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

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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 8765
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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Figure 1
<p>(<b>a</b>) Molecular structure of <span class="html-italic">meso</span>-DMBEDT-TTF and (<b>b</b>) temperature dependence of the electrical resistivity under pressure for <span class="html-italic">β</span>-(<span class="html-italic">meso-</span>DMBEDT-TTF)<sub>2</sub>PF<sub>6</sub> [<a href="#B4-crystals-02-01502" class="html-bibr">4</a>,<a href="#B6-crystals-02-01502" class="html-bibr">6</a>,<a href="#B7-crystals-02-01502" class="html-bibr">7</a>].</p> Full article ">Figure 2
<p>Checkerboard-type charge ordering by crystal structure analysis for <span class="html-italic">β</span>-(<span class="html-italic">meso-</span>DMBEDT-TTF)<sub>2</sub>AsF<sub>6</sub>. The charge-rich and charge-poor molecules are indicated by red and blue. (<b>a</b>) <span class="html-italic">r</span>1, <span class="html-italic">r</span>2, <span class="html-italic">r</span>3, <span class="html-italic">r</span>4, <span class="html-italic">p</span>1, <span class="html-italic">p</span>2, <span class="html-italic">q</span>1, <span class="html-italic">q</span>2, <span class="html-italic">q</span>3, and <span class="html-italic">q</span>4 are transfer integrals. (<b>b</b>) The double, single, and dotted lines indicate the strength of intermolecular interactions.</p> Full article ">Figure 3
<p>(<b>a</b>) Temperature dependence of electrical resistivity (<b>a</b>) from ambient pressure to 1.5 GPa and (<b>b</b>) under 0.38–0.6 GPa for <span class="html-italic">β</span>-(<span class="html-italic">meso-</span>DMBEDT-TTF)<sub>2</sub>AsF<sub>6</sub>.</p> Full article ">Figure 4
<p>Temperature dependence of electrical resistivity under a magnetic field for <span class="html-italic">β</span>-(<span class="html-italic">meso-</span>DMBEDT-TTF)<sub>2</sub>AsF<sub>6</sub>.</p> Full article ">Figure 5
<p>(<b>a</b>) Temperature dependence of electrical resistivity under pressure and (<b>b</b>) pressure dependence of <span class="html-italic">T</span><sub>c</sub>, <span class="html-italic">T</span><sub>min</sub>, and <span class="html-italic">a</span> [the superconducting transition temperature, the temperature of resistivity minimum, and <span class="html-italic">ρ</span> <span class="html-fig-inline" id="crystals-02-01502-i001"> <img alt="Crystals 02 01502 i001" src="/crystals/crystals-02-01502/article_deploy/html/images/crystals-02-01502-i001.png"/></span> <span class="html-italic">T<sup>α</sup></span> in <a href="#crystals-02-01502-f005" class="html-fig">Figure 5</a>(a)] for <span class="html-italic">β</span>-(<span class="html-italic">meso-</span>DMBEDT-TTF)<sub>2</sub>AsF<sub>6</sub>. In (<b>b</b>) CO and SC denote the charge-ordered state and the superconducting state.</p> Full article ">Figure 6
<p>Temperature dependences of magnetic susceptibilities for <span class="html-italic">β</span>-(<span class="html-italic">meso-</span>DMBEDT-TTF)<sub>2</sub>X (X = PF<sub>6</sub> and AsF<sub>6</sub>). The solid line is the fitting curve (see text).</p> Full article ">
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 6618
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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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Bond lengths and angles in the heterocyclic system of (<b>a</b>) 1-hydroxyimidazole; (<b>b</b>) 1-hydroxyimidazole hydrochloride; (<b>c</b>) 1-hydroxyimidazole hydrobromide; (<b>d</b>) and (<b>e</b>) the two independent cations of bis(1-hydroxyimidazolium) sulfate, and (<b>f</b>) 1-hydroxyimidazolium nitrate.</p> Full article ">Figure 2
