174 results on '"Han Myoung lee"'
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2. Complete basis set limit of Ab initio binding energies and geometrical parameters for various typical types of complexes.
- Author
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Seung Kyu Min, Eun Cheol Lee, Han Myoung Lee, Dong Young Kim, Dongwook Kim, and Kwang S. Kim
- Published
- 2008
- Full Text
- View/download PDF
3. Charge-transfer-to-solvent-driven dissolution dynamics of [I.sub.-][([H.sub.2]O).sub.2-5] upon excitation: Excited-state ab initio molecular dynamics simulations
- Author
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Kolaski, Maciej, Han Myoung Lee, Chaeho Pak, and Kwang S. Kim
- Subjects
Coordination compounds -- Research ,Coordination compounds -- Chemical properties ,Electron donor-acceptor complexes -- Research ,Electron donor-acceptor complexes -- Chemical properties ,Chemistry - Abstract
The charge-transfer-to-solvent (CTTS)-driven femtosecond-scale dissolution dynamics for [I.sup.-][([H.sub.2]O).sub.n=2-5] clusters is analyzed by using excited state (ES) ab initio molecular dynamics (AIMD) simulations. The CTTS-driven dissolution dynamics is used for designing the receptors that are able to bind and release ions in host-guest chemistry.
- Published
- 2008
4. Ab initio molecular dynamics simulations of an excited state of X(sup -)[H(sub 2)O](sub 3) (X=Cl, I) complex
- Author
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Kolaski, M., Han Myoung Lee, Chaeho Pak, Dupuis, M., and Kim, Kwang S.
- Subjects
Molecular dynamics -- Analysis ,Excited state chemistry -- Analysis ,Water -- Atomic properties ,Chlorine compounds -- Atomic properties ,Iodine compounds -- Atomic properties ,Chemicals, plastics and rubber industries - Abstract
The process of the electron transfers from the anionic precursor to the solvent, and then the excess electron that is stabilized by polar solvent molecule is investigated using ab initio molecular dynamics (AIMD). The result indicates that the rearrangement of the complex is closely related to that of e(sup -)[H(sub 2)O](sub 3), whereas the role of the halide anion is not as important.
- Published
- 2005
5. Geometrical and electronic structures of gold, silver, and gold-silver binary clusters: origins of ductility of gold and gold-silver alloy formation
- Author
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Han Myoung Lee, Maofa Ge, Sahu, B.R., Tarakeshwar, P., Kwang S. Kim, Akihik Tusda, Takashi Nakamura, and Atsuhiro Osuka
- Subjects
Chemistry, Physical and theoretical -- Research ,Silver alloys -- Structure ,Silver alloys -- Research ,Silver alloys -- Electric properties ,Gold alloys -- Structure ,Gold alloys -- Research ,Gold alloys -- Electric properties ,Chemicals, plastics and rubber industries - Abstract
The structures of neutral and anionic gold-silver binary clusters and pure gold and silver clusters are investigated. It is shown that the calculated electronic properties and dissociation energy of both pure and binary clusters are in agreement with the available experimental data.
- Published
- 2003
6. Halogen−π Interactions between Benzene and X2/CX4 (X = Cl, Br): Assessment of Various Density Functionals with Respect to CCSD(T)
- Author
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Joonho Lee, Michael Filatov, Jenica Marie L. Madridejos, Il Seung Youn, Maciej Kołaski, Chunggi Baig, Seung Koo Shin, Han Myoung Lee, Dong Yeon Kim, Woo Jong Cho, and Kwang S. Kim
- Subjects
Halogen bond ,010304 chemical physics ,Chemistry ,Supramolecular chemistry ,Aromaticity ,Interaction energy ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Crystallography ,Computational chemistry ,0103 physical sciences ,Halogen ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry ,Conformational isomerism - Abstract
Various types of interactions between halogen (X) and π moiety (X−π interaction) including halogen bonding play important roles in forming the structures of biological, supramolecular, and nanomaterial systems containing halogens and aromatic rings. Furthermore, halogen molecules such as X2 and CX4 (X = Cl/Br) can be intercalated in graphite and bilayer graphene for doping and graphene functionalization/modification. Due to the X−π interactions, though recently highly studied, their structures are still hardly predictable. Here, using the coupled-cluster with single, double, and noniterative triple excitations (CCSD(T)), the Moller–Plesset second-order perturbation theory (MP2), and various flavors of density functional theory (DFT) methods, we study complexes of benzene (Bz) with halogen-containing molecules X2 and CX4 (X = Cl/Br) and analyze various components of the interaction energy using symmetry adapted perturbation theory (SAPT). As for the lowest energy conformers (S1), X2–Bz is found to have the...
- Published
- 2016
7. Geometrical and Electronic Characteristics of AunO2– (n = 2–7)
- Author
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Geunsik Lee, Kwang S. Kim, Kee Hag Lee, and Han Myoung Lee
- Subjects
Photoemission spectroscopy ,Chemistry ,Electron ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,Coupled cluster ,Cluster (physics) ,Singlet state ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Triplet state ,Atomic physics ,Relativistic quantum chemistry ,Excitation - Abstract
Most density functionals do not properly describe the characteristics of superoxide (O2–) (i.e., first two vertical electron detachment energies and the excitation energies of neutralized singlet state) of small even-numbered AunO2– clusters. However, the second-order Moller–Plesset theory (MP2) shows significant charge transfer from Au cluster anions to oxygen molecule and so provides proper electronic characteristics of superoxide of small even-numbered AunO2– clusters. This has allowed us to properly describe the properties of even-numbered AunO2– clusters. Even in the case of odd-numbered AunO2– clusters, we find that Au5– is a chemically O2-adsorbed singlet state at 0 K, against a commonly accepted physisorbed triplet state. This is further evidenced by our extensive coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] calculations, including the relativistic effect. However, the entropy effect makes the physisorbed triplet state more stable than the chemisorbed singlet ...
- Published
- 2015
8. Triazine-Based Microporous Polymers for Selective Adsorption of CO2
- Author
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Kwang S. Kim, Muhammad Saleh, Seung Bin Baek, and Han Myoung Lee
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Chemistry ,Carbazole ,Inorganic chemistry ,Microporous material ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Adsorption ,Polymerization ,Selective adsorption ,Specific surface area ,Physical and Theoretical Chemistry ,Selectivity ,Triazine - Abstract
Propeller-shaped triazine was used to synthesize microporous polycarbazole materials through an inexpensive FeCl3-catalyzed reaction using direct oxidative coupling (PCBZ) and extensive cross-linking (PCBZL) polymerization routes. PCBZL has a Brunauer–Emmett–Teller specific surface area of 424 m2 g–1 and shows larger CO2 uptake (64.1 mg g–1 at 273 K, 1 atm). Selective adsorption of CO2 over N2 calculated using the ideal adsorbed solution theory shows that both PCBZ (125) and PCBZL (148) exhibit selectivity at 298 K, which is significantly higher than PCBZ (110) and PCBZL (82) at 273 K. These values of selectivity are among the highest reported for any triazine-based microporous material. By introducing the electron-rich carbazole structure into the nitrogen fertile triazine-based system, the adsorption enthalpy is increased drastically, which in turn contributes to high selective adsorption values. The larger existing binding energy between CO2 and propeller specifies more stable and favorable interaction...
