Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

DOI： 10.1021/acs.iecr.2c02281

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1038/s41524-022-00860-1

researchmap

Authorship：Last author,　Corresponding author   Publisher：American Chemical Society (ACS)  

Efficient CO2 capture is indispensable for achieving a carbon-neutral society while maintaining a high quality of life. Since the discovery that ionic liquids (ILs) can absorb CO2, various solvents composed of molecular ions have been developed and their CO2 solubility has been studied. However, it is challenging to optimize these materials to realize targeted properties as the number of candidate ion combinations for designing novel ILs is of the order of 1018. In this study, electronic- structure informatics was applied as an interdisciplinary approach to quantum chemistry calculations, and combined with machine learning to search 402,114 IL candidates to identify those with better CO2 solubility than known materials. Guided by the machine-learning results, trihexyl(tetradecyl)phosphonium perfluorooctanesulfonate was synthesized and it was experimentally confirmed that this IL has higher CO2 solubility than trihexyl(tetradecyl)phosphonium bis(trifluoromethanesulfonyl)amide, which is the previous best IL for CO2 absorption. The method developed in this study could be transferable to gas-absorbing liquids in general, such as deep eutectic solvents (hydrogen-bonded mixed organic solvents in a broad sense), which also have numerous practical applications. Therefore, we believe that our method for developing functional liquids will significantly contribute to the development of a carbon-neutral society.

DOI： 10.26434/chemrxiv-2022-t1m69

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.jchemed.1c00666

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Invited for the cover of this issue is Toshikazu Ono, Yoshio Hisaeda and co-workers at Kyushu University and their collaborators at Ochanomizu University, Chuo University, and Institute for Molecular Science. The image depicts a molecular assembly structure shining like a jewel, glowing in the red-to-near infrared region. Read the full text of the article at 10.1002/chem.202100906.

DOI： 10.1002/chem.202101685

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Room-temperature phosphorescence (RTP) emitters have attracted significant attention. However, purely organic RTP emitters in red to near-infrared region have not been properly investigated. In this study, a series of naphthalenediimide- halobenzoate -linked molecules are synthesized, one of which exhibits efficient RTP properties, showing red to near-infrared emission in solid and aqueous dispersion. Spectroscopic studies and single-crystal X-ray diffraction analysis have shown that the difference in the stacking modes of compounds affects the optical properties, and the formation of intermolecular charge-transfer complexes of naphthalenediimide-halobenzoate moiety results in a bathochromic shift of absorption and RTP properties. The time-dependent density functional theory calculations showed that the formation of charge-transfer triplet states and the external heavy atom effect of the halogen atom enhance the intersystem crossing between excited singlet and triplet states.

DOI： 10.1002/chem.202100906

PubMed

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/chem.202100906

Publishing type：Part of collection (book)   Publisher：Springer Singapore  

DOI： 10.1007/978-981-15-9235-5_4

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Exploring new types of photochemical reactions is of great interest in the field of synthetic chemistry. Although excited-state hydrogen detachment (ESHD) represents a promising prospective template for additive-free photochemical reactions, applications of ESHD in a synthetic context remains scarce. Herein, we demonstrate the expansion of this photochemical reaction toward oligomerization, disulfidation, and regioselective C(sp2)-H carboxylation of aromatic alcohols, thiols, and amines. In the absence of any radical initiators in tetrahydrofuran upon irradiation with UV light (λ = 280 or 300 nm) under an atmosphere of N2 or CO2, thiols and catechol afforded disulfides and oligomers, respectively, as main products. Especially, the photochemical disulfidation proceeded highly selectively with the NMR and quantum yields of up to 69 and 0.46%, respectively. In stark contrast, the photolysis of phenylenediamines and aminophenols results in photocarboxylation in the presence of CO2 (1 atm). p-Aminophenol was quantitatively carboxylated by photolysis for 17 h with a quantum yield of 0.45%. Furthermore, the photocarboxylation of phenylenediamines and aminophenols proceeds in a highly selective fashion on the aromatic C(sp2)-H bond next to a functional group, which is directed by the site-selective ESHD of the functional groups for the formation of aminyl and hydroxyl radicals.

DOI： 10.1021/acs.joc.0c02456

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.iecr.0c00488

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Computer Chemistry, Japan  

DOI： 10.2477/jccj.2019-0046

researchmap

Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.joc.9b02758

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

DOI： 10.1039/c9dt03392k

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

Effective fragment potential version 2-molecular dynamics (EFP2-MD) simulations, where the EFP2 is a polarizable force field based on ab initio electronic structure calculations, were applied to predict the static and dynamic liquid properties of compressed liquid NH3. By analyzing the temperature dependence of the radial distribution function, the autocorrelation functions of velocity (Cv(t)) and reorientation (Cr(t)), and the self-diffusion constant, we clarified that the ab initio EFP2 force field can effectively describe the properties of compressed liquids. These descriptions can be performed with at least semiquantitative accuracy and at a sufficiently low computational cost. In the EFP2-MD protocol, no force field training is required. This training is mandatory when simulating liquid properties with classical MD techniques (especially in extreme conditions with high pressures and temperatures). EFP2-MD is a promising technique for predicting the physicochemical properties of novel functional compressed liquids, including supercritical fluid phase properties.

DOI： 10.1021/acs.jpcb.8b07446

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

Alternately N-alkylated aromatic amides such as 1–3 bearing various side chains were designed and synthesized as novel helical foldamers. The CD spectra of oligomers with chiral side chains showed a positive Cotton effect, which indicates that these oligomers take helical conformations in solution. The CD intensity gradually increased with increasing chain length, and pentamer 3d showed remarkably strong CD signals in chloroform. The absorption maxima of the UV spectra were increasingly red shifted with increasing chain length, in contrast to the case of poly(p-N-alkylbenzamide)s. Structure optimization of the oligomers based on the crystal structure of 1a as the monomer unit supported the formation of helical structure with a large cavity and also suggested intramolecular hydrogen bond formation between secondary amides. The results of calculation were consistent with the observed spectroscopic features.

