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As common industrial raw materials, malachite green (MG) and Cr(Ⅵ) generally coexist in waste liquids discharged from the paper printing, leather, and textile industries, causing serious harm to humans and the environment. Therefore, developing an effective method for the synergistic removal of MG and Cr(Ⅵ) from aquatic environments is of great research value. In this work, the non-homogeneous Fenton-like catalysts, namely, EDDS-Silica and EDDS-Co 2+ -Silica were successfully prepared using ethylenediamine disuccinic acid (EDDS) and silica gel (Silica) as raw materials, and a non-homogeneous Fenton-like catalytic method was developed for the efficient and synergistic removal of MG and Cr(Ⅵ) from wastewater. EDDS-Silica and EDDS-Co 2+ -Silica were analyzed using Fourier infrared spectroscopy and X-ray photoelectron spectroscopy to determine their structural composition and elemental contents. The catalytic degradation and removal effects of these materials in an MG single-waste system were also investigated. The results demonstrated that the incorporation of both materials can overcome the limitation of the conventional Fenton reaction, which is its applicability to acidic environments only. Moreover, EDDS-Co 2+ -Silica showed better degradation effects on MG than EDDS-Silica. Quantitative calculations based on density functional theory were used to predict the optimal coordination forms between Co 2+ and EDDS-Silica as well as the MG structure. The lowest unoccupied and highest occupied molecular orbitals of the catalysts were then used to predict the active sites on which MG tends to capture or release electrons during the degradation reaction. The optimal conditions for the synergistic removal of MG and Cr(Ⅵ) from a binary system using EDDS-Co 2+ -Silica were further investigated under different influencing factors. The results showed that EDDS-Co 2+ -Silica still had excellent catalytic effect on the degradation rate of MG in the range of pH 3-7, and the optimal conditions were as follows: solution pH, 7; degradation time, 1 h; temperature, 25 ℃; H 2 O 2 concentration, 20 mmol/L; and the initial mass concentration of Cr(Ⅵ), 25 mg/L. Under the above conditions, the degradation rate was increased from 87.25% to 96.67% compared with that in the MG monosystem. Obvious enhancements in degradation effect and efficiency confirmed that the incorporation of EDDS-Co 2+ -Silica was favorable for the synergistic removal of MG and Cr(Ⅵ) in the binary system. Strongly oxidizing Cr(Ⅵ) can participate in the Fenton reaction, thus promoting MG degradation over a wide pH range. Thus, a positive synergistic effect exists between MG and Cr(Ⅵ). Considering that a large number of metal ions remained in the solution after the degradation reaction, EDDS-Silica was added to the degradation solution, and adsorption experiments were performed for 4 h at 30 ℃to adsorb and remove Cr and Fe via the strong chelating property of EDDS. The total residual mass concentrations of Cr and Fe were 4.96 and 1.02 mg/L, respectively, which meet national emission standards. These findings indicate that EDDS-Silica has good effects on the removal of residual metal ions after the nonhomogeneous Fenton reaction. As heterogeneous Fenton-like catalysts, the aminopolycarboxylic acid-modified materials proposed in this study can simultaneously promote the Fenton reaction and remove residual metal ions, thereby effectively removing MG and Cr(Ⅵ) from the binary system while ensuring that the content of residual metal ions in the system meets environmental emission standards. This study has broad application prospects in dye degradation and heavy-metal-ion wastewater treatment, and provides a reference value and theoretical basis for the development of other similar ligand-modified 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.

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, 1 H NMR and 13 C NMR spectral data. The P3HT/dye 1/nc-TiO 2 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-TiO 2 . The dye 1 has rigid fused thiophene rings and its HOMO is located between valence band of TiO 2 and HOMO of P3HT which leads to improve the charge carrier separation and increase the current density to reach 1.2 mA/cm 2 ., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors. Published by Elsevier Ltd.)

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., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Hayyiratul Fatimah Mohd Zaid reports financial support was provided by 10.13039/501100016152UTP Foundation., (© 2023 The Authors.)