- Published
- 2015
9. CO Capture and Conversion to HOCO Radical by Ionized Water Clusters
- Author
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Han Myoung Lee, Il-Seung Youn, and Kwang S. Kim
- Subjects
chemistry.chemical_compound ,Water dimer ,chemistry ,Computational chemistry ,Dimer ,Radical ,Molecule ,Hydroxyl radical ,Protonation ,Trimer ,Water cluster ,Physical and Theoretical Chemistry ,Photochemistry - Abstract
The CO molecule can interact with the hydroxyl radical ((•)OH) via either a weak noncovalent interaction or strong covalent bonding. Upon the ionization of neutral water clusters, the resulting water cluster cations produce protonated water clusters and hydroxyl radicals. In this regard, we investigate the interactions of a CO molecule with water dimer and trimer cations using density functional theory (DFT), Möller-Plesset second-order perturbation theory (MP2), and coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. It is found that the reaction products of CO by the water dimer and trimer cations form a HOĊO radical solvated by a protonated water monomer and dimer, respectively. These radicals are useful intermediates to make oxalic acids, formic acids, metal ligands, and so on, which is important in green chemistry.
- Published
- 2014
10. Halogen-π Interactions between Benzene and X
- Author
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Il Seung, Youn, Dong Yeon, Kim, Woo Jong, Cho, Jenica Marie L, Madridejos, Han Myoung, Lee, Maciej, Kołaski, Joonho, Lee, Chunggi, Baig, Seung Koo, Shin, Michael, Filatov, and Kwang S, Kim
- Abstract
Various types of interactions between halogen (X) and π moiety (X-π interaction) including halogen bonding play important roles in forming the structures of biological, supramolecular, and nanomaterial systems containing halogens and aromatic rings. Furthermore, halogen molecules such as X
- Published
- 2016
11. Hydrogen detachment of the hydrated hydrohalogen acids upon attaching an excess electron.
- Author
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Han Myoung Lee and Kim, Kwang S.
- Subjects
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HYDROGEN , *HALOGENS , *ELECTRONS , *DISSOCIATION (Chemistry) , *HALIDES , *HYDRATION , *MOLECULES - Abstract
High level ab initio calculations are employed to investigate the excess electron attachment to the hydrated hydrohalogen acids. The excess electron leads to the dissociation of hydrogen halide acids, which results in the release of a hydrogen radical. Neutral HCl, HBr, and HI are dissociated by tetrahydration. Upon binding an excess electron, these hydrated hydrohalogen acids show that (i) the H–X bond strength weakens with redshifted H–X stretching frequencies, (ii) HX can have a bound-electron state, a dissociated structure, or a zwitter-ionic structure, and (iii) HCl/HBr is dissociated by tri/mono-hydration, while HI is dissociated even without hydration. This dissociation is in contrast to the case of electron attachment to hydrated hydrogen fluoric acids for which HF is not dissociated by more than ten water molecules. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
12. Hydrated hydride anion clusters.
- Author
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Han Myoung Lee, Dongwook Kim, Singh, N. Jiten, Kołaski, Maciej, and Kim, Kwang S.
- Subjects
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DENSITY functionals , *HYDRIDES , *ANIONS , *BINDING energy , *THERMODYNAMICS , *MOLECULAR dynamics - Abstract
On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion hydrated by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
13. Structures, energetics, and spectra of aqua-cesium (I) complexes: An ab initio and experimental study.
- Author
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Kołaski, Maciej, Han Myoung Lee, Young Cheol Choi, Kim, Kwang S., Tarakeshwar, P., Miller, Dorothy J., and Lisy, James M.
- Subjects
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PHYSICAL & theoretical chemistry , *DENSITY functionals , *CESIUM , *CATIONS , *PROPERTIES of matter - Abstract
The design of cesium-selective ionophores must include the nature of cesium-water interactions. The authors have carried out extensive ab initio and density functional theory calculations of hydrated cesium cations to obtain reasonably accurate energetics, thermodynamic quantities, and IR spectra. An extensive search was made to find the most stable structures. Since water...water interactions are important in the aqua-Cs+ clusters, the authors investigated the vibrational frequency shifts as a function of the number of water molecules and the frequency characteristics with and without the presence of outer-shell water molecules. The predicted vibrational frequencies were then compared with the infrared photodissociation spectra of argon-tagged hydrated cesium cluster ions. This comparison allowed the identification of specific hydrogen-bonding structures present in the experimental spectra. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
14. Ab initio study of hydrated sodium halides NaX(H2O)1–6 (X=F, Cl, Br, and I).
- Author
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Olleta, Adriana C., Han Myoung Lee, and Kim, Kwang S.
- Subjects
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HALIDES , *DISSOCIATION (Chemistry) , *MOLECULES , *BINDING energy , *QUANTUM perturbations , *INFRARED spectroscopy - Abstract
We have studied the dissociation phenomena of sodium halides by water molecules. The structures, binding energies, electronic properties, and IR spectroscopic features have been investigated by using the density-functional theory, second-order Mo\ller-Plesset perturbation theory, and coupled clusters theory with single, double, and perturbative triplet excitations. In the case that the sodium halides are hydrated by three water molecules, the most stable structures show the partial (or half) dissociation feature. The dissociated structures are first found for NaX(H2O)n=5 for X=Br/I, though these structures are slightly higher in energy than the global minimum-energy structure. In the case of hexahydrated sodium halides the global minimum-energy structures (which are different from the structures reported in any previous work) are found to be dissociated (X=F/I) or partially/half dissociated (X=Cl/Br), while other nearly isoenergetic structures are undissociated, and the dissociated cubical structures are higher in energy than the corresponding global minimum-energy structure. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
15. Why the hydration energy of Au+ is larger for the second water molecule than the first one: Skewed orbitals overlap.
- Author
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Han Myoung Lee, Diefenbach, Martin, Seung Bum Suh, Tarakeshwar, P., and Kim, Kwang S.
- Subjects
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HYDRATION , *WATER , *MOLECULAR orbitals , *HEAT of hydration , *ELECTRON distribution , *MOLECULES - Abstract
Using molecular-orbital analysis, we have elucidated the quantum-chemical origin of the intriguing phenomena in sequential hydration energies of the gold cation, which is known to be the most conspicuous among all transition metals. The hydration energy of Au+ with the second water molecule is found to be much larger than that with the first water molecule. Owing to the large relativistic effect of gold (i.e., significant lowering of the 6s orbital energy and significant raising of the 5d orbital energy), the highest occupied molecular orbital of the hydrated gold cation has a large portion of the 6s orbital. As the electron density of the 6s orbital populates in a large outer spherical shell far off the gold nucleus, the p orbitals (or sp hybridized lone-pair orbitals) of the water molecules are able to overlap with the outer part of the 6s orbital in the dihydrated gold cation, resulting in the unusual skewed overlap of p-6s-p orbitals (not the atom-to-atom bond overlap). No previous molecular-orbital analysis has reported this peculiar skewed orbitals overlap. Since this skewed orbitals overlap is saturated with two water molecules, this property is responsible for the low coordination number of the gold ion. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
16. Insights into the structures, energetics, and vibrations of aqua-rubidium(I) complexes: Ab Initio study.
- Author
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Park, Jungwon, Ko&lslash;aski, Maciej, Han Myoung Lee, and Kim, Kwang S.