DOI： 10.1021/acs.joc.8b02045

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Alternately N-alkylated aromatic amides such as 1–3 bearing various side chains were designed and synthesized as novel helical foldamers. The CD spectra of oligomers with chiral side chains showed a positive Cotton effect, which indicates that these oligomers take helical conformations in solution. The CD intensity gradually increased with increasing chain length, and pentamer 3d showed remarkably strong CD signals in chloroform. The absorption maxima of the UV spectra were increasingly red shifted with increasing chain length, in contrast to the case of poly(p-N-alkylbenzamide)s. Structure optimization of the oligomers based on the crystal structure of 1a as the monomer unit supported the formation of helical structure with a large cavity and also suggested intramolecular hydrogen bond formation between secondary amides. The results of calculation were consistent with the observed spectroscopic features.

DOI： 10.1039/c8cp04753g

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society  

N-Alkylbenzanilides generally exist in cis conformation both in the crystalline state and in various solvents, and this cis conformational preference can be utilized to construct dynamic helical oligoamides. Here, we synthesized the pyrrole-containing amides 2-5 and their oligomers 6-8 and examined their conformations in the crystalline state and in solution. All the N-methylated amides showed cis conformational preference in solution, but the ratio of the cis isomer was decreased when the amide bond was attached at the 4-position of the pyrrole ring, probably because the destabilization of the trans conformer due to electronic repulsion between the pyrrole π electrons and the amide carbonyl lone-pair electrons is reduced due to the small torsion angle between the 5-membered N-pyrrole and the amide bond. In the crystalline state, N-methylated amides showed cis structure, except for compound 5, and cis conformational preference was observed for the pyrrole amides. The CD spectra of oligoamides 15-18 bearing chiral N-substituents were consistent with the presence of dynamic and well-defined chiral foldamers, which were structurally distinct from N-alkylated poly(p-benzamide)s 1.

DOI： 10.1021/acs.joc.8b00349

Scopus

PubMed

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Effective fragment potential version 2 - molecular dynamics (EFP2-MD) simulations, where the EFP2 is a polarizable force field based on ab initio electronic structure calculations were applied to water-methanol binary mixture. Comparing EFP2s defined with (aug-)cc-pVXZ (X = D,T) basis sets, it was found that large sets are necessary to generate sufficiently accurate EFP2 for predicting mixture properties. It was shown that EFP2-MD could predict the excess molar volume. Since the computational cost of EFP2-MD are far less than ab initio MD, the results presented herein demonstrate that EFP2-MD is promising for predicting physicochemical properties of novel mixed solvents.

DOI： 10.1016/j.cplett.2018.01.042

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

In the present study, methods to enhance the oxygen reduction reaction (ORR) activity of sub-nanosized Pt clusters were investigated in a theoretical manner. Using ab initio molecular dynamics and Monte Carlo simulations based on density functional theory, we have succeeded in determining the origin of the superior ORR activity of Pt-12 compared to that of Pt-13. That is, it was clarified that the electronic structure of Pt-12 fluctuates to a greater extent compared to that of Pt-13, which leads to stronger resistance against catalyst poisoning by O/OH. Based on this conclusion, a set of sub-nanosized Pt-alloy clusters was also explored to find catalysts with better ORR activities and lower financial costs. It was suggested that Ga4Pt8, Ge4Pt8, and Sn4Pt8 would be good candidates for ORR catalysts.

DOI： 10.1038/srep45381

Web of Science

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Radial distribution functions (RDFs) of imidazolium-based ionic liquids were evaluated by adopting effective fragment potential version 2 - molecular dynamics simulation (EFP2-MD), whose force fields were defined by a set of simple ab initio quantum chemical calculations for each ionic fragment. It was found that EFP2-MD could reproduce RDFs of ion pairs much faster than ab initio MD without losing chemical accuracy. This means that EFP2-MD has a potential to predict and design thermodynamic properties of novel ionic liquids.

DOI： 10.1246/cl.160366

Web of Science

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Pd nano-octahedron absorbs hydrogen gas faster than Pd nano-cube. This means that H-absorption rate of Pd nanoparticles can be controlled by their structural design. For further design of nano materials for H-absorption, it is important to understand tuning mechanism of H-absorption achieved in shape-controlled Pd nano particles. In this study, kinetics of H-absorption into Pd nano-octahedron and Pd nano-cube were investigated by electronic structure calculation and molecular dynamics simulation. Both simulations well support experimental observation. It was clarified that the shape dependency in H-absorption of the Pd nanoparticles originates from difference in H-invasion process from surface to the inside. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2015.11.021

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

Using fragment molecular orbital-molecular dynamics (FMO-MD) simulation at the FMO3-HF/6-31G(d,p) level, the hydration of a Ra2+ ion was theoretically investigated. The first peaks of the radial distribution function (RDF) for Ra-O and Ra-H lengths were predicted to be 2.85 and 3.45 a"<< with broad envelopes in the ranges of 2.5-3.5 and 2.8-4.3 a"<<, respectively. The broad peaks shows that the first hydration shell of Ra2+ is much more flexible than those in the other hydrated divalent alkaline earth metal ions, i.e., Ra2+ is a structure-breaking ion. The hydration number of Ra2+ was predicted to be 8.1. From the angular distribution function (ADF), it was clarified that the octa hydrated Ra2+ ion has a flexible square antiprism structure at room temperature.

DOI： 10.1007/s10953-014-0235-7

Web of Science

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The electronic structures of heteroleptic cyclometalated platinum(II) complexes a-f with 2-arylpyridine derivatives and 1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dione which are candidate materials for phosphorescent organic electroluminescent diodes (OLEDs) were theoretically investigated using relativistic density functional theory (DFT) calculations including spin-orbit effects. The electronic excitation bands and phosphorescent emission wavelengths of the complexes were theoretically calculated and compared with the corresponding experimental results. It was theoretically confirmed that the color of the phosphorescent emission is controlled by the pi-pi* electronic excited state localized on each 2-arylpyridine derivative ligand. Our calculations also gave good predictions for spectral red shifts originating from excimer formations for a-f.

