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Journal articles on the topic 'Antibonding electrons'

Author: Grafiati

Published: 4 June 2025

Last updated: 15 July 2025

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1

Janoschek, Rudolf. "The origin of Rydberg orbitals." Collection of Czechoslovak Chemical Communications 53, no. 10 (1988): 2330–38. http://dx.doi.org/10.1135/cccc19882330.

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The concept of hybridization and the principle of maximum overlap are invoked to explain the origin of the Rydberg character of the lowest excited MO of LiH. It is found that the nodal surface of this antibonding MO is not bisecting the bond. The origin of the Rydberg character of the lowest singlet and triplet MO's of the H2 molecule is studied by means of an energy partitioning. The repulsion of electrons is found to be responsible for the diffuse character of the excited so-called antibonding MO's. The singlet-triplet separation is controlled to a large extent by one-electron contributions.

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2

Hajian, M., M. Zareie, D. Hashemian, and M. Bahrami. "Room-temperature synthesis of graphene-like carbon sheets from C2H2, CO2 and CO on copper foil." RSC Advances 6, no. 77 (2016): 73331–35. http://dx.doi.org/10.1039/c6ra18173b.

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Static electrons, generated from piezoelectric material, flow to the copper foil and increase the charge density of the catalyst surface. Subsequently this density flows from the catalyst into the antibonding orbitals of acetylene molecules and decompose it.

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3

Mohd., Suhail. "An advanced trick to calculate the molecules and ions bond order with practical application." Chemistry International 7, no. 3 (2021): 208–11. https://doi.org/10.5281/zenodo.4900095.

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Every molecule has two or more atoms linked to each other through a bond. The number of bonds between two atoms is called bond order. Hence, the bond order gives information about the total number of bonds between two atoms. Besides, different methods and definitions have been given to find out an exact bond order based on various theories. The most acceptable theory to find an exact bond order is the molecular orbital theory. Using this theory, the whole electronic configuration of the molecule is written first, then total electrons present in bonding orbitals as well as antibonding orbitals

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4

Joy, Jyothish, Eluvathingal D. Jemmis, and Kaipanchery Vidya. "Negative hyperconjugation and red-, blue- or zero-shift in X–Z⋯Y complexes." Faraday Discussions 177 (2015): 33–50. http://dx.doi.org/10.1039/c4fd00183d.

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A generalized explanation is provided for the existence of the red- and blue-shifting nature of X–Z bonds (Z = H, halogens, chalcogens, pnicogens, etc.) in X–Z⋯Y complexes based on computational studies on a selected set of weakly bonded complexes and analysis of existing literature data. The additional electrons and orbitals available on Z in comparison to H make for dramatic differences between the H-bond and the rest of the Z-bonds. The nature of the X-group and its influence on the X–Z bond length in the parent X–Z molecule largely controls the change in the X–Z bond length on X–Z⋯Y bond f

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5

Li, Yu-Qiong, Qian He, Jian-Hua Chen, and Cui-Hua Zhao. "Electronic and chemical structures of pyrite and arsenopyrite." Mineralogical Magazine 79, no. 7 (2015): 1779–89. http://dx.doi.org/10.1180/minmag.2015.079.7.05.

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AbstractThe first-principles plane-wave pseudopotential method is used to study the electronic and chemical structures of pyrite (FeS2) and arsenopyrite (FeAsS). The results indicate that an antibonding interaction occurs between Fe and As atoms in arsenopyrite. This interaction results in the Fe atom being repelled towards the S atom to stabilize antibonding orbitals, causing a larger S–Fe–S angle in arsenopyrite than in pyrite and a distortion in the arsenopyrite structure. In arsenopyrite, Fe–Fe distances are alternately long and short. The low spin density of the Fe d electrons supports th

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6

SUN, CHANG Q. "OXYGEN INTERACTION WITH Rh(111) AND Ru(0001) SURFACES: BOND-FORMING DYNAMICS." Modern Physics Letters B 14, no. 06 (2000): 219–27. http://dx.doi.org/10.1142/s0217984900000318.

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A new description of bonding and band-forming is presented for the nature and dynamics of O–Rh(111) and O–Ru(0001) surface bonding and its consequences on the behavior of atoms and electrons at the surfaces. The sp-orbital hybridization and electron transportation define that oxygen retains inside the hcp hollow site throughout the course of reaction in which O -1 forms and then O -2-hybrid follows with production of nonbonding lone pairs and the lone-pair induced antibonding dipoles. Consequently, the valence band and surface morphology are modified with the corresponding features, and the ra

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7

Bacalis, N. C. "Existence of He2-negative ions with two remote electrons in antibonding orbitals." Journal of Physics B: Atomic, Molecular and Optical Physics 33, no. 7 (2000): 1415–22. http://dx.doi.org/10.1088/0953-4075/33/7/309.

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8

Wang, Bruce, Antonio Bianconi, Ian D. R. Mackinnon, and Jose A. Alarco. "Superlattice Delineated Fermi Surface Nesting and Electron-Phonon Coupling in CaC6." Crystals 14, no. 6 (2024): 499. http://dx.doi.org/10.3390/cryst14060499.