- Subjects
DENSITY functionals ,FUNCTIONAL analysis ,RUBIDIUM ,THERMODYNAMICS ,SCISSION (Chemistry) ,SPECTRUM analysis - Abstract
We have carried out ab initio and density functional theory calculations of hydrated rubidium cations. The calculations involve a detailed evaluation of the structures, thermodynamic properties, and IR spectra of several plausible conformers of Rb
+ (H2 O)n=1–8 clusters. An extensive search was made to find out the most stable conformers. Since the water-water interactions are important in hydrated Rb+ complexes, we investigated the vibrational frequency shifts of the OH stretching modes depending on the number of water molecules and the presence/absence of outer-shell water molecules. The predicted harmonic and anharmonic vibrational frequencies of the aqua-Rb+ clusters reflect the H-bonding signature, and would be used in experimental identification of the hydrated structures of Rb+ cation. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
17. Aqua dissociation nature of cesium hydroxide.
- Author
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Odde, Srinivas, Chaeho Pak, Han Myoung Lee, Kim, Kwang S., and Byung Jin Mhin
- Subjects
DISSOCIATION (Chemistry) ,INFRARED spectroscopy ,CESIUM ,HYDROXIDES ,WATER ,CLUSTER theory (Nuclear physics) - Abstract
To understand the mechanism of aqueous base dissociation chemistry, the ionic dissociation of cesium–hydroxide in water clusters is examined using density functional theory and ab initio calculations. In this study, we report hydrated structures, stabilities, thermodynamic quantities, dissociation energies, infrared spectra, and electronic properties of CsOH·(H
2 O)n=0–4 . With the addition of water molecules, the Cs–OH bond lengthened significantly from 2.46 Å for n=1 to 3.08 Å for n=4, which causes redshift in Cs–O stretching frequency. It is found that three water molecules are needed for the dissociation of Cs–OH, in contrast to the case of strong acid dissociation which requires at least four water molecules. However, the dissociation for n=3 could be considered as incomplete because a very weak CS...OH stretch mode is still present, while that for n=4 is complete since the Cs...OH mode no longer exists. This study can be related with hydration chemistry of cations and anions, and extended into the intra- and intercharge-transfer phenomena. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
18. Theoretical study of photoinduced electron transfer from tetramethylethylene to tetracyanoethylene.
- Author
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Hai-Bo Yi, Wim J., Xiao-Hui Duan, Wim J., Jin Yong Lee, Han Myoung Lee, Xiang-Yuan Li, Wim J., and Kim, Kwang S.
- Subjects
CHARGE exchange ,ETHYLENE compounds ,SOLVENTS - Abstract
Using ab initio and density functional calculations, we studied photoexcitation of a charge-balanced electron donor–acceptor (DA) complex comprised of tetracyanoethylene (TCE) and tetramethylethylene (TME). We considered both the TCE-TME stacked conformer and a possible conformer with a solvent molecule (dichloromethane) inserted between TCE and TME. The photoexcitation of the DA complex can directly form a charge transfer (CT) state. Our theoretical investigations show that the CT state can also be produced from the decay of higher excited states. Using the continuum model, we investigated the solvent effects on CT absorption, local excitation, and CT emission in the polar solvent. The equilibrium solvation energies of the ground and excited states of the DA complex were calculated using the self-consistent reaction field method, and then the correction of nonequilibrium solvation energies for the vertical transitions was made. The transition energies (i.e., CT absorption for the DA complexes and CT emission for the contact ion pair complexes) in the polar solvent show redshifts relative to those in the gas phase. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
19. Solvent rearrangement for an excited electron of I[sup -](H[sub 2]O)[sub 6]: Analog to structural rearrangement of e[sup -](H[sub 2]O)[sub 6].
- Author
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Han Myoung Lee, Seung Bum Suh, and Kim, Kwang S.
- Subjects
- *
CHARGE exchange , *SOLVATION , *ELECTRONS - Abstract
The study of electron solvation dynamics is vital for understanding the phenomena related to the electron transfer process in solvents. On the basis of a recent femtosecond dynamics study of charge-transfer-to-solvent states in photoexcited iodide–water clusters [Lehr et al., Science 284, 635 (1999)], we have investigated the solvent rearrangement process for the excited electron in the iodide–water hexamer using ab initio calculations. Upon excitation of iodide–water hexamer, an electron transfers from the iodide anion to the water cluster. This results in release of the iodine atom and thereby formation of anionic water hexamer which undergoes rearrangement process toward the most stable conformation. The transformation pathway from the low-lying energy structures of the iodide–water hexamer to those of the electron–water hexamer is thus elucidated from the potential energy surface including the global and local minima and transition states of the electron–water hexamer. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
20. Structures, energies, and spectra of aqua-silver (I) complexes.
- Author
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Eun Cheol Lee, Han Myoung Lee, Tarakeshwar, P., and Kim, Kwang S.
- Subjects
- *
SILVER , *OXIDATION-reduction reaction , *HYDRATION - Abstract
Owing to the utility of redox phenomena of silver in many chemical systems, it is important to understand the coordination chemistry of Ag[sup +] ion and hence the hydration structure. The lowest-energy conformations of Ag[sup +](H[sub 2]O)[sub 1–6] are sensitive to the calculation method employed. The coordination number (N[sub c]) of Ag[sup +](H[sub 2]O)[sub n] is predicted to be 2 for n=2–6 at the density functional theory level, while the N[sub c] for n=3–5 is 3, and that for n=6 is 4 at the second-order Møller–Plesset perturbation level. Further accurate analysis based on coupled-cluster singles and doubles theory with perturbative corrections for triple excitations agrees with the MP2 results except that N[sub c] of 4 is also as competitive as N[sub c] of 3 for n=5. To identify the correct N[sub c], it would be useful to facilitate the IR experimental characterization. We thus provide the OH spectra for various possible structures. It is interesting to note that the hydration chemistry of Ag[sup +] ion is somewhat different from that of alkali metal ions. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
21. Halides with Fifteen Aliphatic C–H···Anion Interaction Sites
- Author
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Aaron J. Teator, Bahareh Shirinfar, Kwang S. Kim, Dongwook Kim, Muhammad Yousuf, Lubna Rasheed, Zahra Aliakbar Tehrani, Genggongwo Shi, Dominika N. Lastovickova, Christopher W. Bielawski, Myoung Soo Lah, Nisar Ahmed, Woo Jong Cho, Il-Seung Youn, and Han Myoung Lee
- Subjects
Multidisciplinary ,Denticity ,010405 organic chemistry ,Chemistry ,Hydrogen bond ,Halide ,010402 general chemistry ,01 natural sciences ,Chloride ,Electric charge ,Article ,0104 chemical sciences ,Ion ,Crystallography ,medicine ,QD ,Binding site ,Anion binding ,medicine.drug - Abstract
Since the aliphatic C–H···anion interaction is relatively weak, anion binding using hydrophobic aliphatic C–H (Cali–H) groups has generally been considered not possible without the presence of additional binding sites that contain stronger interactions to the anion. Herein, we report X-ray structures of organic crystals that feature a chloride anion bound exclusively by hydrophobic Cali–H groups. An X-ray structure of imidazolium-based scaffolds using Cali–H···A− interactions (A− = anion) shows that a halide anion is directly interacting with fifteen Cali–H groups (involving eleven hydrogen bonds, two bidentate hydrogen-bond-type binding interactions and two weakly hydrogen-bonding-like binding interactions). Additional supporting interactions and/or other binding sites are not observed. We note that such types of complexes may not be rare since such high numbers of binding sites for an anion are also found in analogous tetraalkylammonium complexes. The Cali–H···A− interactions are driven by the formation of a near-spherical dipole layer shell structure around the anion. The alternating layers of electrostatic charge around the anion arise because the repulsions between weakly positively charged H atoms are reduced by the presence of the weakly negatively charged C atoms connected to H atoms.
