Bond Electron Density Research Articles

Solution of Schrödinger Equation for Simple Diatomic Molecules Using One‐Parameter 1s Slater‐Type Orbitals Wave Function

ABSTRACTThe Schrödinger equation for simple homonuclear and heteronuclear diatomic molecules is analytically solved using one‐parameter Slater‐type orbitals (STOs) to approximate the electronic wave function within a molecular orbital (MO)‐like approach. The resulting total energies, equilibrium bond lengths, potential curves, and electron densities are presented in detail. Calculations using a selected orbital exponent accurately reproduce results from standard methods. Furthermore, the optimization of the orbital exponent allows for a more accurate representation of the electronic wave function, leading to the improved results of the total energy and the equilibrium bond length, as well as minimal computational cost. Seen in the heteronuclear diatomic molecule, the use of the one‐parameter STOs allows the transformation of the heteronuclear problem into the homonuclear one, revealing the electron repulsion effect on the orbital exponent parameter.

Interfacial Thermoconvection and Atomic Relay Catalysis Enable Equilibrium Shifting and Rapid Glucose‐to‐Fructose Isomerization

AbstractThe aqueous glucose‐to‐fructose isomerization is controlled by thermodynamics to an equilibrium limit of ~50 % fructose yield. However, here we report an in situ fructose removal strategy enabled by an interfacial local photothermal effect in combination with relay catalysis of geminal and isolated potassium single atoms (K SAs) on graphene‐type carbon (Ksg/GT) to effectively bypass the equilibrium limit and markedly speed up glucose‐to‐fructose isomerization. At 25 °C, an unprecedented fructose yield of 68.2 % was obtained over Ksg/GT in an aqueous solution without any additives under 30‐min solar‐like irradiation. Mechanistic studies expounded that the interfacial thermoconvection caused by the local photothermal effect of the graphene‐type carbon and preferable glucose adsorption on single‐atom K could facilitate the release of in situ formed fructose. The geminal K SAs were prone to form a stable metal‐glucose complex via bidentate coordination, and could significantly reduce the C−H bond electron density by light‐driven electron transfer toward K. This facilitated the hydride shift rate‐determining step and expedited glucose isomerization. In addition, isolated K SAs favored the subsequent protonation and ring‐closure process to furnish fructose. The integration of the interfacial thermoconvection‐enhanced in situ removal protocol and tailored atomic catalysis opens a prospective avenue for boosting equilibrium‐limited reactions under mild conditions.

Finely tuned energy gaps in host-guest complexes: Insights from belt[14]pyridine and fullerene-based nano-Saturn systems

Over the past few decades, doping, physisorption and chemisorption remained some of the commonly utilized methods to modify the energy gaps and electronic properties of materials. Yet, achieving precise control over tuning the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels within these systems persisted as a remarkable challenge. Therefore, there is a growing need for systems that facilitate exact adjustments of energy gaps and HOMO/LUMO levels. Here, in this research work, the nano-Saturn host-guest complex systems are designed based on belt[14]pyridine as a host and fullerene nanocages (C20, C32, C34 and C36) as guests. The greater thermodynamic stability of the complexes is revealed by the higher values of interaction energies (Eint) for these complexes, ranging from −45.50 to −56.81 kcal/mol. The frontier molecular orbital (FMO) analysis revealed the contribution of HOMO of fullerenes and LUMO of belt[14]pyridine towards the HOMO and LUMO of the designed complexes, respectively. The energy gaps of the complexes also decrease compared to the constituents, with the least Egap of 0.52 eV observed for C20@N-belt. Moreover, the charge transfer from the host towards the guests is predicted and confirmed via natural bond orbital (NBO) and electron density difference (EDD) analyses. The non-covalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses determine the nature and strength of interactions in the host-guest complexes. Moreover, it is noticed through the UV–vis analysis that the bare fullerenes show the maximum absorption in ultraviolet (UV) region, but after complexation, maximum absorption is observed in visible and near infrared (NIR) regions, with highest λmax of 927 nm for C36@N-belt. These findings highlight the successful development of nano-Saturn host-guest complexes with precise control over HOMO-LUMO levels and energy gaps. This work aims to address the challenges in fine-tuning the electronic properties and demonstrates potential applications in optoelectronics, photovoltaics, and NIR-based sensors. Moreover, the ability to tune the electronic properties can guide future material design strategies for advanced energy storage and photonic devices.

