Yuxiang Bu

Shandong University, Chi-nan-shih, Shandong Sheng, China

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Publications (195)542.6 Total impact

  • Wenming Sun · Liang Zhang · Jing Liu · Hong Wang · Yuxiang Bu
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    ABSTRACT: The mechanical, thermodynamic and electronic properties of FeSn5 and CoSn5 intermetallic phases at zero pressure have been systemically investigated by first-principles calculations using ultrasoft pseudopotential and generalized gradient approximation (GGA). The equilibrium lattice constants of FeSn5 and CoSn5 at zero pressure are in good agreement with the available experimental values. Thermodynamic and mechanical properties of FeSn5 and CoSn5 are predicted by calculating formation enthalpy, phonon density of states and elastic constants, respectively. Formation enthalpies calculation indicates that FeSn5 and CoSn5 are energetically unfavorable compare to FeSn2 and CoSn2. This may be the partial reason why FeSn5 and CoSn5 were hidden in the Fe/Co-Sn phase diagrams previously. FeSn5 and CoSn5 exhibit opposite relative incompressible behavior along a-axis and c-axis. Our results reveal that both FeSn5 and CoSn5 are mechanically and dynamically stable at 0 GPa. The quasi-harmonic model is employed to calculate the temperature dependence of specific heat at constant volume. In addition, the electron density of states and electron density difference are calculated to disclose the underlying electronic structure.
    No preview · Article · Jan 2016 · Computational Materials Science
  • Fengying Zhang · Xinyu Song · Yuxiang Bu
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    ABSTRACT: Organic molecules with switchable magnetic properties have extensively technological applications due to the fact that magnetic conversion can be realized through diverse methods. In particular, the redox-induced magnetic reversal is easy to accomplish and exhibits promising application in the field of magnetic materials, and thus it is an imperative task to find magnetism-switchable systems. Herein, we computationally design two couples of nitroxy-pyrazinyl-nitroxy diradicals in which two nitroxy radical groups are connected to a redox-active pyrazinyl coupler in the para or meta modes. We find that the magnetic conversion can occur from ferromagnetic to antiferromagnetic exchange coupling or vice versa by means of the redox method in these designed magnetic organic molecules, and their magnetic exchange coupling constants are considerably large no matter for ferromagnetic or antiferromagnetic couplings, as evidenced at both the B3LYP and M06-2X levels of theory. Analyses indicate that redox-induced structural change of the coupler leads to conversion of its aromaticity and considerable spin delocalization from the π-conjugated structure and spin polarization from non-Kekule structure, which thus determine the spin coupling between two spin centers in the magnetic molecules. In addition, the spin alternation rule, singly occupied molecular orbital (SOMO) effect, and SOMO-SOMO energy splitting of triplet state are utilized to analyze the diradical characters of the molecules, suggesting effective tools for predicting molecular ground states (ferromagnetic, antiferromagnetic, or nonmagnetic). This work provides helpful information for the rational design of promising organic magnetic switches.
    No preview · Article · Nov 2015 · The Journal of Physical Chemistry C
  • Peiwen Zhao · Yuxiang Bu
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    ABSTRACT: In this work, we computationally design radical nucleobases which possess improved electronic properties, especially diradical properties through introducing a cyclopentadiene radical. We predict that the detailed electromagnetic features of base assemblies are based on the orientation of the extra five-membered cyclopentadiene ring. Broken symmetry DFT calculations take into account the relevant structures and properties. Our results reveal that both the radicalized DNA bases and the base pairs formed when they combine with their counterparts remain stable and display larger spin delocalization. The mode of embedding the cyclopentadiene free radical in the structures has some influence on the degree of π-conjugation, which results in various diradical characteristics. Single-layered radical base pairs all have an open-shell singlet ground state, but the energy difference between singlet and triplet is not significant. For two-layered radical base pairs, the situation is more complex. All of them have an open-shell state as their ground state, including an open-shell singlet state and an open-shell triplet state. That is, the majority of radical base pairs possess anti-ferromagnetic or ferromagnetic characteristics. We present here a more in-depth discussion and analyses to study the magnetic characteristics of radical bases and base pairs. As an important factor, two-layered radical base pairs also have been carefully analyzed. We hope that all the measurements and results presented here will stimulate further detailed insights into the related mechanisms in modified DNA bases and the design of better ring-expanded DNA magnetic materials.