DOI： 10.1021/jp500484a

Web of Science

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Computer Chemistry Japan  

The thermodynamic properties and electronic structure of hydrated Ra2+ have been investigated using ab initio quantum chemical calculations that apply the relativistic model core potential method and compared with those of the other hydrated divalent alkaline earth metal ions (Mg2+, Ca2+, Sr2+, and Ba2+). The solvation free energies calculated for [Ra (H2O)n]2+ (n = 1–9) in a continuum dielectric media (semi-continuum model) showed that the hydration number of Ra2+ is in the range of 7–9. Natural population analysis (NPA), natural bond orbital (NBO) analysis and localized molecular orbital energy decomposition analysis (LMO-EDA) showed that the dominant interaction between hydrated Ra2+ ions and solvent water molecules is electrostatic interaction to form coordination bonds which have a strong ionic bond character. On the other hand, not only electrostatic interaction but also covalent interaction accompanying charge-transfer from solvent water molecules to the central ion are important in the interaction between hydrated Mg2+ or Ca2+ (lighter divalent alkaline earth metal ions) and solvent water molecules.

DOI： 10.2477/jccj.2013-0011

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Chem-Bio Informatics Society  

A simulation protocol based on fragment molecular orbital−based molecular dynamics (FMO-MD) was applied to a droplet model consisting of a divalent copper ion and 64 water molecules. The total energy and forces were evaluated at the unrestricted Hartree-Fock (UHF) level with three-body fragment correction (FMO3). Two MD runs were performed: one with a six-coordination setting and the other with a five-coordination setting in the first hydration shell. Both runs resulted in the main peak position of the Cu-O radial distribution function at 2.02 Å, in reasonable agreement with the experimental data. The O-Cu-O angular distribution function showed different characteristics between the two cases.

DOI： 10.1273/cbij.14.1

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Electronic excitation spectra of cis-platin (cis-[(PtCl2)-Cl-II(NH3)(2)]), which is a well-known antitumor drug, and trans-platin (trans-[(PtCl2)-Cl-II(NH3)(2)]) were experimentally observed and theoretically analyzed using ab initio spin-orbit CASPT2 (SO-CASPT2) calculations. Cis-platin showed two series of absorption bands in the wavelength regions of 250-350 nm and 350-450 nm. On the other hand, trans-platin showed three series of absorption bands in the wavelength regions of 260-280 nm, 300-340 nm and 360-400 nm. Comparing SO-CASPT2 calculations at the optimum structures in gas-phase conditions with those in DMF solvent, which were obtained by PCM implicit solvation model, it was clarified that both spin-orbit effect and solvent effect cannot be negligible even for quantitative assignments of electronic excitation spectra of cis/trans-platin. (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molstruc.2012.11.027

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

To design half-metallic materials in thin film form for spintronic devices, the electronic structures of full Heusler alloys (Mn2FeSi, Fe2MnSi, Fe2FeSi, Fe2CoSi, and Co2FeSi) with an L2(1) structure have been investigated using density functional theory calculations with Gaussian-type functions in a periodic boundary condition. Considering the metal composition, layer thickness, and orbital symmetries, a 5-layered Co2FeSi thin film, whose surface consists of a Si layer, was found to have stable half-metallic nature with a band gap of ca. 0.6 eV in the minority spin state. Using the group theory, the difference between electronic structures in bulk and thin film conditions was discussed. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2012.03.045

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Differences in hydration between cis- and trans-platin were investigated using ab initio fragment molecular orbital-based molecular dynamics (FMO-MD) simulations. Analyzing quantum charge fluctuation in water, we found that the Pt-Cl bond fluctuation of cis/trans-platin, which is important for activating their anticancer functions, was induced by charge transfer interaction between an anti-bonding pi(Pt-Cl) orbital of platin complex and unoccupied orbital of solvent water molecules. The hydration number of Cl ligand in the first hydration shell was found to be larger for cis-platin than for trans-platin due to their difference in charge distribution. Our FMO-MD simulations showed that the amplitude of the Pt-Cl bond fluctuation is larger in hydrated cis-platin than in hydrated trans-platin. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.comptc.2012.02.008

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We found that pseudopotentials, used with a recent novel hybrid meta-GGA density functional proposed by Zhao and Truhlar (M06) and density functionals applying long-range correction term (LC-BLYP, LC-BOP), exhibit very good accuracy in predicting thermochemical properties for a wide range of transition-metal complexes. The performance for thermochemistry of transition-metal complexes strongly depends on the valence-only chemical core potential basis sets used in the density functional theory (DFT) calculations. Recent chemical core potentials can be used for the theoretical thermochemistry of transition-metal complexes with an accuracy of about 20 kcal mol(-1). (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2011.11.044

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Structures, chemical bonding nature, and vibrational properties of polyiodide anion species (I(n)(-); n = 3, 5, 7) are investigated by means of density functional theory calculations (B3PW91/MCPtzp+). All polyiodide anion species are predicted to have single or branched chain structures. Natural bond orbital (NBO) analyses of I(n)(-) (n = 5, 7) isomers clearly show that the polyiodide species consists of I(2) and linear I(3)(-) units. A comparison of theoretically predicted Raman spectra with experimental reports revealed the existence of I(n)(-) (n = 5, 7) isomers with three-center four-electron (3c-4e) bonds. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.comptc.2011.07.002

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The open-shell density functional theory calculations with M06 exchange-correlation functional and all-electron Douglas-Kroll second order scalar relativistic correction were performed to interpret the vibrational circular dichroism (VCD) spectra of four kinds of tris(acetylacetonato) metal(III), [M(III)(acac)(3)] (acac = acetylacetonato, M = Ru, Cr, Co, and Rh). It was deduced that the experimental spectra were well reproduced by the calculation with harmonic approximation in case of [Co(III)(acac)(3)] (d(6); S = 0), [Rh(III)(acac)(3)] (d(6); S = 0), and [Ru(III)(acac)(3)] (d(5); S = 1/2). In case of [Cr(III)(acac)(3)] (d(3); S = 3/2), anharmonic effects should be taken into account to predict the accurate vibrational frequencies of closely located modes. Time-dependent density functional theory calculations were performed to estimate the contribution of excited states in the VCD spectra. As a consequence, the presence of the low-lying excited states was predicted for [Ru(III)(acac)(3)] alone, which agreed with the experimental observation. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624605]