<p>(<b>a</b>) ORTEP plot with numbering scheme and (<b>b</b>) hydrogen bonding in the crystal structure of 1-hydroxyimidazole (<b>1</b>).</p> Full article ">Figure 3
<p>Hydrogen bonding in the crystal structures of (<b>a</b>) 1-hydroxyimidazole hydrochloride (<b>2</b>).</p> Full article ">Figure 4
<p>(<b>a</b>) Hydrogen bonding and (<b>b</b>) cyclic arrangement of the ions in bis(1-hydroxyimidazolium) sulfate (<b>4</b>).</p> Full article ">Figure 5
<p>Hydrogen bonding in the crystal structure of 1-hydroxyimidazolium nitrate (<b>5</b>).</p> Full article ">Figure 6
<p>(<b>a</b>) Normalized Hirshfeld surface of 1-hydroxyimidazole and associated fingerprint plots highlighting specific interactions; (<b>b</b>) O…H and (<b>c</b>) N…H.</p> Full article ">Figure 7
<p>Two-Dimensional fingerprint plots of (<b>a</b>) 1-hydroxyimidazole hydrochloride; (<b>b</b>) bis(1-hydroxyimidazolium) sulfate; and (<b>c</b>) 1-hydroxyimidazolium nitrate.</p> Full article ">
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 9009
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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Figure 1

Figure 1
<p>Schematic images and photonic band diagrams of complete-photonic-band 2D structures composed of rutile-TiO<sub>2</sub> columns in electrolytes. Cylindrical (<b>a</b>), square (<b>b</b>) and hexagonal (<b>c</b>) columns were triangularly arrayed and connected by TiO<sub>2</sub> walls. The complete photonic bandgaps are shown as green lines. The maximum gap–midgap ratio appears below the photonic band diagram.</p> Full article ">Figure 2
<p>Maximum gap–midgap ratio dependence on <span class="html-italic">d</span>, <span class="html-italic">x</span>, and <span class="html-italic">Angle</span>. Cylindrical (<b>a</b>), square (<b>b</b>), and hexagonal (<b>c</b>) TiO<sub>2</sub> columns were triangularly arrayed and connected by TiO<sub>2</sub> walls. Each fixed parameter is shown in the inset.</p> Full article ">
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 7522
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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Figure 1
<p>Temperature-Pressure phase diagram of TTF-TCNQ. Preceding work up to 3 GPa [<a href="#B29-crystals-02-01460" class="html-bibr">29</a>], including the (charge density wave) CDW commensurability peak at 1.9 GPa [<a href="#B31-crystals-02-01460" class="html-bibr">31</a>] is reproduced. The CDW is suppressed by pressure even though nesting becomes better. Reproduced with permission from JPSJ.</p> Full article ">Figure 2
<p>Magnetoresistance, which shows field-induced CDW state in HMTSF-TCNQ. Pressure at low temperature may be around 1.3 GPa at low temperature with 1.5 GPa at room temperature and with Daphne 7373 pressure medium in a piston cylinder cell [<a href="#B29-crystals-02-01460" class="html-bibr">29</a>]. Reproduced with permission from JPSJ.</p> Full article ">Figure 3
<p>Temperature-Pressure phase diagram of (TMTTF)<sub>2</sub>X showing that it is connected to that of the (TMTSF)<sub>2</sub>X salts. Note that the superconducting <span class="html-italic">T</span><sub>c</sub> is well above 2 K and spreading to a wide pressure region and the insulating phase varies from charge order to magnetic state [<a href="#B10-crystals-02-01460" class="html-bibr">10</a>]. This is the real system ,which can be compared with Jerome’s generic phase diagram [<a href="#B46-crystals-02-01460" class="html-bibr">46</a>]. Reproduced with permission from JPSJ.</p> Full article ">Figure 4