    No preview · Article · Oct 2015 · Organic & Biomolecular Chemistry
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    ABSTRACT: Possible electron-induced ruptures of C3'-O3', C5'-O5', and N1-C1' bonds in O4-hydrogenated 2'-deoxythymidine-3'-monophsphate (3'-dT(O4H)MPH) and 2'-deoxythymidine-5'-monophsphate (5'-dT(O4H)MPH) are investigated using density functional theory calculations and efficient pathways are proposed. Electron attachment causes remarkable structural relaxation in the thymine C6 site. A concerted process of intramolecular proton transfer (IPT) from the C2' site of 2'-deoxyribose to the C6 site and the C3'-O3' bond rupture is observed in [3'-dT(O4H)MPH]. A low activation barrier (9.32 kcal/mol) indicates that this pathway is the most efficient one as compared to other known pathways leading to backbone breaks of a single strand DNA at the non-3'-end thymine, which prevents the N1-C1' bond cleavage in [3'-dT(O4H)MPH]. However, essentially spontaneous N1-C1' bond cleavage following similar IPT is predicted in [5'-dT(O4H)MPH]. A moderate activation barrier (13.02 kcal/mol) for the rate-controlling IPT step suggests that base release from the N1-C1' cleavage arises readily at the 3'-end of a single strand DNA with the strand ended by a thymine. The C5'-O5' bond has only insignificant change in the IPT process. Solvent effects are found to increase slightly the energy requirements for either bond ruptures (11.23 kcal/mol (C3'-O3') vs. 16.18 kcal/mol (N1-C1') ), but not change their relative efficiencies.
    No preview · Article · Oct 2015 · The Journal of Physical Chemistry B
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    ABSTRACT: Studies on the structure, states, and reactivity of excess electrons (EEs) in biological media are of great significance. Although there is information about EE interaction with desolvated biological molecules, solution effects are hardly explored. In this work, we present an ab initio molecular dynamics simulation study on the interaction and reactivity of an EE with glycine in solution. Our simulations reveal two striking results. Firstly, a pre-solvated EE partially localizes on the negatively charged -COO(-) group of the zwitterionic glycine and the remaining part delocalizes over solvent water molecules, forming an anion-centered quasi-localized structure, due to relative alignment of the lowest unoccupied molecular orbital energy levels of potential sites for EE residence in the aqueous solution. Secondly, after a period of anion-centered localization of an EE, the zwitterionic glycine is induced to spontaneously fragment through the cleavage of the N-Cα bond, losing ammonia (deamination), and leaving a ˙CH2-COO(-) anion radical, in good agreement with experimental observations. Introduction of the same groups (-COO(-) or -NH3(+)) in the side chain (taking lysine and aspartic acid as examples) can affect EE localization, with the fragmentation of the backbone part of these amino acids dependent on the properties of the side chain groups. These findings provide insights into EE interaction mechanisms with the backbone parts of amino acids and low energy EE induced fragmentation of amino acids and even peptides and proteins.
    No preview · Article · Sep 2015 · Physical Chemistry Chemical Physics
  • Wenming Sun · Liang Zhang · Jing Liu · Hong Wang · Yan Zuo · Yuxiang Bu
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    ABSTRACT: The structural, electronic and optical properties of hexagonal ferrites MFe12O19 (M = Sr, Ba, Pb, Sr0.5Ba0.5, Sr0.5Pb0.5 and Ba0.5Pb0.5) are calculated by plane-wave pseudopotential density functional theory with general gradient approximation (GGA) and GGA+U. The calculated lattice constants and band gaps are in good agreement with the available experimental and theoretical values. Lattice constants change corresponding to the cation radii at M-sites. The electronic structure shows that all the six hexaferrites are narrow gap semiconductors and Sr2+ and Ba2+ at M-sites have little contribution to the DOS at the vicinity of Fermi level due to the ionic bond interaction nature between M2+ and O2−. It should be noted that for Pb2+, comparing with the narrow localized s-states of Sr2+ and Ba2+, there is a significant broadening of its s-states from −7 eV to the Fermi level, indicating its minority donation to the valence band near Ef. The six MFOs (FO refers Fe12O19) could be classified into two categories: Pb-containing hexaferrites (PFO, SPFO and BPFO) and others (SFO, BFO and SBFO). The former has larger static dielectric constants. This study will serve as the base for the investigation of the correlation among factors such as site preferences, properties and substitution strategies for MFOs.