DOI： 10.1063/1.3624605

Web of Science

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

4f-in-core large-core model core potentials (LC-MCP), in which the effects of open shell 4f electrons as well as those of other electrons up to 4d were replaced with MCPs, were developed for the lanthanide trivalent ions. In order to achieve desired accuracy, the LC-MCPs were calibrated using static quantum-chemical calculations for LnF(3), and tested by ab initio molecular dynamics simulation on the hydration dynamics of La(3+). Comparing calculated results using the 4f-in-core LC-MCPs with those employing 4f-in-valence MCPs, we found that the 4f-in-core LC-MCPs require less computational costs than the 4f-in-valence MCPs with keeping enough accuracy for describing chemical properties of trivalent lanthanide systems. (C) 2011 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.cplett.2011.05.028

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The DNA-binding ability of the zinc-finger (ZF) protein and the modulation of its affinity to DNA through amino acid mutations were theoretically investigated. Classical molecular dynamics and energy decomposition analysis based on large-scale ab mitio fragment molecular orbital calculations were Used to obtain the DNA binding affinities: of wild type and three: mutant ZFs. Calculated bin ding :free energies qualitatively well explained the DNA binding affinity modulation experimentally observed by Dhanasekaran et al. [Dhamisekaran, M.; et;al., Biochemistry 2007, 46, 7506-7513]. It had been considered that only the alpha-helix domain in the ZF plays an important role in DNA recognition; however, our results clearly show that the N-terminal regions, BR.1 and BR2, also play important roles in DNA recognition.

DOI： 10.1021/jp1097348

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV TOKYO CYTOLOGIA  

Cyclic phosphatidic acid (cPA) has a similar structure to that of lysophosphatidic acid (LPA), but possesses distinct biological functions. For example, cPA suppresses cancer cell invasion and metastasis through the inhibition of autotaxin (ATX) and transient activation of low molecular weight GTPase, RhoA. We designed and chemically synthesized several metabolically stabilized derivatives of cPA, and revealed that 2-carba-cPA was the most potent inhibitor of cancer cell invasion and metastasis. We have developed a novel method of 2ccPA enantiomeric synthesis, and here we examined the effects of natural (R)-cPA, both enantiopure 2ccPA, and (S)-3ccPA (corresponding to the configuration of (R)-2ccPA) on ATX. We also predicted the effects of (R)-cPA, (R)-2ccPA and (S)-3ccPA on ATX activity by combined quantum mechanics and molecular mechanics (QM/MM) computational methods. By these methods, we demonstrated that 2ccPA was the most potent inhibitor on ATX, and the chirality of 2ccPA was not involved in ATX inhibition. These results suggest that racemic-2ccPA may be utilized as an effective compound for cancer therapeutics.

DOI： 10.1508/cytologia.76.73

Web of Science

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The potential energy surface corresponding to the reaction of lanthanide mono-cations (Ln(+); Ln = Ce-Yb) with CH(3)F has been investigated using density functional theory calculations. In the initial step of the C-F activation reaction, Ln(+) directly coordinates to the F atom of CH(3)F, and forms same [Ln center dot center dot center dot F center dot center dot center dot CH(3)](+) type transition state structures with an accompanying electron-transfer from the Ln(+) to the F atom. Performing intrinsic reaction coordinate calculations from the transition states, we found that all Ln(+) reactions can be classified into one of two different reaction mechanisms, "harpoon-like'' and "insertion-elimination'', which were experimentally proposed by Cohrnel et al. and Konayagi et al., respectively. The two mechanisms have been proposed exclusive to each other. Our results show that both reaction mechanisms are possible in Ln(+) reaction systems. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chemphys.2010.12.005

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Molecules HRgF (Rg = Ar, Kr, Xe, Rn) were studied at levels of theory that included electron correlation, taking relativistic effects into account either by using the recently developed parametrization of the extended model core potentials and basis sets or by using the Douglas-Kroll method with all-electron basis sets. Charge distributions were calculated according to Mulliken, Lowdin, and natural bond orbital methods of population analysis and the results of these methods were compared, confirming that bonding in these molecules corresponds to interaction between the fluoride anion and the RgH(+) moiety In contrast to previously reported results, the present calculations show that the radon compound, HRnF, is more stable than compounds of the lighter congeners Trends in the first ionization energies, bond lengths, energies of formation and decomposition, and harmonic vibrational frequencies were discussed and found to be consistent with the periodic trends of the atomic properties of the rare gas atoms.

DOI： 10.1021/jp101765m

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We performed geometry optimization calculations and ab initio molecular dynamics calculations for hydration models of trivalent ions, Y(3+), La(3+), Gd(3+), and Lu(3+), by using molecular orbital calculations to examine the so-called gadolinium break. The geometry optimization calculations revealed that the M-O distances of Y(H(2)O)(8)(3+), Lu(H(2)O)(8)(3+), and La(H(2)O)(9)(3+) calculated at the MP2 level were 2.39 angstrom, 2.36 angstrom, and 2.63 angstrom, respectively, which agreed well with observed values. The calculated Gd-O distance (2.44 angstrom) of Gd(H(2)O)(8)(3+) also agrees reasonably well with the existing observed values. The differences in the M-O distances arise from the differences in the ionic radii. When the coordination number increased, the degree of decrease in the M-O binding energies per bond (B.E.) occurred in the following order: La(3+) < Gd(3+) < Y(3+) < Lu(3+). This order is consistent with the order of the ionic radii's inverse. In ab initio molecular dynamics calculations, by using the Y(H(2)O)(24)(3+) model we could realize the hydration structure where eight water molecules are located around the Y(3+) ion. By using the bigger model of La(H(2)O)(64)(3+), the experimentally suggested structure coordinated by nine water molecules was reproduced. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.theochem.2010.02.032

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

Recently, the method of fragment molecular orbital-based molecular dynamics (FMO-MD) was enhanced by including the three-body corrections (FMO3) [Y. Komeiji, Y. Mochizuki, T. Nakano, Chem. Phys. Lett. 484 (2010) 380]. This simulation protocol was applied to a droplet model consisting of a divalent zinc ion and 64 water molecules, in order to investigate the hydration structure in ab initio fashion. The first peak position of the Zn–O radial distribution function (RDF) was evaluated to be 2.05 Å at the FMO3-HF/6-31G level of theory, which was in agreement with an X-ray value of 2.06 ± 0.02 Å. The coordination number was evaluated to be 6, corresponding to an octahedral coordination.