A refreshing approach to understanding the action on DNA of vanadium (IV) and (V) complexes derived from the anticancer VCp2Cl2

A computational study based on derivatives of the anticancer VCp2Cl2 compound and their interaction with representative models of deoxyribonucleic acid (DNA) is presented. The derivatives were obtained by substituting the cyclopentadienes of VCp2Cl2 with H2O, NH3, OH−, Cl−, O2− and C2O42− ligands. The oxidation states IV and V of vanadium were considered, so a total of 20 derivative complexes are included. The complexes interactions with DNA were studied using two different models, the first model considers the interactions of the complexes with the pair Guanine-Cytosine (G-C) and the second involves the interaction of the complexes with adjacent pairs, that is, d(GG). This study compares methodologies based on density functional theory with coupled cluster like calculations (DLPNO-CCSD(T)), the gold standard of electronic structure methods. Furthermore, the change in the electron density of the hydrogen bonds that keep bonded the G-C pair and d(GG) pairs, due to the presence of vanadium (IV) and (V) complexes is rationalize. To this aim, quantities obtained from the topology of the electron densities are inspected, particularly the value of the electron density at the hydrogen bond critical points. The approach allowed to identify vanadium complexes that lead to significant changes in the hydrogen bonds indicated above, a key aspect in the understanding, development, and proposal of mechanisms of action between metal complexes and DNA.

Exploring the Bonding Nature of Iron(IV)-Oxo Species through Valence Bond Calculations and Electron Density Analysis.

Compound I (Cpd I) plays a pivotal role in substrate transformations within the catalytic cycle of cytochrome P450 enzymes (P450s). A key constituent of Cpd I is the iron(IV)-oxo unit, a structural motif also found in other heme enzymes and nonheme enzymes. In this study, we performed ab initio valence bond (VB) calculations, employing the valence bond self-consistent field (VBSCF) and breathing orbital valence bond (BOVB) methods, to unveil the bonding nature of this vital "Fe(IV)═O″ unit in bioinorganic chemistry. Comparisons were drawn with the triplet O2 molecule, which shares some electronic characteristics with iron(IV)-oxo. Additionally, Cpd I models of horseradish peroxidase (HRP) and catalase (CAT) were analyzed to assess the proximal ligand effect on the electronic structure of iron(IV)-oxo. Our VB analysis underscores the significant role of noncovalent resonance effects in shaping the iron(IV)-oxo bonding. The resonance stabilization within the π and σ frameworks occurs to comparable degrees, with additional stabilization resulting from resonance between VB structures from these frameworks. Furthermore, we elucidated the substantial influence of proximal and equatorial ligands in modulating the relative significance of different VB structures. Notably, in the presence of these ligands, iron(IV)-oxo is better described as iron(III)-oxyl or iron(II)-oxygen, displaying weak covalent character but enhanced by resonance effects. Although both species exhibit diradicaloid characters, resonance stabilization in iron(IV)-oxo is weaker than in O2. Further exploration using the Laplacian of electron density shows that, unlike O2, which exhibits a charge concentration region between its two oxygen atoms, iron(IV)-oxo species display a charge depletion region.

