• Bulletin of the Korean Chemical Society
• /
• v.34 no.2
• /
• pp.515-518
• /
• 2013

We present synthesis of a new kind of organic-inorganic hybrid polymer, poly xylene-hexamethyltrisiloxane hybrid (PXS) by a new synthetic way from o-xylene and 1,1,3,3,5,5-hexamethyltrisiloxane. The merged molecular structure of the two monomeric components for the PXS polymer was confirmed by $^{13}C$- and $^1H$-NMR, and FT-IR. Its optical absorption and emission properties were investigated by UV-vis absorption and photoluminescence (PL) spectroscopy. The PXS exhibits absorption at 265 nm which is the same with the o-xylene but tailing up to nearly 400 nm, which is maybe related the polymeric structure of the PXS. For the PL investigation, the PXS shows red-shift of the peak from 288 nm (o-xylene) to 372 nm in the case of excitation at 265 nm, at which both PXS and o-xylene have sufficiently high absorption for excitation. When 325-nm laser is used for excitation, the PXS shows a broader peak at 395 nm compared to the excitation at 265 nm and the o-xylene shows no luminescence probably due to the lack of absorption at 325 nm.

• Analytical Science and Technology
• /
• v.14 no.2
• /
• pp.159-166
• /
• 2001

A humic acid(HA, Aldrich Co) sample was subjected to ultrafiltration for molecular size fractionation and three fractions of different nominal size($F_1$: 1,000-10,000 daltons; $F_2$: 10,000-50,000 daltons; $F_3$: 100,000-300,000 daltons) were obtained. The structural characteristics of the size-fractionated HA were analyzed using their IR and solid state C-13 NMR spectral data, and the carboxylate group contents of the humic acids were determined using their pH titration data. The $^7F_0-{^5}D_0$ excitation spectra of Eu(III) complexes of the size-fractionated mgHA in aqueous solution were acquired($[Eu(III)]=1.0{\times}10^{-4}mol\;L^{-1}$, $(HA)=470-970mg\;L^{-1}$) at pH 5.0 using a pulsed tunable laser system, in which metal binding properties of the size-fractionated HA were elucidated and compared on another. Characterization of the IR and C-13 NMR spectral data indicated that the fraction($F_3$) with molecules of larger size were primarily aliphatic, while the fractions($F_1$, $F_2$) with smaller molecules of less than 50,000 daltons were predominantly aromatic. Titration data were consistent with an increase in the number of carboxylate groups per unit mass as molecular size became smaller. The $^7F_0-{^5}D_0$ excitation spectral data of Eu(III)-humate complexes showed that the peak maxima on these spectra were shifted toward lower energies with increasing molecular size of HA, indicating the higher degree of bindings of the Eu in the molecules of larger size. We also discussed the relationship of the lower energy shifts of the maximum peaks with increasing the molecular size of HA with the structural differences of the size-fractionated HA.

• Korean Journal of Food Science and Technology
• /
• v.28 no.6
• /
• pp.1157-1163
• /
• 1996

Bangah, one of the herbs grown in Korea, was investigated for its antioxidant activity. The ether extracts of bangah herb was separated into neutral, phenolic, acidic and basic fractions and further separated into subfractions. Antioxidative activities were measured by hydrogen donating activity (HDA), peroxide value (POV), thiobarbituric acid (TBA) value and inhibition activity against lipid peroxidation of rat liver microsomes, The subfraction components were identified by GC/MS and NMR. Phenolic, though being very small in quantity, showed higher antioxidant activity at all assay system by hydrogen donating activity. POV, TBA value and inhibition activity against lipid peroxidation of rat liver microsomes. Five subfractions(P-1, P-2, P-3, P-4 and P-5) were fractionated from phenolic fraction of bangah herbs, and subfraction P-2 among them showed strong antioxidant activity on a level with BHT or gallic acid at each assay system. Four compounds (peak I, peak II, peak III and peak IV) were isolated by gas chromatogram of TMS derivatives of subfraction P-2 and thes compounds were confirmed to be phenolic substance having -OH and COOH group. There subfractions (N-1, N-2 and N-3) were fractionated from neutral fraction of bangah herbs, and subfraction N-2 among them showed highest antioxidant activity and inhibition activity against lipid peroxidation of rat liver microsomes. Subfraction N-2 was indentified to be estragole by H-NMR spectroscopy.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.8
• /
• pp.1299-1304
• /
• 2007

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.