    No preview · Article · Jul 2015 · Computational Materials Science
  • Changzhe Zhang · Yuxiang Bu
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    ABSTRACT: Radiation-generated secondary electrons can induce resonance processes of a target molecule and fragment it via different pathways. Although the associating electronic resonant states at equilibrium geometry have been well studied for many target molecules in the gas phase, the vibrational resonance contributions and solvent effect are still poorly understood for the relevant processes in solution. Taking a radiosensitive drug, 5-bromopyrimidine (5-BrPy), as an example, we here presents a combined ab initio molecular dynamics simulation and time-dependent wave packet study with an emphasis on the vibrational resonance and solvation effects on the excess electron interaction with 5-BrPy in solution. The gaseous results reveal two primary channels for the electron induced C-Br bond cleavage: the highest vibrational resonance on vertical potential energy curve via a tunneling mechanism (e+5-BrPy→5-BrPy*–→Br–+Py•), and the auto-dissociation along repulsive relaxed potential energy curve (e+5-BrPy→5-BrPy*–→Br–+Py•), which account for the two peaks at 0.2 and 0 eV observed in Modelli’s experiment well. However, strong solvation effect modifies the mechanism and dynamics of the dissociation of the electron…5-BrPy system. On one hand, the spontaneous dissociation becomes unfavorable due to a barrier on relaxed free energy surface created by the coupling between the sigma* and pai* states. Seven vibrational resonances (v=0~6) are identified for the solution process and only the high-level v=5, 6 with non-negligible quantum tunneling coefficient can serve the dissociation (e+5-BrPy→5-BrPy*–→[Brδ–...Pyδ–]→Br–+Py•). On the other hand, protonation is also observed at the N sites of hydrated 5-BrPy anion (e+5-BrPy→5-BrPy*–→Prt-5-BrPy), and it inhibits the dissociation along the C-Br bond, suggesting a competing pathway against the C-Br bond cleavage. Clearly, this work provides a combination strategy using ab initio molecular dynamics technique and time-dependent wave packet method for exploring the effects of vibrational resonances and solvation on the interaction of radio-generated excess electrons with target biological molecules in complicated solution surroundings.
    No preview · Article · Jun 2015 · Physical Chemistry Chemical Physics
  • Jing Zhao · Mei Wang · Aiyun Fu · Hongfang Yang · Yuxiang Bu
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    ABSTRACT: We present an ab initio molecular dynamics (AIMD) simulation study into the transfer dynamics of an excess electron from its cavity-shaped hydrated electron state to a hydrated nucleobase (NB)-bound state. In contrast to the traditional view that electron localization at NBs (G/A/C/T), which is the first step for electron-induced DNA damage, is related only to dry or prehydrated electrons, and a fully hydrated electron no longer transfers to NBs, our AIMD simulations indicate that a fully hydrated electron can still transfer to NBs. We monitored the transfer dynamics of fully hydrated electrons towards hydrated NBs in aqueous solutions by using AIMD simulations and found that due to solution-structure fluctuation and attraction of NBs, a fully hydrated electron can transfer to a NB gradually over time. Concurrently, the hydrated electron cavity gradually reorganizes, distorts, and even breaks. The transfer could be completed in about 120-200 fs in four aqueous NB solutions, depending on the electron-binding ability of hydrated NBs and the structural fluctuation of the solution. The transferring electron resides in the π*-type lowest unoccupied molecular orbital of the NB, which leads to a hydrated NB anion. Clearly, the observed transfer of hydrated electrons can be attributed to the strong electron-binding ability of hydrated NBs over the hydrated electron cavity, which is the driving force, and the transfer dynamics is structure-fluctuation controlled. This work provides new insights into the evolution dynamics of hydrated electrons and provides some helpful information for understanding the DNA-damage mechanism in solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    No preview · Article · May 2015 · ChemPhysChem