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The superconductivity of CaC6 as a function of pressure and Ca isotopic composition was revisited using DFT calculations on a 2c–double hexagonal superlattice. The introduction of superlattices was motivated by previous synchrotron absorption and Raman spectroscopy results on other superconductors that showed evidence of superlattice vibrations at low (THz) frequencies. For CaC6, superlattices have previously been invoked to explain the ARPES data. A superlattice along the hexagonal c-axis direction is also illustrative of atomic orbital symmetry and periodicity, including bonding and antibond

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9

Tsuchii, Masato, Zhen Chen, Yasushi Hirose, and Tetsuya Hasegawa. "Electron transport mechanisms in amorphous zinc oxysulfide thin films." Journal of Vacuum Science & Technology B 41, no. 2 (2023): 022201. http://dx.doi.org/10.1116/5.0104988.

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Amorphous mixed-anion semiconductors (AMASs) such as amorphous zinc oxynitride and amorphous zinc oxysulfide (a-ZnOS) have attracted attention as rare-metal-free amorphous semiconductors that exhibit electron mobility comparable to or greater than the electron mobilities of typical amorphous oxide semiconductors (AOSs), including amorphous In–Ga–Zn–O (a-IGZO). A characteristic feature of AMASs is that their conduction-band minimum (CBM) mainly consists of s-orbitals of the single cation, in contrast to conventional AOSs, whose CBM is composed of s-orbitals of multiple cations. This unique band

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10

Wong, Kenneth, Qing Hua Zeng та Ai Bing Yu. "Electronic Structure of Bilayer (Fe, Ni) Metallic α-Al₂O₃(0001) Catalysts Towards CH₄ Adsorption and Dissociation". Materials Science Forum 654-656 (червень 2010): 2747–50. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.2747.

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Density functional theory calculations are performed on the monometallic (Fe or Ni) bilayer modified α-Al2O3(0001) surface. Comparison has been made to their structural and electronic behaviors upon CH4 adsorption and dissociation. Local density of states and frontier orbital analysis show that C-H activation proceeds through weak chemical interactions with the metallic 3d electrons. It was found that electron transport within the sp and 3d type orbitals of the catalyst is important for the equilibration of the system. Such electron transport also promotes electron donation to the σ*(C-H) anti

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11

Lian, Kangkang, Qiang Wan, Rong Jiang, and Sen Lin. "Electrocatalytic Oxygen Reduction to Hydrogen Peroxide on Graphdiyne-Based Single-Atom Catalysts: First-Principles Studies." Catalysts 13, no. 2 (2023): 307. http://dx.doi.org/10.3390/catal13020307.

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The electrocatalytic oxygen reduction reaction (2e− ORR) via a two-electron process is a promising pathway for the production of hydrogen peroxide (H2O2). Here, we systematically investigated the 2e− ORR process on graphdiyne (GDY) supported single transition metal atoms (TM1@GDY) using density functional theory (DFT) calculations. Among the 23 TM1@GDY catalysts, Pt1@GDY showed the best performance for the H2O2 product with an overpotential as low as 0.15 V. The electronic structure analysis, on the one hand, elucidates that the electron transfer between Pt1@GDY and the adsorbed O2 facilitates

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12

Li, Lei, and Haihua Huang. "Fluorine-Modulated Electronic Structure and Atomic Bonding of the Titanium Surface." Materials 15, no. 23 (2022): 8492. http://dx.doi.org/10.3390/ma15238492.

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The fluorine-adsorption-induced local bond relaxation and valence-energy-state evolution of the Ti(0001) surface were examined through density functional theory calculations. The predicted bond–band–barrier (3 B) correlation notation framework for the interaction of the fluorine adsorbate with Ti atoms formed a tetrahedral structure through the creation of four valence density-of-state features, namely bonding electron pairs, nonbonding lone pairs, holes, and antibonding dipoles. The bonding states resulted in the passivation of metal Ti surfaces, the formation of Tip dipoles and Ti+/p H-like

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13

Omiya, Takuma, Yousoo Kim, Rasmita Raval, and Heike Arnolds. "Ultrafast Vibrational Dynamics of CO Ligands on RuTPP/Cu(110) under Photodesorption Conditions." Surfaces 2, no. 1 (2019): 117–30. http://dx.doi.org/10.3390/surfaces2010010.

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We have studied CO coordinated to ruthenium tetraphenylporphyrin (RuTPP)/Cu(110) and directly adsorbed to Cu(110), using femtosecond pump-sum frequency probe spectroscopy, to alter the degree of electron-vibration coupling between the metal substrate and CO. We observe the facile femtosecond laser-induced desorption of CO from RuTPP/Cu(110), but not from Cu(110). A change in the vibrational transients, in the first few picoseconds, from a red- to blue-shift of the C–O stretching vibration under photodesorption conditions, was also observed. This drastic change can be explained, if the cause of

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14

Geng, Caiyun, Jilai Li, Thomas Weiske, and Helmut Schwarz. "Complete cleavage of the N≡N triple bond by Ta2N+ via degenerate ligand exchange at ambient temperature: A perfect catalytic cycle." Proceedings of the National Academy of Sciences 116, no. 43 (2019): 21416–20. http://dx.doi.org/10.1073/pnas.1913664116.