- Published
- 2016
22. Ammonia-water cation and ammonia dimer cation
- Author
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Hahn Kim and Han Myoung Lee
- Subjects
Ammonia -- Chemical properties ,Ammonia -- Electric properties ,Density functionals -- Usage ,Infrared spectroscopy -- Usage ,Water -- Chemical properties ,Water -- Electric properties ,Chemicals, plastics and rubber industries - Published
- 2009
23. Structure, Stabilities, Thermodynamic Properties, and IR Spectra of Acetylene Clusters (C2H2)n=2-5
- Author
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Kwang S. Kim, S. Karthikeyan, and Han Myoung Lee
- Subjects
Chemistry ,Intermolecular force ,Trimer ,Symmetry (physics) ,Computer Science Applications ,chemistry.chemical_compound ,Acetylene ,Ab initio quantum chemistry methods ,Potential energy surface ,Physics::Atomic and Molecular Clusters ,Density functional theory ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Atomic physics ,Basis set - Abstract
There are no clear conclusions over the structures of the acetylene clusters. In this regard, we have carried out high-level calculations for acetylene clusters (C2H2)2-5 using dispersion-corrected density functional theory (DFT-D), Møller-Plesset second-order perturbation theory (MP2); and coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)] at the complete basis set limit. The lowest energy structure of the acetylene dimer has a T-shaped structure of C2v symmetry, but it is nearly isoenergetic to the displaced stacked structure of C2h symmetry. We find that the structure shows the quantum statistical distribution for configurations between the T-shaped and displaced stacked structures for which the average angle (|θ̃|) between two acetylene molecules would be 53-78°, close to the T-shaped structure. The trimer has a triangular structure of C3h symmetry. The tetramer has two lowest energy isomers of S4 and C2h symmetry in zero-point energy (ZPE)-uncorrected energy (ΔEe), but one lowest energy isomer of C2v symmetry in ZPE-corrected energy (ΔE0). For the pentamer, the global minimum structure is C1 symmetry with eight sets of T-type π-H interactions and a set of π-π interactions. Our high-level ab initio calculations are consistent with available experimental data.
- Published
- 2015
24. Interaction of Benzene with Transition Metal Cations: Theoretical Study of Structures, Energies, and IR Spectra
- Author
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Kwang S. Kim, Hai-Bo Yi, and Han Myoung Lee
- Subjects
Chemistry ,Binding energy ,Infrared spectroscopy ,Aromaticity ,Interaction energy ,Computer Science Applications ,Metal ,Crystallography ,Transition metal ,Computational chemistry ,visual_art ,visual_art.visual_art_medium ,Pi interaction ,Density functional theory ,Physical and Theoretical Chemistry - Abstract
The cation-π interactions have been intensively studied. Nevertheless, the interactions of π systems with heavy transition metals and their accurate conformations are not well understood. Here, we theoretically investigate the structures and binding characteristics of transition metal (TM) cations including novel metal cations (TM(n+) = Cu(+), Ag(+), Au(+), Pd(2+), Pt(2+), and Hg(2+)) interacting with benzene (Bz). For comparison, the alkali metal complex of Na(+)-Bz is also included. We employ density functional theory (DFT) and high levels of ab initio theory including Moller-Plesset second-order perturbation (MP2) theory, quadratic CI method with single and double substitutions (QCISD), and the coupled cluster theory with single, double, and perturbative triple excitations (CCSD(T)). Each of the transition metal complexes of benzene exhibits intriguing binding characteristics, different from the typical cation-π interactions between alkali metal cations and aromatic rings. The complexes of Na(+), Cu(+), and Ag(+) favor the conformation of C6v symmetry with the cation above the benzene centroid (πcen). The formation of these complexes is attributed to the electrostatic interaction, while the magnitude of charge transfer has little correlation with the total interaction energy. Because of the TM(n+)←π donation, cations Au(+), Pd(2+), Pt(2+), and Hg(2+) prefer the off-center π conformation (πoff) or the π coordination to a C atom of the benzene. Although the electrostatic interaction is still important, the TM←π donation effect is responsible for the binding site. The TM(n+)-Bz complexes give some characteristic IR peaks. The complexes of Na(+), Cu(+), and Ag(+) give two IR active modes between 800 and 1000 cm(-1),which are inactive in the pure benzene. The complexes of Au(+), Pd(2+), Pt(2+), and Hg(2+) give characteristic peaks for the ring distortion, C-C stretching, and C-H stretching modes as well as significant red-shifts in the CH out-of-plane bending.
- Published
- 2015
25. Anion Binding by Electron-Deficient Arenes Based on Complementary Geometry and Charge Distribution
- Author
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Kwang S. Kim, Inacrist Geronimo, Dong Young Kim, Han Myoung Lee, and N. Jiten Singh
- Subjects
Chemistry ,Halide ,Charge density ,Geometry ,Charge (physics) ,Electron ,Physical and Theoretical Chemistry ,Ring (chemistry) ,Selectivity ,Anion binding ,Computer Science Applications ,Ion - Abstract
Extended electron-deficient arenes are investigated as potential neutral receptors for polyanions. Anion binds via σ interaction with extended arenes, which are composed solely of C and N ring atoms and CN substituents. As a result, the positive charge on the aromatic C is enhanced, consequently maximizing binding strength. Selectivity is achieved because different charge distributions can be obtained for target anions of a particular geometry. The halides F(-) and Cl(-) form the most stable complex with 6, while the linear N3(-) interacts most favorably with 7. The trigonal NO3(-) and tetrahedral ClO4(-) fit the 3-fold rotational axis of 6 but do not form stable complexes with 5 and 7. The Y-shaped HCOO(-) forms complexes with 4, 5, and 7, with the latter being the most stable. Thus, the anion complexes exhibit strong binding and the best geometrical fit between guest and host, reminiscent of Lego blocks.
- Published
- 2015
26. Disulfuric acid dissociated by two water molecules: ab initio and density functional theory calculations
- Author
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Kwang S. Kim, Seong Kyu Kim, and Han Myoung Lee
- Subjects
Ab initio ,General Physics and Astronomy ,Ion ,chemistry.chemical_compound ,Crystallography ,Deprotonation ,Monomer ,chemistry ,Computational chemistry ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry ,Conformational isomerism ,Basis set - Abstract
We have studied geometries, energies and vibrational spectra of disulfuric acid (H2S2O7) and its anion (HS2O7(-)) hydrated by a few water molecules, using density functional theory (M062X) and ab initio theory (SCS-MP2 and CCSD(T)). The most noteworthy result is found in H2S2O7(H2O)2 in which the lowest energy conformer shows deprotonated H2S2O7. Thus, H2S2O7 requires only two water molecules, the fewest number of water molecules for deprotonation among various hydrated monomeric acids reported so far. Even the second deprotonation of the first deprotonated species HS2O7(-) needs only four water molecules. The deprotonation is supported by vibration spectra, in which acid O-H stretching peaks disappear and specific three O-H stretching peaks for H3O(+) (eigen structure) appear. We have also kept track of variations in several geometrical parameters, atomic charges, and hybrid orbital characters upon addition of water. As the number of water molecules added increases, the S-O bond weakens in the case of H2S2O7, but strengthens in the case of HS2O7(-). It implies that the decomposition leading to H2SO4 and SO3 hardly occurs prior to the 2nd deprotonation at low temperatures.
- Published
- 2015
27. Photoexcitation and photoionization dynamics of water photolysis
- Author
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Kumar, Anupriya, Kolaski, Maciej, Han Myoung Lee, and Kwang S. Kim
- Subjects
Photoionization -- Usage ,Photolysis -- Analysis ,Molecular dynamics -- Methods ,Molecular dynamics -- Usage ,Chemicals, plastics and rubber industries - Abstract
Water photoexcitation and ionization process are used for studying the water photolysis. Both photoexcited and photoionized mechanisms are elucidated by using excited-state ab initio molecular dynamics simulations based on complete active space self-consistent field approach and unresistricted Moller-Plesset second-order perturbation theory based Born-Oppenheimer molecular dynamics simulations.