Hydroxyl radical (•OH) and sulfate radical (SO 4 • - ) produced in advanced oxidation processes (AOPs) have been widely studied for organic contaminants degradation, however, the different radical characteristics and reaction mechanisms on organics degradation are still needed. In this study, a homogeneous Co(II)/peroxymonosulfate activation system was established for caffeine (CAF) degradation, and pH was controlled to regulate the radicals production. The different attack routes driven by SO 4 • - and •OH were deeply explored by transformation products (TPs) identification and theoretical calculations. Specifically, a method on dynamic electronic structure analysis of reactants (R), transition state (TS) and intermediates (IMs) during reaction was proposed, which was applied to elucidate the underlying mechanism of CAF oxidation by •OH and SO 4 • - at the molecular orbital level. In total, SO 4 • - is kinetically more likely to attack CAF than •OH due to its higher oxidation potential and electrophilicity index. Single electron transfer reaction (SET) is only favorable for SO 4 • - due to its higher electron affinity than •OH, while only •OH can react with CAF via hydrogen atom abstraction (HAA) route. Radical adduct formation (RAF) is the most favorable route for both •OH and SO 4 • - attack according to both kinetics and thermodynamics results. These findings can significantly promote the understanding on the degradation mechanism of organic pollutants driven by •OH and SO 4 • - in AOPs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Dispersion correction in theoretical determination of cyclopeptide conformations is emphasized. Whether in gas approximation or in solvation simulation, the density functional theory with London dispersion correction (DFT-D3) demonstrates that only 2-3 conformers can stably coexist for cycloaspeptides (A, D, G) at B3LYP-D3 and CAM-B3LYP-D3. Conformational rationality is confirmed by electronic circular dichroism (ECD). Whether for Cotton effect or for excitation energy, TD-B3LYP-D3 has better performances than TD-CAM-B3LYP-D3 because the former can better reproduce the experiment. A molecular orbital analysis is used to interpret ECD, where two energy bands observed in experiment originates from the ππ* transitions other than the σπ* transitions. Long-range correction and solvent effect make H-bonds shorten, and dispersion correction makes them further shorten., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Singly-hydrated HOO - anion was found to induce alternative nucleophile HO - via proton transfer from water molecule when reacting with CH 3 Cl. To investigate the generality of this effect, the competition between the solvent-induced HO - -S N 2 pathway and the normal HOO - -S N 2 pathway is studied for the microsolvated HOO - (H 2 O) n=1,2,3 +CH 3 X (X=F, Cl, Br, I) reaction by quantum chemistry calculations. Incremental hydration increases the barrier heights of both pathways and enlarges the barrier difference between them, which favors the HOO - -S N 2 pathway. Interestingly, the barrier difference is insensitive to the leaving group. Calculations show that the water induced HO - -S N 2 pathway is highly suppressed when the degree of hydration increases beyond two. The differential barrier under incremental hydration can be explained by solvent molecules stabilizing the HOMO level of HO - (HOOH)(H 2 O) n-1 nucleophile more than that of the HOO - (H 2 O) n nucleophile. Comparison between the HO - - and HOO - -nucleophiles suggests that α-effect exists. Activation strain analysis attributes the barrier differences to stronger TS distortion of the HO - -S N 2 pathway than that of the HOO - -S N 2 pathway., (© 2022 Wiley-VCH GmbH.)

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 novel Ti 3+ -based thiospinel ZnTi 2 S 4 is successfully synthesized via a low-temperature ion-exchange reaction. ZnTi 2 S 4 shows a signature of metallic ground state evidenced by a contribution of conduction electrons in the heat capacity and Pauli-like paramagnetic susceptibility. These observations contrast to the electronic state of similar Ti 3+ -based spinel MgTi 2 O 4 exhibiting the metal-insulator transition associated with a molecular orbital crystallization (MOC). Furthermore, the magnetic susceptibility of ZnTi 2 S 4 shows a pseudogap-like behavior indicated by a vast peak in the magnetic susceptibility around 110 K, likely originating from the MOC fluctuation. The origin of the difference in the electronic states of MgTi 2 O 4 and ZnTi 2 S 4 would be due to the different magnitude of overlap between Ti 3 d and p orbitals (O: 2 p and S: 3 p ). The presence of a MOC state in the close vicinity of insulator-metal transition may suggest the importance of itinerancy in a MOC., (© 2021 IOP Publishing Ltd.)

