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This study investigated the relationship between the molecular structure and the corrosion inhibition efficiency of three corrosion inhibitors for steel in acidic media using the DFT method. First, the molecular conformations of the three compounds were optimized and the populations of charges and frontier orbitals were obtained at the B3LYP/6-311G level. Quantum chemical parameters were also obtained by calculations, including the highest occupied molecular orbital energy (EHOMO), the energy gap (ELUMO−EHOMO), the total energy of the molecule, the dipole moment and the number of electrons transferred (ΔN). The results of the correlation between quantum chemical parameters and inhibition efficiencies demonstrated that the inhibition efficiency of the inhibitors increased with the decrease of ELUMO-EHOMO and the increase of ΔN. The regions with nitrogen and oxygen atoms are the sites most likely to bond with iron atoms by donating electrons.

Using Multiwfn, a free wavefunction analyzer, visualization of the descriptors of physical and chemical properties can greatly enrich the classroom-teaching contents, and will present the elegance of chemistry. In the current study, color-filled maps of localized-orbital locator (LOL) purely obtained through π electrons (LOL-π), electron localization function (ELF) color maps, and scanning tunnel microscope (STM) images were created based on the molecular orbitals of monocyclic B5N5. Additionally, molecular surface electrostatic potential, average local ionization energy (ALIE), and local electron affinity (LEA) were employed to visualize the reactive sites of B5N5. Interaction region indicator (IRI) and noncovalent interaction (NCI) analyses were performed and discussed to reveal the bonding and weak interactions in this material. The proposed study is a typical paragon for the usefulness of chemical software in facilitating the teaching of science in classrooms. [ABSTRACT FROM AUTHOR]

Conventional water purification technologies struggle to simultaneously address purification efficiency and energy consumption. Molecular orbital level surface micro-electric field (MEF)-driven water purification is an original and innovative concept conceived and developed by our group in recent years. The core idea involves creating electron-rich and electron-poor micro-areas on the nanomaterial surface, which drive pollutants or H2O molecules to provide electrons in the electron-poor micro-areas while other environmental factors (such as H2O2 and O2) obtain electrons in the electron-rich micro-areas. This process effectively utilizes the internal energy contained within wastewater and emerging contaminants (ECs). Centered on this core, this review systematically examines the discovery, construction, and characteristics of MEF and MEF-like systems and summarizes their application directions. The challenges, bottlenecks, and future development directions of MEF technology are also analyzed and discussed. Reviews of MEFs can facilitate the development of low-consumption, high-efficiency water purification technologies.

The role of the molecular structure in the formation of the bathochromic shift of the S0 → S1 transition for a family of N-substituted porphine derivatives was studied. Molecular conformations of porphine, four of its N-substituted derivatives, and two model porphines with selected fixed bond angles and lengths in the macrocycles were optimized, the energies of the molecular orbitals were determined, and electronic absorption spectra were calculated using quantum-chemistry methods. It was found that N-substitution led to significant pyramidalization of the nitrogen atom. The degree of hybridization λ2 of the N atom depended on the volume of the N-substituent and reached a value of λ2 = 2.729 in porphyrin H(N–CCl3)P. The degree of hybridization λ2 of the N atom was established as the factor determining the energy of the long-wavelength S0 → S1 transition because the conjugation along the inner Ca–N–Ca fragment of the pyrrole ring decreased upon pyramidalization of the N atom while π-conjugation via the outer Ca–Cb–Cb–Ca fragment, which led to an increase in the size of the conjugated π-system, simultaneously strengthened. The tilt of the N-substituted pyrrole ring relative to the macrocycle mean plane and the electron-donating/electron-withdrawing properties of the N-substituents did not directly affect the bathochromic shift of the S0 → S1 transition. [ABSTRACT FROM AUTHOR]

Solar cells are fabricated based on two new dyes. Dye acts as an additive to thin layer interface. The effect of the π-conjugated rigidity of the thiophene rings on the photovoltaic characteristics has been investigated. The structures of the dye 1 was based on dithieno [3,2-b:2′,3′-d] thiophene-2-cyanoacrylic acid, while dye 2 was based on [2,2':5′,2″-terthiophene]-5-cyanoacrylic acid and were confirmed by elemental analysis, mass spectrometry, 1H NMR and 13C NMR spectral data. The P3HT/dye 1/nc-TiO2 solar cell produced the highest efficiency of 0.3 % with an open circuit voltage of 0.7 V compared to dye 2 solar cell. This has been attributed to the difference in energy levels of the dyes and location of their HOMO relative to conduction and valence bands of nc-TiO2. The dye 1 has rigid fused thiophene rings and its HOMO is located between valence band of TiO2 and HOMO of P3HT which leads to improve the charge carrier separation and increase the current density to reach 1.2 mA/cm2.

