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Rhee, Seog-Woo,Na, Yong-Hwan,Do, Young-kyu,Kim, Jin-kwon 공주대학교 자원재활용신소재지역협력센터 2000 2차년도 센터 사업 성과집 Vol.2000 No.1
Condensation of ferrocenecarboxaldehyde and dipyrrolylmethane gave 5,15-diferrocenyl-2,8,12,18-tetraethyl-3,7,13,17-tetramethyl-5,15-dihydroporphyrin (H21), and 5,15-diferrocenyl-2,8,12,18-tetraethyl-3,7,13,17-tetramethylporphyrin (H22) in 31 and 49% yield, respectively. Structures of H21·CHCl3 and H22·0.5C6H5Me have been determined by X-ray diffraction. Compound H21 has syn-axial configuration and H22 has syn configuration of two ferrocenyl groups. Compound H21 was only proven to be an intermediate species of H22 in the photooxidation pathway. The large steric bulkiness of the ferrocenyl group permitted the isolation of compounds H21 and H22 directly from the oxidation reaction of 5,15-diferrocenyl-2,8,12,18-tetraethyl-3,7,13,17-tetramethylporphyinogen. Porphodimethene H21 has exceptional stability toward air and light in the absence of acid. Electrochemically, ferrocene subunits of H21 are oxidized with a reversible two-electron transfer process (0.33 V), while those of H22 are oxidized with two reversible one-electron transfer processes (0.06 and 0.27 V). ⓒ 2000 Elsevier Science B.V. All rights reserved. Keywords: Ferrucenylporphyrin; Porphodimethene; Photooxidation; π-Conjugation; Electrochemical communication
Rhee, Seog-Woo,Jung, Duk-Young Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.1
Photoreaction of guest organic anions in layered organic-inorganic hybrid materials was investigated. The layered hybrids were synthesized by an anion-exchange reaction of $[LiAl_2(OH)_6]Cl{\cdot}yH_2O$ layered double hydroxide with aqueous (Z,Z)- and (E,E)-muconates under inert atmospheric condition, to give new organicinorganic hybrids of $[LiAl_2(OH)_6]_2[(Z,Z)-C_6H_4O_4]{\cdot}zH_2O$ and $[LiAl_2(OH)_6]_2[(E,E)-C_6H_4O_4]{\cdot}H_2O$, respectively. The basal spacings calculated by XRPD of intercalates indicate that muconate anions have almost vertical arrangements against the host $[LiAl_2(OH)_6]^+$ lattices in the interlayer of organic-inorganic hybrid materials. When UV light was irradiated on the suspension of $[LiAl_2(OH)_6]_2[(Z,Z)-C_6H_4O_4]{\cdot}zH_2O$, the (Z,Z)-muconate anions of the gallery space of hybrids were polymerized in the aqueous media while it was isomerized into more stable (E,E)-muconate in the methanollic suspension in the presence of catalytic amount of molecular iodine. All the products were characterized using elemental analysis, TGA, XRPD, FT-IR, $^1H$ NMR and $^{13}C$ CP-MAS NMR.
