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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Bulletin of the Korean Chemical Society
Journal Basic Information
Journal DOI :
Korean Chemical Society
Editor in Chief :
Byeong Moon Kim
Volume & Issues
Volume 28, Issue 12 - Dec 2007
Volume 28, Issue 11 - Nov 2007
Volume 28, Issue 10 - Oct 2007
Volume 28, Issue 9 - Sep 2007
Volume 28, Issue 8 - Aug 2007
Volume 28, Issue 7 - Jul 2007
Volume 28, Issue 6 - Jun 2007
Volume 28, Issue 5 - May 2007
Volume 28, Issue 4 - Apr 2007
Volume 28, Issue 3 - Mar 2007
Volume 28, Issue 2 - Feb 2007
Volume 28, Issue 1 - Jan 2007
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Energy Transfer Pathway in Luminescent Lanthanide Complexes Based on Dansyl-N-methylaminobenzoic Acid through Intramolecular Charge Transfer State for Near Infrared Emission
Roh, Soo-Gyun ; Baek, Nam-Seob ; Kim, Yong-Hee ; Kim, Hwan-Kyu ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1249~1255
DOI : 10.5012/bkcs.2007.28.8.1249
We have investigated the photophysical properties of dansyl-N-methylaminobenzoic acid (DABAH) as a ligand and its lanthanide (Ln3+)-cored complexes (Ln3+-(DABA)3(terpy)) in order to determine the main energy transfer pathway for sensitized near infrared emission of Ln3+ ions (Ln3+ = Nd3+ and Er3+) in Ln3+- (DABA)3(terpy). The fluorescence spectrum of DABAH shows a large Stokes shift with increasing solvent polarity. This large Stokes shift might be due to the formation of a twisted intramolecular charge transfer (TICT) state, as demonstrated by the large dipole moment in the excited state. It is in good agreement with the result that the phosphorescence even in the Gd3+-cored complex based on the DABAH ligand was not observed, maybe due to the highly forbidden character of the S1 → T1 transition in the DABAH ligand. A short decay component (ca. 1 ns) was observed in Er3+-(DABA)3(terpy) whereas the fluorescence lifetimes of DABAH and its Gd3+-(DABA)3(terpy) are observed about ~10 ns. The short component could be originated from the energy transfer process between the ligand and the Ln3+ ion. Based on the fluorescence of DABAH its Ln3+- (DABA)3(terpy), the sensitization of Ln3+ luminescence in the Ln3+-(DABA)3(terpy) takes place by the energy transfer via the TICT state of DABAH in the excited singlet state rather than via the excited triplet state.
Sensitized Near IR Luminescence of Er(Ⅲ) Ion in Lanthanide Complexes Based on Diketone Derivatives: Synthesis and Photophysical Behaviors
Baek, Nam-Seob ; Kwak, Bong-Kyu ; Kim, Yong-Hee ; Kim, Hwan-Kyu ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1256~1260
DOI : 10.5012/bkcs.2007.28.8.1256
Two β-diketone derivatives bearing triphenylene (1-naphthalene-2-yl-3-triphenylen-2-yl-propane-1,3-dione (NTPD)) and naphthalene (1,3-di-naphthalene-2-yl-propane-1,3-dione (DNPD)) and their Ln(III) complexes (Ln = Er or Gd) were synthesized and their photophysical properties were investigated. The sensitized emission of Er3+ ion in Er3+-[NTPD]3(terpy) and Er3+-[DNPD]3(terpy) was observed upon excitation at absorption maximum of ligands. Their photophysical studies indicate the sensitization of Er3+ luminescence by energy transfer through the excited triplet state of β-diketone ligand. The energy transfer rate through the excited triplet state of β-diketone ligand to Er3+ ion occurs faster than that of the oxygen quenching rate.
Isoetin 5'-Methyl Ether, A Cytotoxic Flavone from Trichosanthes kirilowii
Rahman, Md. Aziz Abdur ; Moon, Surk-Sik ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1261~1264
DOI : 10.5012/bkcs.2007.28.8.1261
Bioassay-directed fractionations of the seed extracts of Trichosanthes kirilowii, have resulted in the isolation of two new compounds, 2-(4-hydroxy-3-methoxyphenyl)-3-(2-hydroxy-5-methoxyphenyl)-3-oxo-1-propanol (2) and isoetin 5'-methyl ether (5,7,2',4'-tetrahydroxy-5'-methoxyflavone) (3), together with two known compounds, 7-hydroxychromone (1) and 5,7,4'-trihydroxy-3',5'-dimethoxyflavone (tricin, 4). Their structures were characterized by spectroscopic analysis such as 2D-NMR, HRTOFMS, and UV. Compound 3 showed cytotoxicity against human lung cancer cell line A549, human skin melanoma SK-Mel-2, and mouse melanoma B16F1, with IC50 of 0.92, 8.0, and 7.23 μg/mL, respectively.
