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Crystals
Volume 2
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Crystals, Volume 2, Issue 4 (December 2012) – 12 articles , Pages 1366-1513

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12 pages, 423 KiB  
Article
Magnetism and Pressure-Induced Superconductivity of Checkerboard-Type Charge-Ordered Molecular Conductor β-(meso-DMBEDT-TTF)2X (X = PF6 and AsF6)
by Takahisa Shikama, Tatsuya Shimokawa, Sanguchul Lee, Takayuki Isono, Akira Ueda, Kazuyuki Takahashi, Akiko Nakao, Reiji Kumai, Hironori Nakao, Kensuke Kobayashi, Youichi Murakami, Motoi Kimata, Hiroyuki Tajima, Kazuyuki Matsubayashi, Yoshiya Uwatoko, Yutaka Nishio, Koji Kajita and Hatsumi Mori
Crystals 2012, 2(4), 1502-1513; https://doi.org/10.3390/cryst2041502 - 29 Nov 2012
Cited by 15 | Viewed by 8859
Abstract
The metallic state of the molecular conductor β-(meso-DMBEDT-TTF)2X (DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene)-5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF6, AsF6) is transformed into the checkerboard-type charge-ordered state at around 75–80 K with accompanying metal-insulator (MI) transition on [...] Read more.
The metallic state of the molecular conductor β-(meso-DMBEDT-TTF)2X (DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene)-5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF6, AsF6) is transformed into the checkerboard-type charge-ordered state at around 75–80 K with accompanying metal-insulator (MI) transition on the anisotropic triangular lattice. With lowering temperatures, the magnetic susceptibility decreases gradually and reveals a sudden drop at the MI transition. By applying pressure, the charge-ordered state is suppressed and superconductivity appears in β-(meso-DMBEDT-TTF)2AsF6 as well as in the reported β-(meso-DMBEDT-TTF)2PF6. The charge-ordered spin-gapped state and the pressure-induced superconducting state are discussed through the paired-electron crystal (PEC) model, where the spin-bonded electron pairs stay and become mobile in the crystal, namely the valence-bond solid (VBS) and the resonant valence bonded (RVB) state in the quarter-filled band structure. Full article
(This article belongs to the Special Issue Molecular Conductors)
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10 pages, 411 KiB  
Article
Crystal Structures of 1-Hydroxyimidazole and Its Salts
by Gerhard Laus and Volker Kahlenberg
Crystals 2012, 2(4), 1492-1501; https://doi.org/10.3390/cryst2041492 - 31 Oct 2012
Cited by 8 | Viewed by 6725
Abstract
The crystal structures of 1-hydroxyimidazole and four protic salts (chloride, bromide, sulfate, nitrate) thereof were determined. The molecular geometries (bond lengths and angles) of the free base and the salts were compared. Hydrogen bonding patterns were studied, and OH…N, OH…Cl, OH…Br, OH…O, NH…Cl, [...] Read more.
The crystal structures of 1-hydroxyimidazole and four protic salts (chloride, bromide, sulfate, nitrate) thereof were determined. The molecular geometries (bond lengths and angles) of the free base and the salts were compared. Hydrogen bonding patterns were studied, and OH…N, OH…Cl, OH…Br, OH…O, NH…Cl, NH…Br, and NH…O interactions were identified. Hirshfeld surface analysis gave quantitative insight into these interactions. Full article
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9 pages, 1318 KiB  
Communication
Simulation Design for Rutile-TiO2 Nanostructures with a Large Complete-Photonic Bandgap in Electrolytes
by Sachiko Matsushita, Mikiro Hayashi, Toshihiro Isobe and Akira Nakajima
Crystals 2012, 2(4), 1483-1491; https://doi.org/10.3390/cryst2041483 - 26 Oct 2012
Cited by 3 | Viewed by 9124
Abstract
The photonic bands of various TiO2 2D photonic crystals, i.e., cylindrical, square and hexagonal columns connected with/without walls and filled with acetonitrile, were investigated from the perspective of dye-sensitized solar cells. The finite-difference time-domain methods revealed that two-dimensional (2D) photonic crystals [...] Read more.