- Published
- 2008
28. Water trimer cation
- Author
-
Kwang S. Kim and Han Myoung Lee
- Subjects
chemistry.chemical_compound ,Coupled cluster ,Hydronium ,chemistry ,Ab initio quantum chemistry methods ,Trimer ,Density functional theory ,Water cluster ,Interaction energy ,Physical and Theoretical Chemistry ,Atomic physics ,Molecular physics ,Self-ionization of water - Abstract
By using density functional theory (DFT) and high-level ab initio theory, we have investigated the structure, interaction energy, electronic property, and IR spectra of the water trimer cation [(H2O) 3 + ]. Two structures of the water trimer cation [the H3O+ containing linear (3Lp) structure versus the ring (3OO) structure] are compared. For the complete basis set (CBS) limit of coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)], the 3Lp structure is 11.9 kcal/mol more stable than the 3OO structure. This indicates that the ionization of water clusters produce the hydronium cation moiety (H3O+) and the hydroxyl radical. It is interesting to note that the calculation results of the water trimer cation vary seriously depending on the calculation level. At the level of Moller–Plesset second-order perturbation (MP2) theory, the stability of 3OO is underestimated due to the underestimated O…O hemibonding energy. This stability is also underestimated even for the CCSD(T) single point calculations on the MP2-optimized geometry. For the 3OO structure, the MP2 and CCSD(T) calculations give closed-ring structures with a hemi-bond between two O atoms, while the DFT calculations show open-ring structures due to the overestimated O…O hemibonding energy. Thus, in order to obtain reliable stabilities and frequencies of the water trimer cation, the CCSD(T) geometry optimizations and frequency calculations are necessary. In this regard, the DFT functionals need to be improved to take into account the proper O…O hemibonding energy.
- Published
- 2011
29. H2-Binding by Neutral and Multiply Charged Titaniums: Hydrogen Storage Capacity of Titanium Mono- and Dications
- Author
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Kwang S. Kim, Chaeho Pak, Han Myoung Lee, N. Jiten Singh, and Dong Young Kim
- Subjects
Hydrogen ,Chemistry ,Hydride ,Binding energy ,chemistry.chemical_element ,Covalent Interaction ,Computer Science Applications ,Hydrogen storage ,Crystallography ,Coupled cluster ,Ab initio quantum chemistry methods ,Density functional theory ,Physical and Theoretical Chemistry ,Atomic physics - Abstract
Given that transition metal-hydrogen systems have been studied as a predecessor for hydrogen storage materials, we have investigated the neutral and multiply charged titanium-H2 systems (Ti-H2, Ti(+)-H2, Ti(2+)-H2, Ti(3+)-H2, and Ti(4+)-H2) using density functional theory (DFT) and high-level ab initio calculations, including coupled cluster theory with single, double, and perturbatively triple excitations [CCSD(T)]. These systems show different types of hydrogenation depending on their charged state. The neutral Ti-H2 system shows dihydride structure with covalent interaction where the Ti-H distance is 1.76 Å, while H2 is dissociated into two neigboring hydride ions by withdrawing electrons from Ti. The charged Ti(+)-H2, Ti(2+)-H2, and Ti(3+)-H2 systems show dihydrogen structures with noncovalent interaction, where the Ti(+)-H, Ti(2+)-H, and Ti(3+)-H distances are 2.00, 2.14, and 2.12 Å, respectively. The main binding energies in these systems arise from the hydrogen polarizability driven interaction by the positive charge of Ti(n+) (n = 1-3). Among Ti(n+)-H2 (n = 1-3) the Ti(+)-H2 has the shortest distance against our common expectation, while Ti(2+)-H2 has the longest distance. The Ti(+)-H2 distance is the shortest because of the d-σ* molecular orbital (MO) interaction which is not present in Ti(2+)-H2 and Ti(3+)-H2. The Ti(4+) ion does not bind H2. In this regard, we have investigated the maximal hydrogen binding capacity by Ti complexes. The coordination of titanium mono- and dications complexed with dihydrogen (H2) [Ti(+)(H2)n and Ti(2+)(H2)m] is studied along with their structures, binding energies, electronic properties, and spectra. The titanium monocations of the quartet ground state have up to the hexacoordinaton, while titanium dications of the triplet ground state have up to the octacoordination at very low temperatures. At room temperature, the monocations favor penta- to hexacoordination, while the dications favor hexacoordination. This information would be useful for the design of hydrogen storage devices of Ti complexes, such as Ti-decorated/dispersed polymer-graphene hybrid materials.
- Published
- 2011
30. CO2 Capturing Mechanism in Aqueous Ammonia: NH3-Driven Decomposition−Recombination Pathway
- Author
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Han Myoung Lee, In-Chul Hwang, Kunwoo Han, Yeonchoo Cho, Je Young Kim, Kwang S. Kim, Dong Young Kim, and Seung Kyu Min
- Subjects
Carbonic acid ,Reaction mechanism ,Aqueous solution ,Inorganic chemistry ,Photochemistry ,Decomposition ,Catalysis ,chemistry.chemical_compound ,Ammonia ,Carbamic acid ,chemistry ,General Materials Science ,Amine gas treating ,Physical and Theoretical Chemistry - Abstract
Capturing CO2 by aqueous ammonia has recently received much attention due to its advantages over other state-of-the-art CO2-capture technology. Thus, understanding this CO2-capturing mechanism, which has been causing controversy, is crucial for further development toward advanced CO2 capture. The CO2 conversion mechanism in aqueous ammonia is investigated using ab initio calculations and kinetic simulations. We show full details of all reaction pathways for the NH3-driven conversion mechanism of CO2 with the pronounced effect of microsolvation. Ammonia performs multiple roles as reactant, catalyst, base, and product controller. Both carbamic and carbonic acids are formed by the ammonia-driven trimolecular mechanism. Ammonia in microsolvation makes the formation of carbamic acid kinetically preferred over carbonic acid. As the concentration of CO2 increases, the dominant product becomes carbonic acid. The conversion from carbamic acid into carbonic acid occurs through the decomposition−recombination pathwa...
- Published
- 2011
31. Understanding Drug-Protein Interactions in Escherichia coli FabI and Various FabI Inhibitor Complexes
- Author
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Han Myoung Lee and N. Jiten Singh
- Subjects
Chemistry ,Stereochemistry ,Enoyl-acyl carrier protein reductase ,Binding energy ,Aromaticity ,General Chemistry ,Reductase ,medicine.disease_cause ,Drug protein interactions ,Molecular dynamics ,chemistry.chemical_compound ,Amide ,medicine ,Escherichia coli - Abstract
Many ligands have been experimentally designed and tested for their activities as inhibitors against bacterial enoyl-ACP reductase (FabI), ENR. Here the binding energies of the reported ligands with the E. coli ENR- were calculated, analyzed and compared, and their molecular dynamics (MD) simulation study was performed. IDN, ZAM and AYM ligands were calculated to have larger binding energies than TCL and IDN has the largest binding energy among the considered ligands (TCL, S54, E26, ZAM, AYM and IDN). The contribution of residues to the ligand binding energy is larger in E. coli ENR-NAD+-IDN than in E. coli ENR--TCL, while the contribution of is smaller for IDN than for TCL. The large-size ligands having considerable interactions with residues and have many effective functional groups such as aromatic rings, acidic hydroxyl groups, and polarizable amide carbonyl groups in common. The cation- interactions have large binding energies, positively charged residues strongly interact with polarisable amide carbonyl group, and the acidic phenoxyl group has strong H-bond interactions. The residues which have strong interactions with the ligands in common are Y146, Y156, M159 and K163. This study of the reported inhibitor candidates is expected to assist the design of feasible ENR inhibitors.
- Published
- 2011
32. Hydration phenomena of sodium and potassium hydroxides by water molecules
- Author
-
Kumar, Anupriya, Mina Park, Joo Youn Huh, Han Myoung Lee, and Kim, Kwang S.
