Han Myoung Lee's research while affiliated with Ulsan National Institute of Science and Technology and other places

Publications (94)

Article
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 bi...
Article
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 anio...
Article
Full-text available
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 anio...
Article
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. T...
Article
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 Møller-Plesset theory (MP2) shows significant charge transfer from Au cluster ani...
Article
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 densi...
Article
Propeller shaped triazine was used to synthesize microporous polycarbazole materials through an inexpensive FeCl3 catalyzed reaction using direct oxidative coupling (PCBZ) and extensive crosslinking (PCBZL) polymerization routes. PCBZL has a Brunauer-Emmett-Teller specific surface area (SSA) of 424 m2 g-1 and shows larger CO2 uptake (64.1 mg g-1 at...
Article
The largest obstacles for landfill/flue gas separation using microporous materials are small adsorption values and low selectivity ratios. This study demonstrates that these adsorption and selectivity challenges can be overcome by utilizing a series of hypercrosslinked heterocyclic polymer networks. These microporous organic polymers (MOPs) were sy...
Article
The CO molecule can interact with the hydroxyl radical (∙OH) via either a weak non-covalent 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 di...
Article
Despite utmost importance in understanding water ionization process, reliable theoretical results of structural changes and molecular dynamics (MD) of water clusters on ionization have hardly been reported yet. Here, we investigate the water cations [(H2 O)n = 2-6 (+) ] with density functional theory (DFT), Möller-Plesset second-order perturbation...
Article
Since gold clusters have mostly been studied theoretically by using DFT calculations, more accurate studies are of importance. Thus, small neutral and anionic gold clusters (Au(n) and Au(n) (-) , n=4-7) were investigated by means of coupled cluster with singles, doubles, and perturbative triple excitations [CCSD(T)] calculations with large basis se...
Article
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...
Article
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 comp...
Article
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 inves...
Article
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, Ti2+−H2, Ti3+−H2, and Ti4+−H2) using density functional theory (DFT) and high-level ab initio calculations, including coupled cluster theory with si...
Article
Triclosan (5-chloro-2-(2,4-dichloro-phenoxy)-phenol, TCL) is a well known inhibitor against enoyl-acyl carrier protein reductase (ENR), an enzyme critical for cell-wall synthesis of bacteria. The inhibitory concentration at 50% inhibition (IC(50)) of TCL against the Escherichia coli ENR is 150nM for wild type (WT), 380, 470 and 68,500nM for Ala, Se...
Article
Protonated and deprotonated adipic acids (PAA: HOOC-(CH(2))(4)--COOH(2) (+) and DAA: HOOC-(CH(2))(4)-COO(-)) have a charged hydrogen bond under the influence of steric constraint due to the molecular skeleton of a circular ring. Despite the similarity between PAA and DAA, it is surprising that the lowest energy structure of PAA is predicted to have...
Article
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 perturbati...
Article
Short Strong Hydrogen Bonds (SSHBs) play an important role in many fields of physics, chemistry and biology. Since it is known that SSHBs exist in many biological systems, the role of hydrogen bonding motifs has been particularly interesting in enzyme catalysis, bio-metabolism, protein folding and proton transport phenomena. To explore the characte...
Article
Full-text available
Group I and II metal amidoboranes have been identified as one of the promising families of materials for efficient H(2) storage. However, the underlying mechanism of the dehydrogenation of these materials is not well understood. Thus, the mechanisms and kinetics of H(2) release in metal amidoboranes are investigated using high level ab initio calcu...
Article
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)n=3,4,6 which are compatible with previously reported structures. The binding energies, electronic properties, and IR spectra of these competing low-energy hydr...
Article
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 lowe...
Article
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 (TMn+ = Cu+, Ag+, Au+...
Article
We have investigated the issue of two-dimensional (2D) versus three-dimensional (3D) structures for neutral-state Au10 and clarified the lowest-energy structure among a few 2D Au10− isomers. Though almost all previous works were based on density functional theory (DFT), we here carried out not only extensive DFT calculations but also high levels of...