• YAKHAK HOEJI
• /
• v.42 no.5
• /
• pp.494-499
• /
• 1998

As part of a drug discovery program to discover more effective platinum-based anticancer drugs, a series of platinum complexes of 1,2-bis(diphenylphosphino)ethane(1,2-diaminopro pane)platinum(II)dinitrate (KHPC-070) has been evaluated in vitro against various tumor cell lines and normal kidney cells. The structure of this new compound was determined by elemental analysis, infrared spectroscopy (IR) and $^{13}carbon$ nuclear magnetic resonance (NMR). With the use of nine tumor cell lines, KHPC-070 exhibited a comparable cytotoxic to cisplatin. The cytotoxicity of KHPC-070 in normal cells was quite less than that of cisplatin using 3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and [$^3H$]-thymidine uptake tests in rabbit renal proximal tubular cells and human renal cortical cells. Based on these results, KHPC-070 is considered to have more selective cytotoxicity toward cancer cells than normal human/rabbit kidney cells.

• Macromolecular Research
• /
• v.17 no.11
• /
• pp.912-918
• /
• 2009

An optically active diacid containing the L-histidine moiety was prepared by reacting pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid 1,2,4,5-dianhydride) 1 with L-histidine 2 in acetic acid, and was polymerized with several aromatic diamines 5a-g to obtain a new series of optically active poly(amide-imide)s (PAIs) using two different methods, such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride ($CaCl_2$)/pyridine (Py) and direct polycondensation in a tosyl chloride (TsCl)/pyridine (Py)/N,N-dimethylformamide (DMF) system as a condensation agent. The resulting new polymers 6a-g with inherent viscosity was obtained in good yield. The polymers were readily soluble in polar organic solvents, such as N,N-dimethyacetamide (DMAc), N,N-dimethyformamide (DMF), and dimethyl sulfoxide (DMSO). The obtained polymers were characterized by FTIR, specific rotation, elemental analysis as well as $^1$H-NMR spectroscopy and gel permeation chromatography (GPC). The thermal stability of the resulting PAIs was evaluated with thermogravimetric analysis techniques under a nitrogen atmosphere.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.316.1-316.1
• /
• 2002

Dermatan sulfate (DS) was isolated from eel skin (Anguilla japonica) bv actinase and endonuclease digeslions followed by ${\beta}$-elimination reaction and DEAE-Sephacel chromatography. DS was a major glycosaminoglycan in eel skin with 88% of the total uronic acid. The content of IdoA2S$\alpha$1longrightarrow4GalNAc4S sequence in eel skin. which is known to be a binding site to heparin cofactor II. was two times higher than that of dermatan sulfate from porcine skin. The anti-lla activity of eel skin dermatan sulfate mediated through heparin cofactor ll(NCL) was 25 units/mg. whereas DS from porcine skin shows 23.2 units/mg. The average molecular weight was determined as 14 kDa by gel chromatography on a TSKgel G3000SWXL column. Based on H1 NMR spectroscopy. we suggest that 3-sulfated and/or 2.3-sulfated ldoA residues are present in the chain.

• Macromolecular Research
• /
• v.12 no.3
• /
• pp.316-321
• /
• 2004

We have performed copolymerizations of ethylene with 1-hexene using various ansa-metallocene compounds in the presence of the non-coordinative [CPh$_3$][B(C$\_$6/F$\_$5/)$_4$ion pair as a cocatalyst. The metallocenes chosen for this study are isospecific metallocene diamide compounds, rac-(EBI)Zr(NMe$_2$)$_2$ [1, EBI = ethylene-l ,2-bis(1-indenyl)], rac-(EBI)Hf(NMe$_2$)$_2$ (2), rac-(EBI)Zr(NC$_4$H$\_$8/)$_2$ (3), and rac-(CH$_3$)$_3$Si(1-C$\_$5/H$_2$-2-CH$_3$-4-$\^$t/C$_4$H$\_$9/)2 Zr(NMe$_2$)$_2$ (4), and syndiospecific metallocene dimethyl compounds, ethylidene(cyclopentadienyl)(9-fluorenyl) ZrMe$_2$ [5, Et(Flu)(Cp )ZrMe$_2$] and isopropylidence (cyclopentadienyl)(9-fluorenyl)ZrMe$_2$ [6, iPr(Flu)(Cp)ZrMe$_2$]. The copolymerization rate decreased in the order 4 ＞1-3＞2 ＞5＞6. The reactivity of I -hexene decreased in the order 2 ＞6＞1- 3-5＞ 4. We characterized the microstructure of the resulting poly(ethylene-co-l-hexene) by $\^$l3/C NMR spectroscopy and investigated various other properties of the copolymers in detail.