- Subjects
Thermodynamics -- Analysis ,Water -- Structure ,Water -- Chemical properties ,Water -- Thermal properties ,Dissociation -- Analysis ,Hydration (Chemistry) -- Analysis ,Chemicals, plastics and rubber industries - Abstract
The hydrated structures, dissociation energies, thermodynamic quantities, infrared spectra and electronic properties of alkali-metal hydroxides (MOH, M = Na and K) hydrated by up to six water molecules are investigated by using the density functional theory and Moller-Plesset second-order perturbation theory. The accurate analysis based on the coupled cluster theory with singles, doubles and perturbative triples excitations is more consistent with the MP2 results.
- Published
- 2006
33. Ammonia−Water Cation and Ammonia Dimer Cation
- Author
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Hahn Kim and Han Myoung Lee
- Subjects
Dimer ,Ab initio theory ,Water ,Infrared spectroscopy ,Hydrogen Bonding ,Interaction energy ,Ammonia ,chemistry.chemical_compound ,Crystallography ,Coupled cluster ,Models, Chemical ,chemistry ,Computational chemistry ,Cations ,Quantum Theory ,Computer Simulation ,Density functional theory ,Physical and Theoretical Chemistry ,Dimerization ,Basis set - Abstract
We have investigated the structure, interaction energy, electronic properties, and IR spectra of the ammonia-water cation (NH(3)H(2)O)(+) using density functional theory (DFT) and high-level ab initio theory. The ammonia-water cation has three minimum-energy structures of (a) H(2)NH(+)...OH(2), (b) H(3)N(+)...OH(2), and (c) H(3)NH(+)...OH. The lowest-energy structure is (a), followed by (c) and (b). The ammonia dimer cation has two minimum-energy structures [the lowest H(3)NH(+)...NH(2) structure and the second lowest (H(3)N...NH(3))(+) structure]. The minimum transition barrier for the interconversion between (a), (b), and (c) is approximately 6 kcal/mol. Most DFT calculations with various functionals, except a few cases, overstabilize the N...O and N...N binding, predicting different structures from Moller-Plesset second-order perturbation (MP2) theory and the most reliable complete basis set (CBS) limit of coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. Thus, the validity test of the DFT functionals for these ionized molecular systems would be of importance.
- Published
- 2009
34. Water Dimer Cation: Density Functional Theory vs Ab Initio Theory
- Author
-
Kwang S. Kim and Han Myoung Lee
- Subjects
Water dimer ,Hydronium ,Ionic bonding ,Interaction energy ,Computer Science Applications ,Ion ,chemistry.chemical_compound ,Coupled cluster ,chemistry ,Computational chemistry ,Physical chemistry ,Density functional theory ,Physical and Theoretical Chemistry ,Self-ionization of water - Abstract
By using density functional theory (DFT) and high-level ab initio theory, the structure, interaction energy, electronic property, and IR spectra of the water dimer cation [(H2O)2(+)] are investigated. Two previously reported structures of the water dimer cation [disproportionated ionic (Ion) structure and hydrazine-like (OO) structure] are compared. For the complete basis set (CBS) limit of coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)], the Ion structure is much more stable (by 11.7 kcal/mol). This indicates that the ionization of water clusters produce the hydronium cation moiety (H3O(+)) and the hydroxy radical. The transition barrier for the interconversion from the Ion/OO structure is ∼15/∼9 kcal/mol. It is interesting to note that the calculation results of the water dimer cation vary seriously depending on calculation methods. Moller-Pleset second-order perturbation (MP2) theory gives reasonable relative energies in favor of the Ion structure but reports unreasonable frequencies for the OO structure. On the other hand, most DFT calculations with various functionals overstabilize the OO structure. However, the DFT results with MPW1K and BH&HLYP functionals are very close to the CCSD(T)/CBS results. Thus, as for the validity test of the DFT functionals for ionized molecular systems, the energy comparison of two water dimer cation structures would be a very important criterion.
- Published
- 2009
35. Structures of tri-, tetra-, and hexahydrated hydride anion clusters
- Author
-
Han Myoung Lee, Kwang S. Kim, and David J. Anick
- Subjects
biology ,Hydride ,Chemistry ,Binding energy ,Infrared spectroscopy ,Condensed Matter Physics ,biology.organism_classification ,Atomic and Molecular Physics, and Optics ,Ion ,Crystallography ,Computational chemistry ,Ab initio quantum chemistry methods ,Tetra ,Density functional theory ,Physical and Theoretical Chemistry ,Electronic properties - Abstract
We have reinvestigated the structures of hydrated hydride anion clusters, using density functional theory and high-level ab initio theory. We find new low-lying energy structures for H(H2O)n3,4,6 which are compatible with previously reported structures. The binding energies, electronic properties, and IR spectra of these competing low-energy hydrated hydride anion clusters are reported to facilitate experiments. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 1820 -1826, 2009
- Published
- 2009
36. Photodissociation of Hydrated Hydrogen Iodide Clusters
- Author
-
Kwang S. Kim, Han Myoung Lee, and Maciej Kołaski
- Subjects
Free Radicals ,Hydrogen ,Hydronium ,Photochemistry ,Ultraviolet Rays ,Radical ,Inorganic chemistry ,Iodine Compounds ,chemistry.chemical_element ,Iodic acid ,chemistry.chemical_compound ,Ultraviolet light ,Computer Simulation ,Physical and Theoretical Chemistry ,Chemistry ,Photodissociation ,Water ,Atomic and Molecular Physics, and Optics ,Models, Chemical ,Halogen ,Quantum Theory ,Hydrogen iodide ,Acids ,Iodine - Abstract
Using high-level ab initio calculations and excited state ab initio molecular dynamics simulations, we show that hydrated iodic acids release hydrogen radicals and/or hydrogen molecules as well as iodine radicals upon excitation. Its photoreaction process involving charge transfer to the solvent takes place in four steps: 1) hydration of the acid, 2) charge transfer to water upon excitation of hydrated acid, 3) detachment of the neutral iodine atom, and 4) detachment of the hydrogen radical. The iodine detachment process from excited hydrated hydro-iodic acids is exothermic and the detachment of hydrogen radicals from hydrated hydronium radicals is spontaneous if the initial kinetic energy of the cluster is high enough to get over the activation barrier of the detachment. The complete release of the radicals can be understood in terms of kinetics. This study shows how the hydrogen and halogen radicals are dissociated and released from their hydrated acids. Simple experiments corroborate our predicted mechanism for the release of hydrogen molecules from iodic acid in water by ultraviolet light.
- Published
- 2008
37. Insights into the structures, energetics, and vibrations of monovalent cation-(water)(sub 1-6) clusters
- Author
-
Han Myoung Lee, Tarakeshwar, P., Park, Jungwon, Kolaski, Maciej Roman, Yeo Jin Yoon, Hai-Bo Yi, Woo Youn Kim, and Kwang S. Kim
- Subjects
Alkali metals -- Research ,Chemistry, Physical and theoretical -- Analysis ,Oxonium ions -- Research ,Ammonia -- Research ,Chemicals, plastics and rubber industries - Abstract
The theoretical studies yield several insights into the interactions prevailing in aqueous clusters of monovalent alkali metal, ammonium, and hydronium cations. The second order Moller-Plesset (MPs) and density functional levels of theory are used for the calculations of the structures, thermodynamic energies and IR spectra of several plausible conformers.
- Published
- 2004
38. Photoswitch and nonlinear optical switch: Theoretical studies on 1,2-bis-(3-thienyl)-ethene...
- Author
-
Majumdar, D. and Han Myoung Lee
- Subjects
- *
SEMICONDUCTOR switches , *ALKENES , *NONLINEAR optics - Abstract
Studies photoswitch molecules of the 1,2-bis-(3-thienyl)-ethene derivatives class. Structures; Photophysics; Molecular properties at the ground and excited states; Applications in the design of nonlinear optical switches.