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    Hongfang Yang · Mengzhen Chen · Xinyu Song · Yuxiang Bu
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    ABSTRACT: We unravel intriguing dynamical diradical behavior governed by structural fluctuation in pentacene using ab initio molecular dynamics simulation. In contrast to static equilibrium configuration of pentacene with a closed-shell ground state without diradical character, due to structural fluctuation, some of its dynamical snapshot configurations exhibit an open-shell broken-symmetry singlet ground state with diradical character, and such diradical character presents irregular pulsing behavior in time evolution. Not all structural changes can lead to diradical character, only those involving the shortening of cross-linking C-C bonds and variations of the C-C bonds in polyacetylene chains are the main contributors. This scenario about diradicalization is distinctly different from that in long acenes. The essence is that structural distortion cooperatively raises the HOMO and lowers the LUMO, efficiently reducing the HOMO-LUMO and singlet-triplet energy gaps, which facilitate the formation of a broken-symmetry open-shell singlet state. The irregular pulsing behavior originates from the mixing of normal vibrations in pentacene. This fascinating behavior suggests the potential application of pentacene as a suitable building block in the design of new electronic devices due to its magnetism-controllability through energy induction. This work provides new insight into inherent electronic property fluctuation in acenes.
    Preview · Article · May 2015 · Physical Chemistry Chemical Physics
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    Xiaoli Sun · Ruiping Huo · Yuxiang Bu · Jilai Li
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    ABSTRACT: In this paper, a density functional theory method benchmark study has been conducted on the adsorption energy of hydrogen. The effects of different density functionals, dispersion, and the size of basis sets have been explored on the prediction of adsorption energy. The results show that the adsorp-tion energies predicted by different density functionals varies considerably; the dispersion term cannot be ignored; the basis set and model have minor contributions for the final result; larger models are more independent on the basis set, and large basis set can make up the deficiency of smaller model. We expect that the method selection strategy proposed in this study could provide valuable clues for relevant studies.
    Full-text · Article · Apr 2015
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    Li Xu · Fengying Zhang · Xinyu Song · Zhilei Yin · Yuxiang Bu
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    ABSTRACT: Ternary spherical Ag–Cu2O/reduced graphene oxide (rGO) nanohybrids with excellent hierarchical structures are developed through a simple one-pot, two-stage reduction synthetic route at room temperature without any surfactant. In the resultant complex heterostructures, both Ag and rGO are in direct contact with Cu2O, and Ag nanocrystals are mainly deposited on the surface of Cu2O spheres. The resultant ternary spherical Ag–Cu2O/rGO composite exhibits excellent photocatalytic activity in photocatalytic degradation of methyl orange (MO) under visible light irradiation, which is much higher than that of either the single component (Cu2O) or two component systems (spherical Cu2O/rGO and Ag–Cu2O). In particular, the resultant ternary composites possess excellent stability and extend the light absorption range. The PL spectrum results have demonstrated that not only Ag but also rGO could capture the photogenerated electrons from Cu2O, thus leading to effective separation of electrons and holes. In particular, it is found that the direct junction and interaction between Ag and Cu2O in the ternary composites are more beneficial for charge transportation than the direct contact between Ag and rGO (labeled as sample Ag-rGO-Cu2O), and thereby the resultant Ag–Cu2O/rGO composites with such complex heterostructures exhibit a better photoactivity than the sample Ag-rGO-Cu2O. This work provides an insight into designing and synthesizing new Cu2O-based hybrid materials for effectively improving the photocatalytic performance.
