• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.305-305
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• 2006

The molecular structure and dynamics of inclusion compounds (ICs) consisting of n-perfluoroalkane (PFA) guests and ${\Box}-cyclodextrin$ (${\Box}-CD$) host were investigated using $^{19}F$ magic angle spinning (MAS) and $^{1}H{\to}^{19}F$ cross polarization (CP) / MAS NMR spectroscopy with the aid of thermal analyses, FT-IR spectroscopy, X-ray diffraction, and $^{1}H{\to}^{19}F$ CP/MAS technique revealed that $C_{9}F_{20}$ molecules included in ${\Box}-CD$ undergo vigorous molecular motion and partly come out of the ${\Box}-CD$ channel above $80^{\circ}C$. In case of $C_{20}F_{42}/{\Box}-CD$, an exothermic peak is observed by differential scanning calorimetry (DSC) at ca. $40^{\circ}C$ which suggests that ${\Box}-CD$ molecules become mobile and commence rearrangements that form more ordered structures at higher temperatures.

• Bulletin of the Korean Chemical Society
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• 제15권1호
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• pp.12-14
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• 1994

p-Fluorophenyl bicyclo[3.2.l]oct-6-en-2-yl cation (3) prepared in $FSO_3H-SO_2-CIF$ solution at -90$^{\circ}$C and examined by fluorine-19 nmr spectroscopy. The nmr data give a clear evidence for the formation of a stabilized ${\pi}$-bridging cation species in superacids. The degree of ${\pi}$delocalization in this cation is found to be inferior to the onset of nonclassical stabilization in 2-norbornenyl cation.

• 대한화학회지
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• 제29권3호
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• pp.213-219
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• 1985

고정된 사이크로 프로판환을 가진 양이온계에서 구조적 변화에 따른 상대적 안정도를 불소 19-핵자기공명분광기로 분석 검토했다. 이를 위해 8-파라-불화벤젠트리사이크로 옥탄 양이온과 9-파라불화벤젠 트리사이크로 노난 및 10-파라불화벤젠 트리사이크로데칸 양이온을 해당알코올과 불화황산과의 반응에서 얻었다. 풀루오르 19-NMR 스펙트럼에서 얻어진 결론은 사이크로프로판환이 양이온 탄소의 궤도와 ${\sigma}$ 컨쥬게이션을 위해 대칭적이며 바이섹트 구조의 유지가 하전의 안정화에 매우 중요한 요인인 반면, 사이크로 프로판기의 면과 양하전을 띈 탄소와 연결되는 결합각도(${\theta}$)의 변화는 하전의 안정화에 영향이 없음을 보여주었다.

• Bulletin of the Korean Chemical Society
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• 제8권3호
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• pp.144-145
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• 1987

The relative stability as function of geometry in the rigid tricyclopropylcarbinyl cations with varied bond angle (${\alpha}$) between the plane of cyclopropane ring and the bond connecting cyclopropane ring to cationic carbon was examined by $^{19}F$ nmr spectroscopy. 7-p-Fluorophenyltricyclo[2.2.2.$0^{2,6}$]octan-7-yl(4) and 8-p-fluorophenyltricyclo[3.2.2.$0^{2,7}$]nonan-8-yl cation (8) were generated from corresponding tertiary alcohols under stable ion conditions, and their $^{19}F$ chemical shifts were compared with those of model compounds such as 7-nortricyclyl cation (3) and tricyclo[3.3.1.$0^{2,7}$]octan-8-yl cation (7). Consequently, it is concluded that the varied orientation of bond angle (${\alpha}$) within in the bisected conformation does not affect degree of the charge delocalization into cyclopropane ring.