- Published
- 1999
- Full Text
- View/download PDF
39. Charge-Transfer-to-Solvent-Driven Dissolution Dynamics of I-(H2O)2-5upon Excitation: Excited-State ab Initio Molecular Dynamics Simulations
- Author
-
Kwang S. Kim, Han Myoung Lee, Chaeho Pak, and Maciej Kołaski
- Subjects
Models, Molecular ,education.field_of_study ,Free Radicals ,Chemistry ,Radical ,Population ,Solvation ,Water ,Halide ,Electrons ,General Chemistry ,Biochemistry ,Catalysis ,Dissociation (chemistry) ,Colloid and Surface Chemistry ,Solubility ,Chemical physics ,Computational chemistry ,Excited state ,Computer Simulation ,Water cluster ,education ,Dissolution ,Iodine - Abstract
In contrast to the extensive theoretical investigation of the solvation phenomena, the dissolution phenomena have hardly been investigated theoretically. Upon the excitation of hydrated halides, which are important substances in atmospheric chemistry, an excess electron transfers from the anionic precursor (halide anion) to the solvent and is stabilized by the water cluster. This results in the dissociation of hydrated halides into halide radicals and electron-water clusters. Here we demonstrate the charge-transfer-to-solvent (CTTS)-driven femtosecond-scale dissolution dynamics for I-(H2O)n=2-5 clusters using excited state (ES) ab initio molecular dynamics (AIMD) simulations employing the complete-active-space self-consistent-field (CASSCF) method. This study shows that after the iodine radical is released from I-(H2O)n=2-5, a simple population decay is observed for small clusters (2
- Published
- 2007
40. Hydrogen detachment of the hexahydrated hydroiodic acid upon attaching an excess electron
- Author
-
Han Myoung Lee, Byung Jin Mhin, Kwang S. Kim, Seung Bum Suh, and Srinivas Odde
- Subjects
chemistry.chemical_classification ,Hydrogen ,Iodide ,Biophysics ,Ab initio ,chemistry.chemical_element ,Electron ,Condensed Matter Physics ,Kinetic energy ,Photochemistry ,chemistry ,Computational chemistry ,Excited state ,Cluster (physics) ,Molecule ,Physical and Theoretical Chemistry ,Molecular Biology - Abstract
A hydroiodic acid molecule is dissociated by more than four water molecules. Here, the effect of an excess electron on the hexahydated hydroiodic acid where the dissociated structure [H3O+(H2O)5I−] is much more stable than the undissociated one [(H2O)6HI], is investigated. Upon binding an excess electron (e−), the cluster releases a hydrogen radical and forms the stable hexahydrated iodide [(H2O)6I−] when the initial kinetic energy is above ∼200 K, due to the small transition barrier (∼0.5 eV). The system with the hydrogen radical released, [(H2O)6I− + H·], is much more stable than the systems with an excess electron, [(H3O)+{e−(H2O)5}I−] or [e−(H2O)2(H3O)+(H2O)3I−].
- Published
- 2007
41. Understanding Clusters toward the Design of Functional Molecules and Nanomaterials
- Author
-
Kwang S. Kim, N. Jiten Singh, Eun-Cheol Lee, Han Myoung Lee, and Young Cheol Choi
- Subjects
Functional importance ,Chemistry ,Cluster systems ,Metallic clusters ,Nanotechnology ,General Chemistry ,Nanomaterials - Abstract
In this account, we highlight the theoretical investigations of various cluster systems comprising of water clusters, π-containing clusters, and metallic clusters. We illustrate how these investiga...
- Published
- 2007
42. Designing Ionophores and Molecular Nanotubes Based on Molecular Recognition
- Author
-
Kwang S. Kim, Han Myoung Lee, N. Jiten Singh, and In-Chul Hwang
- Subjects
Molecular recognition ,Interaction forces ,Hydrogen bond ,Chemistry ,Intermolecular force ,Ionic bonding ,Organic chemistry ,Nanotechnology ,General Chemistry ,Self-assembly ,Conformational isomerism ,Electrochemical potential - Abstract
In this mini-review we briefly describe intermolecular interactions ranging from hydrogen bonding to ionic interactions to aromatic interactions. Manifestation of these interaction forces is in the design and realization of various ionophores with chemo-sensing capability for biologically important cations and anions. We also explain how the understanding of hydrogen bonding and π-interactions has led to the design of self-assembled organic nanotubes. We further discuss the conformational changes between stacked and edge-to-face conformers in benzoquinone-benzene complexes, which are controlled by alternating electrochemical potential. The resulting flapping motion illustrates a promising pathway toward the design of nanomechanical devices.
- Published
- 2007
43. Electron bound to hydrated hydrogen fluoric acids
- Author
-
Han Myoung Lee, Byung Jin Mhin, and Srinivas Odde
- Subjects
Phase transition ,Hydrogen ,Coordination number ,chemistry.chemical_element ,Condensed Matter Physics ,Hydrogen fluoride ,Biochemistry ,chemistry.chemical_compound ,Crystallography ,Hydrofluoric acid ,chemistry ,Tetramer ,Computational chemistry ,Cluster (physics) ,Molecule ,Physical and Theoretical Chemistry - Abstract
Electron(e)-binding hydrated hydrogen fluoride clusters [e–HF(H2O)n=1–10] have been studied with density functional and ab intio calculations. The hydrofluoric acid in e–HF(H2O)n clusters is found to be undissociated at 0 K till n = 10. The e–HF(H2O)3 cluster is particularly unstable compared with the corresponding neutral structures, which reflects the particularly unstable antimagic number of e–water tetramer. The characteristic of “magic” numbers of electron–water clusters appears in these e–(HF)(H2O)n clusters. The vertical detachment energies of e–HF(H2O)n are enhanced by the HF acid as compared with those of the e-binding water clusters [e–(H2O)n + 1], and the excess electron is surface bound near the terminal water molecule with two dangling hydrogen atoms. The coordination number of HF is one for n = 1–4 as a linear structure in contrast to two for n = 5–6, and three for n = 7–10. The phase transition from 2- to 3-dimensional structures appears at penta-hydrated system in contrast to hepta-hydrated system for neutral HF–water clusters. The structures for e–HF(H2O)n=2,3 are quite different from those of the corresponding e–(H2O)n + 1 = 3,4, and the structures for e–HF(H2O)n = 2–6 are quite different from those of the corresponding HF(H2O)n = 2–6.
- Published
- 2007
44. De novo design approach based on nanorecognition toward development of functional molecules/materials and nanosensors/nanodevices
- Author
-
Seung Bum Suh, Kwang S. Kim, N. Jiten Singh, and Han Myoung Lee
- Subjects
Molecular switch ,chemistry.chemical_compound ,Hydroquinone ,Chemistry ,Nanosensor ,Hydrogen bond ,General Chemical Engineering ,Ionic bonding ,Nanotechnology ,Protein folding ,General Chemistry ,Conformational isomerism ,Quinone - Abstract
For the design of functional molecules and nanodevices, it is very useful to utilize nanorecognition (which is governed mainly by interaction forces such as hydrogen bonding, ionic interaction, π-H/π-π interactions, and metallic interactions) and nanodynamics (involving capture, transport, and release of electrons, photons, or protons). The manifestation of these interaction forces has led us to the design and realization of diverse ionophores/receptors, organic nanotubes, nanowires, molecular mechanical devices, molecular switches, enzyme mimetics, protein folding/unfolding, etc. In this review, we begin with a brief discussion of the interaction forces, followed by some of our representative applications. We discuss ionophores with chemo-sensing capability for biologically important cations and anions and explain how the understanding of hydrogen bonding and π-interactions has led to the design of self-assembled nanotubes from calix[4]hydroquinone (CHQ). The binding study of neutral and cationic transition metals with the redox system of hydroquinone (HQ) and quinone (Q) predicts what kind of nanostructures would form. Finally, we look into the conformational changes between stacked and edge-to-face conformers in π-benzoquinone-benzene complexes controlled by alternating electrochemical potential. The resulting flapping motion illustrates a promising pathway toward the design of mobile nanomechanical devices.