Physicochemical and Catalytic Properties of NiSO
Catalyst Promoted with CeO
for Acid Catalysis
Sohn, Jong-Rack ; Shin, Dong-Cheol ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1265~1272
DOI : 10.5012/bkcs.2007.28.8.1265
A solid acid catalyst, NiSO4/CeO2-ZrO2 was prepared simply by promoting ZrO2 with CeO2 and supporting nickel sulfate on CeO2-ZrO2. The support of NiSO4 on ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperatures because of the interaction between NiSO4 and ZrO2. The surface area of 10-NiSO4/1-CeO2-ZrO2 promoted with CeO2 and calcined at 600 oC was very high (83 m2/g) compared to that of unpromoted 10-NiSO4/ZrO2 (45 m2/g). This high surface area of 10-NiSO4/1-CeO2-ZrO2 was due to the promoting effect of CeO2 which makes zirconia a stable tetragonal phase as confirmed by XRD. The role of CeO2 was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity of the sample, and high thermal stability of the surface sulfate species. 10-NiSO4/1- CeO2-ZrO2 containing 1 mol% CeO2 and 10 wt% NiSO4, and calcined at 600 oC exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation.
Characterization of NiSO
Supported on Fe
and Catalytic Properties for Ethylene Dimerization
Pae, Young-Il ; Sohn, Jong-Rack ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1273~1279
DOI : 10.5012/bkcs.2007.28.8.1273
The NiSO4 supported on Fe2O3 catalysts were prepared by the impregnation method. No diffraction line of nickel sulfate was observed up to 30 wt %, indicating good dispersion of nickel sulfate on the surface of Fe2O3. The addition of nickel sulfate to Fe2O3 shifted the phase transition of Fe2O3 (from amorphous to hematite) to higher temperatures because of the interaction between nickel sulfate and Fe2O3. 20-NiSO4/Fe2O3 containing 20 wt % of NiSO4 and calcined at 500 oC exhibited a maximum catalytic activity for ethylene dimerization. The initial product of ethylene dimerization was found to be 1-butene and the initially produced 1-butene was also isomerized to 2-butene during the reaction. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method.
Preparation, Characterization and Photoluminescence Properties of Ca
S:Eu Red-emitting Phosphors for a White LED
Sung, Hye-Jin ; Cho, Young-Sik ; Huh, Young-Duk ; Do, Young-Rag ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1280~1284
DOI : 10.5012/bkcs.2007.28.8.1280
A series of Ca1-xSrxS:Eu (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) phosphors were synthesized by solid-state reactions. The Ca1-xSrxS:Eu phosphors have a strong absorption at 455 nm, which corresponds to the emission wavelength of a blue LED. The emission peak of Ca1-xSrxS:Eu is blue shifted from 655 to 618 nm with increasing Sr content. The characteristics of Ca1-xSrxS:Eu phosphors make them suitable for use as wavelengthtunable red-emitting phosphors for three-band white LEDs pumped by a blue LED. In support of this, we fabricated a three-band white LED by coating SrGa2S4:Eu and Ca0.6Sr0.4S:Eu phosphors onto a blue LED chip, and characterized its optical properties.
Simultaneous Control of Au Nanotube Lengths and Pore Sizes with a Single Kind of Polycarbonate Membrane via Interfacial Deposition at the Air/Water Interface
Pyo, Myoung-Ho ; Joo, Jung-Sook ; Jung, Youn-Su ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1285~1288
DOI : 10.5012/bkcs.2007.28.8.1285
Au was electrolessly deposited on polycarbonate (PC) membranes (0.1 μm pores) at the air/water interface. It was found that the Au nanotube dimension can be controlled by adjusting the plating temperature and the solution composition. Interfacial deposition of Au at relatively low temperatures (4℃) produced long nanotubes, which run through the whole membrane thickness with small openings. Increase of plating temperatures resulted in the decrease of nanotube lengths and Au film thicknesses. It was also disclosed that the inside-diameter of Au nanotubes can be controlled with negligible variations in length by changing the composition of a plating solution.
Isolation and Characterization of a New Alkaloid from the Seed of Prunus persica L. and Its Anti-inflammatory Activity
Rho, Jung-Rae ; Jun, Chang-Soo ; Ha, Young-Ae ; Yoo, Myung-Ja ; Cui, Ming-Xun ; Baek, Hwa-Seung ; Lim, Jin-A ; Lee, Young-Haeng ; Chai, Kyu-Yun ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1289~1293
DOI : 10.5012/bkcs.2007.28.8.1289
Persicaside has been isolated as a new alkaloid natural compound from a methanol (EtOA)-soluble extract of Prunus persica seed. It was purified by a combination of chromatographic techniques and recrystallization. The structure of Persicaside was determined by extensive NMR experiments and mass ppectroscopic data. It inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) production via suppression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2 expression in rat osteoblast sarcoma cells (ROS 17/2.8) in concentration-dependent manner whereas it spares the COX-1 enzyme activity.