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An unprecedented, spontaneous, and complete cleavage of the triple bond of N2 in the thermal reaction of 15N2 with Ta214N+ was observed experimentally by Fourier transform ion cyclotron resonance mass spectrometry; mechanistic aspects of the degenerate ligand exchange were addressed by high-level quantum chemical calculations. The “hidden” dis- and reassembly of N2, mediated by Ta2N+, constitutes a full catalytic cycle. A frontier orbital analysis reveals that the scission of the N2 triple bond is essentially governed by the donation of d-electrons from the 2 metal centers into antibonding π*-

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15

Mishra, K. C., I. Osterloh, H. Anton, B. Hannebauer, P. C. Schmidt, and K. H. Johnson. "Electronic Structures and Host Excitation of LaPO4, La2O3, and AlPO4." Journal of Materials Research 12, no. 8 (1997): 2183–90. http://dx.doi.org/10.1557/jmr.1997.0292.

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We report the electronic structures and associated optical properties of three inorganic oxides, namely lanthanum oxide, aluminum phosphate, and lanthanum phosphate, calculated by the first principles augmented spherical wave (ASW) and full potential linear muffin tin orbital (FP-LMTO) band structure methods, and the self-consistent field Xα scattered wave (Xα SW) molecular orbital cluster approach. Our calculations indicate negligible effect of the choice of exchange correlation potentials on the position, shape, and relative ordering of the energy bands. The ASW energy gaps in lanthanum phos

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16

Li, Wan-Lu, Teng-Teng Chen, Deng-Hui Xing, Xin Chen, Jun Li, and Lai-Sheng Wang. "Observation of highly stable and symmetric lanthanide octa-boron inverse sandwich complexes." Proceedings of the National Academy of Sciences 115, no. 30 (2018): E6972—E6977. http://dx.doi.org/10.1073/pnas.1806476115.

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While boron forms a wide range of metal borides with important industrial applications, there has been relatively little attention devoted to lanthanide boride clusters. Here we report a joint photoelectron spectroscopy and quantum chemical study on two octa-boron di-lanthanide clusters, Ln2B8− (Ln = La, Pr). We found that these clusters form highly stable inverse sandwich structures, [Ln–B8–Ln]−, with strong Ln and B8 bonding via interactions between the Ln 5d orbitals and the delocalized σ and π orbitals on the B8 ring. A (d–p)δ bond, involving the 5dδ and the antibonding π orbital of the B8

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17

Wosylus, Aron, Yurii Prots, Ulrich Burkhardt, Walter Schnelle, Ulrich Schwarz, and Yuri Grin. "High-pressure Synthesis of Strontium Hexasilicide." Zeitschrift für Naturforschung B 61, no. 12 (2006): 1485–92. http://dx.doi.org/10.1515/znb-2006-1204.

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The binary phase SrSi6 was prepared at a pressure of 10(1) GPa and a temperature of 1520(150) K. Single crystal refinements and powder diffraction data reveal that the compound crystallizes in the orthorhombic crystal system (Cmcm, a=4.4692(4), b=10.256(1), c=11.698(1)Å ) and is isopointal to EuGa2Ge4 and EuSi6. Exothermic decomposition of the compound into SrSi2 and Si at 797 K and ambient pressure indicates that the compound is a metastable high-pressure phase. Analysis of the chemical bonding using the electron localization function and calculated charge densities reveals covalent bonding w

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18

SUN, CHANG Q., and S. LI. "OXYGEN-DERIVED DOS FEATURES IN THE VALENCE BAND OF METALS." Surface Review and Letters 07, no. 03 (2000): 213–17. http://dx.doi.org/10.1142/s0218625x00000312.

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From the perspective of sp orbital hybrid bonding and its consequence on the behavior of valence electrons, new insight is presented into the nature of oxygen-derived features in the valence band and above of metals. It is suggested that the crystal geometry and the surface morphology may vary from surface to surface and from material to material but the oxygen-derived features in energy space are substantially the same in nature. The derived features can be consistently specified as oxygen–metal bonding (-5 to -8 eV), a nonbond lone pair of oxygen (-1 to -2 eV), holes of metal ions (~EF) and

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19

Sutton, A. P., P. D. Godwin, and A. P. Horsfield. "Tight-Binding Theory and Computational Materials Synthesis." MRS Bulletin 21, no. 2 (1996): 42–48. http://dx.doi.org/10.1557/s0883769400046297.