• Natural Product Sciences
• /
• v.29 no.1
• /
• pp.10-16
• /
• 2023

We previously reported that dried Lysimachia christinae whole plant extract exerted significant neuroprotective activity. In this study, we tried to isolate neuroprotective compounds of L. christinae. We evaluated the neuroprotective activity of the four fractions (hexane, chloroform, ethyl acetate, and n-butanol fractions) of methanol extract. Among them, ethyl acetate and n-butanol fractions showed most potent neuroprotective activity against glutamate excitotoxicity. Nine compounds were isolated from ethyl acetate and n-butanol fractions of L. christinae extract and identified as cynaroside (1), (3,4,5,6-tetrahydroxytetrahydro-2H-pyran-2-yl)methyl-3-hydroxy-2-octyldopentaconta-23,33-dienoate (2), androst-16-ene-3,6-diol (3), 2-hydroxy-24-propoxytetracos-4-enoic acid (4), 2-hydroxy-24-methoxytetracos-4-enoic acid (5), 12-(stearoyloxy)octadec-9-enoic acid (6), β-sitosterol (7), (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-yl palmitate (8) and (1S,2S,3R,4R)-4-(((2S,3R,4R,5R,6S)-2-(((2R,3R,4S,5R,6R)-2-(3,4-dimethoxyphenethoxy)-3,5-dihydroxy-6-(hydroxymethyl) tetrahydro-2H-pyran-4-yl)oxy)-4,5-dihydroxy-6-methyltetrahydro-2H-pyran-3-yl)oxy)cyclohexane-1,2,3-triol (9) by spectroscopic data such as UV, IR, NMR, Mass spectroscopy. Their neuroprotective activity was evaluated by MTT assay. Cynaroside (1) and androst-16-ene-3,6-diol (3) had significant neuroprotective activity against glutamate-injured HT22 cells. The neuroprotective efficacy of cynaroside (1) and androst-16-ene-3,6-diol (3) was related to their anti-oxidative activity.

• Analytical Science and Technology
• /
• v.13 no.4
• /
• pp.494-503
• /
• 2000

A 21-residue peptide corresponding to amino acids 84-104 of $p16^{INK4A}$, the tumor suppressor, has been synthesized and its structure was studied by Circular Dichroism, $^1H$ NMR spectroscopy and molecular modeling. A p16-derived peptide (84-104 amino acids) forming stable complex with CDK4 and CDK6 inhibits the ability of CDK4/6 to phosphorylate pRb in vitro, and blocks cell-cycle progression through G1/S phase as shown in the function of the full-length p16. Its NMR spectral data including NOEs, $^3J_{NH-H{\alpha}}$ coupling constants, $C_{\alpha}H$ chemical shift, the average amplitude of amide chemical shift oscillation and temperature coefficients indicate that the secondary structure of a p16-derived peptide is similar to that of the same region of full-length p16, which consists of helix-turn-helix structure. The 3-D distance geometry structure based on NOE-hased distance and torsion angle restraints is characterized by ${\gamma}$-turn conformation between residues $Gly^{89}-Leu^{91}$(${\varphi}_{i+1}=-79.8^{\circ}$, ${\varphi}_{i+1}=60.2^{\circ}$) as evidenced in a single crystal structure for the corresponding region of p18 or p19, but is undefined at both the N and C termini. This compact and rigid ${\gamma}$-turn region is considered to stabilize the structure of p16-derived peptide and serve as a site recognizing cyelin dependent kinase, and this well-defined ${\gamma}$-turn structure could be utilized for the design of anti-cancer drug candidates.