Rhee, Seog-Woo,Park, Byung-Bin,Do, Young-kyu,Kim, Jin-kwon 공주대학교 자원재활용신소재지역협력센터 2000 2차년도 센터 사업 성과집 Vol.2000 No.1
The reaction of dipyrrylmethane with an equimolar mixture of ferrocenecarboxaldehyde and benzaldehyde in dry acetonitrile in the presence of a catalytic amount of trichloroacetic acid leads to the formation of 5-ferrocenyl-15-phenyl-2,8,12,18-tetraethyl-3,7,13,17-tetramethylporphyrin (1) with a yield of 27%. The metallation of 1 with Zn(OAc)2·2H2O and MnCl2·4H2O gives Zn·1 and MnCl·1, respectively. Cyclic voltammograms of 1, Zn·1 and MnCl·1 show reversible one-electron oxidation processes for the oxidation of ferrocene at 0.29, 0.22, and 0.37 V, respectively. Variable temperature 1H NMR spectra of 1 in toluene-d8 show two distinct singlets of equal intensities and line widths for NH protons. From the plot of ln(k/T) versus 1/T according to the Eyring equation, gave straight line with Δ□=51 kJ mol-1. ⓒ 2000 Elsevier Science Ltd. All rights reserved. Keywords : Ferrocenylporphyrin ; π-Conjugation; Electrochemical communication; Intramolecular hydrogen bonding; NH tautomerism
Sorption of aqueous Pb^(2+) ion on synthetic manganese oxides-intercalated with exchangeable cations
강광철,Seog Woo Rhee,주진희,Seung Soo Kim,백민훈 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3
This paper describes the preparation, characterization, and application of three different synthetic manganese oxides (K–MO, H–MO, and Mg–MO). K–MO was synthesized by the reduction of potassium permanganate in an aqueous acidic medium. H–MO was prepared by an ion exchange reaction of K–MO with H+, while Mg–MO was prepared by reaction of H–MO and an aqueous Mg^(2+) salt solution under reflux. The subsequent solid products were characterized by a chemical composition analysis, XRD, XPS,FT-IR, SEM, and BET measurements. XPS spectra revealed that only tetravalent manganese ions coordinated octahedrally with oxygens. XRD patterns showed that K–MO turned into a layer-structured material while Mg^(2+) ions were incorporated into the gallery space of the tunnel-structured Mg–MO. Each type ofmanganese oxide was used in a sorption study of aqueous Pb2+ at 25℃. The sorption of Pb^(2+) ions by manganese oxide resulted in increases of the concentrations of pre-intercalated ions (potassium ions,protons, or magnesium ions) and Mn^(2+) ions. In spite of the smaller surface area and pore volume, K–MO showed greater sorption capacity for Pb^(2+) ions than that of Mg–MO under the present experimental conditions, thus suggesting that ion exchange is the main mechanism for the sorption of Pb2+ ions on manganese oxides. The results are anticipated to be applicable to the removal of heavy metal ions from wastewater and the prevention of migration of ions in landfill leachates.
Estimation of the cutoff value of vitamin D: the Dong-gu study
Choi, Seong-Woo,Kweon, Sun-Seog,Choi, Jin-Su,Rhee, Jung-Ae,Lee, Young-Hoon,Nam, Hae-Sung,Jeong, Seul-Ki,Park, Kyeong-Soo,Ryu, So-Yeon,Song, Hye-Rim,Shin, Min-Ho BioMed Central 2015 Journal of Physiological Anthropology Vol.34 No.1
<P><B>Background</B></P><P>Vitamin D plays an essential role in bone health and growth, but the optimal serum 25-hydroxyvitamin D (25(OH)D) concentration is not known. This study was performed to investigate the optimal 25(OH)D concentration in regard to parathyroid hormone (PTH) concentration in the Korean general population aged 50 years or older.</P><P><B>Findings</B></P><P>The study population consisted of 8,857 subjects (3,545 men and 5,312 women) who participated in the baseline survey of the Dong-gu study, conducted in Korea between 2007 and 2010. Serum 25(OH)D and PTH concentrations were measured by chemiluminescent microparticle immunoassay. The optimal 25(OH)D concentration was estimated by using nonlinear regression model. Our data show that PTH concentration reached a theoretical plateau at 38.2 pg/ml and corresponding 25(OH)D concentration was 21.1 ng/ml in men and PTH concentration at 42.9 pg/ml and 25(OH)D concentration at 13.8 ng/ml in women.</P><P><B>Conclusions</B></P><P>These results indicate that, for Korean general population aged 50 years or older, the optimal 25(OH)D concentration is 21.1 ng/ml in men and 13.8 ng/ml in women.</P>