Density functional theory (DFT) calculations were used to study the superoxide dismutase (SOD) mimic activity of two Cu 2+ complexes with ligands derived from 8-hydroxyquinoline (8-HQ). Electron-donating and -withdrawing substituent groups were inserted into the structures to verify changes in the reactivity. The theoretical parameters obtained were compared and validated with the experimental data available. The results showed that the reduction process occurs with greater participation of the 8-HQ ligand and the oxidation step occurs with participation of the copper atom in the complexes, where the electron received during the reduction step is used to reduce the Cu 2+ to Cu + . The calculated electronic affinity showed good correlation with the experimental mimetic activity, and the analysis of this property, of total charge and of molecular orbitals indicated an increase in the mimetic activity with the insertion of electron-withdrawing substituent groups in the structures., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This essay describes the successive births of valence bond (VB) theory during 1916-1931. The alternative molecular orbital (MO) theory was born in the late 1920s. The presence of two seemingly different descriptions of molecules by the two theories led to struggles between the main proponents, Linus Pauling and Robert Mulliken, and their supporters. Until the 1950s, VB theory was dominant, and then it was eclipsed by MO theory. The struggles will be discussed, as well as the new dawn of VB theory, and its future.

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., (© 2020 Wiley-VCH GmbH.)

Advances in molecular spintronics rely on the in-depth characterization of the molecular building blocks in terms of their electronic and, more importantly, magnetic properties. For this purpose, inert substrates that interact only weakly with adsorbed molecules are required in order to preserve their electronic states. Here, we investigate the magnetic-field response of a single paramagnetic 5,5'-dibromosalophenatocobalt(II) (CoSal) molecule adsorbed on a weakly interacting magnetic substrate, namely, Fe-intercalated graphene (GR/Fe) grown on Ir(111), by using spin-polarized scanning tunneling microscopy and spectroscopy. We have obtained local magnetization curves, spin-dependent tunneling spectra, and spatial maps of magnetic asymmetry for a single CoSal molecule, revealing its magnetic properties and coupling to the local environment. The distinct magnetic behavior of the Co metal center is found to rely strictly on its position relative to the GR/Fe moiré structure, which determines the level of hybridization between the GR/Fe surface π-system and the molecular orbitals.

Bis(acetylacetonato)copper(II) can be synthesized economically and with ease by the reaction between acetylacetone and a copper salt (Cu(OAc) 2 or CuCl 2 ·2H 2 O). When used as catalyst, bis(acetylacetonato)copper(II) is sometimes being oxidized to Cu(III) or reduced to Cu(I), although only the structure of the neutral form is known experimentally. The content of this paper provides computational chemistry calculated data of the geometry, electronic structure, spin state and frontier orbitals for the neutral, as well as the oxidized and reduced forms of the bis(acetylacetonato)copper(II) molecule. This data shows that both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the neutral molecule are copper based. The neutral molecule is a spin = ½ system. The data shows that the spin state of both the oxidized and reduced molecules is zero., (© 2019 The Author(s).)

Chirality transfer from self-assembly of achiral titanyl phthalocyanine (TiOPc) to its top-sitting TiOPc molecule has been successfully achieved. The TiOPc molecules first assemble into a porous network on Au(111) that contains periodic chiral voids, each being fenced by four axially rotating TiOPc molecules in upward adsorption geometry where their ending O atoms exclusively point away from the substrate. The additional top-sitting TiOPc molecule turns out to be chiral upon adsorption on a chiral void with its ending O atom toward the substrate. The chirality of the top-sitting TiOPc is associated with a charge transfer between its indole rings and the ending O atoms of the underlying TiOPc molecules that form the chiral void, resulting in asymmetric electronic density of the indole rings in the top-sitting molecule and accordingly the chirality of the molecular orbitals. Such a scenario also validates other planar achiral metallophthalocyanines such as copper phthalocyanine that become chiral upon adsorption on the chiral voids in the underlying TiOPc assembly, indicating that the chirality transfer mechanism from assembly to the top-sitting molecule is not uncommon.