In this study, the physicochemical properties and molecular interactions between zirconium-based metal-organic framework (UiO-66) and three different ionic liquids based on bis(trifluoromethanesulfonyl)imide anion (EMIM+, BMIM+ and OMIM+) was performed via a combined experimental and computational approach. The ionic liquid loaded UiO-66 or IL@UiO-66 was synthesized and characterized to understand the host-guest interaction. Density functional theory calculation was performed to analyse the electronic structure of IL@UiO-66 to provide molecular insight on the dominant interactions occurred in the hybrid material. Results showed that all ILs were successfully incorporated into the micropores of UiO-66. The 3D framework was retained even after loaded with ILs as analyzed from XRD pattern. FTIR spectrum reveals that interactions of ILs with UiO-66 influenced by the alkyl chain length of the cation. The anion has a profound affinity with the UiO-66 due to the presence of electronegative atoms. Phase transition study from DSC suggested that the incorporation of ILs has stabilized the framework of UiO-66 by shifting the endothermic peak to a higher state. These findings were further elaborated with DFT calculation. Geometrical optimizations confirmed the structural parameter changes of UiO-66 when loaded with ILs. These was mainly contributed by the non-covalent interactions which was confirmed by the reduced density gradient scattered plot. Another important findings are the strength of hydrogen bonding at the host-guest interface was influenced by the alkyl chain length. The molecular orbital analysis also shows that the size of alkyl chain influence the reactivity of the hybrid material. The present study provides fundamental insights on the molecular interaction of UiO-66 and ILs as a hybrid material, which can open new possibilities for advanced material for metal-organic framework applications in energy storage system, catalysis, gas storage and medicinal chemistry.

Molecular orbital theory is an important chemical bonding theory and also a difficult point in the study of general chemistry. In this article, the problems often encountered by beginners of molecular orbital theory are sorted out and analyzed, and the application of molecular orbital theory is expanded. By tracing the formation and development of the molecular orbital theory, combined with the requirements of the Chemistry Olympiad test questions, summarization and analysis are carried out to deepen the understanding of the molecular orbital theory and promote the teaching of the molecular orbital theory. [ABSTRACT FROM AUTHOR]

Magnesium is an essential element because of its many beneficial properties and advantages over other metals, including its lack of risk to people's health and its reasonable cost. However, Mg has several disadvantages, one of which is its high corrosion rate. This work analysed magnesium alloy characteristics and quantum behaviour, including band structure, molecular orbital, and corrosion behaviour in the presence of water. Magnesium was characterised by density functional theory software using CASTEP and Dmol3. Results showed no Mg band structure displays a conductive Fermi level of 8.85 eV. Curvature studies revealed that Mg has strong curvature and electron mobility. The density of state (DOS) of Mg-Al-Zn changes with Al and Zn alloy atoms, and the electron density increases to −7.5 eV compared with pure Mg. HOMO–LUMO analysis elucidated that Mg-Al-Zn* has a large gap (0.419 eV), leading to its stability and low chemical reactivity. This study analysed the properties of Mg and then examines the effect of corrosion on Mg alloys using DFT at different element positions. Corrosion analysis indicated that Mg-Al-Zn has the highest activation energy, implying that its corrosion is less likely than that of other alloys. [ABSTRACT FROM AUTHOR]

Reaction of bromine and the C=C double bond is one of common elementary reactions in organic chemistry. Bromine and alkenes undergo an electrophilic addition. Aliphatic alkenes undergo formation of three-membered cyclic bromonium intermediates and subsequent ring-opening mechanism, affording stereospecific trans-dibromoadducts, while the three-membered cyclic bromonium intermediates of arylolefins favor to dissociate their benzylic C-Br bond due to aryl stabilizing the generated carbocations, producing a mixture of cis- and trans-dibromoadducts. However, bromine and enols or enolates generated from ketones or carboxylic halides undergo electrophilic substitutions. Bromine does not generate the corresponding three-membered cyclic bromonium intermediates with their C=C bond in the reactions. Similarly, the reactions of viny ethers and enamines with bromine do not undergo the three-membered cyclic bromonium intermediates, either, generating nonstereospecific adducts and substituted products, respectively. This article rationally explains the mechanistic and stereoselective differentiations between the reactions of bromine and these two classes of reactants with reactive molecular orbitals in the elementary reaction, and summarizes the identification method on the reaction mechanism and stereoselectivity of the reactions between bromine and different C=C bonds, hoping to be convenient for teaching and understanding. [ABSTRACT FROM AUTHOR]