DOI： 10.1016/j.cplett.2010.03.020

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Three newly developed families of model core potentials (MCPs) for the main group elements were calibrated in extensive calculations. In the calibration, 90 closed-shell molecules of the main group elements from Li to Rn, with noble gases being excluded, were optimized using the MCPs at different levels of correlation. The optimized structural parameters were compared with the experimental values and the errors were evaluated. The distributions of the errors were studied, and diagnostic conclusions on the efficacies of the MCPs were obtained. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 3235-3245, 2009

DOI： 10.1002/qua.22120

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have produced new relativistic model core potentials (spdsMCPs) for the third-row transition-metal atoms from Lu to Hg explicitly treating explicitly 5s and 5p electrons in addition to 5d and 6s electrons in the same manner for the first- and second-row transition-metal atoms given in the previous Letters [Y. Osanai, M. S. Mon, T. Noro, H. Mori, H. Nakashima, M. Klobukowski, E. Miyoshi, Chem. Phys. Lett. 452 (2008) 210; Y. Osanai, E. Soejima, T. Noro, H. Mori, M. S. Mon, M. Klobukowski, E. Miyoshi, Chem. Phys. Lett. 463 (2008) 230]. Using suitable correlating functions with the split-valence MCP functions, we demonstrate that the present MCP basis sets show reasonable performance in describing the electronic structures of atoms and molecules, bringing about accurate excitation energies for atoms and proper spectroscopic constants for Au(2), Hg(2), and AuH. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2009.06.019

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：East Stroudsburg University, Pennsylvania, USA  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Ab initio calculations at the level of CASPT2 with Dunning's correlation consistent cc-pVXZ (X=D, T, Q) basis sets have been carried out for pyrimidine, quinoxaline, phthalazine, and their substituted compounds to find candidates that show a change in the direction of the electric dipole moment for the S-0 -> S-1 transition. The present calculations reveal that 6,7-difluorophthalazine and 6,7-dichlorophthalazine are strong candidates having a large and clear change in the direction of the electric dipole moment on the S-0 -> S-1 transition.

DOI： 10.1063/1.3127245

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have carried out systematic CASSCF and CASPT2 calculations for the ground states of lanthanide trihalides, LnX(3) (Ln = Ce-Yb, X = F, Cl, Br, and I), using model core potentials to investigate the effects of static and dynamic electron correlations on the structures of these molecules. Dynamic electron correlation is found to be indispensable for obtaining reliable bond distances in these molecules. Static electron correlation has little effect on bond distances, although the ground states of LnX(3) (Ln = Pr, Nd, Pm, Sm, Dy, Ho, Er, and Tm) have more than two major electronic configurations. (C) 2009 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.cplett.2009.04.018

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We investigated the electronic structure of low-lying electronic states of Mn(2) using a newly developed relativistic model core potential (spdsMCP). Calculations were performed at complete active space self-consistent field (CASSCF) and second-order multiconfiguration quasidegenerate perturbation theory (MCQDPT2) levels. The MCQDPT2 calculations reveal that the 1 Sigma g(+) state is the ground state. Calculated spectroscopic constants are very similar to the results of recent all-electron calculations and experimental values, indicating that the spdsMCP works well for Mn(2), which requires a highly correlated calculation. The wave functions of low-lying states are also analyzed at the CASSCF level. (C) 2008 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.cplett.2008.07.011

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have produced new relativistic model core potentials (spdsMCPs) for the second-row transitionmetal atoms from Y to Cd treating explicitly 4s and 4p electrons in addition to 4d and 5s electrons in the same manner as for the first-row transition-metal atoms given in [ Y. Osanai, M. S. Mon, T. Noro, H. Mori, H. Nakashima, M. Klobukowski, E. Miyoshi, Chem. Phys. Lett. 452 (2008) 210]. Using suitable correlating functions together with the split valence MCP functions, we demonstrate that the present MCP basis sets show reasonable performance in predicting the electronic structures of atoms and molecules, bringing about accurate excitation energies for atoms and reasonable spectroscopic constants for AgH. (c) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2008.07.091

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

DFT calculations for M@C(12)H(12)N(6) and M@C(12)H(24)O(6) (where M = Rb(+), Cs(+), Sr(2+), and Ba(2+), C(12)H(12)N(6) = hexaaza[18]annulene, and C(12)H(24)O(6) = 18-crown-6) were performed using the recently developed model core potential parametrization. Results show that the ions bind more strongly to C(12)H(12)N(6) than to 18-crown-6 moiety; the difference is more pronounced for cations with smaller radii. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2007.10.033

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The possibility for photon-mode memory writing of [[Co(Hbim)(C6H4O2)(NH3)(2))(2)](Hbim = 2,2'-biimidazole) is examined from results obtained by spin-orbit complete active space configuration interaction (SO-CASCI) calculations. The spin-crossover phenomenon in the proton-electron-coupled complex monomer [Co(Hbim)(C6H4O2)(NH3)(2)] is a key process in memory writing to the complex dimer. We found a possibility of an efficient spin-crossover in the monomer. UV (ca. 300 nm) irradiation of the monomer (1)A' state leads to a spin-crossover into the high-spin (5)A' state. The back photoreaction from the (5)A' to (1)A' state is also possible with vis (ca. 600-700 nm) excitation. In these spin-crossover and back spin-crossover reactions, the intermediate triplet states, 1(3)A" and 2(3)A", are found to participate.

DOI： 10.1246/bcsj.81.235

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have developed new relativistic model core potentials (MCPs) for the first-row transition-metal atoms from Sc to Zn, in which 3s and 3p electrons are treated explicitly together with the 3d and 4s electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show reasonable performance in describing the electronic structures of atoms and molecules, bringing about accurate excitation energies for atoms and good molecular spectroscopic constants. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2007.12.019

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

A new series of tripods were designed to form anion-responsive, luminescent lanthanide complexes. These tripods contain pyridine, thiazole, pyrazine, or quinoline chromophores combined with amide carbonyl oxygen and tertiary nitrogen atoms. Crystallographic and EXAFS studies of the 10-coordinated tripod-La(NO(3))(3) complexes revealed that each La(3+) cation was cooperatively coordinated by one tetradentate tripod and three bidentate NO(3)(-) anions in the crystal and in CH(3)CN. Quantum chemical calculations indicated that the aromatic nitrogen plays a significant role in lanthanide complexation. The experimentally determined stability constants of complexes of the tripod with La(NO(3))(3), Eu(NO(3))(3), and Tb(NO(3))(3) were in good agreement with the theoretically calculated interaction energies. Complexation of each tripod with lanthanide triflate gave a mixture of several lanthanide complex species. Interestingly, the addition of a coordinative NO(3)(-) or Cl(-) anion to the mixture significantly influenced the lanthanide complexation profiles. The particular combination of tripod and a luminescent Eu(3+) center gave anion-selective luminescence enhancements. Pyridine-containing tripods exhibited the highest NO(3)(-) anion-selective luminescence and thus permit naked-eye detection of the NO(3)(-) anion.

