcal/mol. Electron correlation descriptors showed a direct link with NLO properties and toxicity.

Concurrently Boosting Activity and Stability of Oxygen Reduction Reaction Catalysts via Judiciously Crafting Fe–Mn Dual Atoms for Fuel Cells

The ability to unlock the interplay between the activity and stability of oxygen reduction reaction (ORR) represents an important endeavor toward creating robust ORR catalysts for efficient fuel cells. Herein, we report an effective strategy to concurrent enhance the activity and stability of ORR catalysts via constructing atomically dispersed Fe-Mn dual-metal sites on N-doped carbon (denoted (FeMn-DA)-N-C) for both anion-exchange membrane fuel cells (AEMFC) and proton exchange membrane fuel cells (PEMFC). The (FeMn-DA)-N-C catalysts possess ample dual-metal atoms consisting of adjacent Fe-N4 and Mn-N4 sites on the carbon surface, yielded via a facile doping-adsorption-pyrolysis route. The introduction of Mn carries several advantageous attributes: increasing the number of active sites, effectively anchoring Fe due to effective electron transfer to Mn (revealed by X-ray absorption spectroscopy and density-functional theory (DFT), thus preventing the aggregation of Fe), and effectively circumventing the occurrence of Fenton reaction, thus reducing the consumption of Fe. The (FeMn-DA)-N-C catalysts showcase half-wave potentials of 0.92 and 0.82V in 0.1M KOH and 0.1M HClO4, respectively, as well as outstanding stability. As manifested by DFT calculations, the introduction of Mn affects the electronic structure of Fe, down-shifts the d-band Fe active center, accelerates the desorption of OH groups, and creates higher limiting potentials. The AEMFC and PEMFC with (FeMn-DA)-N-C as the cathode catalyst display high power densities of 1060 and 746mWcm-2, respectively, underscoring their promising potential for practical applications. Our study highlights the robustness of designing Fe-containing dual-atom ORR catalysts to promote both activity and stability for energy conversion and storage materials and devices.

Efficient and Stable Red‐Orange Emission from Polaronic Magnetic Excitons in Mn (II)‐Doped 0D All‐Inorganic Rb4CdCl6

AbstractThe impact of magnetic coupling effects on the luminescence of 0D (zero‐dimensional) perovskite materials doped with TM (transition metal) ions remains underexplored. This study synthesizes Mn2+‐doped 0D Rb4CdCl6 halide structures using a solvent‐based method, with Rb+ ions systematically arranged around isolated [CdCl6]4− octahedra. The resulting Rb4Cd1‐xMnxCl6 powder exhibits stable orange‐red luminescence under UV (ultraviolet) excitation, achieving a PLQY (photoluminescence quantum yield) of 88.96%. The parent Rb4CdCl6 is non‐luminescent, but doping with Mn2+ induces strong luminescence due to combined emissions from d‐d transitions of Mn2+, weakly ferromagnetically coupled Mn2+ pairs, and STEs (self‐trapped excitons). Characterization via XRD (X‐ray diffraction) and DFT (density functional theory) reveals that Mn2+ doping occurs through both substitutional and interstitial processes, facilitating magnetic coupling. Raman spectroscopy identifies strong electron‐phonon coupling at a phonon mode of 112 cm−1, supporting STEs generation. Magnetic property analysis shows significant ferromagnetic coupling between Mn2+ pairs and paramagnetic single Mn2+ ions, enhancing luminescence. The material demonstrates remarkable structural and thermal stability, positioning Rb4Cd1‐xMnxCl6 as a promising candidate for optoelectronic applications.

Revisiting Thomson's model with multiply charged superfluid helium nanodroplets.