Identification of New Compounds from Catharanthus roseus Hairy Root Cultures
Chung, Ill-Min ; Ali, Mohd ; Yang, Young-Mok ; Peebles, Christie A. M. ; Chun, Se-Chul ; Lee, Sun-Joo ; San, Ka-Yiu ; Ahmad, Ateeque ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1294~1298
DOI : 10.5012/bkcs.2007.28.8.1294
Two new compounds lanast-5,8-dien-3β-ol-27-oic acid-3β-D-glucopyranosyl (4'-1'')-10'',11''-dimethoxy anthracene (1), 2-methoxy-6-(n-nonacontan-5'',6''-dionyl)-11-hydroxy-13-methyl-11β-D-rhamnopyranoside anthracene (2) have been isolated from the hairy root cultures of Catharanthus roseus. Their structures have been elucidated with the help of 500 MHz NMR using one- and two-dimensional NMR in combination with IR, EI/MS, FAB/MS and HRFABMS spectroscopy.
Preparation and Characterization of Half-Sandwich Cobalt(III) Complexes of Cp Ligands with a Rigid Thioanisole Side-Chain
S, Sujith ; Lee, Bun-Yeoul ; Han, Jin-Wook ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1299~1304
DOI : 10.5012/bkcs.2007.28.8.1299
New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2- (thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (3- 5) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)4·2Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1H, 13C and 19F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.
Cyclopolymerization of 1,1-Dipropargyl-1-silacyclohexane by Transition Metal Catalysts
Gal, Yeong-Soon ; Lee, In-Sook ; Chang, Eun-Hee ; Jeong, Yun-Cheol ; Kwak, Young-Woo ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1305~1310
DOI : 10.5012/bkcs.2007.28.8.1305
A conjugated spirocyclic polymer was synthesized via the cyclopolymerization of 1,1-dipropargyl-1- silacyclohexane with various transition metal catalysts. The monomer, 1,1-dipropargyl-1-silacyclohexane was synthesized by Grignard reaction of 1,1-dichloro-1-silacyclohexane with propargyl magnesium bromide. This polymerization proceeded well to give the corresponding poly(1,1-dipropargyl-1-silacyclohexane). The catalytic activity of WCl6 was found to be similar with that of MoCl5. The structure of polymer having the conjugated backbone with silacyclohexane moieties was characterized by such instrumental methods as NMR (1H-, 13C-), IR, and UV-visible spectroscopies. The resulting polymers were mostly yellow or light-brown powders, depending on the catalyst systems used. This polymer was completely soluble in halogenated and aromatic hydrocarbons such as chloroform, 1,2-dichloromethane, benzene, toluene, and chlorobenzene, etc. The thermal and oxidative stabilities of polymer were also studied and discussed.
Synthesis and Application of New Ru(II) Complexes for Dye-Sensitized Nanocrystalline TiO
Seok, Won-K. ; Gupta, A.K. ; Roh, Seung-Jae ; Lee, Won-Joo ; Han, Sung-Hwan ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1311~1316
DOI : 10.5012/bkcs.2007.28.8.1311
To develop photo-sensitizers for dye-sensitized solar cells (DSCs) used in harvesting sunlight and transferring solar energy into electricity, we synthesize novel Ru(II) polypyridyl dyes and describe their characterization. We also investigate the photo-electrochemical properties of DSCs using these sensitizers. New dyes contain chromophore unit of dafo (4,5-diazafluoren-9-one) or phen-dione (1,10-phenanthroline-5,6-dione) instead of the nonchromophoric donor unit of thiocyanato ligand in cis-[RuII(dcbpy)2(NCS)2] (dcbpy = 4,4'-dicarboxy- 2,2'-bipyridine) coded as N3 dye. For example, the photovoltaic data of DSCs using [RuII(dcbpy)2(dafo)](CN)2 as a sensitizer show 6.85 mA/cm2, 0.70 V, 0.58 and 2.82% in short-circuit current (Jsc ), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (Eff), which can be compared with those of 7.90 mA/ cm2, 0.70 V, 0.53 and 3.03% for N3 dye. With the same chelating ligand directly bonded to the Ru metal in the complex, the CN ligand increases the Jsc value by double, compared to the SCN ligand. The extra binding ability in these new dyes makes them more resistant against ligand loss and photo-induced isomerization within octahedral geometry.