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At the heart of any atomistic simulation is a description of the atomic interactions. A whole hierarchy of models of atomic interactions has been developed over the last twenty years or so, ranging from ab initio density-functional techniques, to simple empirical potentials such as the embedded-atom method and Finnis-Sinclair potentials in metals, valence force fields in covalently bonded materials, and the somewhat older shell model in ionic systems. Between the ab initio formulations and empirical potentials lies the tight-binding approximation: It involves the solution of equations that tak

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20

Torres, Vitor J. B., J. Coutinho, and Patrick R. Briddon. "Local Vibrational Modes of Zn-H-P in GaP, InP and ZnTe." Defect and Diffusion Forum 261-262 (January 2007): 31–36. http://dx.doi.org/10.4028/www.scientific.net/ddf.261-262.31.

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We have investigated the hydrogenation of the zinc acceptor in GaP and InP, and of the phosphorus acceptor in ZnTe, by computer modeling. We used a density-functional supercell code and pseudopotentials to deal with the core electrons. However zinc 3d electrons were explicitly taken to be valence electrons. We have determined the relaxed atomic geometry for seven hydrogen sites. We have found that, in the lowest total energy configuration, hydrogen sits in a bond centered position between zinc and arsenic atoms in all GaP, InP and ZnTe semiconductors and is bonded to the phosphorus atom. We fo

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21

Burguera, Sergi, Rosa M. Gomila, Antonio Bauzá, and Antonio Frontera. "Square Planar Pt(II) Ion as Electron Donor in Pnictogen Bonding Interactions." Inorganics 11, no. 2 (2023): 80. http://dx.doi.org/10.3390/inorganics11020080.

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It has been proposed that late transition metals with low coordination numbers (square planar or linear) can act as nucleophiles and participate in σ-hole interactions as electron donors. This is due to the existence, in this type of metal complexes, of a pair of electrons located at high energy d-orbitals (dz2 or dx2-y2), which are adequate for interacting with antibonding σ-orbitals [σ*(X–Y)] where Y is usually an electron withdrawing element and X an element of the p-block. This type of d[M]→σ*(X–Y) interaction has been reported for metals of groups 9–11 in oxidation states +1 and +2 (d8 an

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22

Kameo, Hajime, Tatsuya Kawamoto, Shigeyoshi Sakaki та Hiroshi Nakazawa. "Can One σ*-Antibonding Orbital Interact with Six Electrons of Lewis Bases? Analysis of a Multiply Interacting σ* Orbital". Organometallics 33, № 21 (2014): 5960–63. http://dx.doi.org/10.1021/om500951e.

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23

Hale, William, and Pabitra Choudhury. "Thermodynamic Stability and Intrinsic Activity of La1−xSrxMnO3 (LSM) as an Efficient Bifunctional OER/ORR Electrocatalysts: A Theoretical Study." Catalysts 12, no. 3 (2022): 260. http://dx.doi.org/10.3390/catal12030260.

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Perovskite oxides, being transition metal oxides, show promise as bifunctional catalysts being able to catalyze both oxygen evolution reactions (OER) and oxygen reduction reactions (ORR). These two reactions play a crucial role in energy storage and energy conversion devices. An important feature of perovskite catalyst is their ability to be tuned, as tuning can positively affect both reactivity and stability. In this study, Density Functional Theory (DFT) has been utilized to calculate both the equilibrium phase stability and the overpotentials (reactivity performance indicator of the catalys

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24

Luz, Eduardo Q., Francielli S. Santana, Gabriel L. Silverio, et al. "Crystal structures of 3-halo-2-organochalcogenylbenzo[b]chalcogenophenes." Acta Crystallographica Section E Crystallographic Communications 78, no. 3 (2022): 275–81. http://dx.doi.org/10.1107/s2056989022000962.

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The structure of the title compounds 3-bromo-2-(phenylsulfanyl)benzo[b]thiophene (C14H9BrS2; 1), 3-iodo-2-(phenylsulfanyl)benzo[b]thiophene (C14H9IS2; 2), 3-bromo-2-(phenylselanyl)benzo[b]selenophene (C14H9BrSe2; 3), and 3-iodo-2-(phenylselanyl)benzo[b]selenophene (C14H9ISe2; 4) were determined by single-crystal X-ray diffraction; all structures presented monoclinic (P21/c) symmetry. The phenyl group is distant from the halogen atom to minimize the steric hindrance repulsion for all structures. Moreover, the structures of 3 and 4 show an almost linear alignment of halogen–selenium–carbon atoms

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25

Eufrasio, Andreza M., Ian Pegg, Amrit Kafle, Winnie Wong-Ng, Qingzhen Huang, and Biprodas Dutta. "Metal–Insulator Transition in Doped Barium Plumbates." Electronic Materials 2, no. 3 (2021): 428–44. http://dx.doi.org/10.3390/electronicmat2030029.

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Solid solutions in the Ba(Pb1−xSrx)O3−z system were prepared by aliovalent substitution of Pb4+ by Sr2+ ions to investigate the effect of cation stoichiometry on thermal and electrical properties as x was varied between 0 and 0.4, in the temperature range 300–523 K. The starting compound, barium plumbate (BaPbO3), has a perovskite structure and is known to exhibit metallic conductivity due to an overlap of the O2p nonbonding and the Pb–O spσ antibonding band, which is partially filled by the available electrons. The large difference in the ionic radii between the Pb4+ and Sr2+ ions introduces

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26

Trievel, Raymond C., and Steve Scheiner. "Crystallographic and Computational Characterization of Methyl Tetrel Bonding in S-Adenosylmethionine-Dependent Methyltransferases." Molecules 23, no. 11 (2018): 2965. http://dx.doi.org/10.3390/molecules23112965.