<p>Temperature-Pressure phase diagram of SDW (left-bottom region of the lines) and metal in (TMTSF)<sub>2</sub>PF<sub>6</sub> [<a href="#B52-crystals-02-01460" class="html-bibr">52</a>]. Reproduced with permission from JPSJ.</p> Full article ">Figure 5
<p>Temperature of anion ordering (left) and its strength (right) as a function of pressure [<a href="#B45-crystals-02-01460" class="html-bibr">45</a>]. Reproduced with permission from JPSJ.</p> Full article ">Figure 6
<p>Temperature-Pressure phase diagram of ofβ-(BEDT-TTF)<sub>2</sub>I<sub>3</sub>[<a href="#B55-crystals-02-01460" class="html-bibr">55</a>]. It seemed that the two superconducting <span class="html-italic">T</span><sub>c</sub>’s, <span class="html-italic">i.e.</span>, inner structure of superconductivity was suggested. However, the different series of <span class="html-italic">T</span><sub>c</sub> were proved related to the structure difference. Reproduced with permission from JPSJ.</p> Full article ">Figure 7
<p>Temperature dependence of resistivity of α-(BEDT-TTF)<sub>2</sub>I<sub>3</sub> as examined by the present authors. It is obvious that the Dirac cone state is stabilized even at 8 GPa.</p> Full article ">Figure 8
<p>Temperature-Strain phase diagram of α-(BEDT-TTF)<sub>2</sub>I<sub>3</sub> [<a href="#B18-crystals-02-01460" class="html-bibr">18</a>]. Superconductivity is seen only with the strain along the <span class="html-italic">a</span>-axis. Around the superconductivity, charge ordered phase is located. Reproduced with permission from JPSJ.</p> Full article ">Figure 9
<p>Temperature dependence of resistivity of κ-(MeDH-TTP)<sub>2</sub>AsF<sub>6 </sub>under hydrostatic pressure by cubic anvil cell with pressure medium of Daphne7373(top left). Temperature-Pressure phase diagram showing quantum critical point (top right). Divergence of the prefactor, <span class="html-italic">A</span> of <span class="html-italic">T</span><sup>2</sup>-term in resistivity and the residual resistivity (bottom) [<a href="#B84-crystals-02-01460" class="html-bibr">84</a>].Reproduced with permission from JPSJ.</p> Full article ">Figure 10
<p>Giant Shubnikov-de Haas oscillation in τ-(EDO-<span class="html-italic">S</span>,<span class="html-italic">S</span>-MEEDT-TTF)<sub>2</sub>(AuBr<sub>2</sub>)<sub>1+<span class="html-italic">y</span></sub> (top), and it 1/<span class="html-italic">B</span>-plot (bottom) [<a href="#B89-crystals-02-01460" class="html-bibr">89</a>]. Reproduced with permission from <span class="html-italic">Physical Review B</span>.</p> Full article ">
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 6905
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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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Synthesis of dalcetrapib (<b>3</b>). Step A: reduction; Step B: acylation (see text).</p> Full article ">Figure 2
<p>O<span class="html-small-caps">RTEP</span> plot of dalcetrapib (thermal ellipsoids drawn at the 50% level).</p> Full article ">Figure 3
<p>Packing diagram of dalcetrapib (3). Atoms engaged in hydrogen bonding are drawn as balls, and all other hydrogen atoms are omitted for clarity.</p> Full article ">
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 7660
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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Figure 1

Figure 1
<p>The chemical structure and numbering scheme of pyranocoumarins.</p> Full article ">Figure 2