Article
Alkali-metal amidoboranes have been recently highlighted as materials that satisfy many of the criteria required to make hydrogen-storage media. It is, therefore, crucial for us to understand the dehydrogenation mechanism of these materials for further development towards making successful hydrogen-storage media. In the present study, we attempt to...
Article
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....
Article
Despite the importance of water photolysis in atmospheric chemistry, its mechanism is not well understood. Two different mechanisms for water photolysis have been proposed. The first mechanism is driven by water photoexcitation, followed by the reaction of the active hydrogen radical with water clusters. The second mechanism is governed by the ioni...
Article
Using basis-set extrapolation schemes for a given data set, we evaluated the binding energies and geometries at the complete basis set (CBS) limit at the levels of the second order Møller-Plesset perturbation theory (MP2) and the coupled cluster theory with singles, doubles, and perturbative triples excitations [CCSD(T)]. The systems include the hy...
Article
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, thes...
Article
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,...
Article
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 stabi...
Article
Full-text available
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) sho...
Article
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)(5)I-] is much more stable than the undissociated one [(H2O)(6)HI], is investigated. Upon binding an excess electron (e(-)), the cluster releases a hydrogen...
Article
In this account, we highlight the theoretical investigations of various cluster systems comprising of water clusters, -containing clusters, and metallic clusters. We illustrate how these investigations help us understand and design struc-tures and properties of nanowires, novel functional ionophores/receptors, and nanomaterials. Many of these theor...
Article
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 unders...
Article
The ionic dissociation of salts was examined with a theoretical study of KX (X=F,Cl,Br,I) hydrated by up to six water molecules KX(H2O)n (n=1-6). Calculations were done using the density functional theory and second order Møller-Plesset (MP2) perturbational theory. To provide more conclusive results, single point energy calculations using the coupl...
Article
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 0K till n=10. The e–HF(H2O)3 cluster is particularly unstable compared with the corresponding neutral structures, which reflects t...
Article
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 stabl...
Article
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 [MOH(H(2)O)(n=1-6)], are investigated by using the density functional theory and Møller-Plesset second-order perturbation theory. Further accurate...
Article
Full-text available
Despite intensive studies of the neutral tropyl radical, none of its structure, energetics, and vibrational modes are still clear. This system has puzzled scientists for over a decade since one vibrational mode frequency sharply varies from imaginary number 3000i cm-1 to the real number 6000 cm-1, depending on the calculation methods employed. We f...
Article
Full-text available
On the basis of first-principles calculations of clusters and one dimensional infinitely long subnanowires of the binary systems, we find that alkali-noble metal alloy wires show better linearity and stability than either pure alkali metal or noble metal wires. The enhanced alternating charge buildup on atoms by charge transfer helps the atoms line...
Article
On the basis of first-principles calculations of clusters and one dimensional infinitely long subnanowires of the binary systems, we find that alkali-noble metal alloy wires show better linearity and stability than either pure alkali metal or noble metal wires. The enhanced alternating charge buildup on atoms by charge transfer helps the atoms line...
Article
The hydration and dissociation phenomena of HF(H(2)O)(n)() (n < or = 10) clusters have been studied by using both the density functional theory with the 6-311++G[sp] basis set and the Møller-Plesset second-order perturbation theory with the aug-cc-pVDZ+(2s2p/2s) basis set. The structures for n > or = 8 are first reported here. The dissociated form...
Article
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...
Article
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 interaction...
Article
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 Moller-Plesset perturbation theory, and coupled clusters theory with single, double, and perturbative trip...
Article
We review various types of hydrogen bond characteristics based on our theoretical work of diverse chemical systems. The systems include water clusters, hydrated clusters, enzymes, ionophores/receptors, and assembled molecules such as organic nanotubes. Special features of weak, normal, short, short strong H-bonding are discussed in terms of structu...