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Tetrel bonds represent a category of non-bonding interaction wherein an electronegative atom donates a lone pair of electrons into the sigma antibonding orbital of an atom in the carbon group of the periodic table. Prior computational studies have implicated tetrel bonding in the stabilization of a preliminary state that precedes the transition state in SN2 reactions, including methyl transfer. Notably, the angles between the tetrel bond donor and acceptor atoms coincide with the prerequisite geometry for the SN2 reaction. Prompted by these findings, we surveyed crystal structures of methyltra

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27

Shi, Xue, Sumin Li, Bao Zhang, et al. "The Regulation of O2 Spin State and Direct Oxidation of CO at Room Temperature Using Triboelectric Plasma by Harvesting Mechanical Energy." Nanomaterials 11, no. 12 (2021): 3408. http://dx.doi.org/10.3390/nano11123408.

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Oxidation reactions play a critical role in processes involving energy utilization, chemical conversion, and pollutant elimination. However, due to its spin-forbidden nature, the reaction of molecular dioxygen (O2) with a substrate is difficult under mild conditions. Herein, we describe a system that activates O2 via the direct modulation of its spin state by mechanical energy-induced triboelectric corona plasma, enabling the CO oxidation reaction under normal temperature and pressure. Under optimized reaction conditions, the activity was 7.2 μmol h−1, and the energy consumption per mole CO wa

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28

Sellmann, Dieter, Nicole Blum та Frank W. Heinemann. "Transition Metal Complexes with Sulphur Ligands, Part 151 [1]. Ligand Enforced Configurations and Low-Spin States of [FeNS4] Cores in [FeII(L)('pyS4')] Complexes with σ and σ-π Ligands (L = N2H4, pyridine, PMe3, PnPr3; 'pyS4'2- = 2,6-bis(2-mercaptophenylthiomethyl)pyridine (2-))". Zeitschrift für Naturforschung B 56, № 7 (2001): 581–88. http://dx.doi.org/10.1515/znb-2001-0704.

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The reactions of [Fe('pyS4')]2 with PMe3 , PnPr3 , N2H4 and pyridine afforded mononuclear [Fe(L)('pyS4')] complexes with L = PMe3 ( 1 ), PnPr3 (2 ), N2H4 (3) and pyridine (4). NMR spectroscopy, magnetic measurements and X-ray structure determinations revealed that all complexes exhibit frans-thiolate donors and low-spin FeII centres, irrespective of the σ-π or σ ligand character of L. In this regard, the properties of [Fe(L)('pyS4')] complexes strongly contrast with those of [Fe(L)('NHS4')] complexes ('NHS4'2- = 2 ,2 '-bis(2 -mercaptophenylthio)- diethylamine(2 -)) and indicate that the rigid

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Ghoshal, S. K., K. P. Jain, and R. Elliott. "Optical and Electron Correlation Effects in Silicon Quantum Dots." Journal of Metastable and Nanocrystalline Materials 23 (January 2005): 129–32. http://dx.doi.org/10.4028/www.scientific.net/jmnm.23.129.

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We study (through computer simulation) the variation of the band gap as a function of sizes and shapes of small Silicon (Si) dots using pseudo-potential approach. We have used empirical pseudo-potential Hamiltonian and a plane wave basis expansion and a basic tetrahedral structure. It is found that the gap decreases for increasing dot size. Furthermore, the band gap increases as much as 0.13eV on passivation the surface of the dot with hydrogen. So both quantum confinement and surface passivation determine the optical and electronic properties of Si quantum dots. Visible luminescence is probab

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Tokarz-Sobieraj, Renata, and Piotr Niemiec. "Oxygen Adsorption and Activation on Cobalt Center in Modified Keggin Anion-DFT Calculations." Catalysts 10, no. 2 (2020): 144. http://dx.doi.org/10.3390/catal10020144.

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The influence of the cobalt cation geometric environment on catalytic activity, namely, oxygen adsorption and its activation, was investigated by exploring two groups of systems. The first group was formed by cobalt cation complexes, in which the Co2+ was surrounded by water-H2O or acetonitrile-CH3CN solvent molecules. This represents heteropolyacids salts (ConH3-nPW(Mo)12O40), where the Co2+ acts as a cation that compensates for the negative charge of the Keggin anion and is typically surrounded by solvent molecules in that system. The second group consisted of tungsten or molybdenum Keggin a

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31

Riggs, NV, and L. Radom. "A Simple Model for the Mean and Difference of NH-Stretching Frequencies for NH2 Groups, and Its Application to Results of Some ab initio Vibrational-Frequency Calculations." Australian Journal of Chemistry 41, no. 3 (1988): 387. http://dx.doi.org/10.1071/ch9880387.