<p>(<b>a</b>) Morphology of crystals of aegelinol (<b>1</b>) obtained by slow evaporation from a solution in ethanol; (<b>b</b>) Conformation of the three independent molecules in the asymmetric unit showing thermal motion (ORTEP, 30% probability).</p> Full article ">Figure 3
<p>Crystal packing of aegelinol. (<b>a</b>) Stacking along the <span class="html-italic">a</span> axis; (<b>b</b>) Stacking along the <span class="html-italic">b</span> axis.</p> Full article ">Figure 4
<p>(<b>a</b>) Morphology of crystals of aegelinol-β-cyclodextrin inclusion complex (<b>1-BCD</b>). Two forms of crystals are observed: (<span class="html-italic">I</span>) corresponds to cell parameters of aegelinol alone, and (<span class="html-italic">II</span>) corresponds to cell parameters of the inclusion complex; (<b>b</b>) Two perpendicular views showing the conformation of the <b>1-BCD</b> inclusion complex (ORTEP, 30% probability) and confirming the R configuration at C2’. Only one component of the disorder of the guest molecule inside the cyclodextrin cavity is presented and hydrogen atoms and water molecules are removed for clarity; (<b>c</b>) View of the two aegelinol molecules after removing all the rest of the structure to show their configuration.</p> Full article ">Figure 5
<p>Crystal packing of β-cyclodextrins in the <b>1-BCD</b> crystal structure shown along the <span class="html-italic">a</span>, <span class="html-italic">b</span> and <span class="html-italic">c</span> directions. Guest molecules (aegelinol) and waters are omitted for clarity.</p> Full article ">
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 6249
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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Figure 1

Figure 1
<p>View onto a [Cu<sub>2</sub>Br<sub>3</sub>]<sup>−</sup> ladder of (HPip)Cu<sub>2</sub>Br<sub>3</sub> centered at [<span class="html-italic">x</span>, 0.5, 0]. The atoms are labeled according to <a href="#crystals-02-01434-t002" class="html-table">Table 2</a>.</p> Full article ">Figure 2
<p>View onto a piperidinium ion of (HPip)Cu<sub>2</sub>Br<sub>3</sub> in chair conformation. The atoms are labeled according to <a href="#crystals-02-01434-t002" class="html-table">Table 2</a>.</p> Full article ">Figure 3
<p>View along the [Cu<sub>2</sub>Br<sub>3</sub>]<sup>−</sup> ladders of CsCu<sub>2</sub>Br<sub>3</sub> (left) and (HPip)Cu<sub>2</sub>Br<sub>3</sub> (right).</p> Full article ">
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 9738
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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Figure 1
<p>Schematic model for hydrogenation via (<b>a</b>) gas phase (<b>b</b>) electrolyte.</p> Full article ">Figure 2
<p>Pressure composition isotherms for hydrogen absorption [<a href="#B10-crystals-02-01410" class="html-bibr">10</a>].</p> Full article ">Figure 3
<p>The concept of a sealed rechargeable Ni-metal hydride (MH) battery seen from a schematic point of view [<a href="#B12-crystals-02-01410" class="html-bibr">12</a>].</p> Full article ">Figure 4
<p>Pressure–Composition isotherm of yttrium film during gas phase hydrogenation (black square) and transmission spectrum depending on the hydrogen concentration (red circle) [<a href="#B16-crystals-02-01410" class="html-bibr">16</a>].</p> Full article ">Figure 5
<p>Electrode potential (solid black line) and optical transmission (dashed red line) intensity of yttrium film during electrochemical hydrogenation (a) and dehydrogenation (b) [<a href="#B17-crystals-02-01410" class="html-bibr">17</a>].</p> Full article ">Figure 6
