• Bulletin of the Korean Chemical Society
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• v.21 no.9
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• pp.923-928
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• 2000

[FeIII(BBA)DBC]ClO4 as a new functional model for catechol dioxygenases has been synthesized, where BBA is a bis(benzimidazolyl-2-methyl)amine and DBC is a 3,5-di-tert-butylcatecholate dianion.The BBA complex has a structuralfeature that iron cent er has a five-coordinate geometry similar to that of catechol dioxygenase-substrate complex.The BBA complex exhibits strong absorptionbands at 560 and 820 nm in CH3CN which are assigned to catecholate to Fe(III) charge transfer transitions. It also exhibits EPR signals at g = 9.3 and 4.3 which are typical values for the high-spin FeIII (S = 5/2) complex with rhombicsymmetry. Interestingly, the BBA complex reacts with O2 within an hour to afford intradiol cleavage (35%) and extradiol cleavage (60%) products. Surprisingly, a green color intermediate is observed during the oxygenation process of the BBA com-plex in CH3CN. This green intermediate shows a broad isotropic EPR signal at g = 2.0. Based on the variable temperature EPR study, this isotropic signalmight be originated from the [Fe(III)-peroxo-catecholate] species havinglow-spin FeIII center, not from the simple organic radical. Consequently,it allows O2 to bind to iron cen-ter forming the Fe(III)-superoxide species that converts to the Fe(III)-peroxide intermediate. These present data can lead us tosuggest that the oxygen activation mechanism take place for the oxidative cleavingcatechols of the five-coordinate model systems for catechol dioxygenases.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.216-220
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• 2013

The hydroalumination of cyclopropane has been investigated using the B3LYP density functional method employing several split-valence basis sets. It is shown that the reaction proceeds via an intermediate weakly bound complex and a four-centered transition state. Calculations at higher levels of theory were also performed at the geometries optimized at the B3LYP level, but only slight changes in the barriers were observed. Structural parameters for the transition state are also reported.

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1127-1131
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• 1996

[FeⅡ2(N-Et-HPTB)Cl2]BPh4(1), where N-Et-HPTB is the anion of N,N,N',N'-tetrakis(N-ethyl-2-benzimidazolylmethyl)-2-hydroxy-l,3-diaminopropane, has been synthesized to model dioxygen binding to the diferrous centers of proteins. 1 has a singly bridged structure with a μ-alkoxo of N-Et-HPTB and contains two five-coordinate iron(Ⅱ) centers with two chloride ligands as exogenous ligands. 1 exhibits an electronic spectrum with a λmax at 336 nm in acetone. 1 in acetone exhibits no EPR signal at 4 K, indicating diiron(Ⅱ) centers are antiferromagnetically coupled. Exposure of acetone solution of 1 to O2 at -90 ℃ affords an intense blue color intermediate showing a broad band at 586 nm. This absorption maximum of the dioxygen adduct(1/O2) was found in the same region of μ-l,2-peroxo diiron(Ⅲ) intermediates in the related complexes with pendant pyridine or benzimidazole ligand systems. However, this blue intermediate exhibits EPR signals at g = 1.93, 1.76, and 1.59 at 4 K. These g values are characteristic of S = 1/2 system derived from an antiferromagnetically coupled high-spin Fe(Ⅱ)Fe(Ⅲ) units. 1 is the unique example of a (μ-alkoxo)diferrous complex which can bind dioxygen and form a metastable mixed-valence intermediate. At ambient temperature, most of 1/O2 intermediate decays to form a diamagnetic species. It suggests that the dacay reaction of the intermediate might be bimolecular, implying the formation of mixed-valence tetranuclear species in transition state.

• Journal of Photoscience
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• v.9 no.2
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• pp.314-316
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• 2002

In halobacterial membrane, pharaonis phoborhodopsin (or pharaonis sensory rhdopsin II, psRII) forms a complex with its transducer pHtrII. Flash-photolyis of D75N mutant did not yield M-intermediate but an O-like intermediate is observed. We examined the interaction between D75N of ppR and t-Htr (truncated pHtrII). These formed a complex in the presence of n-dodecyl-$\beta$-D-maltoside, and the association accelerated the decay of the 0 of D75N from 15 to 56 s$\^$-1/. From the decay time constants under varying ratios of D75N and t-Htr, n, the molar ratio of D75N/t-Htr in the complex, and K$\_$D/, the dissociation constant, were estimated. The value of n was unity and K$\_$D/ was estimated to 146 nM. This K$\_$D/ value can be considered as the association between the photo-intermediate and t-Htr, which is deduced by the method of estimation. Previously we (Photochem. Photobiol. 74, 489-494 (2001)) reported K$\_$D/ of 15 $\mu$M for the interaction between the wild-type and t-Htr by means of the change of M-decay rates. Therefore, this value should be the K$\_$D/ value for the interaction between M of the wild-type and t-Htr.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.5
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• pp.455-465
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• 2020

As cities continue to expand and additional underground structures are constructed, a policy is being planned to expand addresses, which are national framework data. In this study, the application scope of a proposed 3D (three-dimensional) mixed-use complex space for assigning 3D addresses was defined, based on past research on 3D address systems and by analyzing related laws. Underpass shopping malls, underground walkways (excluding underground shopping malls), and 3D mixed-use transfer centers with a gross floor area of 2,000㎡ or more are connected with each space by underground walkways or public paths. In addition, the detailed space corresponding to the public space of the 3D mixed-use complex space was presented and distinguished from the space to which the detailed address is assigned. The criteria for setting the road section were presented based on the intermediate space, which is a characteristic of 3D mixed-use complex spaces. The proposed criteria were applied to the Express Bus Terminal station (3D mixed-use transfer center) and COEX mall (underpass shopping malls). Thus, the road section was set for an unfamiliar 3D mixed-use complex space. However, by applying the proposed criteria to various 3D mixed-use complex spaces, additional and detailed criteria for different cases should be prepared.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.447-452
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• 1974

A mechanistic possibility for the initiation of the thermal polymerization reactions are envisaged theoretically. As result of the considerations, it is assumed that the thermal polymerization reactions take place via the pseudo molecular complex which has been supposed to be an intermediate in the transition state of Diels-Alder reactions.