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The expression for the sum of the eigenvalues of the 2×2 GF matrix for two interacting NH bonds suggests that the mean NH-stretching frequency for an NH2 group should be closely proportional to ( Σf )½, where Σf is the sum of the two corresponding force constants. Ab initio results for the NH2 groups in various conformations of ethanamine , hydrazine and 1,1-dimethylhydrazine confirm such constancy to within 0.1%. The corresponding expression for the difference of the eigenvalues suggests, counterintuitively, that the difference of NH-stretching frequencies for an NH2 group in a given molecula

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Yang, Huiying, and Xiangchao Meng. "Bimetallic Fe, Co-Modified TiO2 Derived from NH2-MIL-125(Ti) as an Efficient Photocatalyst for N2 Fixation." Processes 12, no. 9 (2024): 1879. http://dx.doi.org/10.3390/pr12091879.

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The conversion of nitrogen (N2) and water (H2O) into NH3 by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N2 fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO2 derived from NH2-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N2 fixation. It was found that the photocatalytic N2 reduction efficiency of bimetallic FC@TiO2-JH was improved, enabling an NH3 yield rate of 110.14 µmol g−1 h−1 without any sacrificial agents. Furthermore, the rat

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Garcias-Morales, Cesar, David Ortegón-Reyna, and Armando Ariza-Castolo. "Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction." Beilstein Journal of Organic Chemistry 11 (October 22, 2015): 1973–84. http://dx.doi.org/10.3762/bjoc.11.213.

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This paper reports the synthesis of a series of piperidones 1–8 by the Mannich reaction and analysis of their structures and conformations in solution by NMR and mass spectrometry. The six-membered rings in 2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones, compounds 1 and 2, adopt a chair–boat conformation, while those in 2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ones, compounds 3–8, adopt a chair–chair conformation because of stereoelectronic effects. These stereoelectronic effects were analyzed by the 1 J C–H coupling constants, which were measured in the 13C satellites of the 1H NMR sp

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Kuterasiński, Łukasz, Jerzy Podobiński, and Jerzy Datka. "Oxidation of Ethanol in Cu-Faujasites Studied by IR Spectroscopy." Molecules 26, no. 9 (2021): 2669. http://dx.doi.org/10.3390/molecules26092669.

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In this study, IR studies of the coadsorption of ethanol and CO on Cu+ cations evidenced the transfer of electrons from ethanol to Cu+, which caused the lowering of the frequency of the band attributed to CO bonded to the same Cu+ cation due to the more effective π back donation of d electrons of Cu to antibonding π* orbitals of CO. The reaction of ethanol with acid sites in zeolite HFAU above 370 K produced water and ethane, polymerizing to polyethylene. Ethanol adsorbed on zeolite Cu(2)HFAU containing acid sites and Cu+exch also produced ethene, but in this case, the ethene was bonded to Cu+

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Kazachenko, Aleksandr S., Emine Tanış, Feride Akman, et al. "A Comprehensive Study of N-Butyl-1H-Benzimidazole." Molecules 27, no. 22 (2022): 7864. http://dx.doi.org/10.3390/molecules27227864.

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Imidazole derivatives have found wide application in organic and medicinal chemistry. In particular, benzimidazoles have proven biological activity as antiviral, antimicrobial, and antitumor agents. In this work, we experimentally and theoretically investigated N-Butyl-1H-benzimidazole. It has been shown that the presence of a butyl substituent in the N position does not significantly affect the conjugation and structural organization of benzimidazole. The optimized molecular parameters were performed by the DFT/B3LYP method with 6-311++G(d,p) basis set. This level of theory shows excellent co

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36

Vassilev, Nikolay G., and Ivo C. Ivanov. "A Small Change in Structure, a Big Change in Flexibility." Molecules 28, no. 24 (2023): 8004. http://dx.doi.org/10.3390/molecules28248004.

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Studies of the rotational barrier energy of the amide bond using quantum computing and nuclear magnetic resonance (NMR) are focused mainly on its use as a model of the peptide bond. The results of these studies are valuable not only in terms of the fundamental conformational properties of amide bonds, but also in the design of molecular machines, which have recently attracted interest. We investigate the fluxionality of the amide and enamide bonds of compound 3-[(E)-(dimethylamino)methylidene]-1,1-dimethylurea using advanced dynamic NMR experiments and a theoretical evaluation of the density f

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SUN, CHANG Q. "O–Cu(001): I. BINDING THE SIGNATURES OF LEED, STM AND PES IN A BOND-FORMING WAY." Surface Review and Letters 08, no. 03n04 (2001): 367–402. http://dx.doi.org/10.1142/s0218625x01001257.

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This work consists of two sequential parts, which review the advances in uncovering the capacity of VLEED, STM and PES in revealing the nature and kinetics of oxidation bonding and its consequences for the behavior of atoms and valence electrons at a surface; and in quantifying the O–Cu(001) bonding kinetics. The first part describes the model in terms of bond making and its effect on the valence DOS and on the surface potential barrier (SPB) for surfaces with chemisorbed oxygen. One can replace the hydrogen in a H 2 O molecule with an arbitrary less electronegative element and extend the M 2

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Singh, Ratna, Jens Smiatek, and Bruno M. Moerschbacher. "Unraveling the Impact of Acetylation Patterns in Chitosan Oligomers on Cu2+ Ion Binding: Insights from DFT Calculations." International Journal of Molecular Sciences 24, no. 18 (2023): 13792. http://dx.doi.org/10.3390/ijms241813792.