<p>Influence of Gd-Mg composition upon the transmission of GdMgH<sub>3 </sub>thin films [<a href="#B18-crystals-02-01410" class="html-bibr">18</a>].</p> Full article ">Figure 7
<p>Three optical states of Mg-Gd switchable mirror: reflecting (<b>a</b>), absorbing (<b>b</b>) and transmitting (<b>c</b>) states [<a href="#B19-crystals-02-01410" class="html-bibr">19</a>].</p> Full article ">Figure 8
<p>Electrochemical (de)hydrogenation cycle (line) with switching optical response (dashed) between reflective and transparent states of Mg-Ni alloy and its hydride respectively [<a href="#B21-crystals-02-01410" class="html-bibr">21</a>].</p> Full article ">Figure 9
<p>Fundamental band gaps of complex magnesium hydrides [<a href="#B22-crystals-02-01410" class="html-bibr">22</a>].</p> Full article ">Figure 10
<p>Rutile MgH<sub>2</sub> (a) and fluorite Mg<sub>x</sub>TM<sub>(1-x)</sub>H<sub>2</sub> (b).</p> Full article ">Figure 11
<p>Comparison between (<b>a</b>) AB<sub>5</sub> type compound and (<b>b</b>) Mg<sub>0.72</sub>Sc<sub>0.28</sub>(Pd<sub>0.012</sub>Rh<sub>0.012</sub>).</p> Full article ">Figure 12
<p>Galvanostatic discharge curves of: thin films (<b>a</b>) and bulk materials (<b>b</b>); the current density was 1000 mA/g for the thin films and 50 mA/g for the bulk materials [<a href="#B28-crystals-02-01410" class="html-bibr">28</a>].</p> Full article ">Figure 13
<p>Neutron diffraction of Mg<sub>0.65</sub>Sc<sub>0.35</sub> (<b>a</b>) before deuterium loading (<b>b</b>) after deuterium loading [<a href="#B30-crystals-02-01410" class="html-bibr">30</a>].</p> Full article ">Figure 14
<p>Relaxation map showing rate ω<sub>H</sub> of H hopping as a function of reciprocal temperature in MgH<sub>2</sub>, ScH<sub>2</sub>, Mg<sub>(1-y)</sub>Sc<sub>y</sub>H<sub>x</sub>, and LaNi<sub>5</sub>H<sub>6.8</sub> [<a href="#B31-crystals-02-01410" class="html-bibr">31</a>].</p> Full article ">Figure 15
<p>Enthalpies of formation of Mg<sub>1-y</sub>Sc<sub>y</sub>H<sub>2</sub>. (<b>a</b>) Rutile (<b>b</b>) fluorite [<a href="#B32-crystals-02-01410" class="html-bibr">32</a>].</p> Full article ">Figure 16
<p>Electrochemical determined reversible electrochemical capacity at room temperature as a function of magnesium content in Mg-Ti thin film electrodes.</p> Full article ">Figure 17
<p><span class="html-italic">In-situ</span> electrochemical XRD measurements of Mg<sub>0.90</sub>Ti<sub>0.10</sub> (<b>a</b>) and Mg<sub>0.70</sub>Ti<sub>0.30</sub> (<b>b</b>) during hydrogenation [<a href="#B34-crystals-02-01410" class="html-bibr">34</a>].</p> Full article ">Figure 18
<p>Electrochemically determined dehydrogenation isotherms of 200 nm; (i-a) Mg<sub>0.69</sub>Ti<sub>0.21</sub>Al<sub>0.10</sub> and (i-b) Mg<sub>0.80</sub>Ti<sub>0.20</sub> thin films with a 10 nm Pd top-coat (ii-a) Mg<sub>0.55</sub>Ti<sub>0.35</sub>Si<sub>0.10</sub> and (ii-b) Mg<sub>0.69</sub>Ti<sub>0.21</sub>Si<sub>0.10</sub> films capped with 10 nm Pd [<a href="#B44-crystals-02-01410" class="html-bibr">44</a>].</p> Full article ">Figure 19
<p>Pressure-optical transmission isotherms of (<b>a</b>) continuously gradient Mg<sub>y</sub>Ti<sub>(1-y)</sub>; (<b>b</b>) discrete compositions of Mg<sub>y</sub>Ti<sub>(1-y)</sub>; and (<b>c</b>) phase image of ternary gradient Mg-Ni-Ti alloy hydrides. [<a href="#B45-crystals-02-01410" class="html-bibr">45</a>]</p> Full article ">
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 6860
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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Figure 1

Figure 1