Local charge distortion due to Cr in Ni-based concentrated alloys

Due to the presence of multiple elements consisting of a range of atomic radii, local lattice distortion (LLD) is commonly observed in concentrated (and high entropy) alloys. However, since these elements also have diverse electronegativities, recent works show that atoms can have a range of atomic charges. In this work, using density functional theory (DFT), we investigate electronic charge distribution in face centered cubic (FCC) Ni-based alloys and find significant charge-density distortion in HEAs. Specifically, Cr atoms have large charge density distortion that results in a wide range of bond lengths, atomic charges, and electronic density of states in Cr-containing alloys. The charge distortion impacts the stacking fault energies (SFEs) as a wide range of SFEs are observed in Cr-containing alloys (e.g., NiCr, NiFeCr and NiCoCr), which are otherwise narrow and converged in non-Cr containing alloys such as NiFe, NiCo and NiFeCo. These observations provide insights into the role of local charge distortion towards local lattice distortion in HEAs and illustrate the effect of charge distortion on the mechanical properties of the alloys.

Density functional theory and spectroscopic analysis of stigmasterol from Garcinia wightii: Deciphering its inhibitory potential against drug-resistant tuberculosis via insilico molecular docking and molecular dynamics simulations

This study investigates the molecular structure and electronic properties of stigmasterol, isolated from Garcinia wightii, using density functional theory (DFT) alongside experimental techniques including FT-IR, FT-Raman, UV–Vis, 1H and 13C NMR spectroscopy. Theoretical predictions are compared with experimental results, facilitated by vibrational energy distribution analysis for unambiguous vibrational wavenumber assignments. Natural bond orbitalanalyzes reveal donor-acceptor bond energies and electron densities, while Fukui functions identify reactive sites susceptible to electrophilic and nucleophilic attacks. Electronic properties are further explored through various analyzes, unveiling reactive surface sites. Non-covalent interactions are examined using reduced density gradient analysis. Assessment of absorption, distribution, metabolism, and excretion attributes aids in drug discovery efforts. Molecular docking studies against 20 target proteins for antitubercular screening show a stable glide score of -9.52 kcal/mol for the protein 4FDO (Mycobacterium tuberculosis DprE1 in complex with CT319). Molecular dynamics simulations over 100 ns indicate the stability of the ligand-protein complex, suggesting its potential as an antituberculosis agent. Stigmasterol's structural, vibrational, electronic, and topological properties are thoroughly investigated, revealing its ring skeleton with a flexible isooctyl side chain, adhering to C1 point group symmetry. Steric and stereo electronic interactions play crucial roles in conformation and binding to target proteins. Theoretical and experimental analyzes align, confirming the compound's bioactive properties. This comprehensive investigation underscores stigmasterol's potential as a tuberculosis treatment option, providing valuable insights into its structural characteristics and therapeutic possibilities.

Unraveling the leverage effect in phases stability and mechanical properties of Al-Zn-Mg-Cu alloy

In order to further improve the comprehensive performance of advanced aluminum (Al) alloys, especially 7xxx Al-Zn-Mg-Cu alloys, tuning the relative ratios between major alloying elements (Zn, Mg, Cu) while maintaining the total alloying amount has been widely adopted. However, the specific influence of these relative element ratios on various properties has yet to be well understood. In this work, the leverage effect of those alloying element pairs (Al:Cu, Mg:Zn, Cu:Mg, and Cu:Zn) on the phase stability and mechanical properties of Al-Zn-Mg-Cu alloy is systematically investigated by means of first-principles calculations, cluster expansion, and quasi-harmonic Debye model. The tradeoffs in formation energy, elastic strength, and anisotropy are unraveled when the element pairs deviate from the equal ratio (1:1), indicating a strong leverage effect in element pairs. Among those element pairs, Al:Cu and Cu:Mg are the major lever in phase stability, in which the stable phase reversed on the two sides of 1:1; while the Mg:Zn lever dominates the elastic strength and anisotropy. Cu:Zn, on the other hand, has less impact on material properties. The underlying mechanism of those leverage effect is analyzed by the bonding electron density and lattice distortion around the major alloying elements. Our results are in good agreement with experimental observations and clarify the controversaries of those element pairs on the material properties. The weight of each lever could provide a practical guidance to the optimization of the alloy composition of 7xxx Al-Zn-Mg-Cu alloys, and also shed lights on the development of other advanced alloy systems.