The photonic bands of various TiO2 2D photonic crystals, i.e., cylindrical, square and hexagonal columns connected with/without walls and filled with acetonitrile, were investigated from the perspective of dye-sensitized solar cells. The finite-difference time-domain methods revealed that two-dimensional (2D) photonic crystals with rods connected with walls composed of TiO2 and electrolytes had complete photonic band gaps under specific conditions. This optimally designed bandgap reaches a large Δω/ωmid value, 1.9%, in a triangular array of square rods connected with walls, which is the largest complete 2D bandgap thus far reported for a photochemical system. These discoveries would promote the photochemical applications of photonic crystals. Full article
(This article belongs to the Special Issue Current Trends in Application of Photonic Crystals)
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23 pages, 1571 KiB  
Review
Pressure Effect on Organic Conductors
by Keizo Murata, Keiichi Yokogawa, Sonachalam Arumugam and Harukazu Yoshino
Crystals 2012, 2(4), 1460-1482; https://doi.org/10.3390/cryst2041460 - 23 Oct 2012
Cited by 13 | Viewed by 7648
Abstract
Pressure is a powerful tool to unveil the profound nature of electronic properties in a variety of organic conductors. Starting from technology of high pressure, we plan to review what kind of physics or phenomena have previously been discussed. Full article
(This article belongs to the Special Issue Molecular Conductors)
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5 pages, 252 KiB  
Article
Improved Synthesis and Crystal Structure of Dalcetrapib
by Gerhard Laus, Volker Kahlenberg, Frank Richter, Sven Nerdinger and Herwig Schottenberger
Crystals 2012, 2(4), 1455-1459; https://doi.org/10.3390/cryst2041455 - 19 Oct 2012
Cited by 3 | Viewed by 7031
Abstract
An improved synthesis of the Cholesteryl Ester Transfer Protein inhibitor dalcetrapib is reported. The precursor disulfide was reduced (a) by Mg/MeOH or (b) by EtSH/DBU/THF. The resulting thiol was acylated (a) by a known procedure or (b) in a one-pot process. Impurities were [...] Read more.
An improved synthesis of the Cholesteryl Ester Transfer Protein inhibitor dalcetrapib is reported. The precursor disulfide was reduced (a) by Mg/MeOH or (b) by EtSH/DBU/THF. The resulting thiol was acylated (a) by a known procedure or (b) in a one-pot process. Impurities were removed (a) by dithiothreitol (DTT) or (b) by oxidation using H2O2. Dalcetrapib crystallized in space group P21/c. Full article
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14 pages, 684 KiB  
Article
Determination of the Absolute Configuration of Aegelinol by Crystallization of Its Inclusion Complex with β-Cyclodextrin
by Kossay Elasaad, Racha Alkhatib, Thierry Hennebelle, Bernadette Norberg and Johan Wouters
Crystals 2012, 2(4), 1441-1454; https://doi.org/10.3390/cryst2041441 - 17 Oct 2012
Cited by 3 | Viewed by 7790
Abstract
The absolute configuration and structure of aegelinol, a pyranocoumarin isolated from Ferulago asparagifolia Boiss (Apiaceae), has been determined by crystallography. Crystal structure of the inclusion complex of aegelinol in β-cyclodextrin was determined (a = 15.404(1) Å, b = 15.281(1) Å, c = [...] Read more.
The absolute configuration and structure of aegelinol, a pyranocoumarin isolated from Ferulago asparagifolia Boiss (Apiaceae), has been determined by crystallography. Crystal structure of the inclusion complex of aegelinol in β-cyclodextrin was determined (a = 15.404(1) Å, b = 15.281(1) Å, c = 17.890(1) Å, α = 99.662(1), β = 113.4230(1), γ = 102.481(1)°, P1; R1 = 6.71%) and allowed unambiguous determination of the absolute configuration of the stereogenic center of aegelinol. The pyranocoumarin guest is included within the cylindrical cavity formed by dimeric β-cyclodextrin molecules with a head-to-head arrangement. Crystal structure of aegelinol alone was also determined (a = 6.8921(3) Å, b = 11.4302(9) Å, c = 44.964(3) Å, P212121; R1 = 4.44%) and allowed precise determination of its geometry. Aegelinol crystallizes with three molecules in the asymmetric unit held together by H-bonds and π-stacking interactions. Full article
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7 pages, 291 KiB  
Article
(C5H12N)Cu2Br3: A Piperidinium Copper(I) Bromide with [Cu2Br3]− Ladders
by Theresa Komm, Daniel Biner, Antonia Neels and Karl W. Krämer
Crystals 2012, 2(4), 1434-1440; https://doi.org/10.3390/cryst2041434 - 16 Oct 2012
Cited by 1 | Viewed by 6379
Abstract
Piperidinium copper(I) bromide, (C5H12N)Cu2Br3, was obtained from a solution of CuBr2, piperidine, and HBr in ethanol. At 60 °C ethanol slowly reduces copper(II) to copper(I). Colorless plates of (C5H12N)Cu [...] Read more.