The generation of collision-induced vacancies and their transfer within the electronic inner shells are the source of several unprecedented phenomena, which have been revealed in recent experimental studies conducted using state-of-the-art next-generation accelerators and detectors. Despite the multitude of studies conducted over the years, our understanding of the atomic vacancy transfer mechanisms remains exiguous. The detection and analysis of collision-induced X-rays is a widely-used powerful technique for analysing atomic-scale phenomena. However, both experimental and theoretical investigations on ion–atom collision-induced X-rays have remained mostly restricted to high-energy light-ion impact on heavy atoms. To date, only a few studies have been reported on the investigation of very-low-energy heavy-ion impact on heavy atoms using X-rays, especially M-shell X-rays of the heavy atom. This study was conducted to evaluate the inner-shell ionisation of Au (135 and 508 μ g / cm 2 ) and Pb (107, 157 and 390 μ g / cm 2 ) targets due to low-energy (2–5 MeV) 54 Xe q + -ion impact. The collision-induced X-ray spectra of both the collision partners were examined, and the corresponding intensity ratios and cross-sections were compared with those calculated using two well-known ionisation theories, viz. PWBA and ECPSSR. The measured cross-sections were underestimated by these theories. Moreover, the cross-sections measured in this study were found to be several orders of magnitude higher than those obtained in other reported studies on low-energy lighter-ion-impact on Au and Pb. The significant discrepancies observed between the experimental and theoretical values have been explained qualitatively within the framework of quasi-molecular orbital formation using level correlations. The insights obtained from the results of this study can be applied to analyse the vacancy transfer mechanisms in very-heavy systems (combined atomic number > 100). • 2–5 MeV Xe-ions bombarded on foils of Au and Pb with different thicknesses. • Target energy shift, intensity ratios and M-shell production cross-sections investigated. • Discrepancy observed between measured and theoretical (PWBA and ECPSSR) results. • Measured values higher than those reported by other authors. • Cross-section enhancements qualitatively explained using level correlations. [ABSTRACT FROM AUTHOR]

The lightning impulse breakdown strength of natural ester is lower than that of mineral oil. This article focuses on a discharge mechanism difference analysis of natural ester and mineral oil under a strong impulse electric field (EF). Based on density functional theory (DFT), the ionization energy, electron affinity (EA), and excitation energy of natural ester and mineral oil were calculated under different EF strengths. The microparameters related to the discharge of natural ester and mineral oil were compared, showing that the former has a lower ionization energy and a larger dipole moment. This quality makes natural ester more likely to ionize and produce electrons, which more easily promotes the formation of electron avalanches and streamer. Meanwhile, natural ester molecules are more prone to transition from the ground state to the excited state than mineral oil molecules, exacerbating the photon release and formation of discharges in natural ester. The greater conductivity of natural ester leads to its dispersion and the rapid development of discharge streamers. In addition, an electrostatic potential (ESP) analysis on molecular surfaces was used to predict the active sites of the oil molecular structure. This article provides help for understanding the relationship between the micromolecular structure and the macroscopic discharge characteristics for different types of oil molecules. [ABSTRACT FROM AUTHOR]

The influence of the architecture of NH2-peripheral substitution of porphine derivatives on the intersystem T1 → S0-transition energy was studied theoretically. The molecular conformations of 15 porphine derivatives and 8 Zn-porphine derivatives in the ground singlet (S0) and lowest triplet (T1) states were optimized, the molecular orbital energies were determined, and the energies of the T1 → S0 transition were calculated using quantum chemical methods. The T1 → S0-transition energy was found to decrease from 11,700 to 6200 cm–1 upon increasing the number of NH2 groups in the macrocycle Cm-positions. The T1 → S0-transition energy was a linear function of the weighted sum of inductive and resonant Hammett constants 0.2σI + 0.8σR of the substituents. The ratio of inductive and resonant contributions of the NH2 groups depended on the method of attachment to the macrocycle, with the contribution of resonant interactions decreasing with increasing spacer length. The main reason for the bathochromic shift of the T1 → S0 transition was a significant increase in the energy of the b1-orbital, which had antinodes on the macrocycle Cm atoms. The dependence also held for Zn-porphyrins with the same peripheral substitution architecture. The energy of the T1 → S0 transition was noted to differ for both NH tautomers and conformers differing in the position of NH2 groups relative to the macrocycle mean plane. The calculations showed that experimental studies of aminoporphyrins were promising for obtaining new phosphors in the IR spectral region. A method for predicting the T1 → S0-transition energy for the synthesis of compounds with the required spectral and luminescent characteristics was proposed based on the results. [ABSTRACT FROM AUTHOR]

To get insights into glassy Se at Kauzmann temperature, Se clusters including helical and disordered H–nSe–H chains with n ≤ 20 are constructed, using an ab initio molecular orbital package. The study demonstrates the existence of kinked chains with bistable dihedral‐angular conformations, which have similar total energies to that in straight helical chains. Electronically, such kinked chains possess wider optical gaps with no gap states, which is less efficient in localized electronic excitation. This would predict that the photodarkening cannot appear in fully stabilized glasses at Kauzmann temperatures, the behavior being similar to that demonstrated for liquid Se lying in thermal equilibrium. [ABSTRACT FROM AUTHOR]

