• Carbon letters
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• 제4권4호
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• pp.175-179
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• 2003

It is well established that halogenated fullerene derivatives act as synthetic intermediates for further substitution via replacement with nucleophlies. In the present work, systematic studies were carried out on the synthesis of bromofullerenes under different experimental conditions. The effect of reaction time on the product formed was observed. We observed the formation of new compound of bromofullerenes in a different stoichiometric ratio i.e., $C_{60}Br_{14}$; in addition to previous reported bromofullerenes in the stoichiometric ratio of $C_{60}Br_6$, $C_{60}Br_8$, and $C_{60}Br_{24}$. The new derivative of bromofullerene was isolated and well characterized by various analytical techniques like FT-IR, TGA, DSC, and elemental analysis. In this paper, detail of the synthesis and characterization of the bromofullerene prepared are described. The yields obtained were better than those reported previously.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.336-338
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• 2016

Recent multifunctional two-dimensional material research has triggered huge interests in various modifications for substitution of atoms. Instead of novel metals used as the most popular catalysts, nonprecious transition metals are promising candidates for efficient oxidation-reduction transfers. The recent discovery of $Co@C_2N$ has an alternate possiblity as catalysts for the ORR(Oxygen Reduction Reaction) in DSSc(Dye Sensitized Solar Cell) and OER(Oxygen evolution cobalt oxides). Here we report spin-polarized DFT calculations of the structure doped Iron that is one of ferromagnetism atoms like Co to provide a basic desciption of the ferromagnetism of the elemental metals. The spin-density-funtional results present the most stable state energetically is when having pairwise up/down spin.

• 한국염색가공학회지
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• 제32권3호
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• pp.135-141
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• 2020

The primary and secondary alcohols in cellulose reacted with acrylonitrile(AN) in the presence of strong alkalis to form cyanoethylated cellulose. The partially cyanoethylated cotton(CEC) fabric with AN in the presence of aqueous sodium hydroxide solution was described, including effects of treatment time and reagent concentrations. The weight increases of cotton fabric were shown to be linearly related to the treatment time, temperature and concentration of sodium hydroxide. The physical properties such as shrinkage ratio and tensile strength were proportional to the weight increases without significant impact on elongation. But the moisture regain decreased with decreasing hydrophilicity. The degree of substitution(DS) and transfer ratio were linearly related to the weight increases. In the CEC with increasing weight up to 24.9%, it has been obtained with DS up to 0.63-0.67 cyanoethyl groups per anhydroglucose and transferring ratio up to 87.7%. The color fastness to washing by sublimation transfer printing was improved by the cyanoethylation.

• Food Science and Biotechnology
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• 제17권4호
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• pp.870-872
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• 2008

Barley $\beta$-glucan was subjected to chemical modification and the anticoagulant activity of the derivative was investigated. The barley $\beta$-glucan was successfully sulfated, showing the degree of substitution calculated by elemental analysis of 0.40. In addition, the Fourier transform infrared (FT-IR) spectra of the derivative confirmed the sulfation, which generated two new absorption bands at 1,250/cm (S=O) and 810/cm (C-O-S) compared to the native. Specially, the anticoagulant activity of barley $\beta$-glucan was created by sulfation, which increased in a concentration-dependent manner. This result demonstrated that the incorporation of sulfate groups into the $\beta$-glucan structure added a blood clotting prevention effect.

• Bulletin of the Korean Chemical Society
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• 제11권3호
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• pp.251-253
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• 1990

L-Alanine(L-ala) and S-methyl-L-cysteine(L-mcy) cobalt(III) complexes of a flexible $N_2O_2$-type tetradentate ligand ethylenediamine-N,N'-di- -butyric acid(eddb), s-cis-[Co(eddb)(L-ala)] and s-cis-[Co(eddb)(L-mcy), have been prepared via the substitution reactions of the s-cis-$[Co(eddb)Cl_2]$-complex with, respectively, L-alanine and S-methyl-L-cysteine. Both L-alanine and S-methyl-L-cysteine are found to coordinate to the cobalt(III) ion via the nitrogen and oxygen donor atoms to give the meridional s-cis isomer. Electronic absorption, ir and pmr spectra are used to characterize the complexes obtained in this work along with elemental analysis data.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.75-81
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• 2010

The reaction of N,N-diethyl carbamates of 1H-[1,2,3]triazolo[4,5-b]pyridin-1-ol (4-HOAt) 7, 3H-[1,2,3]triazolo[4,5-b]pyridin-3-ol (7-HOAt) 8, 1H-benzo[d][1,2,3]triazol-1-ol (HOBt) 9, 6-chloro-1H-benzo[d][1,2,3]triazol-1-ol (Cl-HOBt) 10, 6-(trifluoromethyl)-1H-benzo[d][1,2,3]triazol-1-ol ($CF_3$-HOBt) 11, and 6-nitro-1H-benzo[d][1,2,3]triazol-1-ol ($NO_2$-HOBt) 12 with morpholine and piperidine in $CH_3CN$ underwent acyl nucleophilic substitution to give the corresponding carboxamide derivatives. The reactants and products were identified by elemental analysis, IR and NMR. We measured the kinetics of these reactions spectrophotometrically in $CH_3CN$ at a range of temperatures. The rates of morpholinolysis and piperidinolysis were found to fit the Hammett equation and correlated with $\sigma$-Hammett values. The values were 1.44 - 1.21 for morpholinolysis and 1.95 - 1.72 for piperidinolysis depending on the temperature. The $Br{\phi}$nsted-type plot was linear with a $\beta_lg = -0.49 \pm 0.02$ and $-0.67 \pm 0.03$. The kinetic data and structure-reactivity relationships indicate that the reaction of 9-12 with amines proceeds by a concerted mechanism. The deviation from linearity of the correlation ${\Delta}H^#$ vs. ${\Delta}S^#$ and plot of $logk_{pip}$ vs. $logk_{morph}$ and $Br{\phi}$nsted-type correlation indicate that the reactions of amines with carbamates 7 and 8 is attributed to the electronic nature of their leaving groups.