Piperidinium copper(I) bromide, (C5H12N)Cu2Br3, was obtained from a solution of CuBr2, piperidine, and HBr in ethanol. At 60 °C ethanol slowly reduces copper(II) to copper(I). Colorless plates of (C5H12N)Cu2Br3 crystallize in the triclinic space group P-1 with lattice parameters of a = 6.2948(10) Å, b = 8.2624(14) Å, c = 10.7612(17) Å, α = 75.964(19)°, β = 89.232(19)°, γ = 84.072(19)°, and Z = 2 at 173 K. [CuBr4] tetrahedra share edges and form [Cu2Br3]− ladders parallel to the a-axis. (C5H12N)+ ions adopt a chair conformation and connect the [Cu2Br3]− ladders via H-bonding. The (C5H12N)Cu2Br3 structure is related to the mineral rasvumite, KFe2S3, space group Cmcm, which is isostructural to several alkali copper(I) halides. Full article
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24 pages, 3045 KiB  
Review
Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed
by Thirugnasambandam G. Manivasagam, Kamil Kiraz and Peter H. L. Notten
Crystals 2012, 2(4), 1410-1433; https://doi.org/10.3390/cryst2041410 - 15 Oct 2012
Cited by 21 | Viewed by 9953
Abstract
As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase [...] Read more.
As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal-hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g) of reversibly stored hydrogen in MgyTM(1-y)Hx (TM: Sc, Ti) has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content. Optical switching occurs during (de)hydrogenation between the reflective metal and the transparent metal hydride states. The chronological sequence of the optical improvements in optically active metal hydrides starts with the rare earth systems (YHx), followed by Mg rare earth alloy hydrides (MgyGd(1-y)Hx) and concludes with Mg transition metal hydrides (MgyTM(1-y)Hx). In-situ optical characterization of gradient thin films during (de)hydrogenation, denoted as hydrogenography, enables the monitoring of alloy composition gradients simultaneously. Full article
(This article belongs to the Special Issue Hydrogen Storage Alloys)
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17 pages, 1385 KiB  
Review
Applications of Random Nonlinear Photonic Crystals Based on Strontium Tetraborate
by Aleksandr S. Aleksandrovsky, Andrey M. Vyunishev and Alexandre I. Zaitsev
Crystals 2012, 2(4), 1393-1409; https://doi.org/10.3390/cryst2041393 - 1 Oct 2012
Cited by 14 | Viewed by 7006
Abstract
Properties of strontium tetraborate (SBO) and features of as-grown anti-parallel domains are summarized. From the point of view of nonlinear optics, these domains form nonlinear photonic crystals (NPC). Applications of NPC to the deep ultraviolet generation and fs pulse diagnostics are described. NPC [...] Read more.
Properties of strontium tetraborate (SBO) and features of as-grown anti-parallel domains are summarized. From the point of view of nonlinear optics, these domains form nonlinear photonic crystals (NPC). Applications of NPC to the deep ultraviolet generation and fs pulse diagnostics are described. NPC and SBO are prospective media for the creation of a widely tunable source of fs pulses in the vacuum ultraviolet and for autocorrelation diagnostics of broadly tunable sources. Full article
(This article belongs to the Special Issue Current Trends in Application of Photonic Crystals)
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11 pages, 455 KiB  
Article
Optical Fiber for High-Power Optical Communication
by Kenji Kurokawa
Crystals 2012, 2(4), 1382-1392; https://doi.org/10.3390/cryst2041382 - 28 Sep 2012
Cited by 6 | Viewed by 6932
Abstract
We examined optical fibers suitable for avoiding such problems as the fiber fuse phenomenon and failures at bends with a high power input. We found that the threshold power for fiber fuse propagation in photonic crystal fiber (PCF) and hole-assisted fiber (HAF) can [...] Read more.