Chapter
This chapter discusses how the insights obtained from theoretical investigations of various cluster systems have enabled a researcher to predict structures and properties of novel functional molecular systems. Clusters are self-assembled structures comprised of a number of monomers under the given condition. Apart from aiding the development of nov...
Article
Upon excitation of Cl(-)(H(2)O)(3) and I(-)(H(2)O)(3) clusters, the electron transfers from the anionic precursor to the solvent, and then the excess electron is stabilized by polar solvent molecules. This process has been investigated using ab initio molecular dynamics (AIMD) simulations of excited states of Cl(-)(H(2)O)(3) and I(-)(H(2)O)(3) clus...
Article
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...
Article
The structures, stabilities, thermodynamic quantities, dissociation energies, infrared spectra, and electronic properties of LiOH hydrated by up to seven water molecules are investigated by using the density-functional theory and the Møller-Plesset second-order perturbation theory (MP2). Further accurate analysis based on the coupled-cluster theory...
Article
Full-text available
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 interacti...
Article
To understand the hydration phenomena of noble transition metals, we investigated the structures, hydration energies, electronic properties, and spectra of the Cu+(H3O)1–6 and Au+(H2O)1–6 clusters using ab initio calculations. The coordination numbers of these clusters are found to be only two, which is highly contrasted to those of Ag+(H2O)n (whic...
Article
Electron-bound water clusters [e(-)(H(2)O)(n)] show very strong peaks in mass spectra for n=2, 6, 7, and (11), which are called magic numbers. The origin of the magic numbers has been an enigma for the last two decades. Although the magic numbers have often been conjectured to arise from the intrinsic properties of electron-bound water clusters, we...
Article
The structures of electron-bound and neutral clusters of HF(H2O)n (n=1-3) were optimized at the level of second-order Moller-Plesset perturbation theory (MP2). Then, the energies were studied using the coupled cluster singles, doubles, and perturbative triples correction [CCSD(T)] method. The vertical detachment energies of the electron-bound clust...
Article
Upon excitation of Cl-(H2O)3 and I-(H2O)3 clusters, the electron transfers from the anionic precursor to the solvent, and then the excess electron is stabilized by polar solvent molecules. This process has been investigated using ab initio molecular dynamics (AIMD) simulations of excited states of Cl-(H2O)3 and I-(H2O)3 clusters. The AIMD simulatio...
Article
This chapter discusses theoretical approaches to the design of functional nanomaterials. A theoretical description of nanomaterials that belongs to the mesoscopic phase is fraught with a number of problems because neither quantum–chemical methods used to investigate the microscopic phase nor solid-state physics methods used to investigate the macro...
Article
We have investigated the solvent rearrangement process for the excited electron in the iodide–water pentamer using density functional and ab initio calculations. Upon excitation of the iodide–water pentamer, an electron transfers from the iodide anion to the water cluster, resulting in release of the iodine atom and formation of the anionic water p...
Article
The structures, energetics, electronic properties, and spectra of hydrated hydroxide anions are studied using density functional and high level ab initio calculations. The overall structures and binding energies are similar to the hydrated anion clusters, in particular, to the hydrated fluoride anion clusters except for the tetrahydrated clusters a...
Article
Density functional and ab intio calculations are employed in order to understand the base dissociation of rubidium hydroxide by water molecules. The hydrated structures, stabilities, thermodynamic quantities, dissociation energies, infrared spectra, and electronic properties of RbOH(H2O)(n = 0-5) are investigated. With the successive addition of wa...
Article
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+ (H2O)(n=1-8) clusters. An extensive search was made to find out the most stable conformers. Since the...
Article
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 properti...
Article
To understand the mechanism of aqueous acid dissociation, which plays a fundamental role in aqueous chemistry, the ionic dissociation of HX acids (X=F, Cl, Br, and I) in water clusters up to hexamer is examined using density functional theory and Møller-Plesset second-order perturbation methods (MP2). Further accurate analysis based on the coupled...