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Chitosans are partially acetylated polymers of glucosamine, structurally characterized by their degree of polymerization as well as their fraction and pattern of acetylation. These parameters strongly influence the physico-chemical properties and biological activities of chitosans, but structure-function relationships are only poorly understood. As an example, we here investigated the influence of acetylation on chitosan-copper complexation using density functional theory. We investigated the electronic structures of completely deacetylated and partially acetylated chitosan oligomers and their

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Perrott, A. L., H. J. P. De Lijser та D. R. Arnold. "The importance of conformational effects on the carbon–carbon bond cleavage of β-phenethyl ether radical cations". Canadian Journal of Chemistry 75, № 4 (1997): 384–97. http://dx.doi.org/10.1139/v97-044.

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The photosensitized (electron transfer) bond cleavage of some β-phenylethyl ether radical cations has been investigated. In previous studies the feasibility of the bond cleavage was thought to depend on the bond dissociation energy (BDE). However, this simple hypothesis led to several incorrect predictions and therefore additional criteria, conformational effects, were added to the hypothesis. This study has now been extended and additional examples of the importance of the conformation on the carbon–carbon bond cleavage of radical cations are provided. The four β-phenylethyl ethers studied ar

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Tudor, Spataru. "The Electronic Structure and Mechanism of the Adenosylcobalamin-Dependent Bio-Processes as Determined by the MCSCF Method." Medicinal Chemistry 11, no. 8 (2021): 11. https://doi.org/10.5281/zenodo.10669291.

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The CASSCF geometry optimization of the adenosylcobalamin cofactor dependent processes common models with 12 orbitals and 12 electrons in the active space has been performed. The MCSCF geometry optimization shows a strong HOMO-LUMO coupling during the CASSCF orbitals mixing process. The HOMO-LUMO coupling causes an electronic density transfer from the HOMO, which at the beginning of the optimization process is constituted from the substrate atoms orbitals, to the LUMO, which is constituted from the adenosylco(III)balamin structure atomic orbitals. The Co-C bond cleavage reaction is starting fr

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Ou, Lihui, and Junxiang Chen. "Theoretical insights into the effect of the overpotential on CO electroreduction mechanisms on Cu(111): regulation and application of electrode potentials from a CO coverage-dependent electrochemical model." Physical Chemistry Chemical Physics 22, no. 1 (2020): 62–73. http://dx.doi.org/10.1039/c9cp05043d.

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Zhang, Qi, Haixia Zhong, Can Chen, Juexian Cao, Liwen Yang, and Xiaolin Wei. "Bonding–antibonding state transition induces multiple electron modulations toward oxygen reduction reaction electrocatalysis." New Journal of Chemistry 44, no. 20 (2020): 8191–97. http://dx.doi.org/10.1039/d0nj00660b.

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Nazar, Laith, and T. A. Salman. "Tunneling magnetoresistance calculation for double quantum dot connected in parallel shape to ferromagnetic Leads." Journal of Kufa-Physics 15, no. 01 (2023): 69–76. http://dx.doi.org/10.31257/2018/jkp/2023/v15.i01.11428.

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In this paper, a theoretical model for electron transport through symmetric system consisting of two baths interferometer with one single-level quantum dot in each of its arms was considered. In this model, the dots are attached to ferromagnetic leads with parallel and antiparallel magnetic configurations. Green's function technique in this model was used. Our focus is on the Transport characteristics of conductance (G) and tunnel magnetoresistance (TMR). A special attention to the influence of an applied magnetics flux on the characteristics of conductance and tunneling magnetoresistance was

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Kalaiarasi, N., and S. Manivarman. "Structural, vibrational (FTIR and FT-Raman), NMR, UV–vis spectral analysis, and DFT study of 2-(6-oxo-2-thioxotetrahydropyrimidin-4(1H)-ylidene) hydrazine carboxamide." Canadian Journal of Chemistry 95, no. 5 (2017): 580–89. http://dx.doi.org/10.1139/cjc-2016-0655.

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Vibrational and spectral characterizations of 2-(6-oxo-2-thioxo tetrahydro pyrimidin-4(1h)-ylidene) hydrazine carboxamide (OTHHPYHC) were experimentally presented for the ground state using FTIR and FT-Raman and theoretically presented by density functional theory (DFT) using B3LYP correlation function with the basis set 6-31G(d,p). The geometrical parameters, energies, and wavenumbers have been obtained. The fundamental assignments were performed on the basis of total energy distribution. The first order hyperpolarizability (β0) and relative properties (β, α0, and Δα) were calculated using B3

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Jensen, William B., Roger W. Kugel, and Allan R. Pinhas. "The Mechanism of Friedel-Crafts Chlorination Historically Reconsidered." International Journal of Chemistry 15, no. 2 (2023): 50. http://dx.doi.org/10.5539/ijc.v15n2p50.