We examined optical fibers suitable for avoiding such problems as the fiber fuse phenomenon and failures at bends with a high power input. We found that the threshold power for fiber fuse propagation in photonic crystal fiber (PCF) and hole-assisted fiber (HAF) can exceed 18 W, which is more than 10 times that in conventional single-mode fiber (SMF). We considered this high threshold power in PCF and HAF to be caused by a jet of high temperature fluid penetrating the air holes. We showed examples of two kinds of failures at bends in conventional SMF when the input power was 9 W. We also observed the generation of a fiber fuse under a condition that caused a bend-loss induced failure. We showed that one solution for the failures at bends is to use optical fibers with a low bending loss such as PCF and HAF. Therefore, we consider PCF and HAF to be attractive solutions to the problems of the fiber fuse phenomenon and failures at bends with a high power input. Full article
(This article belongs to the Special Issue Current Trends in Application of Photonic Crystals)
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8 pages, 831 KiB  
Communication
An Unusual Bismuth Ethanedisulfonate Network
by Fabienne Gschwind and Martin Jansen
Crystals 2012, 2(4), 1374-1381; https://doi.org/10.3390/cryst2041374 - 28 Sep 2012
Cited by 6 | Viewed by 6589
Abstract
The three dimensional bismuth ethanedisulfonate framework Bi(O3SC2H4SO3)1.5(H2O)2 was synthesized under hydrothermal conditions using the bidentate ligand 1,2-ethanedisulfonate and then characterized through X-ray diffraction and elemental analyses. The bismuth cation coordinates [...] Read more.
The three dimensional bismuth ethanedisulfonate framework Bi(O3SC2H4SO3)1.5(H2O)2 was synthesized under hydrothermal conditions using the bidentate ligand 1,2-ethanedisulfonate and then characterized through X-ray diffraction and elemental analyses. The bismuth cation coordinates at three different ethanedisulfonate ligands and has a coordination number of eight, which is accompanied by a distorted square antiprismatic configuration. Here, we report on the crystal structure of this bismuth metal–organic framework and its coordination behavior, which has thus far not been reported in heavier main group elements. Full article
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8 pages, 379 KiB  
Short Note
A One-Dimensional Coordination Polymer Constructed from Cadmium(II) Cations and Sparfloxacinate Anions
by Zhe An, Jing Gao and William T. A. Harrison
Crystals 2012, 2(4), 1366-1373; https://doi.org/10.3390/cryst2041366 - 28 Sep 2012
Cited by 4 | Viewed by 5360
Abstract
The synthesis and crystal structure of the one-dimensional coordination polymer, [Cd(spar)2]n·n(H2O), are described, where spar− is the sparfloxacinate anion, C19H21N4O3F2−. The Cd2+ [...] Read more.
The synthesis and crystal structure of the one-dimensional coordination polymer, [Cd(spar)2]n·n(H2O), are described, where spar− is the sparfloxacinate anion, C19H21N4O3F2−. The Cd2+ ion is bonded to four spar− ligands: Two O,O-chelate with their β-keto carboxylate groupings and two are monodentate-bound through a carboxylate O atom, to result in a distorted CdO6 octahedral coordination geometry. The bridging ligands lead to [100] polymeric chains in the crystal and N–H···O hydrogen bonds and possible weak aromatic p–p stacking interactions help to consolidate the structure. Crystal data: C38H44CdF4N8O7, Mr = 913.21, triclinic, (No. 2), Z = 2, a = 9.2256(4) Å, b = 12.8767(5) Å, c = 17.4297(7) Å, α = 89.505(2)°, β = 85.062(2)°, g = 70.757(2)°, V = 1947.20(14) Å3, R(F) = 0.036, wR(F2) = 0.082. Full article
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