• Journal of Photoscience
• /
• v.10 no.1
• /
• pp.81-87
• /
• 2003

Based on structural information provided by recently reported crystal structures of rhodopsin, we present rationales for the regiospecific protein perturbation on the previously reported $\^$19/F chemical shifts of the vinyl and trifluoromethylrhodopsins and their photoproducts. The crystal structures also suggest that H-bonding is a likely cause for the earlier reported regiospecific photoisomerization of the 10-fluororhodopsins. Photoisomerization was revealed by chemical shift of the photoproducts. Additionally, possible use of 3-bond F,F coupling constants for following photoisomerization of retinal-binding proteins is discussed.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.11
• /
• pp.3253-3256
• /
• 2013

Lithium is a highly attractive material for high-energy-concentration batteries, since it has low weight and high potential. Rechargeable lithium-ion batteries (LIBs), which have the extremely high gravimetric and volumetric energy densities, are currently the most preferable power sources for future electric vehicles and various portable electronic devices. In order to improve the efficiency and lifetime, new electrode compounds for lithium intercalation or insertion have been investigated for rechargeable batteries. Solid-state nuclear magnetic resonance (NMR) is a very useful tool to investigate the structural changes in electrode materials in actual working lithium-ion batteries. To detect the in-situ microstructural changes of electrode and electrolyte materials, $^7Li-^{19}F$ double-resonance solid-state NMR probe with a static solenoidal coil for a 600-MHz narrow-bore magnet was designed, constructed, and tested successfully.

• Journal of Magnetics
• /
• v.2 no.2
• /
• pp.35-37
• /
• 1997

A sample of YBa2Cu3O7-x fluorinated by a high temperature (400$^{\circ}C$) gas exchange technique has been investigated by means of 19F NMR (nuclear magneti resonance) measurements in both superconducting and normal state. As a result, behaviors characteristic of the superconductor, including a peculiarity in the spin-lattice relaxation rate (1/T1) around 250 K, were observed.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.5
• /
• pp.1577-1580
• /
• 2012

The orientational and dynamic behavior of liquid crystal molecules on the alignment layer surfaces of liquid crystal display (LCD) devices is crucial to their performance, but there are only a few methods of experimentally elucidating the interactions between the liquid crystals and the alignment layers. Inspired by the natural and technical similarities between membrane proteins in lipid bilayers and liquid crystals in LCDs, we employed solid-state NMR methodologies originally developed for the study of membrane proteins in lipid bilayers for the in-situ analysis of liquid crystal display panels. In this article, we present a home-built 500 MHz narrowbore (NB) The orientational and dynamic behavior of liquid crystal molecules on the alignment layer surfaces of liquid crystal display (LCD) devices is crucial to their performance, but there are only a few methods of experimentally elucidating the interactions between the liquid crystals and the alignment layers. Inspired by the natural and technical similarities between membrane proteins in lipid bilayers and liquid crystals in LCDs, we employed solid-state NMR methodologies originally developed for the study of membrane proteins in lipid bilayers for the in-situ analysis of liquid crystal display panels. In this article, we present a home-built 500 MHz narrowbore (NB) $^{19}F-^{13}C$ double resonance solid-state NMR probe with a flat-square coil and the first application of this probe for the in-situ analysis of LCD panel samples. double resonance solid-state NMR probe with a flat-square coil and the first application of this probe for the in-situ analysis of LCD panel samples.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.1
• /
• pp.12-14
• /
• 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.

• Journal of the Korean Magnetics Society
• /
• v.3 no.1
• /
• pp.13-17
• /
• 1993

We have studied $CuF_{2}.2H_{2}O$ using $^{1}H$ and $^{19}F$ pulsed nuclear magnetic resonance at 30 MHz. From the data of lineshapes, the spin-lattice relaxation times ($T_1$) and the spin echo decay times, lattice dynamics in the structure is investigated. $T_1$ data from both $^{1}H$ and $^{19}F$ NMR indicate that spin-lattice relaxation is dominated by the paramagnetic ion centers at the Cu sites. The lineshapes at room temperature appear to be strongly affected by exchange narrowing and motional narrowing.

• Bulletin of the Korean Chemical Society
• /
• v.8 no.3
• /
• pp.144-145
• /
• 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.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.12
• /
• pp.2499-2501
• /
• 2008

• Journal of Magnetics
• /
• v.21 no.4
• /
• pp.599-602
• /
• 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.

• Journal of the Korean Chemical Society
• /
• v.26 no.3
• /
• pp.165-171
• /
• 1982

The thioxanthylium ion ard anthracenium ion have coplanar geometries. The empty $P_z$-orbitals of the positive centers in the cations, therefore, overlap with the ${\pi}$-orbitals of the fused benzen rings. These cations have aromatic characters, obeying Huckel's (4n + 2)${\pi}$ rule. The contribution of the sulfur atom to aromatic stabilization was estimated by comparing the ${^19F}$-nmr chemical shifts of the thioxanthylium ions and anthracenium ions.