The relative extent of protonation in oxygen and carbon atoms and the position of protonation in carbons depend on several factors. We seek to locate the frontier molecular orbitals involved in the protonation reactions of substituted phenols using the FERMO concept through the MOLPROJ software, to compare the computational results with experimental NMR data obtained in the literature. We evaluate computationally the stereo-electronic effects that govern reactions of aromatic electrophilic substitution using an experimental study as an example. The MOLPROJ returned a percentage of correct answers of approximately 86% in the protonation sites. The experimental results on the protonation sites were rationalised in terms of stereoelectronic effects. [ABSTRACT FROM AUTHOR]

Diarylethene is a prototypical molecular switch that can be reversibly photoisomerized between its open and closed forms. Ligands bpy-DAE-bpy, consisting of a phenyl-diarylethene-phenyl (DAE) central core and bipyridine (bpy) terminal substituents, are able to self-organize. They are investigated by scanning tunneling microscopy at the solid–liquid interface. Upon light irradiation, cooperative photochromic switching of the ligands is recognized down to the submolecular level. The closed isomers show different electron density of states (DOS) contrasts, attributed to the HOMO or LUMO molecular orbitals observed. More importantly, the LUMO images show remarkable differences between the open and closed isomers, attributed to combined topographic and electronic contrasts mainly on the DAE moieties. The electronic contrasts from multiple HOMO or LUMO distributions, combined with topographic distortion of the open or closed DAE, are interpreted by density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

A superatom is a cluster composed of a specific number of atoms. We recently found that the superatom-like X@Ga12 (X = Li~Kr) clusters has the periodic energy levels of the specific orbitals 2S and 2P by means of the DV-Xα molecular orbital calculation method. This periodicity in energy levels has not been seen in 1D or 1F orbitals. We supposed that the periodicity of the energy levels of the 2S and 2P superatomic-like orbitals come from the same symmetry between atomic orbitals as the central atom X and the surrounding specific orbitals, according to the Jellium model. Both the s and p atomic orbitals of the central atom X in the superatom-like X@Ga12 have a large shielding effect, suggesting that the s and p atomic orbitals interact strongly with both 2S and 2P superatomic-like orbitals. The energy level periodicity has the potential to periodically change the number of electrons located in the 1D and 1F orbitals, which is related to magnetic properties and is expected to be useful for novel magnetic devices by periodically controlling the magnetism of superatoms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electron momentum spectroscopy study of 1,3-dimethyladamantane. • Momentum profiles of the outer valence orbitals have been obtained with high statistical accuracy. • The momentum profiles are compared with those of adamantane to examine the effects of methyl substitution on the molecular orbitals. • The findings suggest that the substitution of methyl groups results in a more spatial delocalization of the highest occupied orbital, which consequently enhances the absorption cross section of the 3 s Rydberg excitation. This paper investigates the effects of methyl substitution on the valence orbital momentum distributions of adamantane. Kinematically complete electron-impact ionization experiments on 1,3-dimethyladamantane are performed at an incident electron energy of 1.2 keV, and the resulting electron momentum profiles are compared with those of pristine adamantane. Moreover, the influences of molecular vibration and distorted-wave effects on the electron momentum profiles are examined. The highest occupied molecular orbital (HOMO) of adamantane, 7t 2 , is split into the 10b 1 , 18a 1 , and 12b 2 orbitals in 1,3-dimethyladamantane. It is revealed that the momentum profile for the sum of the 10b 1 , 18a 1 , and 12b 2 orbitals exhibits a markedly higher intensity at low momentum than that of the 7t 2 parent orbital. This strongly suggests that the HOMO is spatially more extended when surface hydrogens are replaced with methyl groups, which causes an increase in the absorption cross section of the 3 s Rydberg excitation. [ABSTRACT FROM AUTHOR]

• Ab initio molecular-orbital studies on defects in Se, As 2 S 3 , and GeS 2 glasses. • Defect energies and densities are estimated from analyses of small clusters. • Densities of wrong bonds and intimate valence-alternation pairs are considerable. • Charged dangling bonds are negligible in density. • The three glasses seem to possess electronic gap states having different origins. Dangling bonds in Se, As 2 S 3 , and GeS 2 glasses and wrong bonds in the compounds have been comparatively studied using an ab initio molecular-orbital software. Defect energies and the densities in the chalcogenide glasses are estimated from the total energy E t of small clusters such as H- n Se-H, As3S4H, and Ge4S4H. Properties of corner- and edge-shared connections are also explored for the As-S and Ge-S systems. The three kinds of clusters show for a meta-stable energy ΔE t , relative to the total energy E t of normal bonding structures, a magnitude order of ΔE t (IVAP) < ΔE t (2D0) < ΔE t (D+ / D − ). Based on this result, we discuss why only GeS 2 exhibits unpaired electron spins. The analysis also manifests that ΔE t s of clusters containing wrong bonds (As-As, Ge-Ge, and S-S) are comparable with those of ΔE t (IVAP). Regarding electronic levels, the three glasses seem to possess marked gap states having different origins. [ABSTRACT FROM AUTHOR]