    Preview · Article · Mar 2015
  • Mei Wang · Jing Zhao · Laibin Zhang · Xiyu Su · Hanlei Su · Yuxiang Bu
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    ABSTRACT: We present a theoretical investigation of the structural and electronic properties of double-electron oxidized adenine–thymine base pair as well as its deprotonated Watson–Crick derivatives. Double-electron oxidation can destabilize the AT unit, leading to a barrier-hindered metastable A+T+ state with a dissociation channel featuring negative dissociation energy. This unusual energetic phenomenon originates from the competition of electrostatic repulsion and attractively hydrogen-bonding interaction co-existing between A+ and T+. The associated double-proton-transfer process is also explored, suggesting a possible two-step mechanism. Magnetic coupling interactions of various diradical structures are controlled by both intra- and inter-molecular interactions.
    No preview · Article · Jan 2015 · Chemical Physics Letters
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    ABSTRACT: Density functional theory calculations suggest that β-turn peptide segments can act as a novel dual-relay elements to facilitate long-range charge hopping transport in proteins, with the N terminus relaying electron hopping transfer and the C terminus relaying hole hopping migration. The electron- or hole-binding ability of such a β-turn is subject to the conformations of oligopeptides and lengths of its linking strands. On the one hand, strand extension at the C-terminal end of a β-turn considerably enhances the electron-binding of the β-turn N terminus, due to its unique electropositivity in the macro-dipole, but does not enhance hole-forming of the β-turn C terminus because of competition from other sites within the β-strand. On the other hand, strand extension at the N terminal end of the β-turn greatly enhances hole-binding of the β-turn C terminus, due to its distinct electronegativity in the macro-dipole, but does not considerably enhance electron-binding ability of the N terminus because of the shared responsibility of other sites in the β-strand. Thus, in the β-hairpin structures, electron- or hole-binding abilities of both termini of the β-turn motif degenerate compared with those of the two hook structures, due to the decreased macro-dipole polarity caused by the extending the two terminal strands. In general, the high polarity of a macro-dipole always plays a principal role in determining charge-relay properties through modifying the components and energies of the highest occupied and lowest unoccupied molecular orbitals of the β-turn motif, whereas local dipoles with low polarity only play a cooperative assisting role. Further exploration is needed to identify other factors that influence relay properties in these protein motifs.
    No preview · Article · Nov 2014 · ChemPhysChem
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    ABSTRACT: Ab initio molecular dynamics simulations reveal that an excess electron (EE) can be more efficiently localized as a cavity-shaped state in aqueous glucose solution (AGS) than in water. Compared with that (similar to 1.5 ps) in water, the localization time is shortened by similar to 0.7-1.2 ps in three AGSs (0.56, 1.12, and 2.87 M). Although the radii of gyration of the solvated EEs are all close to 2.6 angstrom in the four solutions, the solvated EE cavities in the AGSs become more compact and can localize similar to 80% of an EE, which is considerably larger than that (similar to 40-60% and occasionally similar to 80%) in water. These observations are attributed to a modification of the hydrogen-bonded network by the introduction of glucose molecules into water. The water acts as a promoter and stabilizer, by forming voids around glucose molecules and, in this fashion, favoring the localization of an EE with high efficiency. This study provides important information about EEs in physiological AGSs and suggests a new strategy to efficiently localize an EE in a stable cavity for further exploration of biological function.
    No preview · Article · Oct 2014 · Journal of Chemical Theory and Computation
  • Xiaohua Chen · Yuxiang Bu
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    ABSTRACT: Amino fragments (-NH2) are well-known to exist widely in biological systems and their protonated forms are inclined to trap electrons and form Rydberg radicals (-NH3 center dot) in the electron-excess systems. Taking CH3-NH3+ as a mimicking group of the protonated alkylamine side-chain of lysine, ab initio calculations indicate that the proton/electron cooperatively transfer from CH3NH3 to CH3NH2 via a single-proton-coupled Rydberg-state electron transfer (ET) mechanism with an Rydberg-orbital channel for ET outside the -NHn hydrogens and a N-H+ -> N proton migrating pathway. Besides, in big amine clusters, CH3NH3 center dot(NH3)(n)center dot NH2CH3 (n = 1-3), the proton/electron transfer along an amine wire is stepwise and every step takes place via the similar single-proton-coupled Rydberg-state ET mechanism with low energy barrier (<4.0 kcal/mol). When a water chain, (H2O)(n) (n = 1-3), lies between CH3NH3 and NH2CH3 as a bridge, the energy barriers (8.5-15.0 kcal/mol) of proton/electron cooperatively transfer between CH3NH3 and NH2CH3 are raised significantly as compared to these of the pure amine wires (<4.0 kcal/mol). We attribute this fact to the combined effects of the proton binding energies and electron affinities of CH3NH2 and H2O. Interestingly, different from the amine-wire case, movement of the solvated electron along the water-wire can promote two or three protons synchronously moving at the same direction. This process can be described in terms of a multi-proton-coupled solvated-ET mechanism.