• Journal of Magnetics
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• 제21권4호
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• pp.599-602
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• 2016

Fluoride (F) is an important element for the mineralization of body tissues. The purpose of this study was to administer fluoride prenatally to rats to evaluate its beneficial concentration for rat bone using microstructural analysis, to analyze its effect on the bone structure, and to evaluate the effect of its transfer through rat placenta. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectrometry (NMR) were performed. The $^{19}F$ NMR and $^{31}P$ NMR signals suggested the existence of fluoride ions in the apatite lattice because the signals were caused by the fluoride ions that were coupled to the phosphate atoms and were affected in the phosphate phases other than the element phases in the apatite. Consequently, if it was not affected too much, the desirable concentration of prenatal fluoride treatment could have a helpful effect on the bone crystal structure through placental fluoride transfer.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2345-2350
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• 2011

Variable temperature high-resolution $^{19}F$ magic angle spinning (MAS) solid-state NMR spectroscopy was used to characterize fluorocarbon (FKM) rubbers. The high-resolution spectra of copolymers made from two monomers, vinylidene fluoride and hexafluoropropene, and terpolymers composed of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene, were obtained using MAS speeds of up to 18 kHz combined with high temperatures of up to 200 $^{\circ}C$ at a magnetic field strength of 9.4 Tesla. From these high resolution solid-state NMR spectra, we were able to assign the spectral peaks and differentiate the copolymer FKM from the terpolymer FKM. We also determined quantitatively the monomer compositions of each FKM rubber.

• Bulletin of the Korean Chemical Society
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• 제29권12호
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• pp.2499-2501
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• 2008

• 한국자기공명학회논문지
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• 제17권2호
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• pp.81-85
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• 2013

Various fluorine-containing materials are used in electronic devices like LCD display panels and Li-ion batteries. The structural conformation of fluorine in fluorinated materials is an important contributing factor that influences the chemical and physical properties. The conformation can be changed by heat and stress during manufacture or use. Understanding the conformational changes is critical for understanding the performance and durability of electronic devices. Solid-state NMR spectroscopy could be widely used for the analysis of various fluorine-containing materials for electronic devices. However, conventional CPMAS probes cannot be used for in-situ analysis of fluorine-containing electronic devices like LCD panels and Li-ion batteries. In this paper, we show the design, construction, and optimization of a $^{19}F-^{13}C$ double-resonance solid-state NMR probe for a 400MHz wide-bore magnet with a flat square coil for in-situ analysis of fluorine-containing electronic devices without observing fluorine background signals. This custom-built probe does not show any fluorine background signals, and can have higher efficiency for lossy samples.

• Bulletin of the Korean Chemical Society
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• 제3권2호
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• pp.66-70
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• 1982

The question of the bicyclohomoaromatic stabilization and destabilization is examined. The chemistry of bicyclo(3.2.1)octa-3,6-dienide anion has been studied on order to test these concepts. The bicyclooctadienide anion is shown to be stable delocalized ion which undergoes a facile proton-deuterium exchange reaction. The solvolysis of bicyclo(3.2.1)octa-3,6-dienyl p-nitrobenzoate is much slower than the monoene analog. We have made direct observation of the bicyclooctadienyl and octenyl cations by $^{19}F$-nmr spectroscopy, and were able to demonstrate that the bicyclooctadienyl cation was bishomoantiaromatic.

• 폴리머
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• 제27권3호
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• pp.176-182
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• 2003

피리딘을 촉매로 사용하여 2-chloro-$\alpha$,$\alpha$,$\alpha$-trifluorotoluene과 glycerol diglycidyl ether를 반응시켜 불소함유 에폭시 수지인 2-trifluorotoluene diglycidylether (FER)을 합성하였다. FER/DM 시스템의 격화 거동은 동적 DSC와 등온 DSC 열분식을 통하여 알아보았으며, Flynn-Wall-Ozawa식을 사용하여 경화 활성화 에너지 (Ea)를 계산하였다. 또한, 본 시스템의 유변학적 특성은 레오미터를 이용하여 등온 조건하에서 고찰하였으며, Arrhenius식을 사용하여 젤화 시간과 경화 온도에 의해 가교 활성화 에너지 (Ec)를 구하였다. 실험 결과, FT-IR, $^{13}$C NMR, 그리고 $^{19}$ F NMR 분광법 분석을 통하여 합성한 수지의 화학 구조를 확인하였으며, FER/DDM 시스템의 Ea는 53.4 kJ/mol이었으며, 경화 반응의 전환율과 전환 속도는 경화 온도가 높을수록 높은 값을 나타내었다. 시스템의 Ec는 41.6 kJ/mol이었으며, 경화 온도가 높을수록 젤화 시간이 단축되었다.