Synthesis and Characterization of a Hydroxylated Dendrimeric Gene Delivery Carrier
Kim, Tae-Il ; Bai, Cheng-Zhe ; Park, Jong-Sang ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1317~1321
DOI : 10.5012/bkcs.2007.28.8.1317
Arginine conjugated PAMAM dendrimer, PAMAM-R was modified with propylene oxide via hydroxylation of primary amines of arginine residues. About 49 amines were detected to be converted to amino alcohols by 1H NMR. The newly synthesized polymer, PAMAM-R-PO was able to completely retard pDNA from a charge ratio of 2. The average diameter of PAMAM-R-PO polyplex was found to be 242 nm at a charge ratio of 30. The Zeta-potential value of PAMAM-R-PO polyplex was able to reach 20-30 mV over a charge ratio of 10. PAMAM-R-PO indicated higher cell viability than unmodified PAMAM-R on HeLa and 293 cells because of its hydroxylated amines. Transfection experiments on 293 cells showed that the transfection efficiency of PAMAM-R-PO was found to be 1.5-1.9 times higher than that of PEI25kDa at a charge ratio of 30. The polymer eventually displayed about 2 times greater transfection efficiency than PAMAM-R at the same charge ratio in the absence of serum. Therefore, we concluded that the modification of primary amines of PAMAMR to amino alcohols gives positive effects such as reduced cytotoxicity and enhanced transfection efficiency on 293 cells for gene delivery potency of PAMAM-R.
Electrocatalysis of Oxygen Reduction by Cu-containing Polymer Films on Glassy Carbon Electrodes
Kim, Jong-Won ; Gewirth, Andrew A. ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1322~1328
DOI : 10.5012/bkcs.2007.28.8.1322
The catalytic activity of poly[(2,2'-bipyridine)copper(II)-μ4-oxalato] coated on a glassy carbon electrode (GCE) for O2 electroreduction is examined using cyclic voltammetry and rotating disk electrode techniques. The cyclic voltammograms show that O2 is electroreduced on pBpCuOx-coated GCE surfaces at a peak potential of ? 0.25 V in pH 4.7 acetate buffer media. The electroreduction of O2 on pBpCuOx-coated GCE occurs at 450 mV more positive potential than that found at a bare GCE. The catalytic activity originates from Cu(II) coordinated by bipyridine in the complexes and the polymer type Cu-complex films exhibit an enhanced stability compared to monomeric Cu-complexes during the O2 electroreduction. The rotating disk electrode measurements reveal that the electroreduction of O2 on pBpCuOx-coated GCE is a four-electron process. Kinetic parameters for O2 reduction on pBpCuOx-coated GCE are obtained from rotating disk experiments and compared with those on bare glassy carbon electrode surfaces.
Electro-oxidation Kinetics of Cerium(III) in Nitric Acid Using Divided Electrochemical Cell for Application in the Mediated Electrochemical Oxidation of Phenol
Matheswaran, Manickam ; Balaji, Subramanian ; Chung, Sang-Joon ; Moon, Il-Shik ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1329~1334
DOI : 10.5012/bkcs.2007.28.8.1329
The electrochemical oxidation of cerium(III) was carried out using divided and undivided electrochemical cells in nitric acid medium. It was found that divided cell with Nafion 324 as the separator gave good conversion yield with high current efficiency compared to the undivided cell. The efficiency of the divided electrochemical cell was further optimized in terms of cell voltage, temperature, flow rate of solution recirculation, concentrations of Ce(III) and nitric acid. The better conditions for 1 M Ce(III) in 3 M nitric acid were found to be 2.5 V, 363 K and 100 mL/min recirculation flow rate based on the current efficiency under the experimental conditions investigated. The Ce(IV) oxidant produced was used as a mediator for the mineralization of phenol. The mineralization efficiency of the cerium mediated electrochemical oxidation was found rapid and higher compared to the direct electrochemical oxidation based on CO2 evolution under the same conditions.