• Bulletin of the Korean Chemical Society
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• v.11 no.4
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• pp.281-286
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• 1990

The kinetics and mechanism of reduction of Cu(II) with an excess D-penicillamine have been examined at pH = 6.2 and 0.60M in ionic strength. The reaction at the initial stage is biphasic with a rapid complexation process to give "red" transient complex of $[Cu(II)(pen)_2]^2$- that is partially reduced to another transient "brown" intermediate. The "brown" intermediate is finally reduced to diamagnetic "yellow" complex, $[Cu(I)(Hpen)]_n$. The final reduction process is pseudo-first order in ["brown" transient] disappearance $with {\kappa} = {{\kappa}_{3a} + {\kappa}_{3b}[pen]^{2-}},$ where ${\kappa}_{3a} = (5.0{\pm}0.8){\times}10^{-3}sec^{-1}$ and ${\kappa} = (0.14{\pm}0.02) M^{-1}sec^{-1}$ at $25^{\circ}C$. The activation parameters for the $[H_2pen]$-independent and $[H_2pen]$-dependent paths are ${\Delta}H^{\neq} = (52{\pm}5)kJmol^{-1},$ and ${\Delta}S^{\neq} = ( - 27{\pm}3)JK^{-1}mo^{l-1},$ and ${\Delta}H^{\neq} = (56{\pm}2)kJmol^{-1}$ and ${\Delta} S^{\neq} = ( - 18{\pm}0.7)JK^{-1}mol^{-1}$ respectively. The nature of "brown" intermediate is not clearly identified, but this intermediate seems to be in the mixed-valence state, judging from the kinetic and spectroscopic informations.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.376-380
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• 1987

The cyclobutane forming photocycloaddition reaction of 5(E)-styryl-1,3-dimethyluracil with some olefins occurs on the 5,6-double bond of uracil ring rather than the expected central double bond via an intermediate, probably the photochemical Diels-Alder type adduct. This intermediate formed on short term irradiation of 5(E)-styryl-1,3-dimethyluracil and 2,3-dimethyl-2-butene solution is converted into the $C_4$-cycloadduct on the prolonged irradiation. Quantum yield of the intermediate formation is not linear with the concentration of 2,3-dimethyl-2-butene probably due to the secondary reaction accompanied with the complex reaction kinetics. The intermediate is formed from the lowest excited singlet state.

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.951-952
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• 2000

Acylation of an intermediate tetrahydroxoplatinum(IV) complex, $[Pt(OH)_4(dach)]$ (dach = $trans-(\pm)-12-di-aminocyclohexane)$, with one or two kinds of carboxylic anhydrides in stepwise manner afforded various car-boxylatoplatinum(IV) complexes, $[Pt(O_2CR)\chi(OR’)4-\chi(dach)]$ (R = $(CH_2)_3CH_3$ or $C(CH_3)_3$, R’ = H or $OCCH_3$, and $\chi$ = 1-4) with a wide range of lipophilicity. The title complexes were subjected to bioassay using the murine leukemia L1210 cell line, and in particular, their in vivo oral antitumor activity was attempted to correlate with their lipophilicity and water solubility. The most orally active complex exhibited intermediate lipophilicity and water solubility, but it has been found that an exact relationship between the lipophilicity and oral anticancer activity could not be established, since the lipophilicity of the complexes is not the sole parameter to determine the oral activity. One of the important intermediate complexes partially substituted was subjected to X-ray anal-ysis for positit of the substituted group: $[Pt(OPiv)_3(OH)(dach)]$ crystallizes in the tetragonal sys-tem, space group $P42_1c$ with a = 21.161(3) $\AA$, b = 21.161(6) $\AA$, c = 12.816(3) $\AA$, $\alpha=\beta=$ r $=90^{\circ}$, V = 5739(2) $\AA^3$ and Z = 8.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1801-1808
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• 2006

The interaction between whey carrier protein $\beta$-lactoglobulin type A and B (BLG-A and -B) and 2,2'-bipyridin n-hexyl dithiocarbamato Pd(II) nitrate (BPHDC-Pd(II)), a new heavy metal complex designed for anticancer property, was investigated by fluorescence spectroscopy combined with chemometry and circular dichroism (CD) techniques. A strong fluorescence quenching reaction of BPHDC-Pd(II) to BLG-A and -B was observed. Hence, BPHDC-Pd(II) complex can be bound to both BLG-A and -B, and quench the fluorescence spectra of the proteins. The quenching constant was determined using the modified Stern-Volmer equation. The binding parameters were evaluated by fluorescence quenching method. The results of binding study provided evidences presence of two and three sets of binding sites on the BLG-B and -A, respectively, for BPHDC-Pd(II) complex. Using fluorescence spectroscopy and chemometry, the ability of BLG-A and -B to form an intermediate upon interaction with BPHDC-Pd(II) complex was assessed. CD studies displayed that under influence of different concentrations of BPHDC-Pd(II) complex, the regular secondary structure of BLG-B had no significant changes, whereas for BLG-A a transition from $\alpha$-helix to $\beta$-structure was appeared. The results for both of BLG-A and -B displayed that BPHDC-Pd(II) complex can induce a conformational transition from the native form to an intermediate state with a slightly opened conformation, which is detectable with chemometry analyses.