Theoretical calculations of optical activities in steroid ketones are presented by using modern semi-empirical PM7 wavefunctions. Both circular dichroism (CD) and specific rotation, which is proportional to optical rotation dispersion (ORD), are well simulated, and signs of the Cotton effect at the most long-wavelength region are fully in accordance with the experimental results. The good accordance is related to the octant rule, which is deduced within the framework of the perturbation theory. Our treatment is promising to predict the signs of the Cotton effect of large molecules, and thus, the absolute configurations can also be grasped without demanding procedures., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The coupling between localized plasmon and molecular orbital in the light emission from a metallic nanocavity has been directly detected and imaged with sub-0.1 nm resolution. The light emission intensity was enhanced when the energy difference between the tunneling electrons and the lowest unoccupied molecular orbital (LUMO) of an azulene molecule matches the energy of a plasmon mode of the nanocavity defined by the Ag-tip and Ag (110) substrate of a scanning tunneling microscope (STM). The spatially resolved image of the light emission intensity matches the spatial distribution of the LUMO obtained by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. Our results highlight the near-field coupling of a molecular orbital to the radiative decay of a plasmonic excitation in a confined nanoscale junction.

Using the smallest non-classical fullerene, we investigate the impact of endohedral fullerene molecules on the quantum transport through molecular junctions, and then compared this with the pure C 20 -based molecular junction. By employing the density functional theory combined with the non-equilibrium Green's function, we contemplated different electronic parameters, namely, density of states, transmission coefficient, energy levels, molecular orbitals, conduction gaps, electron density and their charge transfer. A knowledge of these physical parameters is necessary in order to calculate current and conductance computed using Landauer-Büttiker formalism. The molecule-electrode coupling influenced by endohedral molecules affects junction devices in a unique manner. We observe that the highest quantum transport is possible in an Au-N@C 20 -Au and Au-O@C 20 -Au junction device, and is even higher than that of the intrinsic C 20 fullerene junction. Another notable observation is that the F@C 20 molecule exhibits the least conducting nature, being even lower than that of the endohedral molecule formed by inserting the noble element, neon. Graphical abstract Electrical characteristics of Endohedral fullerene junctions.

