• Molecules and Cells
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• v.19 no.2
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• pp.205-211
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• 2005

The Arg-Gly-Asp (RGD) sequence serves as the primary recognition site in extracellular matrix proteins, and peptides containing this sequence can mimic the biological activities of matrix proteins. We have initiated structure-function studies of two RGD containing peptides, RGD-5(AGGDD) and cyclic RGD-6(CARGDDC). Assays have shown that cyclic RGD-peptides inhibit platelet aggregation more efficiently than linear ones. NMR data revealed that RGD-5 and RGD-6 have entirely different conformation. RGD-5 has a linear extended structure and RGD-6 has a stable loop conformation. In RGD-5 the guanidinium group of Arg2 and the carboxyl group of Asp4 lie in parallel, whereas the side-chains of Arg3 and Asp5 of RGD-6 are located in different planes, supporting the idea that the stability of the cyclic form derives from the packing of the side chain of the Arg and Asp residues. The structural features of these peptides could provide a basis for designing new drugs against diseases related to platelet aggregation and as cancer antagonists.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.63-63
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• 2011

The donor-${\pi}$-acceptor (D-${\pi}$-A) chromophoric dye system has received great attention in variety fields such as electroluminescent materials, sensors and optoelectronic devices. There are many research activities focused on the development for abovementioned application materials with the high-performance properties. In the previous work, we are reported that novel D-${\pi}$-A dye, 2-[4-(9H-carbazol-9-yl)benzylidene]-2,3-dihydroinden-1-one, is successfully attained and exhibited a positive fluorescence solvatochromism. In this work, the molecular structure and packing geometry of 2-[4-(9H-carbazol-9-yl)benzylidene]-2,3-dihydroinden-1-one was discussed by their conformational structure. Their single yellow prism crystal having approximate dimensions of $0.30{\times}0.10{\times}0.10$ mm was carried out with a Rigaku RAXIS RAPID imaging plate area detector with graphite monochromated $CuK_{\alpha}$ radiation. Their crystal structure were solved by using the CrystalStructure crystallographic software package.

• Bulletin of the Korean Chemical Society
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• v.7 no.5
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• pp.331-334
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• 1986

The crystal structure of thiamin tetrahydrofurfuryl disulfide, one of the ring-opened derivatives of thiamin, has been determined by the X-ray diffraction methods. The crystal is monoclinic with cell dimensions of a = 8.704 (1), b = 11.207 (2), c = 21.260 (3) ${\AA}$ and ${\beta}$ = 92.44 (2)$^{circ}$, space group P2$_{1}$/c and Z = 4. The structure was solved by direct methods and refined to R = 0.076 for 1252 observed reflections measured on a diffractometer. The molecule assumes a folded conformation in which the pyrimidine and the tetrahydrofurfuryl rings are on the same side of the ethylenic plane. The pyrimidinyl, N-formyl and ethylenic planes are mutually perpendicular to each other and the N(3)-C(4) bond retains a single bond character. The structure is stabilized by an intramolecular N(4'${\alpha})-H{\cdots}O(2{\alpha}$) hydrogen bond. The molecules are connected via N(4'${\alpha}$)-H{\cdots}(N3')$ and O(5${\gamma})-H{\cdots}(N1')$ hydrogen bonds, forming a two-dimensional hydrogen-bonding network. The tetrahydrofurfuryl ring is dynamically disordered. The overall conformation as well as the packing mode is very similar to that of thiamin propyl disulfide.

• Journal of Integrative Natural Science
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• v.9 no.2
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• pp.94-102
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• 2016

The crystal structure of the potential active 6-ethoxy-3-phenyl-5a,9a-dihydro-3H-chromen[4,3-c][1,2]oxazole-3a(4H)-carbonitrile ($C_{19}H_{15}N_2O_3$) has been determined from single crystal X-ray diffraction technique. The title compound crystallizes in the monoclinic space group C2/c with unit cell dimension a= 29.3026(9) ${\AA}$, b= 6.7695(2) ${\AA}$ and c= 19.7597(6) ${\AA}$ [${\alpha}= 90^{\circ}$, ${\beta}= 125.709(10)^{\circ}$ and ${\gamma}= 90^{\circ}$]. Single crystals suitable for X-ray diffraction were obtained by slow evaporation method, the isoxazole and six membered pyran rings adopts envelope conformation. The crystal packing of the molecules is stabilized by the weak $C-H{\ldots}N$ hydrogen bond interaction.