Insights into the role of RAHB and IHB interactions for the structure- Activity relationship of caged xanthone Morellic Acid: Spectroscopic and DFT exploration, molecular docking, and molecular dynamics simulation studies as an Antituberculosis agent

The current study elaborates on experimental and simulated methods using density functional theory (DFT) to analyze the structure, electronic characteristics, and vibrational features of morellic acid, an isolate from Garcinia wightii. The in-depth examination of the stabilized structure indicates that the compound achieves equilibrium through conjugative, hyperconjugative, resonance-assisted hydrogen bonding (RAHB), and intramolecular hydrogen bonding (IHB) interactions, resulting in a well-supported conformation. The vibrational spectra were recorded, and the wavenumbers were comprehensively assigned using Potential Energy Distribution with a scaled quantum mechanical force field. Natural bond orbital (NBO) studies were utilized to calculate donor and acceptor bond interaction energy and electron densities. The TD-DFT computations were performed in solvent (chloroform) and gaseous phase, which agreed with the experimental values. Molecular electrostatic potential (MEP), reduced density gradient (RDG), electron localized function (ELF), and localized orbital locator (LOL) of the molecule were also analyzed. The molecular docking studies revealed that the compound holds great promise as a drug candidate for tuberculosis treatment, with the most thermodynamically stable binding score of -11.542 kcal/mol with 4BFS (protein of Mycobacterium tuberculosis PanK). The molecular dynamics (MD) simulation studies examined the stability and hydrogen bonding system of the ligand-protein complex formed between the molecule and the essential target protein for 100 ns. The findings revealed that the complex remained stable with minimal fluctuations throughout the simulation, suggesting that the molecule may prevent tuberculosis and be used as a treatment candidate.

A modified co-polyacrylamide to depress molybdenite in Cu/Mo separation and its competitive adsorption mechanism between reagents

In this research, a co-poly(acrylamide-allyldithiocarbamate) (PAMDTC) depressant was prepared by modifying polyacrylamide (PAM) and firstly utilized to depress molybdenite in Cu/Mo flotation separation. PAMDTC exhibited superior depression efficacy on molybdenite to unmodified polyacrylamide (PAM) based on micro-flotation tests results when using diethyldithiocarbamate (DEDTC) as the collector. In addition, it was found that the degree of substitution (DS) of allyldithiocarbamate group in PAMDTC would greatly influence its depression power and selectivity to minerals as an important factor. Finally, a competitive adsorption between PAMDTC and DEDTC on molybdenite surface was discovered and detected by adsorption tests, contact angle measurements, FTIR, XPS analysis and DFT simulations. The findings from adsorption tests and contact angle measurements implied that PAMDTC could prevent DEDTC collector adsorbing on molybdenite surface, but had few influences on the adsorption of DEDTC on chalcopyrite surface, providing adequate evidence of a competitive adsorption. Moreover, FTIR, XPS and DFT simulation analysis results further confirmed that PAMDTC physically adsorbed on molybdenite surface, simultaneously, it showed a stronger adsorption than DEDTC collector judging from these results of bond length, adsorption energy and electron density in DFT simulations.

Structure, stability, reactivity and bonding in noble gas compounds.

Noble gases (Ngs) are recognized as the least reactive elements due to their fully filled valence electronic configuration. Their reluctance to engage in chemical bond formation necessitates extreme conditions such as low temperatures, high pressures, and reagents with high reactivity. In this Perspective, we discuss our endeavours in the theoretical prediction of viable Ng complexes, emphasizing the pursuit of synthesizing them under nearly ambient conditions. Our research encompasses various bonding categories of Ng complexes and our primary aim is to comprehend the bonding mechanisms within these complexes, utilizing state-of-the-art theoretical tools such as natural bond orbital, energy decomposition, and electron density analyses. These complex types manifest distinct bonding scenarios. In the non-insertion type, the donor-acceptor interaction strength hinges on the polarizing ability of the binding atom, drawing the electron density of the Ng towards itself. In certain instances, especially with heavier Ng elements, this interaction reaches a magnitude where it can be considered a covalent bond. Conversely, in most insertion cases, the Ng prefers to share electrons to form a covalent bond on one side while interacting electrostatically on the other side. In rare cases, both bonds may be portrayed as electron-shared covalent bonds. Furthermore, a host cage serves as an excellent platform to explore the limits of achieving Ng-Ng bonds (even for helium), under high pressure.