Homology Modeling and Docking Study of β-Ketoacyl Acyl Carrier Protein Synthase Ⅲ from Enterococcus Faecalis
Jeong, Ki-Woong ; Lee, Jee-Young ; Kim, Yang-Mee ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1335~1340
DOI : 10.5012/bkcs.2007.28.8.1335
β-Ketoacyl acyl carrier protein synthase (KAS) III is a particularly attractive target in the type II fatty acid synthetic pathway, since it is central to the initiation of fatty acid synthesis. Enterococcus faecalis, a Grampositive bacterium, is one of the major causes of hospital acquired infections. The rise of multidrug-resistant of most bacteria requires the development of new antibiotics, such as inhibition of the KAS III. In order to block the fatty acid synthesis by inhibition of KAS III, at first, three dimensional structure of Enterococcus faecalis KAS III (efKAS III) was determined by comparative homology modeling using MODELLER based on x-ray structure of Staphylococcus aureus KAS III (saKAS III) which is a gram-positive bacteria and is 36.1% identical in amino acid sequences with efKAS III. Since His-Asn-Cys catalytic triad is conserved in efKAS III and saKAS III, substrate specificity of efKAS III and saKAS III and the size of primer binding pocket of these two proteins are expected to be similar. Ligand docking study of efKAS III with naringenin and apigenin showed that naringenin docked more strongly with efKAS III than apigenin, resulting in the intensive hydrogen bond network between naringenin and efKAS III. Also, only naringenin showed antibacterial activity against E. faecalis at 256 μg/mL. This study may give practical implications of flavonoids for antimicrobial effects against E. faecalis.
The Effects of Ar-ion Bombardment and Annealing of D
O/Zircaloy-4 Surfaces Using XPS and UPS
Oh, Kyung-Sun ; Kang, Yong-Cheol ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1341~1345
DOI : 10.5012/bkcs.2007.28.8.1341
The surface chemistry of D2O dosed Zircaloy-4 (Zry-4) surface followed by Ar-ion bombardment and annealing was studied by means of X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS). In the XPS study, Ar-ion bombardment caused decrease of the oxygen on the surface region of Zry-4 and therefore led to change the oxidation states of the zirconium from oxide to metallic form. In addition, oxidation states of zirconium were changed to lower oxidation states of zirconium due to depopulation of oxygen on the surface region by annealing. Up to about 787 K, the bulk oxygen diffused out to the subsurface region and after this temperature, the oxygen on the surface of Zry-4 was depopulated. UPS study showed that the valence band spectrum of the D2O exposed Zry-4 exhibited a dominant peak at around 13 eV and no clear Fermi edge was detected. After stepwise Ar+ sputtering processes, the decrease of the oxygen on the surface of Zry-4 led to suppress the dominant peak around 13 eV, the peak around 9 eV and develop a new peak of the metallic Zr 4d state (20.5-21.0 eV) at the Fermi level.
A Kinetic Consideration on the Selective Adsorption and Molecular Recognition by Molecularly Imprinted Polymer
Li, Wuke ; Li, Songjun ; Luo, Gang ; Ding, Kerong ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1346~1352
DOI : 10.5012/bkcs.2007.28.8.1346
This article presents an original work on kinetically studying the selective adsorption and recognition by molecularly imprinted polymer (MIP). With S-naproxen as template, the imprinted polymer was prepared. The result indicates that the prepared polymer shows a more complicated sorption toward S-naproxen than toward its enantiomer R-naproxen. The rate constant in the case of template appears to be a variable. There are also significant deviations from the idealized Langmuir model. Related information indicates that these, in logic, can be a result of biomimic structural and functional complements between imprint and the template, which makes the polymer capable of selectively recognizing the imprint species.
Aminolyses of Y-substituted Phenyl 2-Furoates and Cinnamates: Effect of Nonleaving Group Substituent on Reactivity and Mechanism
Um, Ik-Hwan ; Akhtar, Kalsoom ; Park, Youn-Min ; Khan, Sher Bahadar ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1353~1357
DOI : 10.5012/bkcs.2007.28.8.1353
Second-order rate constants (kN) have been determined spectrophotometrically for reactions of Y-substituted phenyl 2-furoates (1a-h) with piperidine and morpholine in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 oC. The Brønsted-type plot exhibits a downward curvature for the reactions with strongly basic piperidine but is linear for the reactions with weakly basic morpholine. The slope of the curved Brønsted-type plot changes from -1.25 to ?0.28 as the pKa of the conjugate acid of the leaving aryloxides decreases. The pKa at the center of the Brønsted curvature, defined as pKa°, was determined to be 6.4. The aminolysis of 1a-h has been concluded to proceed through a stepwise mechanism on the basis of the curved Brønsted-type plot. The reactions of Ysubstituted phenyl cinnamates (2a-g) with piperidine resulted in a curved Brønsted-type plot with a pKa° values of 6.4. However, the curved Brønsted-type plot has been suggested to be not due to a change in the RDS but due to a normal Hammond effect of a concerted mechanism, since the Brønsted-type plot for the corresponding reactions with morpholine results in also a curved Brønsted-type plot with a pKa° values of 6.1. The furoates with a basic leaving group (i.e., 1b-g) are less reactive than the corresponding cinnamates (i.e., 2b-g). The k2/ k-1 ratios for the reactions of 1b-h are much smaller than unity, which has been suggested to be responsible for their low reactivity.