    No preview · Article · Aug 2014 · The Journal of Physical Chemistry C
  • Haiying Liu · Genqin Li · Peng Zhao · Gang Chen · Yuxiang Bu
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    ABSTRACT: Due to the fact that natural DNA may lack sufficient conductance for direct application in molecular electronics, a novel design of outer-expanded purine analogues was proposed by incorporating an aromatic ring at the N7-C8 site into natural G and A bases from the outside. The effect of the outer-expansion modification on electronic properties of DNA was investigated by density functional theory and molecular dynamics. The analyses revealed that these purine analogues not only preserve the same sizes of natural purine bases, thus avoiding distortions of DNA skeleton induced by the normal ring-inner-expansion modification, but also keep the selectivity of pairing with their natural counterpart C and T bases. More importantly, their electronic properties are enhanced, indicated by the narrowed HOMO–LUMO gaps, the lowered ionization potentials and the improved ultraviolet absorption spectra. This work may provide helpful information for designing of artificial bases as promising building blocks of biomolecular nanowires. © 2014 Wiley Periodicals, Inc.
    No preview · Article · Jul 2014 · International Journal of Quantum Chemistry
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    ABSTRACT: We present an ab initio molecular dynamics simulation study of a CH3CN-(H2O)40 cluster with an excess electron (EE) injected vertically in this work. Instead of surface bound or internally solvated electron, a hydrated CH3CN- is firstly formed as the CN transient after geometrical relaxation. The driving forces for the formation of CH3CN- are bending vibration of <CCN angle which initiates transfer of an extra charge to the CH3CN LUMO and hydration effect of the immediate water molecules which plays a stabilizing role. Solvent thermal fluctuation can lead to different resonances (the quasi-C2-resonance versus quasi-N-resonance) from the CN transient and further cause the hydrated CH3CN- system to evolve via two distinctly different pathways featuring spontaneous proton transfer to the central C and N sites, producing two different protonation products, respectively. The solvent thermal fluctuation induced formation of hydrogen bonding with the corresponding sites (C2 versus N) are responsible for the quasi-resonances and interconversion between three resonant structures and further proton transfers featuring spontaneous transfer of a proton to C2 or to N from its a interacting water molecule. The duration of CH3CN- for either of the two proton transfer processes is less than 200 fs. On the basis of experimental ESR results in which only the CH3CHN radical was found and present theoretical calculations, it is suggested that the trans-CH3CNH radical can be further converted to the CH3CHN radical via a water-mediated hydrogen atom transfer path.
    No preview · Article · May 2014 · The Journal of Physical Chemistry A
  • Hongfang Yang · Jing Zhao · Xinyu Song · Yuxiang Bu
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    ABSTRACT: Unrestricted density functional theory calculations in combination with the broken symmetry approach have been employed to study several benzylic carbanions. As a free anion, 2-(3,5-dinitrophenyl)-1,3-dithiane carbanion has near-degenerate singlet and triplet states and appears to be a promising magnetism-tunable species. In this work, we computationally design some of its derivatives in two ways: expanding the π-conjugated structures and introducing Lewis acids (Li+, Na+, and K+, and polar molecules are considered here) with different acidities. Calculations reveal that ring expansion does not change its open-shell broken symmetry singlet diradical ground state and antiferromagnetic character, but decreases its magnetism, whereas introduction of Lewis acids can lead to different ground states (triplet vs. singlet) and different magnetism, depending on the binding sites of the Lewis acid. That is, they show closed-shell singlet ground states without magnetism when a cation locates near the anionic center of the 1,3-dithiane ring, but convert to triplet as their ground states with ferromagnetic character when the cation moves to one nitro group of the 3,5-dinitrophenyl-based π-conjugation-expanded fragment. These findings regarding modulation through ring expansion and Lewis acid-binding ways make the magnetisms of 2-(3,5-dinitrophenyl)-1,3-dithiane-based carbanions tunable, and thus provide prospects of a new extension of the results from the previous study for designing magnetism-tunable building blocks for novel electromagnetic materials.