Photodegradation characteristics of pharmaceuticals and personal care products (PPCPs) during UV irradiation are of practical and scientific importance in selecting operational parameters during water treatment processes. In this study, the molar extinction coefficient (ε), quantum yield (φ), and degradation kinetics of neutral/anionic forms of sulfamethoxazole (SMX) and ibuprofen (IBU) were compared by varying solution pH. The degradation kinetics of the target compounds were observed to reversely correlate to the energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) values of the target compounds. Then, a kinetic model for predicting the direct photolytic rates at different solution pH was established based on ε and φ of neutral/anionic species. The root mean squared errors for the modeled values suggest that the model exhibits good predictive power. Finally, in order to evaluate the electrical energy consumption during the UV direct photolysis process, the electrical energy per order (EE/O) was assessed. The experimental and modelling results are important to elucidate the mechanism of degradation of target PPCPs under UV irradiation and allow for the selection of optimal conditions in water treatment processes., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The present work reports detailed photophysics of a coumarin based Schiff base, namely, (E)-7-(((8-hydroxyquinolin-2-yl)methylene)amino)-4-methyl-2H-chromen-2-one (HMC) in different solvents of varying polarity exploiting steady state absorption, fluorescence and time resolved fluorescence spectroscopy. The dominant photophysical features of HMC are discussed in terms of emission from an intramolecular charge transfer (ICT) excited state. Molecular orbital (MO) diagrams as obtained from DFT based computational analysis confirms the occurrence of charge transfer from 8'-hydroxy quinoline moiety of the molecule to the coumarin part. The notable difference in the photophysical response of HMC from its analogous coumarin (C480) lies in a lower magnitude of fluorescence quantum yield of the former, particularly in the solvents of low polarity, which is rationalized by considering the higher rate of non-radiative decay of HMC in apolar solvents. Phosphorescence emission as well as phosphorescence lifetime of HMC has also been reported in 77K frozen matrix., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: P-glycoprotein (P-gp) causes the efflux of cancer chemotherapy drugs from tumor cells, so its inhibition can be one target for designing and synthesis of new anticancer drugs., Objective: In this study, new compounds of 1,4-dihydropyridine (DHP) were recommended as inhibitors of P-gp., Methods: We synthesized new symmetrical DHP with 36% - 43% yield by the reaction of new reactants. In biological studies, these compounds have high lipophilicity, and thus low water solubility. Four reactants I with different reactivity was computed and compared using DFT study. The LUMO-map was differently distributed on each reactant. Amine intermediate underwent tautomerism as a transition state and it seems to play important role in reaction progress. Calculations were performed to select suitable reactants., Results: Two different reactants I, including one polar group and a non-polar group, were used to produce asymmetric compounds with 49% - 60% yield. These asymmetric DHPs were more soluble than symmetric DHPs. In the final step, another selected symmetric product (by the elimination of chlorine atom) was synthesized in high yield (74%) by using DFT study., Conclusion: In this study, selected reactants by DFT calculation have increased the yield of reaction from 36% to 74% without any catalyst. The diversity of products is a noticeable topic. Racemic asymmetric compounds with R and S enantiomers have the potential for enantiomeric separation. Each of these enantiomers could have a different physiological effect., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Most of the α-halo carbonyl (AHC) compounds tend to be predicted as mutagenic by structure-activity relationship based on structural category only, because they have an alkyl halide structure as a structural alert of mutagenicity. However, some AHC compounds are not mutagenic. We hypothesized that AHC reacts with DNA by S N 2 reaction, and the reactivity relates to mutagenicity. As an index of S N 2 reactivity, we focused on molecular orbitals (MOs), as the direction and position of two molecules in collision are important in the S N 2 reaction. The MOs suitable for S N 2 reaction (SN2MOs) were selected by chemical-visual inspection based on the shape of the MO. We used the level gap and the energy gap between SN2MO and the lowest unoccupied molecular orbital as the descriptors of S N 2 reactivity. As the results, S N 2 reactivity related to mutagenicity and we were able to predict mutagenicity of 20 AHC compounds with 95.0% concordance. It was suggested that S N 2 reaction is a reaction mechanism of AHC compounds and DNA in the mutagenic process. The method allows for discrimination among structurally similar compounds by combination with quantitative structure-activity relationships. The combination approach is expected to be useful for the mutagenic assessment of pharmaceutical impurities.

Using the smallest non-classical fullerene, we investigate the impact of doping at the molecule-electrode interface on the electron transport of molecular junctions. This is accomplished by employing the density functional theory combined with the non-equilibrium Green's function. We contemplate different electronic parameters, namely, density of states, transmission coefficient, energy levels, molecular orbitals, conduction gaps, electron density, and their charge transfer. The relevance of these physical parameters is obtained to calculate their electrical parameters, current, and conductance, computed from Landauer-Büttiker formalism. The molecule-electrode coupling is influenced by the nature of doping atoms and affects the junction devices in a unique course. A particular aftermath is noticed in Au-C 18 O 2 -Au device with highest ballistic transport despite the electro-negative nature of oxygen atoms. Moreover, an interesting feature is observed in Au-C 18 Be 2 -Au device with double-barrier transmission resonance and corresponding oscillating conductance. Graphical abstract The doped C 20 fullerene in molecular and device mode.

Understanding the energy-level alignment and charge transfer of organic molecules at large bandgap semiconductors is of crucial importance to optimize device performance in organic electronics. We have studied submonolayer coverage of manganese phthalocyanine (MnPc) on hexagonal boron nitride (h-BN) on Rh(111) as a model system by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). The adsorbed molecules show three distinctly different bias-dependent topographic signatures, which depend on their adsorption positions on the h-BN. Among these three types of MnPc, one shows pronounced charging because of the proximity of the highest occupied molecular orbital (HOMO) to the Fermi level on the decoupling h-BN substrate. The charging of the MnPc from its neutral to the MnPc(+) state leads to a down shift of the Mn 3d-related orbital by 840 meV as determined from the difference in energy position between high- and low-bias charging. We find that the charging field is linearly related to the HOMO position with respect to the Fermi level, with a clear correlation to the adsorption orientations of the MnPc. Our results show how critically energy level alignment and field-induced charge transfer process can depend on adsorption configurations, even on an apparently low-interacting substrate like metal supported monolayer h-BN.