Ab initio Studies on Acene Tetramers: Herringbone Structure
Park, Young-Hee ; Yang, Ki-Yull ; Kim, Yun-Hi ; Kwon, Soon-Ki ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1358~1362
DOI : 10.5012/bkcs.2007.28.8.1358
The structures, energetics and transfer integrals of the acene tetramers up to pentacene are investigated with the ab initio molecular orbital method at the level of second-order Møller-Plesset perturbation theory (MP2). Calculated geometries for the herringbone-style structures found in the crystal structure were characterized as local minima, however the geometrical discrepancy between crystal and MP2 theoretical structure is reasonably small. The binding energy of pentacene tetramer was calculated up to 40 kcal/mol (MP2/6-31G(d)) and about 90 kcal/mol (MP2/aug-cc-pVDZ), and the latter seems to be too much overestimated. The tendency of the hole transfer integrals computed with ab initio MP2/3-21G(d) geometry is well agreement with those estimated with crystal structure with some discrepancy, and the gradual increment of the transfer integrals at the crystal geometry is attributed to mainly packing structure rather than the intrinsic property of acene such as a size of acene.
Characteristic Effects of 4,5-Disubstituted Pyridazin-3-one Derivatives with Various Functional Groups: Ab initio Study
Yoon, Yong-Jin ; Koo, In-Sun ; Park, Jong-Keun ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1363~1370
DOI : 10.5012/bkcs.2007.28.8.1363
The geometrical structures of pyridazin-3-one derivatives (4,5-dihalopyridazin-3-one and 4-halo-5- alkoxypyridazin-3-one) with various functional and substituent groups were fully optimized using the ab initio Hartree-Fock (HF) and second order Moller-Plesset perturbation (MP2) methods. At the N2-, C4-, and C5- positions on the pyridazin-3-one rings, the structural and electronic features pertaining to the variations of the functional and substituent groups were analyzed, respectively. The trends in the variation of the bond lengths, atomic charges, and energetics (relative energy, binding energy) of the derivatives induced by changing the electron donating functional groups (X1 = OMe, OEt) to electron withdrawing groups (X1 = Cl, NO2) were examined. The variations of the bond lengths, atomic charges, and binding energies with the electron withdrawing strength of the substituent groups (Y = Me → F) were also investigated.
Molecular Dynamics Simulation Study of the Transport Properties of Liquid Argon: The Green-Kubo Formula Revisited
Lee, Song-Hi ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1371~1374
DOI : 10.5012/bkcs.2007.28.8.1371
The velocity auto-correlation (VAC) function of liquid argon in the Green-Kubo formula decays quickly within 5 ps to give a well-defined diffusion coefficient because the velocity is the property of each individual particle, whereas the stress (SAC) and heat-flux auto-correlation (HFAC) functions for shear viscosity and thermal conductivity have non-decaying, long-time tails because the stress and heat-flux appear as system properties. This problem can be overcome through N (number of particles)-fold improvement in the statistical accuracy, by considering the stress and the heat-flux of the system as properties of each particle and by deriving new Green-Kubo formulas for shear viscosity and thermal conductivity. The results obtained for the transport coefficients of liquid argon obtained are discussed.
Determination of Cadmium(II) and Copper(II) by Flame Atomic Absorption Spectrometry after Preconcentration on Column with Pulverized Amberlite XAD-4 with Bismuthiol I
Park, Dong-Seok ; Choi, Hee-Seon ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1375~1382
DOI : 10.5012/bkcs.2007.28.8.1375
A column preconcentration method with pulverized Amberlite XAD-4 loaded with bismuthiol I (BI) has been developed for the determination of trace Cd(II) and Cu(II) in various real samples by flame atomic absorption spectrophotometry. Various experimental conditions, such as the size of XAD-4, adsorption flow rate, amount of bismuthiol I, stirring time for adsorbing bismuthiol I on XAD-4, pH of sample solution, amount of XAD-4- BI, desorption solvent, and desorption flow rate, were optimized. Also, the adsorption capacity and the adsorption rate of Cd(II) and Cu(II) on XAD-4-BI were investigated. The interfering effects of various concomitant ions were investigated, Bi(III), Sn(II) and Fe(III) were found to affect the determination. But the interference by these ions was completely eliminated by adjusting the amount of XAD-4-BI resin to 0.70 g, although the adsorption flow rate was slower. For Cd(II) our proposed technique obtained a dynamic range of 0.5-40 ng mL-1, a correlation coefficient (R2) of 0.9913, and a detection limit of 0.3 ng mL-1. For Cu(II), the corresponding values were 2.0-120 ng mL-1, 0.9921 and 1.02 ng mL-1. To validate this proposed technique, the aqueous samples (stream water, reservoir water, tap water and wastewater), the diluted brass sample and the plastic sample, as real samples, were used. Recovery yields of 91-103% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. Our proposed method was also validated using rice flour CRM (normal, fortified) samples. From the results of our experiment, we found that the technique we present here can be applied to the determination of Cd(II) and Cu(II) in various real samples.