Ab initio investigation of the competition of pnicogen, halogen, and hydrogen bonds resulting from the interactions between cyanophosphine and hypohalous acids.

The complexes formed as a result of the interactions between cyanophosphine (CP, H2PCN) and hypohalous acid molecules (HOX, X = F, Cl, Br, and I) were studied by employing ab initio computations conducted at the MP2/aug-cc-pVTZ level. Three types of complexes were acquired (I, II, and III) as a result of the (O∙∙∙P) pnicogen bond, the (N∙∙∙H) hydrogen bond, and the (N∙∙∙X) halogen bond interaction, respectively. The results of harmonic vibrational frequency calculations with no imaginary frequencies confirmed the structures as minima. In addition, given the interaction energy of the complexes, hydrogen bond complexes of structure II have the highest stability compared to other structures. In all studied complexes, the strength of the interactions depended on the electronegativity of the halogen atoms. The characteristics and nature of the whole three types of complexes were examined and evaluated with natural bond orbital (NBO), atom in molecules (AIM), molecular electrostatic potential (MEP) maps, non-covalent interaction (NCI) index, and electron density difference (EDD) analyses. The optimization of all complexes and corresponding monomers was conducted through the ab initio method, employing the MP2 level along with the aug/cc-pVTZ basis set for all atoms, except for the iodine (I) atom, for which the aug-cc-pVTZ (PP) basis set was employed. Subsequent frequency calculations were executed to ascertain the minimum energy state of the complexes at the MP2 level and the aug/cc-pVTZ basis set, utilizing Gaussian09 software. The MEP maps of the monomers were generated using the analysis-surface suite (WFA-SAS) software package. To probe the orbital interactions within the studied complexes, NBO analysis was performed employing NBO software. The assessment of bond nature, topological features, and electron density values at critical points for the studied complexes was undertaken using AIMAll software. The NCI index was derived utilizing Multiwfn software, and its three-dimensional representation was rendered using VMD software.

Metallofullerenes as Robust Single-Atom Catalysts for Adsorption and Dissociation of Hydrogen Molecules: A Density Functional Study.

Hydrogen is currently considered as the best alternative for traditional fuels due to its sustainable and ecofriendly nature. Additionally, hydrogen dissociation is a critical step in almost all hydrogenation reactions, which is crucial in industrial chemical production. A cost-effective and efficient catalyst with favorable activity for this step is highly desirable. Herein, transition-metal-doped fullerene (TM@C60) complexes are designed and investigated as single-atom catalysts for the hydrogen splitting process. Interaction energy analysis (Eint) is also carried out to demonstrate the stability of designed TM@C60 metallofullerenes, which reveals that all the designed complexes have higher thermodynamic stability. Furthermore, among all the studied metallofullerenes, the best catalytic efficiency for hydrogen dissociation is seen for the Sc@C60 catalyst Ea = 0.13 eV followed by the V@C60 catalyst Ea = 0.19 eV. The hydrogen activation and dissociation processes over TM@C60 metallofullerenes is further elaborated by analyzing charge transfer via the natural bond orbital and electron density difference analyses. Additionally, quantum theory of atoms in molecule analysis is carried out to investigate the nature of interatomic interactions between hydrogen molecules and TMs@C60 metallofullerenes. Overall, results of the current study declare that the Sc@C60 catalyst can act as a low cost, highly efficient, and noble metal-free single-atom catalyst to efficiently catalyze hydrogen dissociation reaction.