Density functional theory (DFT) calculations are carried out to investigate the structural and electronic properties of a series of hexanuclear vanadium oxide clusters V6On(-/0) (n=12-15). Generalized Koopmans' theorem is applied to predict the vertical detachment energies (VDEs) and simulate the photoelectron spectra (PES) for V6On(-) (n=12-15) clusters. Extensive DFT calculations are performed in search of the lowest-energy structures for both the anions and neutrals. All of these clusters appear to prefer the polyhedral cage structures, in contrast to the planar star-like structures observed in prior model surface studies for the V6O12 cluster. Molecular orbitals are performed to analyze the chemical bonding in the hexanuclear vanadium oxide clusters and provide insights into the sequential oxidation of V6On(-) (n=12-15) clusters. The V6On(-) (n=12-15) clusters possess well-defined V(5+) and V(3+) sites, and may serve as molecular models for surface defects. Electron spin density analyses show that the unpaired electrons in V6On(-) (n=12-14) clusters are primarily localized on the V(3+) sites rather than on the V(5+) sites. The difference gas phase versus model surface structures of V6O12 hints the critical roles of cluster-substrate interactions in stabilizing the planar V6O12 cluster on model surfaces., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The molecular pathogenesis of Alzheimer's disease (AD) is deeply involved in aggregations of amyloid β-proteins (Aβ) in a diseased brain. The recent experimental studies indicated that the mutation of Asp23 by Asn (D23N) within the coding sequence of Aβ increases the risk for the pathogeny of cerebral amyloid angiopathy and early-onset familial ADs. Fibrils of the D23N mutated Aβs can form both parallel and antiparallel structures, and the parallel one is considered to be associated with the pathogeny. However, the structure and the aggregation mechanism of the mutated Aβ fibrils are not elucidated at atomic and electronic levels. We here investigated solvated structures of the two types of Aβ dimers, each of which is composed of the wild-type or the D23N mutated Aβ, using classical molecular mechanics and ab initio fragment molecular orbital (FMO) methods, in order to reveal the effect of the D23N mutation on the structure of Aβ dimer as well as the specific interactions between the Aβ monomers. The results elucidate that the effect of the D23N mutation is significant for the parallel structure of Aβ dimer and that the solvating water molecules around the Aβ dimer have significant contribution to the stability of Aβ dimer., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Geometries of three [Ru(OAc)(2cqn)2NO] (H2cqn=2-chloro-8-quinolinol) isomers were fully optimized with density functional theory (DFT), and compared with their crystal structures. Their electronic spectra, infrared and NMR spectra were also calculated at the B3LYP level with Lanl2dz and 6-311G(d,p) as the basis set. And good agreement had been achieved between experimental and theoretical values of structural parameter, UV-vis absorption and scaled vibration frequency. With the gauge independent atomic orbital (GIAO) method, chemical shifts in (1)H and (13)C NMR of these isomers were also calculated, which could reasonably match with the experimental data. The calculated frontier molecular orbitals suggested that the electronic transition from a ligand-based orbital to an antibonding overlap of the Ru(d) and π(∗) NO(p) control the photo-induced reactivity of [Ru(OAc)(2cqn)2NO] complexes., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The pseudonatural orbital procedure has been applied to the calculation of the potential energy curve of LiH and the dissociation energy of BeH + . Only the two-electron bonding pair is correlated and estimates of σ and π type correlation are obtained. The results for LiH are in good agreement with the most accurate previously published calculations. Comparison with experimental results for LiH indicates that the calculated dissociation energies are accurate to about 0.15 to 0.2 eV.