Cohort Profile: The Namwon Study and the Dong-gu Study
Kweon, Sun-Seog,Shin, Min-Ho,Jeong, Seul-Ki,Nam, Hae-Sung,Lee, Young-Hoon,Park, Kyeong-Soo,Ryu, So-Yeon,Choi, Seong-Woo,Kim, Bok-Hee,Rhee, Jung-Ae,Zheng, Wei,Choi, Jin-Su Oxford University Press 2014 International journal of epidemiology Vol.43 No.2
<P>These two cohorts were designed to examine the increasing burden of chronic diseases among Korean populations. The studies investigated determinants for stroke, osteoporosis, dementia and cancer among middle-aged and elderly Korean populations. The Namwon Study baseline survey was performed between 2004 and 2007 (<I>n</I> = 10 667), and followed up 4 years later (<I>n</I> = 8157, follow-up rate = 76.5%). The baseline survey of the Dong-gu Study was administered over 2007–2010 (<I>n</I> = 9260), and will be followed up between 2014 and 2015. Questionnaires included assessment of cognitive function, psychiatric health and lifestyle factors. Clinical examinations, biochemical tests and genotyping focused on evaluating the determinants of target diseases and their intermediate phenotypes. Potential collaborators will be invited to contact the chief investigators.</P>
Ramasamy, Parthiban,Chandra, Prakash,Rhee, Seog Woo,Kim, Jinkwon RSC Pub 2013 Nanoscale Vol.5 No.18
<P>The visible green and red upconversion emissions in Er(3+)/Yb(3+) doped β-NaGdF4 nanoparticles were enhanced by tridoping with Fe(3+) ions (0-40 mol%). XRD, XPS, ICP-AES and EDS data demonstrated successful incorporation of Fe(3+) ions in NaGdF4:Yb(3+)/Er(3+) nanoparticles. The effect of Fe(3+) tridoping on the upconversion luminescence in NaGdF4:Yb(3+)/Er(3+) NPs was investigated in detail. The green and red emission intensities were enhanced by 34 and 30 times, respectively. The maximum emission was observed in a sample containing 30 mol% Fe(3+) ions. A possible mechanism for the enhanced upconversion emission is proposed. In addition, a layer of silica was coated onto the surface of UCNPs to improve the biocompatibility. Folic acid was covalently linked to the silica coated UCNPs to form UCNP@SiO2-FA nanoprobes, which have been successfully applied to the fluorescent imaging HeLa cells.</P>
Ag Nanowires Prepared by a Modified Polyol Method with 1,4-Benzoquinone Additives
강미선,정은선,김상호,Seog Woo Rhee 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.11
This paper describes a selective synthetic method of fabricating Ag nanowires by using a modified polyol process. To synthesize the Ag nanowire, an ethylene glycolic solution of silver nitrate and an ethylene glycolic solution of polyvinylpyrrolidone solution containing a small amount of organic oxidant, 1,4-benzoquinone, were slowly added to a hot ethylene glycol medium at 160 oC for 8 min using a syringe pump. The reaction mixtures were heated for an additional 45 min and cooled to room temperature. Finally, the silver nanomaterials were isolated from the mixture by centrifugation. The crystal structure of the nanomaterials was investigated by powder X-ray diffraction analyses, and their morphology was investigated by scanning electron microscopy. A small amount of organic oxidant, 1,4-benzoquinone, played a significant role in controlling the morphology during crystal growth. Consequently, Ag nanowires rather than Ag nanoparticles were selectively obtained.
Step-wise Anion-Exchange in Layered Double Hydroxide Using Solvothermal Treatment
Lee, Jong-Hyeon,Rhee, Seog-Woo,Jung, Duk-Young Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.2
Synthetic layered double hydroxides (LDHs), [$Mg_4Al_2(OH)_{12}]CO_3{\cdot}nH_2O$, were prepared in the submicron size of plate-like polycrystals. Anion-exchange reactions with various linear dicarboxylic acids were performed to produce LDH/organic hybrid materials by solvothermal treatment in toluene. X-ray powder diffraction spectra for the products indicated that the interlayer spacings of LDHs remarkably changed, up to 20 $\AA$ when 1,10-decanedicarboxylic acid anions were intercalated as an organic guest. Dicarboxylates-LDHs samples could be also re-exchanged consecutively with other dicarboxylic acids or carbonate without serious destruction of layer structure under the scanning electron microscopic observation.