We study superfluid helium droplets multiply charged with Na+ or Ca+ ions. When stable, the charges are found to reside in equilibrium close to the droplet surface, thus representing a physical realization of Thomson's model. We find the minimum radius of the helium droplet that can host a given number of ions using a model whose physical ingredients are the solvation energy of the cations, calculated within the helium density functional theory approach, and their mutual Coulomb repulsion energy. Our model goes beyond the often used liquid drop model, where charges are smeared out either within the droplet or on its surface, and which neglects the solid-like helium shell around the ions. We find that below a threshold droplet radius R0, the total energy of the system becomes higher than that of the separated system of the pristine helium droplet and the charges embedded in their solvation microcluster ("snowball"). However, the ions are still kept within the droplet by the presence of energy barriers, which hinder Coulomb explosion. A further reduction of the droplet radius below a value Rexpl eventually results in the disappearance of such barrier, leading to Coulomb explosion. Surprisingly, our results are rather insensitive to the ion atomic species. This makes room to discuss them in the context of intrinsic multicharged helium droplets, where the charges are triatomic He3+ ions. Our calculated values for Rexpl display the correct scaling with the number of cations compared to the available experimental results, at variance with other estimates for the critical radii.

On the increase of the melting temperature of water confined in one-dimensional nano-cavities.

Water confined in nanoscale cavities plays a crucial role in everyday phenomena in geology and biology, as well as technological applications at the water-energy nexus. However, even understanding the basic properties of nano-confined water is extremely challenging for theory, simulations, and experiments. In particular, determining the melting temperature of quasi-one-dimensional ice polymorphs confined in carbon nanotubes has proven to be an exceptionally difficult task, with previous experimental and classical simulation approaches reporting values ranging from ∼180K up to ∼450K at ambient pressure. In this work, we use a machine learning potential that delivers first principles accuracy (trained to the density functional theory approximation revPBE0-D3) to study the phase diagram of water for confinement diameters 9.5 < d < 12.5 Å. We find that several distinct ice polymorphs melt in a surprisingly narrow range between ∼280 and ∼310K, with a melting mechanism that depends on the nanotube diameter. These results shed new light on the melting of ice in one-dimension and have implications for the operating conditions of carbon-based filtration and desalination devices.

Structural, Spectroscopic, and Docking Analysis of N,O-Donor Ligand Metal Complex Nanoparticles with Hypolipidemic Effects via Lipoprotein Lipase Activation in High-Fat Diet Mice.

New Cd(II), Zn(II) and Cu(II)-chelates with cetirizine.2HCl (CETZ.2HCl) in incidence of 1,10 phenanthroline monohydrate (Phen.H2O) were synthesized in search of new biologically active compounds. The ligands and their chelates were described by 1H NMR, FT-IR, elemental analysis, UV-vis. spectrophotometry, thermal-analyses, molar conductance, X-ray-diffraction (XRD) and magnetic-susceptibility measurements. FT-IR demonstrated that CETZ.2HCl is bonded with metal ions, as a monodentate via carboxylate oxygen atom and Phen.H2O chelated via two nitrogen atoms. The molar conductivity data showed that the complexes were non-electrolytes, while XRD data supported that the compounds were crystalline. Density functional theory-(DFT) was utilized to gain insight into the compounds' optimized design. The effects of CETZ.2HCl and the complexes on the activity of Lipoprotein-(L)-lipase activity in mice were investigated. Unlike Cd(II) complex, all the other compounds exhibited significant increase in lipase activity, with reduction in triglycerides. Cu(II) and Zn(II) complexes showed robust hypolipidemic efficacy evidenced by lower levels of total cholesterol and LDL, concomitant with higher levels of HDL. Furthermore, Zn(II) complex was a safe alternative since it has a lower liver toxicity. Molecular docking demonstrated that Cu(II) and Zn(II) chelates exhibited greater affinities to lipase than the parent ligand. Finally, Cu(II) complex showed the highest antibacterial activity.