Evaluation Method on Destruction and Removal Efficiency of Perfluorocompounds from Semiconductor and Display Manufacturing
Lee, Jee-Yon ; Lee, Jin-Bok ; Moon, Dong-Min ; Souk, Jun-Hyung ; Lee, Seung-Yeon ; Kim, Jin-Seog ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1383~1388
DOI : 10.5012/bkcs.2007.28.8.1383
Recently, the semiconductor and display industries have tried to reduce the emissions of perfluorocompounds (PFCs) from the globally environmental regulation. Total amount of PFC emission can be calculated from the flow rate and the partial pressures of PFCs. For the precise measurement of PFC emission amount, the mass flow controlled helium gas was continuously injected into the equipment of which scrubber efficiency is being measured. The partial pressures of PFCs and helium were accurately measured using a mass spectrometer in each sample extracted from inlet and outlet of the scrubber system. The flow rates are calculated from the partial pressures of helium and also, PFC destruction and removal efficiency (DRE) of the scrubber is calculated from the partial pressure of PFC and the flow rate. Under this method, the relative expanded uncertainties of the flow rate and the partial pressures of PFCs are ± 2% (k = 2) in case the concentrations of NF3 and SF6 are as low as 100 μmol/mol.
Synthesis, Photophysical and Electrochemical Properties of Novel Conjugated Donor-Acceptor Molecules Based on Phenothiazine and Benzimidazole
Zhang, Xiao-Hang ; Kim, Seon-Ho ; Lee, In-Su ; Gao, Chun-Ji ; Yang, Sung-Ik ; Ahn, Kwang-Hyun ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1389~1395
DOI : 10.5012/bkcs.2007.28.8.1389
Two series of new organic fluorophores such as asymmetrical 3-(benzimidazol-2-yl)-10-hexylphenothiazine derivatives 1 and symmetrical 3,7-bis(benzimidazol-2-yl)-10-hexylphenothiazine derivatives 2 have been synthesized. Electronic absorption, fluorescence, and electrochemistry measurements reveal that the electron withdrawing benzimidazole subunit directly connected to the phenothiazine core facilitates the charge transfer characters which were also verified by the theoretical calculations. Various substituents on the benzimidazole moieties can allow a fine-tuning of the LUMO energy levels of the molecules without significantly affecting the HOMO energy levels. The method provides a new route for designing ambipolar molecules whose energy levels are well-matched with the Fermi levels of the electrodes to facilitate the electron or hole injection/transfer in OLED devices.
Sebum Absorption Characteristics of Polymer Microgel-containing Face Powder
Lee, Young-Keun ; Jin, Fan-Long ; Park, Soo-Jin ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1396~1400
DOI : 10.5012/bkcs.2007.28.8.1396
In this study, poly(iso-butyl methacrylate-co-ethylene glycol dimethacrylate) [poly(iso-BMA-co-EGDMA)] microgel was prepared and used as a face powder additive. The spreading, adhesiveness, and skin reactivity of poly(iso-BMA-co-EGDMA) microgel-containing face powder II were investigated and compared with the same properties of commercially available Silica bead 700-containing face powder I. In the results, the particle size of the poly(iso-BMA-co-EGDMA) microgel was significantly swelled as a result of sebum absorption. Face powder II showed a lower primary irritation index and a higher adhesiveness than did face powder I. Face powder I showed a low sebum absorption ratio and a relatively high rate of sebum absorption, whereas face powder II, contrastingly, exhibited a high sebum absorption ratio and a low rate of sebum absorption, which properties would reduce the phenomena of facial strain and sliminess. These results indicate that poly(iso- BMA-co-EGDMA) microgel has outstanding sebum absorption characteristic and adhesiveness, and thus that it is a good candidate for use as a face powder additive.
Synthesis of Calycotomine via Pictet-Spengler Type Reaction of N,O-Acetal TMS Ethers as N-Acyliminium Ion Equivalents
Yang, Jung-Eun ; In, Jin-Kyung ; Lee, Mi-Sung ; Kwak, Jae-Hwan ; Lee, Hee-Soon ; Lee, Soo-Jae ; Kang, Han-Young ; Suh, Young-Ger ; Jung, Jae-Kyung ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1401~1404
DOI : 10.5012/bkcs.2007.28.8.1401
An efficient Pictet-Spengler type reaction of N,O-acetal TMS ethers for the practical synthesis of 1-substituted tetrahydroquinolines, medicinally important alkaloids, has been accomplished. To demonstrate the versatility of this novel procedure, the total synthesis of calycotomine, a representative 1-hydroxymethyl substituted tetrahydroisoquinoline, is also described.