DOI： 10.1002/chem.200701898

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

We developed new model core potentials (MCPs) for s-block elements from Na to Ra, in which the outer core (n - 1)s and (n - 1)p electrons are treated explicitly together with the rrs electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate ionization potentials of atoms and very good spectroscopic constants of ionic and covalent molecules. The results obtained with the new MCPs are very close to the ones obtained using the all-electron correlation consistent basis sets of Dunning. (c) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/jcc.20612

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

We carried out computational studies Of OPX3 and SPX3 (X = Br and I) molecules and their corresponding anions using density functional theory, Moller-Plesset, and CCSD(T) methods with newly developed model core potentials (MCP). Reliabilities of the MCP were demonstrated by comparing experimental and calculated results. We computed the geometric structure, electron affinities, and electrostatic moments using systematic sequences of the dzp-, tzp-, and qzp-quality basis sets. Both C-3v, and C-s, symmetries were assumed to ascertain that minima on the potential energy surface were found. Infrared and Raman frequencies were calculated and compared with available experimental data. Natural population analyses were performed and used to determine distribution of the extra electron in anions. (c) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/jcc.20726

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The electronic and vibrational spectra of a proton-electron-coupled inorganic complex [Co(Hbim)(C6H4O2)-(NH3)(2)](2) having multistable states, were theoretically investigated using density functional theory calculations using B3LYP parameters. The electronic excitation spectrum in the low-spin ground (1)A(g) state of the complex has no strong absorption in the visible region (600-700 nm), while in the high-spin (5)A(1), and (9)A(g) complexes, some prominent peaks were predicted in the visible region. Frequency analyses of the (1)A(g), (5)A(1), and (9)A(g) states showed the strong band of the NH stretching vibration at 2690, 2120, and 2770 cm(-1), respectively. Based on this, it is possible to distinguish (5)A(1) from (1)A(g) and (9)A(g) by measuring IR light absorption at 2120 cm(-1), showing that [Co(Hbim)(C6H4O2)(NH3)(2)](2) would be a good candidate for use as optically durable molecular level memory.

DOI： 10.1246/bcsj.80.1335

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The most stable structure of the benzene trimer cation was systematically searched using CCSD(T)/6-31G(d)//MP2/6-31G calculations, and several stable structures were obtained. A sandwich structure (SW) is found to be the most stable, though a few other structures have similar energies. Calculated differential spin densities indicate that the positive charge of SW is localized around a dimer core in SW, as suggested from experiments. A calculated infrared spectrum and the low-lying excited states of the obtained stable structures are compared with the experimental results. It is also shown that the core switching of a dimer cation can occur in SW. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2007.02.072

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC AND ENGINEERING ACAD AND SOC  

We have examined newly developed relativistic model core potentials (MCPs) for the first row transition-metal atoms from Sc to Zn, in which 3s and 3p electrons are treated explicitly together with the 3d and 4s electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate excitation energies for atoms and very good molecular spectroscopic constants.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

A photo-induced geometry isomerization reaction mechanism of a photochromic inorganic complex, [Cu(dieten)(2)](2+) (dieten = N,N'-diethyletylenediamine), was investigated with density functional molecular orbital theory calculations. A new stable cis-isomer that is assigned to a photo-irradiated (PI) phase was found. In the PI geometry, two N,N'-diethyl groups are placed more closely than in the most stable low-temperature (LT) phase, and the complex has a slightly twisted structure with steric hindrance. Recently, Takahashi et al. have suggested that two ethyl groups were in trans position in the PI phase from the EXAFS and XANES observation; however, no energy minimum corresponds to such a PI state was found. The photochromic reaction mechanism and electronic structure of [Cu-II(dieten)(2)](2+) are discussed from a theoretical point of view.

DOI： 10.1142/S0219633606002714

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The fragment molecular orbital (FMO) scheme has been successfully used for a variety of large-scale molecules such as proteins and nucleic acids so far. We have applied the FMO calculations to the silicon-containing systems like polysilanes. The error caused by the fragmentation was examined by the Hartree-Fock method and the second-order Moller-Plesset (MP2) perturbation method for the ground state energy. The dynamic polarizability as a linear response property was also evaluated with and without the fragmentation. A series of numerical comparisons showed that the FMO scheme is applicable to silicon-based molecules with reasonable accuracy. This implied a potential availability of FMO calculations for the issues relevant to nanoscience and nanotechnology. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2006.09.015

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have realized a fully quantum mechanical treatment of large scale systems containing heavy metal atom, by introducing the model core potential (MCP) technique into the fragment molecular orbital (FMO) scheme. The scalar relativistic effects are incorporated by the use of MCP. This FMO/MCP method was applied to the divalent mercury ion hydrated, with 256 water molecules at the second-order Moller-Plesset (MP2) perturbation level. The complex between cisplatin and DNA was also calculated with MP2, where about a thousand of water molecules and dozens of sodium ions were employed for the explicit treatment of hydration. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2006.06.103

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：VSP BV-C/O BRILL ACAD PUBL  

A proton-electron coupling inorganic complex [Co(Hbim)(C6H4O2)(NH3)(2)](2) (Hbim = 2.2'-biimidazolate) and its derivatives that can be used as a new optically durable molecular switch were theoretically designed in the framework of density functional and ab inilio spin-orbit CI theory. Theoretically predicted infrared spectra of [Co(Hbim)(C6H4O2)(NH3)(2)](2) showed that a strong peak of NH stretching vibration is observed at 2690, 2120, and 2770 cm(-1) in stable (1)A(g), (5)A(1), and (9)A(g) states. respectively. The apparent red shift of the NH stretching vibration band in the 5 A, state make it possible to distinguish the electronic state from others ((1)A(g), and (9)A(g)). This means that the complex can be used as a molecular level switch whose memory can be stably read by IR light without an), photoreaction process; namely, without memory degradation. The electronic structure and further extension of the molecular function are discussed.