The density-functional theory of quantum droplets

Abstract In quantum droplets, the mean-field energy is comparable to the Lee-Huang-Yang (LHY) energy. In the Bogoliubov theory, the LHY energy of the quantum droplet has an imaginary part, but it is neglected in most studies for practical purposes. So far, most theoretical studies of quantum droplets have been based on the extended Gross-Pitaevskii (GP) equation obtained by including the contribution of the LHY energy to the chemical potential. In this article, we present the density-functional theory of quantum droplets. In our approach, the quantum fluctuations in quantum droplets, as described by an effective action, generate the correlation energy which is real and can be determined self-consistently. Using the density-functional theory, we calculate the energy, the quantum depletion fraction, and the excitations of the droplet. Our results for the ground-state energy and the quantum depletion fraction are consistent with the Monte Carlo results. The implications of our theory are discussed.

Reactivity Study of the Bis(phosphine)-Stabilized Antimony(I) Cation.

The 5,6-Bis(diisopropylphosphino)acenaphthene L-stabilized Sb(I) cationic compound [LSb][OTf] (OTf = CF3SO3) 1 possessing two lone pairs of electrons on the Sb(I) center showed nucleophilic behavior toward methyl trifluoromethanesulfonate forming the oxidized product [LSbMe][OTf]2 2 (OTf = CF3SO3). Reaction of compound 1 with Lewis acids such as GaCl3 and AlBr3 led to changes in the counteranions only giving products [LSb][GaCl4] 3 and [LSb][SbBr4] 4, respectively. A metathesis reaction was observed when compound 1 was reacted with PI3. The Sb(I) cation in 1 underwent the metathesis reaction with the P(I) cation, forming the more stable product [LP][OTf] 5. The Sb(I) center in 1 was completely oxidized to Sb(V) by reacting with two equivalents of o-chloranil to give the Bis(phosphine)-stabilized Bis(perchloro catecholato)stibonium cation [L(O2C6Cl4)2Sb][OTf] 6. Both compounds 1 and 6 were employed as proof-of-concept Lewis acid catalysts for the hydrosilylation of p-methyl benzaldehyde. All the compounds were characterized using single-crystal X-ray diffraction analysis, multinuclear nuclear magnetic resonance spectroscopy, mass spectrometry, and absorbance spectroscopy. Density functional theory calculations were performed on the relevant compounds.

Mechanism of Hot-Carrier Photoluminescence in Sn-Based Perovskites.

Metal halide perovskites have shown exceptionally slow hot-carrier cooling, which has been attributed to various physical mechanisms without reaching a consensus. Here, experiment and theory are combined to unveil the carrier cooling process in formamidinium (FA) and caesium (Cs) tin triiodide thin films. Through impulsive vibrational spectroscopy and molecular dynamics, much shorter phonon dephasing times of the hybrid perovskite, which accounts for the larger blueshift in the photoluminescence seen at high excitation density for FASnI3 compared to CsSnI3 is reported. Density functional theory investigations reveal that the largest contribution to the blueshift is accounted by a giant, dynamic band-filling effect in Sn-based perovskites, which in turn can explain the cooling disparity with the Pb-based counterparts. Several years after the first experimental observations, here a deeper understanding of the cooling mechanism of these materials is provided. Design principles for hot-carrier materials, which may be useful for future implementations of hot-carrier solar cells are further provided.

Bifuruzan skeleton: developing new high-energy and high-density energetic materials.

High-energy density materials (HEDMs) are integral to modern society and are in high demand. Consequently, the design and synthesis of energetic material molecules have garnered significant research interest. This study focuses on the furazan ring system as a core for developing superior HEDMs. We employed density functional theory (DFT) to assess the properties of 27 novel energetic compounds, including their geometries, densities, enthalpies of formation, detonation velocities, detonation pressures, and molecular orbital energies (HOMO-LUMO). The computation of detonation velocity and detonation pressure was based on theoretical density and enthalpy of formation. The findings revealed that incorporating energetic groups into the furazan framework, linked by sec-ammonia bridge (-NH-), enhances both the detonation performance and oxygen content of the materials. This enhancement guides the future synthetic endeavors aimed at creating advanced HEDMs. DFT has been employed to investigate the detonation performance and stability of energetic materials. Molecular optimization and performance metrics were all calculated using the DFT-B3LYP method with a 6-311 + G* basis set. The optimization and volume calculations were performed using the Gaussian 09 package. The electrostatic potential energy was computed using Multiwfn software. The impact sensitivity of the designed molecules was calculated using the heat of detonation model.