Article
This study details the interactions prevailing in aqueous clusters of monovalent alkali metal, ammonium, and hydronium cations. The calculations involve a detailed evaluation of the structures, thermodynamic energies, and IR spectra of several plausible conformers of M+·(H2O)1-6 (M = Li, Na, K, Rb, Cs, NH4, H3O) clusters at the second-order Møller−...
Article
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 TM...
Article
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 proc...
Article
Owing to the utility of redox phenomena of silver in many chemical systems, it is important to understand the coordination chemistry of Ag+ ion and hence the hydration structure. The lowest-energy conformations of Ag+(H2O)1–6 are sensitive to the calculation method employed. The coordination number (Nc) of Ag+(H2O)n is predicted to be 2 for n = 2–6...
Article
The highly stereospecific and regiospecific recognition of alpha-amino acids exhibited by a novel Co(III) metal complex embodied in the experimental work (Nature 1999, 401, 254) is rationalized from the energetics and structural characteristics with the use of density functional calculations. The steric repulsion between the chiral center of the re...
Article
The structures of pure gold and silver clusters (Auk, Agk, k = 1−13) and neutral and anionic gold−silver binary clusters (AumAgn, 2 ≤ k = m + n ≤ 7) have been investigated by using density functional theory (DFT) with generalized gradient approximation (GGA) and high level ab initio calculations including coupled cluster theory with relativistic ab...
Article
Although various low-lying energy structures of electron–water clusters, e−–(H2O)2–6, have been reported, some of the global minimum energy structures (in particular, for the tetramer and pentamer) are still not clearly characterized yet. Therefore, using high-level ab initio calculations, we have investigated several new low-lying energy conformer...
Article
The relative stabilities of weak binding clusters are sensitive to temperature due to the entropy effect. Thus, here we report significant changes in relative stabilities between two low-energy electron-water trimer structures and those between three low-energy electron-water pentamer structures, as the temperature increases. The trimer and pentame...
Article
The electron–water heptamer is one of the ''magic'' numbers in the mass spectra of electron–water clusters, but up to now the structure of the electron–water heptamer is not known. Thus we have investigated a number of low-energy structures, and report the lowest-energy structure using ab initio calculations. The relative energies, vertical electro...
Article
Using the computer-aided molecular design approach, we recently reported the synthesis of calix[4]hydroquinone (CHQ) nanotube arrays self-assembled with infinitely long one-dimensional (1-D) short hydrogen bonds (H-bonds) and aromatic−aromatic interactions. Here, we assess various calculation methods employed for both the design of the CHQ nanotube...
Article
The structure of the electron–water octamer has been investigated for the first time, using ab initio calculations. The lowest-energy conformer and the next lowest energy conformer are predicted to be the major and minor isomers with small and large vertical electron detachment energies. The binding energies and vibrational spectra are investigated...
Article
The structures, vibrational frequencies, electronic properties, and cis-trans photoisomerization process of retinal chromophore and its derivatives i.e., Schiff base and protonated Schiff base are studied using the density-functional theory with Becke's three-parameter exchange functional together with the correlation functionals of Lee–Yang–Parr B...
Article
Full-text available
Various structures of halide-water pentamers and hexamers have been investigated using extensive ab initio calculations. Then, we compare the structures, spectra, and electronic properties of the hydrated fluoride, chloride, bromide, and iodide systems. Although some of the fluoride and iodide systems have been investigated earlier, we have carried...
Article
The structures, energies, Spectra, and charge transfer to solvent (CTTS) energies of the hydrated superoxide anion clusters have been investigated using both density functional calculations (DFT) with Becke-3-parameters employing Lee-Yang-Parr functionals (B3LYP) and second-order Mller Plesset perturbation (MP2) calculations employing highly diffus...