Web of Science

researchmap

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：有機 EL 討論会  

researchmap

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：有機 EL 討論会  

researchmap

Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)   Publisher：有機 EL 討論会  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：World Scientific  

A new inorganic molecule [Co(Hbim)(C6H4O 2)(NH3)2]2 that can be used as a new optically durable molecular switch was theoretically designed in the framework of density functional theory. Three stable minima, belonging to 1Ag, 5A1, and 9A g states, were found in the complex. Theoretically predicted infrared spectra of the complexes showed that a strong peak of NH stretching vibration is observed at 2690, 2120, and 2770 cm-1 in the 1A g, 5A1, and 9Ag states, respectively. The apparent red shift of the NH stretching vibration band in the 5A1 state make it possible to distinguish the electronic state from others (1Ag and 9Ag). This means that the complex can be used as a molecular level switch whose memory can be stably read by IR light without any photoreaction process
namely, without memory degradation. © World Scientific Publishing Company.

DOI： 10.1142/S0219633605001477

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We propose compact and efficient valence-function sets for s- and p-block elements from Li to Rn to appropriately describe valence correlation in model core potential (MCP) calculations. The basis sets are generated by a combination of split MCP valence orbitals and correlating contracted Gaussian-type functions in a segmented form. We provide three types of basis sets. They are referred to as MCP-dzp, MCP-tzp, and MCP-qzp, since they have the quality comparable with all-electron correlation consistent basis sets, cc-pVDZ, cc-pVTZ, and cc-pVQZ, respectively, for lighter atoms. MCP calculations with the present basis sets give atomic correlation energies in good agreement with all-electron calculations. The present MCP basis sets systematically improve physical properties in atomic and molecular systems in a series of MCP-dzp, MCP-tzp, and MCP-qzp. Ionization potentials and electron affinities of halogen atoms as well as molecular spectroscopic constants calculated by the best MCP set are in good agreement with experimental values. (C) 2005 American Institute of Physics.

DOI： 10.1063/1.1845392

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A new inorganic molecule that can be used as a new optical durable molecular switch was theoretically designed in the framework of density functional theory. Two energy minima were found in the molecule, and their electronic states were (1)A(g) and (5)A(1), respectively. The predicted infrared spectra in each state showed that the new inorganic molecule have quite different spectra. This means that the molecule can be used as an optical durable molecular switch.

DOI： 10.1246/cl.2004.758

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The topologies of hydrogen-bond potential energy surfaces of one-dimensional assembled 2,2'-biimidazole (H(2)bim) and its deprotonated Ni complex ([Ni-II(Hbim)(2)])were investigated by density functional theory calculations at the B3LYP/CEP-31G(d,p) level. It was revealed that the formation of coordination bonds between Hbim and Ni makes the N-(HN)-N-... hydrogen bond between Hbim units linear and strong.

DOI： 10.1246/bcsj.77.687

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The effects of binding of CO2 or H2O with 9-hydroxyphenalenone (9HPO) on proton tunneling in the S-0 state have been theoretically investigated. High-level ab initio calculations predict that CO2 is van der Waals-bonded to the C=O.OH moiety of 9HPO in the most stable structure. This planar structure is more stable than the nonplanar structure where CO2 is bonded above the aromatic rings of 9HPO. In the 9HPO-H2O complex, H2O is hydrogen-bonded to the carbonyl group in the most stable structure. Two-dimensional potential energy surfaces (PESs) for 9HPO-CO2 and 9HPO-H2O have been calculated with the reaction surface method, and the contour plots of PESs for the complexes are compared with those for the 9HPO monomer. The binding of CO2 with 9HPO induces slight asymmetry in the double-minimum potential well, whereas the asymmetry of the PES is very large for the binding of H2O. The transition state energy for 9HPO-CO2 drastically decreases to be about a half that of 9HPO, while that for 9HPO-H2O is only slightly smaller than the transition energy for 9HPO. The vibrational wave function for in 9HPO-CO2 is substantially delocalized over two potential minima, but that for 9HPO-H2O is completely localized around a single potential minimum. The calculated tunneling splitting of the zero-point level in 9HPO-CO2 is only 10% smaller than the corresponding splitting of 9HPO, whereas proton tunneling is quenched in 9HPO-H2O. The calculated results are consistent with the prediction from the electronic spectra measured in a supersonic free jet. (C) 2003 American Institute of Physics.

DOI： 10.1063/1.1592505

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We investigated the interactions between the Si(111) surface and the Na, Mg, and Al atoms using cluster model calculations. Calculations were performed at levels of complete-active-space self-consistent-field (CASSCF) and multi-reference singly and doubly excited configuration interaction (MRSDCI) calculations using the model core potential method. Our calculations revealed that the most favorable sites of Na, Mg, and Al adsorption on Si(111) are on top (T-1), bridge (B-2), and 3-fold filled (T-4) sites, respectively. The nature of chemical bonds between these metal atoms and the dangling bonds of the surface Si atoms are found to be essentially covalent. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0166-1280(03)00172-6

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The laser induced fluorescence (LIF) and dispersed fluorescence spectra of jet-cooled N-salicylideneaniline have been observed in a supersonic free jet for the first time. The spectrum shows a very broad feature with no vibronic structure in the 24,800-28,800 cm(-1) region except for a broad peak at 28,200 cm(-1). The broad feature of the spectrum has been ascribed to the homogeneous broadening of vibronic bands due to very fast internal conversion from the (1)(pipi*) to (1)(npi*) state which is located below the (1)(pipi*) state as well as to the excited-state intramolecular proton transfer (ESIPT) reaction. No resonance emission has been detected following the excitation of the (1)(pipi*) state of the enol form, while anomaly Stokes-shifted fluorescence was observed at 15,000-20,500 cm(-1). The dispersed fluorescence spectra show two broad maxima separated by 700-1000 cm(-1), suggesting that two keto tautomers are produced via the ESIPT reaction. The existence of the corresponding two cis-keto tautomers with similar energies has been suggested by density functional theory (DFT) calculations at the B3LYP/6-31G** level and ab initio calculations at the HF/6-31G** level. Published by Elsevier Science B.V.