Solar Assisted Mitigation of Chloramphenicol and H2 Evolution Using CuNi Alloy Nanoparticles on h-BN Doped g-C3N4: A Comprehensive Approach Combining Synchrotron and DFT Analysis.

A simple one-step deposition-precipitation method was used to synthesize highly active and well-defined CuNi alloy bimetallic nanoparticles supported on h-BN/g-C3N4. The nanocomposite was applied for hydrogen gas evolution via seawater splitting and photocatalytic chloramphenicol (CHP) removal. Through TEM and synchrotron studies, the formation of CuNi alloy and uniform distribution of CuNi bimetallic nanoparticles on the h-BN/g-C3N4 surface was observed. The EXAFS analysis verified the successful formation of the alloy, while the XPS and XANES spectra showed that the bimetallic nanoparticles are in a metallic state. Additionally, XANES revealed nanoparticle distortion upon interaction with the support, confirming the effective formation of the nanocomposite. The nanocomposite achieved a maximum hydrogen evolution rate of 3658.9 μmol g-1 h-1 for 5 wt % CuNi(3:1)/h-BN/g-C3N4, outperforming CuNi(3:1) nanoparticles and pristine g-C3N4 by 1.82 and 4.31 times, respectively. Additionally, it degraded chloramphenicol with a rate constant (kapp) of 0.018 min-1. Optical and electrochemical analysis revealed enhanced charge mobility, extended lifetime, improved photostability, and superior photoresponse. X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations attributed the performance to the synergy between the bimetallic nanoparticles and the h-BN/g-C3N4 sheet. DFT calculations demonstrated the effective breakdown of chloramphenicol and the promotion of hydrogen gas evolution, aligning with experimental observations. Cytotoxicity of CHP post-treatment was analyzed using Drosophila melanogaster (fruit fly) and the Oregon-R strain of D. melanogaster.

Low Potential Electrochemical CO2 Reduction to Methanol over Nickel‐Based Hollow 0D Carbon Superstructure

AbstractElectrochemical carbon dioxide reduction reaction (CO2RR) to valuable fuels and chemical feedstock is a sustainable strategy to lower the anthropogenic CO2 concentration, thereby dynamising the carbon cycle in the environment. CH3OH on the other hand is undoubtedly the most desirable C1 product of CO2RR. However, selective electroreduction of CO2‐to‐CH3OH is very challenging and only limited catalysts are reported in literature. Pyrolyzing metal‐organic frameworks (MOFs) to generate carbon matrix impregnated with metal nanoparticles, heralds exciting electrocatalytic properties. This study unveiled the morphological evolution of a mixed‐ligand Ni‐MOF (Ni‐OBBA‐Bpy) during pyrolysis, to generate Ni nanoparticles anchored 0D porous hollow carbon superstructures (Pyr‐CP‐800 and Pyr‐CP‐600). This unique morphology invokes high specific surface area and surface roughness to the materials, which synergistically facilitates the selective electroreduction of CO2‐to‐CH3OH. In comparison to most of the previously reported Ni electrocatalysts that mainly produced CO, Pyr‐CP‐800 selectively yielded CH3OH with Faradaic efficiency (FE) of 32.46% at −0.60 V versus RHE (reversible hydrogen electrode) in 1.0 M KOH solution, which is highest among other reported Ni‐based electrocatalysts in the literature, to best of our knowledge. Additionally, insights from density functional theory (DFT) calculations revealed that Ni (111) plane to be the active site toward the electrochemical. CO2‐to‐CH3OH formation.

Assignment of IR spectra of ethanol at Brønsted sites of H-ZSM-5 to monomer adsorption using a Fermi resonance model.