Magnesium is an essential element because of its many beneficial properties and advantages over other metals, including its lack of risk to people’s health and its reasonable cost. However, Mg has several disadvantages, one of which is its high corrosion rate. This work analysed magnesium alloy characteristics and quantum behaviour, including band structure, molecular orbital, and corrosion behaviour in the presence of water. Magnesium was characterised by density functional theory software using CASTEP and Dmol3. Results showed no Mg band structure displays a conductive Fermi level of 8.85 eV. Curvature studies revealed that Mg has strong curvature and electron mobility. The density of state (DOS) of Mg-Al-Zn changes with Al and Zn alloy atoms, and the electron density increases to −7.5 eV compared with pure Mg. HOMO–LUMO analysis elucidated that Mg-Al-Zn* has a large gap (0.419 eV), leading to its stability and low chemical reactivity. This study analysed the properties of Mg and then examines the effect of corrosion on Mg alloys using DFT at different element positions. Corrosion analysis indicated that Mg-Al-Zn has the highest activation energy, implying that its corrosion is less likely than that of other alloys.

Energetic pentazolate compound generally releases extremely large energy in the explosion and generates environment‐friendly nitrogen as the main product. Cyclo‐N5− as the mono‐dentate ligand always forms planer structure by σ‐type bonds between center metal cation and ligands in most of the metal pentazolate complexes based on the corresponding XRD results, which is completely different from the well‐known perpendicular structure of ferrocene with the η5‐π‐bonds, although it is known for us that cyclo‐N5− is isoelectronic species of the pentadienide anion C5H5−. In order to understand the differences between the planer Fe(N5)2 and 'sandwich‐like' Fe(η5‐C5H5)2, here we design Fe(η5‐N5)2 with η5‐π‐bonds as the possible isomer of the planer Fe(N5)2. Besides the mono‐dentate planer Fe(N5)2, Cyclo‐N5− is possibly as a bidentate ligand to coordinate with Fe2+ to form η2‐σ‐bond. Therefore, the three isomers of Fe(N5)2 and its isoelectronic Fe(η5‐C5H5)2 are compared including their structures of ligands, bonding structures, coordinative pathways and reactivity in the decompositions by applying the DFT and CPMD calculation. The results indicate the formation of σ‐type Fe−N bonds between Fe2+ and mono‐dentate cyclo‐N5− is the most favored. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations were performed to investigate electronic and structural properties of barbituric acid (BA) and sixtheen of its derivatives to show impacts of structural functionalization on the features of parent BA. The models were optimized and the minimum energy structures were confirmed by frequency calculations. Molecular and atomic descriptors were evaluated for the optimized models, in which the results of formation binding strength and molecular orbital features indicated significance of such functionalization processes on the observed properties. The highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) and their related parameters all indicated magnitudes of changes from one molecule to another one. Furthermore, atomic scale quadrupole coupling constants (Cq) were evaluated for the nitrogen and oxygen atoms of BA compounds showing significance of structural functionalization impacts on the atomic properties of parent BA. As a consequence, such structural analyses of BA compounds could show their characteristic features for further developments especially for their efficient pharmaceutical applications. [ABSTRACT FROM AUTHOR]

The reaction mechanism between phosphacyclopropenylidene and ethylene has been systematically investigated at the B3LYP/6-311++G(d,p) level of theory in order to better understand the reactivity of unsaturated cyclic phosphorus-bearing carbene. Geometry optimizations and vibrational analyses have been performed for the stationary points on the potential energy surface of the system. Calculations show that the spiro bicyclic intermediate could be produced through the cycloaddition process between phosphacyclopropenylidene and ethylene initially. The reaction mechanism is illustrated with the frontier molecular orbital theory. Introduction of electron-withdrawing group in phosphacyclopropenylidene will better facilitate the addition process. Through subsequent ring-expanding and hydrogen-migrating process, fuse-ring and allene compounds could be produced, respectively. Furthermore, it’s easy for spiro bicyclic intermediate and another ethylene to form a spiro tricyclic compound. This study is helps to understand the reactivity of phosphacyclopropenylidene, the evolution of phosphorus-bearing molecules in space, and to offer an alternative approach to the formation of phosphorus-bearing heterocyclic compound.