DOI： 10.1016/S1010-6030(02)00306-4

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BULLETIN POLISH ACAD SCI  

The fluorescence excitation, dispersed fluorescence, and hole-burning spectra of the 9-hydroxyphenalenone (9HPO)-CO2 1:1 complex have been measured to investigate the effects of the van der Waals interaction on proton tunneling in the So state. The Si-so electronic origin is only 4 cm(-1) red-shifted with respect to that of the monomer, suggesting that proton tunneling occurs in both the S-0 and S-1 states of the 9HPO-CO2 complex, although the tunneling splittings have not been observed, in the excitation spectrum. The structure of the observed complex and its tunneling potential for the So state of 9HPO have been theoretically investigated by using the reaction surface Hamiltonian method. The intermolecular interaction significantly changes the shape of two dimensional potential energy surface along the reaction coordinates, and slightly decreases the tunneling splitting in the zero-point level.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We investigated the interactions between the Si(111) surface and the Na and Mg atoms using cluster model calculations. Calculations were performed at levels of the complete-active-space self-consistent-field and multi-reference single and double excited configuration interaction calculations using the model core potential method. Our calculations revealed that the most favorable sites of Na and Mg adsorption on Si(111) are on-top (T-1) and bridge (B-2) sites, respectively. The nature of chemical bonds between these metal atoms and the dangling bonds of the surface Si atoms are found to be essentially covalent. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0039-6028(02)01656-4

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society for Deuterium Science  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Intermolecular interaction and stable structures of the p-aminophenol-M (M=CO, N-2) 1:1 complexes have been studied by measuring the S-1 <-- S-0 (pipi*) fluorescence excitation spectra and the IR dip spectra in the OH and NH stretch region combined with ab initio calculations. The S-1-S-0 electronic origin of the CO complex is 141 cm(-1) red shifted from the origin of the monomer. The red shift for the CO complex is smaller than 153 cm(-1) for the N-2 complex, although the molecular polarizability of carbon monoxide is larger than that of molecular nitrogen. The OH stretching frequency of the CO complex is 26 cm(-1) red shifted from that of the monomer in, the IR dip spectrum, but the N-2 complex shows no shift. On the basis of these findings we conclude that carbon monoxide is bonded to the OH group via a hydrogen bond, whereas nitrogen is van der Waals-bonded to the pi cloud of the aromatic ring.

DOI： 10.1021/jp014594j

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The structure and hydrogen bonding interaction in jet-cooled p-aminophenol-H2O 1:1 complex have been studied by measuring the fluorescence excitation, dispersed fluorescence, and IR-dip spectra. In the electronic spectrum we identified only one isomer, where the oxygen atom of water is bonded to the hydroxy proton of p-aminophenol. Four stable isomers are obtained by ab initio calculations at the MP2/6-31G(d) level, while density functional theory calculations provide four or three isomers depending on the basis sets. It has been shown that theoretical IR spectra with small basis sets are not in agreement with the experimental IR spectrum. The experimental IR spectrum has been well reproduced by the B3LYP/6-311 + G(d,p) calculations, showing that diffuse functions are necessary to describe the intermolecular hydrogen bond in p-aminophenol-H2O. The vibronic levels in the S I state of p-aminophenol-H, 0 have been assigned with the aid of the dispersed fluorescence spectra. The formation of the intermolecular hydrogen bond substantially reduces the frequency of the amino inversion mode in the S-1 state due to nonlocal character of this mode. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0301-0104(02)00308-7

Web of Science

researchmap

Language：Japanese  

J-GLOBAL

researchmap

Language：Japanese  

J-GLOBAL

researchmap

Language：Japanese  

CiNii Books

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

Audience： College students,　Graduate students,　Researchesrs,　Scientific,　Company

Type：Seminar, workshop

現在、電子状態理論は化学の幅広い分野で活用されています。最近では、ナノ・バイオ系など複雑系への応用も可能になっています。これらの研究においては、 電子状態理論の基礎を十分理解しておく必要があります。そこで今回は、電子状態理論の基礎的理解を深めることを目的としたスクールを企画しました。 電子状態理論の基礎として、分子軌道法、計算アルゴリズム、化学反応理論、電子相関理論、相対論的量子化学について、解説していただきます。
いずれの講義についても、最先端で研究を行っておられる先生方を講師としてお招きし、基礎から分かりやすく解説していただきます。また、講師陣との 見交換や交流もできるように、参加者によるポスター発表も行います。積極的な参加をよろしくお願いします。

researchmap

Audience： College students,　Graduate students,　Researchesrs,　Scientific,　Company

Type：Seminar, workshop

現在、電子状態理論は大規模系や複雑系への適用が可能になっています。その背景には、大規模系を目指した理論開発や高並列化など、様々な取り組みがあります。今回のスクールでは電子状態理論の基礎からはじめて、これらの大規模系の理論までをカバーする講義を企画しました。具体的には、分子軌道法の基礎、有効ポテンシャル、第二量子化、分子系の磁気的性質、大規模系の理論への展開について、解説していただきます。また、講義では簡単な演習も行います。
いずれの講義についても、最先端で研究を行っておられる先生方を講師としてお招きし、基礎から分かりやすく解説していただきます。また、講師陣との意見交換や交流もできるように、参加者によるポスター発表も行います。積極的な参加を期待しています。

researchmap

Audience： College students,　Graduate students,　Teachers,　Researchesrs,　General,　Scientific,　Company

Type：Other

巨大分子を志向した電子状態理論「フラグメント分子軌道法」に対応している量子化学計算プログラム ABINIT-MP Open において、重金属の物性評価に必須な相対論的電子状態計算を可能とする、相対論的モデルポテンシャルのプログラムを開発し公開している。

researchmap

Audience： College students,　Graduate students,　Teachers,　Researchesrs,　General,　Scientific,　Company

Type：Other

量子化学計算プログラムGAMESSにおいて相対論的電子状態計算を可能とする、相対論的モデルポテンシャルのプログラムを開発し公開している。

researchmap