Electric Field-induced Charge Transfer of (Bu
] on Gold, Silver, and Copper Electrode Surfaces Investigated by Means of Surface-enhanced Raman Scattering
Joo, Sang-Woo ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1405~1409
DOI : 10.5012/bkcs.2007.28.8.1405
The potential-induced charge transfer of the dye (Bu4N)2[Ru(dcbpyH)2-(NCS)2] (N719) on Au, Ag, and Cu electrode surfaces has been examined by surface-enhanced Raman scattering (SERS) in the applied voltage range between 0.0 and ?0.8 V. N719 is assumed to have a relatively perpendicular geometry with its bipyridine ring on the metal surfaces. A strong appearance of the carboxylate band at ~1370 cm-1 indicates that the carboxyl group will likely be deprotonated on the metal surfaces. As the electric potential is shifted from ?0.8 to 0.0 V, the ν (NCS) band at ~2100 cm-1 on the electrode surfaces appears to undergo a shift in frequency and intensity change. This indicated that the charge transfer between the dye and metal electrode surfaces had occurred. Electric-field-dependent charge transfer differs somewhat depending on the type of metal surfaces as suggested from the dissimilar frequency positions of the ν (NCS) band.
Determination of the Rate Constants for Bimolecular Reactions of O(
P) Atom with SiH
Lee, Jee-Yon ; Yoo, Hee-Soo ; Kim, Jin-Seog ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1410~1412
DOI : 10.5012/bkcs.2007.28.8.1410
Binding Study of Naringenin Derivatives and Cyclin Dependent Kinase 2
Kim, Ho-Jung ; Lee, Eun-Jung ; Kim, Ji-Hye ; Kim, Jin-Young ; Lim, Hae-Young ; Lee, Chul-Hoon ; Ahn, Joong-Hoon ; Chong, You-Hoon ; Lim, Yoong-Ho ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1413~1415
DOI : 10.5012/bkcs.2007.28.8.1413
Synthesis and Structure of a Cadmium Selenite-Sulfate Cd
Xie, Yiming ; Wu, Jihuai ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1416~1418
DOI : 10.5012/bkcs.2007.28.8.1416
An NMR Chiral Solvating Agent for the Chiral Recognition of the Two Enantiomers of N-(3,5-Dinitrobenzoyl)-α-amino Acids
Hyun, Myun-Ho ; Kim, Seung-Nam ; Choi, Hee-Jung ; Sakthivel, Pachagounder ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1419~1421
DOI : 10.5012/bkcs.2007.28.8.1419
A Practical and Simple Method of Recycling Catalyst in Asymmetric Aminohydroxylation of Olefins
Sun, Xiao Li ; Jin, Ying ; He, Wei ; Nan, Peng Juan ; Zhang, Sheng Yong ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1422~1424
DOI : 10.5012/bkcs.2007.28.8.1422
Existence of Critical Aggregation Concentration at the Very Dilute Regime of Poly(vinylidene fluoride)/Propylene Carbonate System
Park, Il-Hyun ; Xu, Zhi Yang ; Ling, Yun ; Kim, Bong-Soo ; Lee, Jang-Oo ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1425~1428
DOI : 10.5012/bkcs.2007.28.8.1425
Weak Forces in Inorganic Lattices: Anion Roles in Lattice Assembly
Lee, Young-Hoon ; Park, Yu-Chul ; Harrowfield, Jack M. ; Thuery, Pierre ; Kim, Yang ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1429~1432
DOI : 10.5012/bkcs.2007.28.8.1429
Preparation of Novel Nonlinear Optical Polyester with Enhanced Thermal Stability of Dipole Alignment
Lee, Ju-Yeon ; Kim, Jin-Hyang ; Won, Dong-Seon ; Jang, Han-Na ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1433~1436
DOI : 10.5012/bkcs.2007.28.8.1433
Direct Formation of Silver Cluster Ions from Silver Salts by Laser Desorption/Ionization
Choi, Sung-Seen ; Ha, Sung-Ho ; Lee, Hye-Min ; Kim, Jong-Chul ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1437~1439
DOI : 10.5012/bkcs.2007.28.8.1437
Molecular Engineering. Part 14. Self-Assembled Oligovelcraplexes by π-π Stacking Interaction and Metal Coordination
Kwak, Min-Jung ; Paek, Kyung-Soo ;
Bulletin of the Korean Chemical Society, volume 28, issue 8, 2007, Pages 1440~1442
DOI : 10.5012/bkcs.2007.28.8.1440