Synthesis of η2-platinum complexes on the rim of open-cage fullerenes

Three new open-cage fullerene derivatives with a 19-membered orifice have been prepared, two of which readily formed Pt complexes when treated with Pt(PPh3)4. Several related open-cage fullerene derivatives were also found to form very stable platinum complexes, which could be purified by chromatography on silica gel under ambient conditions. Single crystal X-ray diffraction data revealed that the Pt metal formed η2-type coordination pattern with a fullerene double bond on the rim of the orifice. Regio-selectivity of the platinum coordination is determined by the electron density of double bonds on the cage. The most electron deficient double bond shows the highest reactivity.

First-principles calculation of various phase transition in Al–Sc system

Sc as one of the most important microalloying elements in advanced Al alloys has gained tremendous attentions in recent years. The newly identified Sc-rich clusters demonstrate new strengthening effect in Al alloys and thus entail a comprehensive understanding on their phase relationship. In this work, various phase transitions of binary Al–Sc system are systematically investigated by first-principles calculation together with cluster expansion. The results show the phase transition from FCC Al to HCP Sc bypass a BCC structure as a function of Sc concentration. The ordered BCC lattice experiences BCC to FCC, BCC to HCP and BCC to ω phase transitions through the Bain, Burgers and ω phase transition paths, respectively. The possibility of those phase transitions is evaluated from the calculated energy landscape along the transition paths. BCC to FCC and BCC to ω phase transitions are energetically more favorable in Al–Sc system. The bonding electron density and effective cluster interaction suggests the Al–Sc interactions play a key role in individual phase transition at different Sc concentration.

Synergistic Spectroscopic and Computational Characterization Evidencing the Preservation or Flipping of the Hydroxyl Group of 2-Phenylethyl Alcohol upon Single and Double Hydration.

Even apparently simple, obtaining and analyzing observations on molecules and clusters and unambiguously assigning their structures is challenging. We report here the first ionization-loss Raman spectra compared to quantum chemical predictions for establishing the structural preferences of hydrates of the neurotransmitters hydroxy analogue, 2-phenylethyl alcohol (PEAL). The spectra encode two monohydrates and two previously unnoticed dihydrates, consequences of water insertion and sidewise attachment to the O-H group of gauche PEALs, in PEAL-H2O and PEAL-(H2O)2, or the higher-energy gauche-trans PEAL in the latter. The electronic structures retain the stable PEAL or flip its O-H to convert the gauche-trans PEAL conformer to the global minimum-energy dihydrate. We disclose conventional and bifurcated hydrogen bonds and electron steric repulsions by noncovalent interaction analysis and correlations between the experimental O-H stretching vibrational frequencies and the O-H and H···X bond lengths and electron densities, pointing to implications on hydrate forms and our approach virtue.

Electronic Densification and Stiffening of Diamond

Diamond, with a bulk modulus of 435 GPa, is the most incompressible natural material. Searching for ultra-incompressible materials with a bulk modulus significantly higher than diamond has attracted much attention. However, this search has been long questioned since it has not found incompressible materials significantly superior to diamond to date. From first-principles calculations, we here demonstrate that the density (4.34 g/cm3) and the bulk modulus (645 GPa) of the electronically modified diamond can exceed 23% and 48% of the pristine diamond. Meanwhile, the tensile strength and strain-to-failure increase from 86 GPa and 13% for the pristine diamond to 242 GPa and 30% for the electronically modified diamond. These results indicate simultaneous stiffening, strengthening, and toughening of the diamond upon electronic modifications. Electronic structure analyses show that the ultrahigh density and mechanical performance of the electronically modified diamond are attributed to the shortening and stiffening of covalent bonds from the increase of bonding electron density.