- Published
- 2007
45. Interactions of CO2 with various functional molecules
- Author
-
Kwang S. Kim, Il Seung Youn, Muhammad Saleh, Jung Woo Lee, and Han Myoung Lee
- Subjects
Models, Molecular ,Indoles ,Triazines ,Binding energy ,Ab initio ,Molecular Conformation ,General Physics and Astronomy ,Carbon Dioxide ,Vibration ,chemistry.chemical_compound ,Coupled cluster ,chemistry ,Computational chemistry ,Molecule ,Quantum Theory ,Metal-organic framework ,Density functional theory ,Physical and Theoretical Chemistry ,Guanidine ,Melamine ,Azabicyclo Compounds - Abstract
The CO2 capturing and sequestration are of importance in environmental science. Understanding of the CO2-interactions with various functional molecules including multi-N-containing superbases and heteroaromatic ring systems is essential for designing novel materials to effectively capture the CO2 gas. These interactions are investigated using density functional theory (DFT) with dispersion correction and high level wave function theory (resolution-of-identity (RI) spin-component-scaling (scs) Moller-Plesset second-order perturbation theory (MP2) and coupled cluster with single, double and perturbative triple excitations (CCSD(T))). We found intriguing molecular systems of melamine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-azaindole and guanidine, which show much stronger CO2 interactions than the well-known functional systems such as amines. In particular, melamine could be exploited to design novel materials to capture the CO2 gas, since one CO2 molecule can be coordinated by four melamine molecules, which gives a binding energy (BE) of ∼85 kJ mol(-1), much larger than in other cases.
- Published
- 2015
46. Highly stereospecific epimerization of alpha-amino acids: conducted tour mechanism
- Author
-
Bandyopadhyay, Indrajit, Han Myoung Lee, Tarakeshwar, P., Chunzhi Cui, Kyong Seok Oh, Jik Chin, and Kwang S. Kim
- Subjects
Density functionals -- Usage ,Cobalt ,Coordination compounds -- Composition ,Amino acids ,Stereochemistry -- Research ,Organic compounds -- Composition ,Chemistry, Organic -- Research ,Biological sciences ,Chemistry - Abstract
The authors have investigated alpha-amino acids exhibited by cobalt(III) metal complex. They report that the stereospecific and regiospecific recognition of these acids has been rationalized from the structural characteristics via the use of density functional calculations.
- Published
- 2003
47. Interactions of Neutral and Cationic Transition Metals with the Redox System of Hydroquinone and Quinone: Theoretical Characterization of the Binding Topologies, and Implications for the Formation of Nanomaterials
- Author
-
Han Myoung Lee, Kwang S. Kim, Martin Diefenbach, Eun Cheol Lee, Byung Hee Hong, Young Cheol Choi, and Hai-Bo Yi
- Subjects
Hydroquinone ,Chemistry ,Organic Chemistry ,Quinones ,Cationic polymerization ,General Chemistry ,Electrochemistry ,Photochemistry ,Redox ,Catalysis ,Hydroquinones ,Nanostructures ,Nanoclusters ,Quinone ,chemistry.chemical_compound ,Transition metal ,Metals ,Cations ,Transition Elements ,Pi interaction ,Oxidation-Reduction - Abstract
To understand the self-assembly process of the transition metal (TM) nanoclusters and nanowires self-synthesized by hydroquinone (HQ) and calix[4]hydroquinone (CHQ) by electrochemical redox processes, we have investigated the binding sites of HQ for the transition-metal cations TM(n+)=Ag(+), Au(+), Pd(2+), Pt(2+), and Hg(2+) and those of quinone (Q) for the reduced neutral metals TM(0), using ab initio calculations. For comparison, TM(0)-HQ and TM(n+)-Q interactions, as well as the cases for Na(+) and Cu(+) (which do not take part in self-synthesis by CHQ) are also included. In general, TM-ligand coordination is controlled by symmetry constraints imposed on the respective orbital interactions. Calculations predict that, due to synergetic interactions, silver and gold are very efficient metals for one-dimensional (1D) nanowire formation in the self-assembly process, platinum and mercury favor both nanowire/nanorod and thin film formation, while palladium favors two-dimensional (2D) thin film formation.
- Published
- 2006
48. Assembling phenomena of calix[4]hydroquinone nanotube bundles by one-dimensional short hydrogen bonding and displaced pi-pi stacking
- Author
-
Kwang S. Kim, Seung Bum Suh, Chi-Wan Lee, Seung Joo Cho, Sukmin Jeong, Jun-Hyung Cho, Jong Chan Kim, Byung Hee Hong, Eun Cheol Lee, Sunggoo Yun, Tarakeshwar, P., Jin Yong Lee, Yukyung Kim, Hyejae Ihm, Heon Gon Kim, Jung Woo Lee, Jung Kyung Kim, Han Myoung Lee, Dongwook Kim, Chunzhi Cui, Suk Joo Youn, Hae Yong Chung, and Hyuck Soon Choi
- Subjects
Hydrogen bonding -- Observations ,Nanotubes -- Research ,Cyclic compounds -- Research ,Chemistry - Abstract
The synthesis of calix[4]hydroquinone nanotube arrays self-assembled with infinitely long one-dimensional (1-D) short hydrogen bonds and aromatic-aromatic interactions is presented. The competition between H-bonding and displaced pi-pi stacking in the assembling process is described.
- Published
- 2002
49. Study of interactions of various ionic species with solvents toward the design of receptors
- Author
-
Adriana C. Olleta, Mina Park, Kwang S. Kim, Han Myoung Lee, Anupriya Kumar, Indrajit Bandyopadhyay, Pilarisetty Tarakeshwar, N. Jiten Singh, and Hai-Bo Yi
- Subjects
Solvent ,chemistry.chemical_compound ,Hydronium ,Chemistry ,Computational chemistry ,Ab initio quantum chemistry methods ,Inorganic chemistry ,Ab initio ,Halide ,Ionic bonding ,Hydroxide ,Physical and Theoretical Chemistry ,Alkali metal - Abstract
In earlier studies, the interactions of isolated ionic species with various solvents were investigated using ab initio calculations. The ionic species investigated included cations (proton, hydronium, ammonium, and metal cations) and anions (single electron, hydroxide, and halide anions). However in the present study, we investigate the interactions of these ionic species with the solvent in the presence of other competing ionic species. We also elaborate on how the information obtained from these extensive studies have been employed in designing and synthesizing various kinds of novel ionophores and receptors.
- Published
- 2005
50. Theoretical Investigation of Normal to Strong Hydrogen Bonds
- Author
-
Kwang S. Kim, Chaeho Pak, Han Myoung Lee, Dongwook Kim, and Jong Chan Kim
- Subjects
Ab initio quantum chemistry methods ,Computational chemistry ,Chemistry ,Hydrogen bond ,Chemical polarity ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Spectral line - Abstract
We review our theoretical work done on a variety of different chemical systems, which show different H-bonding characteristics. The systems include water clusters, its interactions with polar molecules and π-systems, organic nanotubes, enzymes, and ionophores/receptors. Special features of normal, short, short strong, and π-type H-bonding interactions in these systems are discussed in terms of structures, interaction energies, and spectra.
- Published
- 2005
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