• Journal of Integrative Natural Science
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• v.8 no.1
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• pp.30-39
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• 2015

The crystal structure of the potential active 2-amino-4-(4-hydroxy-3-methoxyphenyl)-7, 9-dimethyl-5-oxo-4, 5, 6, 7-tetrahydropyrano [2, 3-d] pyrazolo [3, 4-b] pyridine-3-carbonitrile ($C_{21}H_{22}N_5O_6S$) has been determined from single crystal X-ray diffraction data. In the title compound crystallizes in the monoclinic space group P-1 with unit cell dimension a=8.1201(9)${\AA}$, b=12.2684(4)${\AA}$ and c=12.387(2)${\AA}$ [${\alpha}=69.573^{\circ}$, ${\beta}=12.168^{\circ}$ and ${\gamma}=76.060^{\circ}$]. In the structure the pyrazole, pyridine and pyran are almost coplanar each other. The crystal packing is stabilized by intermolecular C-H...O and N-H... O hydrogen bond interaction.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04a
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• pp.1-6
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• 1999

A study was made to determine the effect of plastic pigment on the coating structure and printability of coated paper. Three basic plastic pigments were investigated such as solid-bead type of plastic pigment, binder type of plastic pigment and hollow type of plastic pigment. In the systems investigated, it was observed that particle shape and structure of plastic pigment had influenced on the rheology of coating color, the state of packing, and the properties of coated paper. The materials investigated were restricted to plastic pigments commonly uesd in paper coating formualtion. Inorganic pigments used in this research were kaolin clay which is platelets and calcium carbonate which is rhombic. Three kinds of plastic pigments were blended in the color made up with two inorganic pigments, respectively. The combination of pigments were carried out (1) to determined the effect of paticle structure of plastic pigment on the state of dispersion of coating color, (2) to observe the effect of temperature of calender on the property of coated paper prepared with plastic pigment. The data indicated that binder and hollow type of plastic pigment had the best results on improving the properties of coated paper such as paper gloss, opacity and air permeability ect. and solid-bead type of plastic pigment in the next place.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1021-1025
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• 2009

A novel supramolecular network containing binuclear copper unit $[Cu(phen)_{2}({\mu}-ID\;A)Cu(phen){\cdot}(NO_{3})](NO_{3}){\cdot}4(H_{2}O)$ (1) was synthesized through the self-assembly of iminodiacetic acid ($H_2IDA$) and 1,10-phenanthroline (phen) in the condition of pH = 6. It has been characterized by the infrared (IR) spectroscopy, elemental analysis, single crystal X-ray diffraction, and thermogravimetric analysis (TGA). 1 shows a 2-D supramolecular structure assembled through strong and unique $\pi-\pi$ packing interactions. Density functional theory (DFT) calculations show that theoretical optimized structures can well reproduce the experimental structure. The TGA and powder X-ray diffraction (PXRD) curves indicate that the complex 1 can maintain the structural integrity even at the loss of free water molecules. The magnetic property is also reported in this paper.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.795-799
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• 2007

The bulk properties of poly(γ-benzyl-L-glutamate)-poly(ethylene glycol), PBLG-PEO, diblock copolymer were investigated. The helical transition from 7/2 to 13/5 for pure PBLG was at 120 oC while those of GE-1 and GE-2, which contain flexible PEO block 40 wt% and 60 wt% respectively, were shown at 135℃ on DSC experiments. FT-IR and XRD experiments were shown that the diblock copolymers maintained their α-helical structure in the temperature range between 25℃ and 175℃. Increasing relative size of coil part resulted in the increase of intermolecular packing distances. Due to well-maintained helical structure, lyotropic LC phases were observed for the PBLG-PEO block copolymer by the polarized optical microscope (POM). Especially, GE-3 copolymer, which has 12.5 wt% PEO contents, showed the smectic C phase. The competition of favorable aggregation energy between rod-rod and coil-coil, and unfavorable aggregation energy of rod-coil give rise to change the supramolecular structure in mixed solvent.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.144-148
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• 1997

the molecular and crystal 3-dimensional structure of bentazone, C10H12N2O3S, has been determined from single crystal x-ray diffraction study. Crystal system is monoclinic: a=8.7817(9)Å, b=9.6059(9) Å, c=13.574(9) Å, β=97.269(1)', V=1136.1(6)Å, space group : P21/c, z=4. The molecular structure model was solved by direct method and refined by full matrix least squares. The final reliable factor, R, is 0.045 for 1396 independent reflections(Fo2>4σFo2). A molecule has a staggered conformation with thiocarbazin ring and isopropyl functional group and the molecules by hydrogen bonds are cross stacked along the c-axis.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1755-1759
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• 2009

Surface structure and molecular orientation of self-assembled monolayers (SAMs) formed by the spontaneous adsorption of tetrahydrothiophene (THT) and thiophene (TP) on Au(111) were investigated by means of scanning tunneling microscopy (STM) and carbon K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy. STM imaging revealed that THT SAMs have a commensurate (3 ${\times}\;2\sqrt[]{3}$) structure containing structural defects in ordered domains, whereas TP SAMs are composed of randomly adsorbed domains and paired molecular row domains that can be described as an incommensurate packing structure. The NEXAFS spectroscopy study showed that the average tilt angle of the aliphatic THT ring and $\pi$-conjugated TP ring in the SAMs were calculated to be about $30^o\;and\;40^o$, respectively, from the surface normal. It was also observed that the $\pi$* transition peak in the NEXAFS spectrum of the TP SAMs is very weak, suggesting that a strong interaction between $\pi$-electrons and the Au surface arises during the self-assembly of TP molecules. In this study, we have clearly demonstrated that the surface structure and adsorption orientation of organic SAMs on Au(111) are strongly influenced by whether the cyclic ring is saturated or unsaturated.