Understanding how alcohol molecules interact with the Brønsted acid sites (BAS) of zeolites is a prerequisite to the design of zeolite catalysts and catalytic processes. Here, we report IR spectra for the adsorption of ethanol on a highly crystalline sample of H-ZSM-5 zeolites exposed to ethanol gas at increasing pressure. We use density functional theory in combination with a FERMI resonance model to assign the measured spectra to a single adsorbed ethanol molecule per BAS. Specifically, we assign the bands at 2450 cm-1 and 1670 cm-1 to a FERMI resonance between the fundamental (Z)O-H stretching band of a single-ethanol-loaded BAS and the first overtone of the (Z)O-H out-of-plane bending. We conclude that adsorbed dimers do not contribute in a noticeable way up to a concentration of almost one ethanol molecule per BAS site. We further show that hybrid functionals (B3LYP) are required to get a close match between the predicted and experimental spectra, whereas commonly used generalized gradient type functionals such as PBE incorrectly describe the potential energy surface. They overestimate the redshift of the OH stretching band on hydrogen bond formation which results in an erroneous assignment of the IR bands.

Investigating the Origin of Automatic Rhodopsin Modeling Outliers Using the Microbial Gloeobacter Rhodopsin as Testbed.

The automatic rhodopsin modeling (ARM) approach is a computational workflow devised for the automatic buildup of hybrid quantum mechanics/molecular mechanics (QM/MM) models of wild-type rhodopsins and mutants, with the purpose of establishing trends in their photophysical and photochemical properties. Despite the success of ARM in accurately describing the visible light absorption maxima of many rhodopsins, for a few cases, called outliers, it might lead to large deviations with respect to experiments. Applying ARM toGloeobacter rhodopsin (GR), a microbial rhodopsin with important applications in optogenetics, we analyze the origin of such outliers in the absorption energies obtained for GR wild-type and mutants at neutral pH, with a total root-mean-square deviation (RMSD) of 0.42 eV with respect to the experimental GR excitation energies. Having discussed the importance and the uncertainty of one particular amino-acid pKa, namely histidine at position 87, we propose and test several modifications to the standard ARM protocol: (i) improved pKa predictions along with the consideration of several protonation microstates, (ii) attenuation of the opsin electrostatic potential at short-range, (iii) substitution of the state-average complete active space (CAS) electronic structure method by its state-specific approach, and (iv) complete replacement of CAS with mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT). The best RMSD result we obtain is 0.2 eV combining the protonation of H87 and using MRSF/CAMH-B3LYP.

Multicomponent synthesis of stereogenic-at-boron fluorophores (BOSPYR) from boronic acids, salicylaldehydes, and 2-formylpyrrole hydrazones.

This work describes one-step syntheses of various stereogenic-at-boron fluorochromes (BOSPYR) via multicomponent reactions involving readily accessible boronic acids, salicylaldehydes, and 2-formylpyrrole hydrazones. The dyes absorb and emit in the visible region of the electromagnetic radiation, and are characterized by large Stokes shifts (2850-4930 cm-1) with weak fluorescence emissions (Φfl: 1.5-9.1%). Notably, the dimmed fluorescence of BOSPYRs recovers upon transition to viscous media (21-fold for 1a). The representative compound 1a exhibits clear Cotton effects with dissymmetry factors of ca. |gabs| ∼ 1.9 × 10-3 in the visible region, indicating efficient asymmetry induction to the chromophore. The X-ray molecular structure of 1a shows that the chromophore deviates from planarity by 17.2°, which may contribute significantly to the inherent chirality of the fluorophore. A computational examination of excited states by time-dependent density functional theory (TD-DFT) identifies the emission mechanism as arising from a locally-excited (LE) state.

Defective h-BNs-Supported Pd Nanoclusters: An Efficient Photocatalyst for Selective Oxidation of 5-Hydroxymethylfurfural.