Theoretical and experimental studies on mechanochromic triphenylamine based fluorescent “ON-OFF-ON” sensor for sequential detection of Fe3+ and deferasirox

A novel triphenylamine (TPA) based sensor TTU was rationally designed and synthesized that exhibited reversible mechanochromic and aggregation induced emission enhancement (AIEE) properties. The AIEE active sensor was employed for fluorometric detection of Fe3+ in aqueous medium, with distinguished selectivity. The sensor showed a highly selective quenching response towards Fe3+ that is ascribed to complex formation with paramagnetic Fe3+. Subsequently, TTU-Fe3+ complex acted as a fluorescence sensor for the detection of deferasirox (DFX). The subsequent addition of DFX to TTU-Fe3+ complex led to the recovery of fluorescence emission intensity of sensor TTU that was attributed to the displacement of Fe3+ by DFX and release of sensor TTU. The proposed sensing mechanisms for Fe3+ and DFX was confirmed through 1H NMR titration experiment and DFT calculations. Frontier molecular orbitals (FMO), density of states (DOS), natural bond orbital (NBO), non-covalent interaction (NCI) and electron density difference (EDD) analysis were performed using DFT calculations to support the experimental results. Moreover, sensor TTU displayed colorimetric detection of Fe3+. Further, the sensor was employed for the detection of Fe3+ and DFX in real water samples. Finally, logic gate was fabricated by using sequential detection strategy.

Novel Bis-1,3,4-Thiadiazoles Derivatives: Synthesis, Spectroscopic Characterization, DFT Calculations and Evaluation of their Antimicrobial and Antioxidant Activities

Two new, bis-1,3,4-thiadiazoles derivatives (I and II), were prepared by cyclization reaction of oxalic acid with N-alkyl/allyl thiosemicarbazides and phosphorous oxychloride (POCl3). Then the newly prepared products screened for their antimicrobial and antioxidant activities. The biological activity results shown that tested compounds exhibited effective antibacterial activity against six different bacteria. However, the compound II demonstrated greater ABTS˙+ scavenging ability. The characterization of the synthesized molecules was done by FT-IR, 1H NMR, 13C NMR spectroscopic methods and elemental analysis. Moreover, the experimental FT-IR and NMR spectra of the molecules were compared with the results calculated at the cc-pvtz, 6-311g(2d,2p), and 6-311++g(2d,2p) levels of theory. The effect of substituted groups on the spectral and electronic properties of the compounds was investigated. NCI and QTAIM analyses were performed to examine the effects of allyl group and intramolecular interactions on σ and π bonds. How the N-H bonds of the substituted groups affect the bond degrees was investigated using Fuzzy, Laplacian and Mayer approaches, and the relationship of the data with the antioxidant properties of the compounds was examined. In addition, the relationship between bond stretching force constant and intrinsic bond strength index, electron density, and delocalization index for some bonds was revealed.

Adsorption and dissociation of H2 molecule over first-row transition metal doped C24 nanocage as remarkable SACs: A comparative study

Transition metal doped carbon materials such as carbon nanotubes and fullerenes have been extensively investigated for hydrogen adsorption and storage applications. However, the strength of these hydrogen storage material is mainly dependent on the metal-support and hydrogen-metal interaction energies. In this work, we have designed, and explored transition metal doped C24 (TM@C24) complexes as single atom catalysts for hydrogen dissociation. Adsorption energy results for all studied TM@C24 complexes reveal the high thermodynamic stability of designed TM@C24 catalysts. Among all considered TMs@C24 catalysts, the highest adsorption energy (−6.22 eV) is calculated for Mn@C24 catalyst. Moreover, H2 dissociation mechanism is evaluated for both gas phase and in aqueous media to get insight into the solvent effect. In both gas phase and in aqueous media, the best catalytic activity for hydrogen dissociation is computed for Mn@C24 catalyst with the lowest energy barrier of 0.04 eV and 0.30 eV, respectively. NCI analysis is carried out to confirm the shared shell interactions (covalent interactions) between adsorbed hydrogen and TM@C24 complexes. Furthermore, natural bond orbital and electron density differences analysis are also performed to explore the activation and dissociation of H2 molecule. Overall results reveal that Mn@C24 complex can at as a promising low cost, highly abundant and noble metal free single atom catalyst to effectively catalyze hydrogen dissociation reaction.