• 대한화학회지
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• 제57권2호
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• pp.246-251
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• 2013

With -$OCH_2CO$- as a linker, a non ${\beta}$-substituted cationic bisporphyrin (4a) and a ${\beta}$-substituted cationic bisporphyrin (4b) were prepared through methylation of the intermediate which was obtained from ${\beta}$-amino-5,10,15,20-tetra (4-cyanophenyl) porphyrin or 5-hydroxylphenyl-10,15,20-tris(4-cyanophenyl) reacting with 5-hydroxy-10,15,20-trispyridinylporphyrin. Their structures were confirmed by $^1H$ NMR, IR, UV-vis, MS and elemental analysis. DNA photocleavage ability and the singlet oxygen ability of those cationic bisporphyrins were investigated. DNA photocleavage activity of ${\beta}$-substituted cationic bisporphyrin was significantly weaker than that of $H_2TMPyP$, but similar to that of non ${\beta}$-substituted cationic bisporphyrin. While 4a and 4b showed substantial photocleavage activities toward DNA, with 68% and 66% observed at 10 ${\mu}M$. The assessment of indirectly measured $^1O_2$ production rates against $H_2TMPyP$ were described and the relative singlet oxygen production yields were: free cationic bisporphyrins > $H_2TMPyP$. The results showed the cationic bisporphyrins with ${\beta}$-substitution and non ${\beta}$-substitution could be developed as potential photodynamic agents.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.511-517
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• 2002

The complex 1 $([Cp*Fe(CO)_2]_2-(\mu-CH=CH-CH=CH))$ which have butadiene as a bridge were synthesized from $Cp*(CO)_2FeK$ and cis-3,4-dichlorocyclobutene. The derivatives of complex 1 where one or two carbonyl groups are replaced by phosphine ligands have been prepared by photochemical substitution. The new derivatives $([Cp*Fe(L)_2]_2-(\mu-CH=CH-CH=CH))$ where L = $(Ph_2PCH_2CH_2PPh_2)$ and $([Cp*Fe(CO)(L)]_2-(\mu-CH=CH-CH=CH))$ where L : $PPh_3$ have been characterized from $^^1H-$, $^^13C-$,$^^31P-NMR$ and elemental analysis. Obtained complexes have been studied in electrochemical experiment and UV/VIS-near-IR. The mixed-valence radical cation forms of complex 2, 3 species were found to be delocalized as the Class III. Based on the separation of the waves ($\triangle E$ : 0.470 ~ 0.605 V), the efficiency of electronic communication between two metal centers of cation species leading to stabilization relative to neutral species. The phosphine-substitute complexes (2, 3) displays two reversible oxidation waves and oxidation state of metal centers-dependent color change, electrochromism, was observed from yellow to orange and deep blue in methylene chloride.

• Macromolecular Research
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• 제17권12호
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• pp.1003-1009
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• 2009

Copolymers of N-vinylpyrrolidone (NVP) comonomer with styrene (St), hydroxypropyl methacrylate (HPMA) and carboxyphenyl maleimide (CPMI) were synthesized by free radical polymerization using 2,2'-azobisisobutyronitrile (AIBN) initiator in 1,4-dioxane solvent. The copolymers formed were characterized by FTIR, $^1H$ NMR and $^{13}C$ NMR techniques and their thermal properties were studied by DSC and TGA. Copolymer composition was determined by $^1H$ NMR and/or by elemental analysis and monomer reactivity ratios (MRR) were estimated by the linear methods of Kelen-Tudos (K-T) and extended Kelen-Tudos (EK-T) and the non-linear approach. Copolymers of St and HPMA with NVP formed blocks of one of the monomer units, whereas alternating copolymers were obtained in CPMI-NVP, depending upon the side chain substitution. The MRR values are discussed in terms of monomer structural properties such as electronegativity and electron delocalization. The sequence distribution of monomers in the copolymers was studied by statistical method based on the average reactivity ratios obtained by EK-T method.

• 펄프종이기술
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• 제42권2호
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• pp.1-11
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• 2010

The possibility of applying birchwood xylan in papermaking process to improve dry strength of paper was investigated. Unmodified xylan barely adsorbed onto pulp fibers while cationically modified xylan adsorbed substantially. Adsorption of cationically modified xylan by quaternarization with 3-chloro-2-hydroxypropy trimethylammonium chloride improved dry strength of paper. Chemical structure and degree of substitution of the cationically modified xylan was determined by 400 MHz 13CNMR spectroscopy and elemental analyzer. The amount of adsorbed xylan on cellulose fibers was greater when the cationicity was moderate, and it was interpreted that the conformation of this cationic xylan adsorbed on fiber surface was more favorable for greater adsorption due to its greater loop formation tendency while highly cationic xylan tends to adsorbed in stretched conformation. The physical properties of handsheets increased as the amount of adsorbed cationic xylan increased. On the other hands, the optical properties decreased with xylan adsorption.