5-hydroxymethylfurfural (HMF) is one of the most promising biomass-based chemicals that is used to produce many kinds of important compounds. Especially, the selective conversion of HMF to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), an important chemical feedstock, has high industrial significance but is technically challenging. In this study, we present a high-performance photocatalyst for selective oxidation of HMF to HMFCA. By integrating an ultrasmall amount of palladium (Pd) nanoclusters (1.12‰ in weight) on defective hexagonal boron nitride nanosheets (Pd/defective h-BN nanosheets (dh-BNs)), outstanding photocatalytic performance can be achieved, resulting in up to a 95% HMF conversion ratio with an 82% HMFCA selectivity. The performance is considerably higher than that of pristine dh-BNs and Pd on defect-free h-BNs. More importantly, this Pd/dh-BNs catalyst maintains a high catalytic activity after eight cycles, demonstrating robust catalytic stability. Density functional theory calculations indicate that Pd/dh-BNs can lower the energy barrier for HMF oxidation and facilitate the desorption of HMFCA, which contributes to the high selectivity catalytic performance. This study not only introduces a promising photocatalyst for sustainable chemical transformations but can also provide valuable insights into the design of advanced photocatalytic material for biorefinery applications.

N-Doped Carbon-Incorporated Cobalt-Iron Mixed-Metal Phosphide Nanoboxes as Efficient Bifunctional Catalysts for Overall Water Splitting.

Optimizing the composition and structure of nanocatalysts is an efficient approach to achieving the top electrocatalytic performance. However, the construction of hollow nanocomposites composed of metal phosphides and highly conductive carbon to promote the electrocatalytic performance of metal phosphide-based catalysts is rarely reported. Herein, a CoFeP/C nanobox nanocomposite consisting of Co-Fe mixed-metal phosphides and N-doped carbon was successfully fabricated through an ion-exchange phosphidation strategy derived from ZIF-67 nanocubes. Benefiting from the synergistic effects between multiple components and the unique hollow structure, CoFeP/C nanoboxes can catalyze the alkaline oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with high activity and stability. Furthermore, in the construction of an alkaline water electrolyzer using CoFeP/C nanoboxes as both OER and HER catalysts, they were capable of efficiently splitting water with a current density of 10 mA cm-2 achieved by applying only 1.62 V of cell voltage and exhibited outstanding durability. Density functional theory calculations demonstrate that synergistic effects among multiple components in CoFeP/C nanoboxes can lower the hydrogen adsorption free energy of the HER and OER energy barrier of the rate-determining step, thus promoting the catalytic reactions. The design and synthesis of CoFeP/C nanoboxes highlight the importance of the composition and structural characteristics in achieving high-performance water electrolysis.

Influence of Curvature on the Physical Properties and Reactivity of Triplet Corannulene Nitrene.

Although nitrene chemistry is promising for the light-induced modification of organic compounds, the reactivity of large polycyclic aromatic compounds and the effects of their curvature remain unexplored. Irradiation of azidocorannulene (1) in methanol/acetonitrile followed by HCl addition produced diastereomers 5 and 5'. Azirine 2 is apparently trapped by methanol to form diastereomeric acetal derivatives that are hydrolyzed with HCl to yield 5 and 5'. ESR spectroscopy in a glassy matrix at 77 K showed that irradiation of 1 yields corannulene nitrene 31N, which has significant 1,3-biradical character. Irradiation of 1 in a glassy matrix resulted in a new absorption band in the region of 360-440 nm, with λmax at 360 and 410 nm, attributed to 31N, as supported by time-dependent density function theory calculations, which placed the major electronic transitions of 31N at 367 nm (f = 0.0407) and 440 nm (f = 0.0353). Laser flash photolysis of 1 revealed a similar absorption spectrum. Nitrene 31N had a lifetime of only a few hundred nanoseconds and was efficiently quenched by oxygen, because of its 1,3-biradical character. CASPT2(12,11)/6-311G** calculations revealed small energy gap (7.2 kcal/mol) between singlet and triplet configurations, suggesting that 31N is formed by intersystem crossing of 11N to 31N. Spin-density, nucleus-independent chemical shift, and anisotropy of the induced current density calculations verified that 31N is a triplet vinylnitrene with unpaired electrons localized on the C═C-N moiety; decaying by intersystem crossing to 2, which is more stable owing to its aromaticity, as supported by calculations (SA-CASSCF/QD-NEVPT2/CBS).