    No preview · Article · Apr 2014 · Theoretical Chemistry Accounts
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    ABSTRACT: The proton/electron transfer reactions between cysteine residue (Cys) and tyrosinyl radical (Tyr(•)) are an important step for many enzyme-catalyzed processes. Based on the statistical analysis of protein data bank, we designed three representative models to explore the possible proton/electron transfer mechanisms from Cys to Tyr(•) in proteins. Our ab initio calculations on simplified models and quantum mechanical/molecular mechanical (QM/MM) calculations on real protein environment reveal that the direct electron transfer between Cys and Tyr(•) is difficult to occur, but an inserted water molecule can greatly promote the proton/electron transfer reactions by a double-proton-coupled electron transfer (dPCET) mechanism. The inserted H2O plays two assistant roles in these reactions. The first one is to bridge the side chains of Tyr(•) and Cys via two hydrogen bonds which acts as the proton pathway, and the other one is to enhance the electron overlap between the lone-pair orbital of sulphur atom and the π-orbital of phenol moiety, and to function as electron transfer pathway. This water-mediated dPCET mechanism may offer great help for us to understand the detailed electron transfer processes between Tyr and Cys residues in proteins, such as the electron transfer from Cys439 to Tyr730(•) in the class I ribonucleotide reductase.
    Full-text · Article · Mar 2014 · Journal of the American Chemical Society
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    Xiaoli Sun · Caiyun Geng · Ruiping Huo · Ulf Ryde · Yuxiang Bu · Jilai Li
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    ABSTRACT: In this article we present density functional theory (DFT) calculations on the iron(IV)-oxo catalyzed methane C-H activation reactions for complexes in which the FeIV=O core is surrounded by five negatively charged ligands. We found that it follows a hybrid pathway that mixes features of the classical σ and π pathways in quintet surfaces. These calculations show that, the Fe-O-H arrangement in this hybrid pathway is bent, in sharp contrast to the collinear character as observed for the classical quintet σ pathways before. The calculations have also shown that it is the equatorial ligands that play key roles in tuning the reactivity of FeIV=O complexes. The strong π-donating equatorial ligands employed in the current study cause a weak π(FeO) bond and thereby shift the electronic accepting orbitals (EAO) from the vertically orientated O pz orbital to the horizontally orientated O px. In addition, all the equatorial ligands are small in size and would therefore be expected have small steric effects upon substrate horizontal approaching. Therefore, for the small and strong π-donating equatorial ligands, the collinear Fe-O-H arrangement is not the best choice for the quintet reactivity. This study adds new element to iron(IV)-oxo catalyzed C-H bond activation reactions.
    Full-text · Article · Jan 2014 · The Journal of Physical Chemistry B

Publication Stats

2k Citations
542.60 Total Impact Points


  • 1997-2016
    • Shandong University
      • • Department of Chemistry
      • • Department of Chemical Engineering
      • • Institute of Theoretical Chemistry
      • • Key Laboratory for Colloid and Interface Chemistry
      Chi-nan-shih, Shandong Sheng, China
  • 1994-2015
    • Qufu Normal University
      Küfow, Shandong Sheng, China
  • 2005-2009
    • Michigan State University
      • Department of Chemistry
      East Lansing, Michigan, United States
  • 2000
    • The University of Hong Kong
      Hong Kong, Hong Kong