Diarylethene is a prototypical molecular switch that can be reversibly photoisomerized between its open and closed forms. Ligands bpy-DAE-bpy, consisting of a phenyl-diarylethene-phenyl (DAE) central core and bipyridine (bpy) terminal substituents, are able to self-organize. They are investigated by scanning tunneling microscopy at the solid–liquid interface. Upon light irradiation, cooperative photochromic switching of the ligands is recognized down to the submolecular level. The closed isomers show different electron density of states (DOS) contrasts, attributed to the HOMO or LUMO molecular orbitals observed. More importantly, the LUMO images show remarkable differences between the open and closed isomers, attributed to combined topographic and electronic contrasts mainly on the DAE moieties. The electronic contrasts from multiple HOMO or LUMO distributions, combined with topographic distortion of the open or closed DAE, are interpreted by density functional theory (DFT) calculations.

A superatom is a cluster composed of a specific number of atoms. We recently found that the superatom-like X@Ga12 (X = Li~Kr) clusters has the periodic energy levels of the specific orbitals 2S and 2P by means of the DV-Xα molecular orbital calculation method. This periodicity in energy levels has not been seen in 1D or 1F orbitals. We supposed that the periodicity of the energy levels of the 2S and 2P superatomic-like orbitals come from the same symmetry between atomic orbitals as the central atom X and the surrounding specific orbitals, according to the Jellium model. Both the s and p atomic orbitals of the central atom X in the superatom-like X@Ga12 have a large shielding effect, suggesting that the s and p atomic orbitals interact strongly with both 2S and 2P superatomic-like orbitals. The energy level periodicity has the potential to periodically change the number of electrons located in the 1D and 1F orbitals, which is related to magnetic properties and is expected to be useful for novel magnetic devices by periodically controlling the magnetism of superatoms.

XMHFL is a computer program that implements the Single Center Expansion (SCE) method to describe ground, excited and ionized states of a molecular system with one or more vacancies. The simulation mechanism is based on a combination of the three-point difference Numerov scheme and Thomas algorithm. The modular architecture of the XMHFL solvers allows using the generated code as the basis for the development of new methods and algorithms, as well as increasing the possibilities of molecular characterization calculation for X-ray molecular spectroscopy research and training as an educational platform.

The aqueous organic flow battery (AOFB) holds enormous potential as an energy storage device for fluctuating renewable electricity by exploiting the redox reactions of water‐soluble organic molecules. The current development is impeded by lack of organic molecules adequate as catholyte, yet how the catholyte structure impacts the battery lifetime remains unexplored. Here, six ferrocene derivatives with deliberately tuned chemical structure were devised. They underwent reversible redox reactions in water, and the redox potentials were inversely related to the lowest unoccupied molecular orbital (LUMO) energy of their energized forms. The stability of the ferrocene derivatives was evaluated in full flow cells and in symmetric cells. Density function theory calculations, along with experimental results, revealed that the localized LUMO density on Fe led to fast capacity fading. BQH−Fc, which has the lowest LUMO density on Fe, showed the highest stability. No capacity loss was observed for the BQH−Fc/BTMAP−Vi cell at 0.1 m, and a high capacity retention rate of 99.993 % h−1 was recorded at 1.5 m, which could be attributed to electrolyte crossover. To facilitate explorations of robust and high capacity catholytes, a method was established to predict the water solubility of ferrocene molecules, and calculations were in good accordance with measured values. [ABSTRACT FROM AUTHOR]

The CO molecular ionization and Coulomb explosion are systematically investigated utilizing a high-resolution time-of-flight mass spectrometer. It is found that the main dissociation channels of highly charged CO 3 + , CO 4 + , and CO 5 + are (2,1), (2,2), and (3,2) respectively, i.e., the charge-symmetric dissociation channel, and their kinetic energy release keep constant with increasing the laser intensity. We obtain the contribution of different molecular states to the dissociation channel by Gaussian fitting the distribution of the channel's kinetic energy release. With the laser intensity of 1.0 × 10 15 W/ cm 2 , the angular distributions of CO x + ( x =2,3,4), which exhibit high anisotropy, are generated from these different dissociation channels. According to the present theory, we can qualitatively understand that the anisotropy depends on the molecular orbital profile. [ABSTRACT FROM AUTHOR]

The molecular structure of lubricating oil affects its lubrication properties, catalytic and hydrolytic stability, and anti-wear properties. Based on the idea of material genomics, researchers are trying to find the correlation between structural characteristics and functional performances of lubricating oil, but the correlation can only explore the influence weight of structural parameters on performance, it is also very important to research the influence mechanism. In this study, through quantum mechanics/molecular mechanics calculations, (i) the spatial configurations of four typical ester lubricants with different chain length structures were studied, (ii) effects of active functional groups and charge distribution on the properties of the ester lubricants were discussed, and (iii) electronic transition and molecular orbital contributions were compared. The calculated results are expected to provide considerable support for theoretical research on the anti-wear and anti-oxidation mechanisms of ester lubricants and assist the rapid design, development and application of lubricating materials.

Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have shown broad application prospects in organic wastewater treatment. Alkoxy radicals including CH 3 COO • and CH 3 COOO • are primary reactive species in PAA-AOP systems; however, their reaction mechanism on attacking organic pollutants still remains controversial. In this study, a Co(II)/PAA homogeneous AOP system at neutral pH was constructed to generate these two alkoxy radicals, and their different reaction mechanisms with a typical emerging contaminant (sulfacetamide) were explored. Dynamic electron distribution analysis was applied to deeply reveal the radical-meditated reaction mechanism based on molecular orbital analysis. Results indicate that hydrogen atom abstraction is the most favorable route for both CH 3 COO • and CH 3 COOO • attacking sulfacetamide. However, both radicals cannot react with sulfacetamide via the radical adduct formation route. Interestingly, the single-electron transfer reaction is only favorable for CH 3 COO • due to its lower E SUMO . In comparison, CH 3 COOO • can react with sulfacetamide via a similar radical self-sacrificing bimolecular nucleophilic substitution (S N 2) route owing to its high E SOMO and easy escape of unpaired electrons from n orbitals of O atoms in the peroxy bond. These findings can significantly improve the knowledge of reactivity of CH 3 COO • on attacking organic pollutants at the molecular orbital level.3 COOO • on attacking organic pollutants at the molecular orbital level.

Density functional theory and time-dependent density functional theory (DFT/TD-DFT) methods have been used to study the photo-voltaic and photophysicochemical properties of some metal-free and metal-containing phthalocyanine (Pc) derivatives (1–12) for application in dye-sensitized solar cells (DSSCs). The TD-DFT and molecular ground-state data were used to estimate the relative position of the TiO2 conduction band edge to the lowest unoccupied molecular orbital (LUMO) position (δp). The diffusion coefficients (Dπ), and oscillator strengths (f) at maximum absorption wavelengths of the molecules in the visible or near-infrared (near-IR) region were also estimated. Fluorescence emission (ϕf) and charge collection (ηc) efficiencies obtained using the method reported recently by our group were used in estimating the dyes' incident photon conversion efficiency (IPCE). The estimated parameters have been used to characterize the dyes and evaluate their suitability for application in photo-voltaic technology both in gas phase and in acetonitrile. The overall results showed that iron(II) could be a possible substitute for ruthenium ion, as the choice metal ion for phthalocyanine-based DSSCs. [ABSTRACT FROM AUTHOR]

The reaction mechanism between phosphacyclopropenylidene and ethylene has been systematically investigated at the B3LYP/6-311++G(d,p) level of theory in order to better understand the reactivity of unsaturated cyclic phosphorus-bearing carbene. Geometry optimizations and vibrational analyses have been performed for the stationary points on the potential energy surface of the system. Calculations show that the spiro bicyclic intermediate could be produced through the cycloaddition process between phosphacyclopropenylidene and ethylene initially. The reaction mechanism is illustrated with the frontier molecular orbital theory. Introduction of electron-withdrawing group in phosphacyclopropenylidene will better facilitate the addition process. Through subsequent ring-expanding and hydrogen-migrating process, fuse-ring and allene compounds could be produced, respectively. Furthermore, it's easy for spiro bicyclic intermediate and another ethylene to form a spiro tricyclic compound. This study is helps to understand the reactivity of phosphacyclopropenylidene, the evolution of phosphorus-bearing molecules in space, and to offer an alternative approach to the formation of phosphorus-bearing heterocyclic compound. [ABSTRACT FROM AUTHOR]

The synthesis and characterizations for a series of dinuclear gold (I)‐di‐NHC complexes, 1–8 through the trans‐metalation method of their respective silver (I)‐di‐NHC complexes, i–viii are reported (where NHC = N‐heterocyclic carbene). The successful complexation of a series of unusual non‐symmetrical and symmetrical di‐NHC ligands, 3,3'‐(ethane‐1,2‐diyl)‐1‐alkylbenzimidazolium‐1'‐butylbenzimidazolium (with alkyl = methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, benzyl) with the gold (I) ions are suggested by elemental analysis, Fourier transform‐infrared, 1H‐ and 13C‐NMR data. The 13C‐NMR spectra of 1–8 show a singlet sharp peak in the range of 190.00–192.00 ppm, indicating the presence of a carbene carbon that bonded to the gold (I) ion. From single crystal X‐ray diffraction data, the structure of complex 6 with the formula of [di‐NHC‐Au (I)]2·2PF6 is obtained [where NHC = 3,3'‐(ethane‐1,2‐diyl)‐1‐hexylbenzimidazolium‐1'‐butylbenzimidazolium]. The photophysical study in solid state of 6 displays an intense photoluminescence with a strong emission maxima, λem = 480 nm, upon excitation at 340 nm at room temperature. Interestingly, the emission maximum at 77 K shows a structural character with a strong peak at 410 nm, a medium at 433 nm and a weak at 387 nm, accompanied by a tail band to about 500 nm. [ABSTRACT FROM AUTHOR]