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This short review proposes a revision to the currently accepted textbook mechanism for the direct Friedel-Crafts chlorination of benzene. After briefly reviewing the history of Friedel-Crafts chemistry and the origins of the current textbook mechanism for the direct chlorination of benzene, it is pointed out how this mechanism is at variance with the predictions of both generalized Lewis acid-base chemistry and simple frontier orbital theory, which require that dichlorine should function as a sigma antibonding electron-pair acceptor (&sigma;*-EPA) or electrophile (Lewis acid) rather than a

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Alarco, Jose A., and Ian D. R. Mackinnon. "Superlattices, Bonding-Antibonding, Fermi Surface Nesting, and Superconductivity." Condensed Matter 8, no. 3 (2023): 72. http://dx.doi.org/10.3390/condmat8030072.

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Raman and synchrotron THz absorption spectral measurements on MgB2 provide experimental evidence for electron orbital superlattices. In earlier work, we have detected THz spectra that show superlattice absorption peaks with low wavenumbers, for which spectral density evolves and intensifies after cooling below the superconducting transition temperature for MgB2. In this work, we show how these observations indicate a direct connection to superconducting properties and mechanisms. Bonding–antibonding orbital character is identified in calculated electronic band structures and Fermi surfaces con

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Radoń, Mariusz, Paweł Kozyra, Adam Stępniewski, Jerzy Datka, and Ewa Broclawik. "Electronic propensity of Cu(II) versus Cu(I) sites in zeolites to activate NO — Spin- and orbital-resolved Cu–NO electron transfer." Canadian Journal of Chemistry 91, no. 7 (2013): 538–43. http://dx.doi.org/10.1139/cjc-2012-0536.

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Electronic factors responsible for the notable decline of NO activation by Cu(II) with respect to Cu(I) sites in zeolites are investigated within spin-resolved analysis of electron transfer channels between the copper center and the substrate. The results of natural orbitals for chemical valence (NOCV) charge transfer analysis for a minimal model of Cu(II) sites in zeolite ZSM-5 ({T1Cu}+ NO) are compared with those for Cu(I)–NO and referenced to an interaction of NO with bare Cu+ cations. The bonding of NO, which is an open-shell and non-innocent ligand, gives rise to a noticeable nondynamical

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48

Ilisca, Ernest, and Filippo Ghiglieno. "Nuclear conversion theory: molecular hydrogen in non-magnetic insulators." Royal Society Open Science 3, no. 9 (2016): 160042. http://dx.doi.org/10.1098/rsos.160042.

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The hydrogen conversion patterns on non-magnetic solids sensitively depend upon the degree of singlet/triplet mixing in the intermediates of the catalytic reaction. Three main ‘symmetry-breaking’ interactions are brought together. In a typical channel, the electron spin–orbit (SO) couplings introduce some magnetic excitations in the non-magnetic solid ground state. The electron spin is exchanged with a molecular one by the electric molecule–solid electron repulsion, mixing the bonding and antibonding states and affecting the molecule rotation. Finally, the magnetic hyperfine contact transfers

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Kruszynski, Rafal, and Tomasz Sieranski. "The intermolecular interactions in the aminonitromethylbenzenes." Open Chemistry 9, no. 1 (2011): 94–105. http://dx.doi.org/10.2478/s11532-010-0118-8.

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AbstractThe intermolecular non-covalent interactions in aminonitromethylbenzenes namely 2-methyl-4-nitroaniline, 4-methyl-3-nitroaniline, 2-methyl-6-nitroaniline, 4-amino-2,6-dinitrotoluene, 2-methyl-5-nitroaniline, 4-methyl-2-nitroaniline, 2,3-dimethyl-6-nitroaniline, 4,5-dimethyl-2-nitroaniline and 2-methyl-3,5-dinitroaniline were studied by quantum mechanical calculations at RHF/311++G(3df,2p) and B3LYP/311++G(3df,2p) level of theory. The calculations prove that solely geometrical study of hydrogen bonding can be very misleading because not all short distances (classified as hydrogen bonds

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Cruz-Cabeza, Aurora J., та Frank H. Allen. "Geometry and conformation of cyclopropane derivatives having σ-acceptor and σ-donor substituents: a theoretical and crystal structure database study". Acta Crystallographica Section B Structural Science 68, № 2 (2012): 182–88. http://dx.doi.org/10.1107/s0108768111054991.

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The structures of cyclopropane rings which carry σ-acceptor or σ-donor substituents have been studied using density-functional theory (DFT), and mean bond lengths and conformational parameters retrieved from the Cambridge Structural Database. It is confirmed that σ-acceptor substituents, e.g. halogens, generate positive ring bond-length asymmetry in which there is lengthening of the distal bond (opposite to the point of substitution), and shortening of the two vicinal bonds. This is due to withdrawal of electron density from the cyclopropane 1e′′ orbitals, which are bonding for the distal bond

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