Understanding the influence of adsorption sites to the electronic properties of adsorbed molecules on two-dimensional (2D) ultrathin insulator is of essential importance for future organic-inorganic hybrid nanodevices. Here, the adsorption and electronic states of manganese phthalocyanine (MnPc) on a single layer of hexagonal boron nitride (h-BN) have been comprehensively studied by low-temperature scanning tunneling microscopy/spectroscopy and tight binding calculations. The frontier orbitals of the MnPc can change drastically by reversible manipulation of individual MnPc molecules onto and away from the single atomic vacancies at the h-BN surface. Particularly, the change of the molecular electronic configuration can be controlled depending on whether the atomic vacancy is below the metal center or the ligand of the MnPc. These findings give new insight into defect-engineering of the organic-inorganic hybrid nanodevices down to submolecular level. [ABSTRACT FROM AUTHOR]

The reaction mechanism between phosphacyclopropenylidene and methyleneimine has been systematically investigated at the M06–2X/6–311++G(d,p) level of theory in order to better understand the reactivity of unsaturated cyclic phosphorus-bearing carbene. Geometry optimizations and vibrational analyses have been conducted for the stationary points on the potential energy surface of the system. Calculations show that the spiro bicyclic intermediate could be produced through the cycloaddition process between phosphacyclopropenylidene and methyleneimine initially. The reaction mechanism is illustrated with frontier molecular orbital theory. Introduction of electron-withdrawing group in phosphacyclopropenylidene will better facilitate the addition process. Through subsequent ring-expanding and hydrogen-migrating process, fuse-ring and allene compounds could be produced, respectively. Furthermore, it's easy for spiro bicyclic intermediate and another methyleneimine to form a spiro tricyclic compound. This study is helpful to understand the reactivity of phosphacyclopropenylidene, the evolution of phosphorus-bearing molecules in space, and to offer an alternative approach to the formation of phosphorus-bearing heterocyclic compound. [ABSTRACT FROM AUTHOR]

The spectral and luminescent properties of 21-thia- and 21,23-dithia-5,10,15,20-tetraphenylporphyrin were studied in solutions at 293 K. The origin of the spectral shifts of the absorption bands upon heterosubstitution was discussed based on the Gouterman four-orbital model. Fluorescence quenching of the heteroporphyrins was shown to be due to an internal heavy-atom effect of the thiophene-ring heteroatom. [ABSTRACT FROM AUTHOR]

The electronic properties of quercetin (Q)–π–cyanoacrylic acid (CNA) dye molecules using heteroaromatic rings, namely cyclopentadiene (F1), furan (F2), pyrrole (F3), thiophene (F4), oxazole (F5), imidazole (F6), thiazole (F7), isoindene (FF1), benzofuran (FF2), indole (FF3), benzothiophene (FF4), benzoxazole (FF5), benzimidazole (FF6), and benzothiazole (FF7), as π-linkers are studied for the first time using Time-Dependent Density Functional Theory (TDDFT) with dimethyl sulfoxide (DMSO) as solvent to predict their excitation energy, absorption wavelength, oscillator strength, light harvesting efficiency, and exciton binding energy. The charge transfer and charge regeneration in the ground and excited states of the dyes are established. The photon to electron energy transfer from the dye (quercetin) to the semiconductor (TiO2) surface is analyzed based on intramolecular charge transfer. The results of the electron transfer studies on these newly designed dyes could be used to enhance the performance of resulting dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

The optical, electrochemical, and electronic properties of a perylene derivative, N,N′-bis(5-amino-1,10-phenanthroline)perylene-3,4,9,10-tetracarboxidiimide (pPDIp), have been investigated. The optical properties were investigated by fluorescence and absorption spectroscopies. The effect of solvent polarity on the optical properties showed that the Stokes shift increased with decreasing solvent polarity, from 252 cm−1 in dimethylformamide to 1011 cm−1 in acetone, indicating greater stability of intramolecular charge transfer (ICT) species in nonpolar solvents, which suggests significant changes in interactions with more compared with less polar solvents. The use of pPDIp as a catalyst in direct ethanol fuel cells was also investigated, using cyclic voltammetry and chronoamperometry. The electrochemical data indicated that pPDIp dispersed in Pt/C (Pt/C:pPDIp) can be used as a catalyst in ethanol electrooxidation, showing catalytic activity analogous to that of metal Pt/C-based catalysts. Direct scanning indicated that the peak current density for the 2:1 Pt/C:pPDIp catalyst was higher than that for mixed catalysts. In addition, chronoamperometry data indicated better catalytic activity at 0.6 V for Pt/C:pPDIp-based catalysts. [ABSTRACT FROM AUTHOR]