<p>Domain structure in strontium tetraborate visualized by etching. Crystallographic axes are shown by arrows. Thickness of structure in <span class="html-italic">a</span> direction is 1 mm.</p> Full article ">Figure 2
<p>(<b>a</b>) Angular dependence of the second harmonic for nonlinear photonic crystals (NPC) and strontium tetraborate (SBO); (<b>b</b>) Maker fringes for single domain sample of SBO. Input radiation (532 nm) direction <span class="html-italic">k</span>, polarization of input radiation and second harmonic (266 nm) <span class="html-italic">E</span>.</p> Full article ">Figure 3
<p>Random Maker fringes for NPC SBO calculated by varying the wavelength.</p> Full article ">Figure 4
<p>Spectral dependence of the second harmonic for a sample of NPC SBO (blue) and single domain sample (black) calculated by varying the fundamental wavelength. Real domain structure of NPC SBO mapped via optical microscopy was used in the calculation.</p> Full article ">Figure 5
<p>The spectra of deep ultraviolet (DUV) generated in several samples (S2, S4, S7, S8) obtained in separate growth experiments.</p> Full article ">Figure 6
<p>DUV tuning curves for several samples (S2, S4, S7, S8) obtained in separate growth experiments. DUV power is normalized to the square of the power of the fundamental beam.</p> Full article ">Figure 7
<p>An example of angular dependence of DUV generated in NPC SBO.</p> Full article ">Figure 8
<p>RQPM autocorrelation trace of Tsunami oscillator measured with NPC SBO (blue) and BBO (black). Central wavelength 780 nm. SBO: pulse duration 83.3 fs; power 3.49 microwatts; SNR-2992; BBO: pulse duration 83.7 fs; power 929.9 microwatts; SNR-15079.</p> Full article ">Figure 9
<p>Spectra of autocorrelation signal (<b>a</b>) and single-beam second harmonic (<b>b</b>).</p> Full article ">Figure 10
<p>Pulse duration of Tsunami oscillator measured with NPC SBO throughout the tuning range at fixed angular position of the crystal.</p> Full article ">Figure 11
<p>Variation of autocorrelation beam spectra on the NPC position. (<b>a</b>) Net data; (<b>b</b>) Data normalized to the maximal value in every section of constant coordinate.</p> Full article ">Figure 12
<p>Optical scheme of autocorrelation measurement in nonlinear diffraction from virtual beam (NLDVB) geometry. 1-Tsunami oscillator; 2-beamsplitter; 3-mirror; 4-delay line; 5-focusing lens; 6-NPC SBO; 7-BG39 filter; 8-918D-UV-OD3 sensor.</p> Full article ">Figure 13
<p>NLDVB autocorrelation trace of Tsunami oscillator measured with NPC SBO (blue) and BBO (black). Central wavelength 840 nm. SBO: pulse duration 75.7 fs; power 5.99 microwatts; SNR-1877; BBO: pulse duration 77.0 fs; power 770 microwatts; SNR-17510.</p> Full article ">
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 6773
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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Figure 1

Figure 1
<p>Cross-Sections of (<b>a</b>) Photonic Crystal Fiber (PCF);(<b>b</b>) Hole-Assisted Fiber (HAF); and (<b>c</b>) conventional Single-Mode Fiber (SMF).</p> Full article ">Figure 2
<p>Experimental setup.</p> Full article ">Figure 3
<p>Dynamics of fiber fuse termination near the splice point between PCF and Dispersion-Shifted Fiber (DSF). (<b>a</b>)–(<b>d</b>) were obtained at intervals of 0.1 ms. Exposure time was 2.3 μs.</p> Full article ">Figure 4
<p>Dynamics of fiber fuse termination near the splice point between HAF and SMF. (<b>a</b>)–(<b>d</b>) were obtained at intervals of 0.15 ms. Exposure time was 2.3 μs.</p> Full article ">Figure 5
<p>Example of R1 failure in SMF at a bend diameter of 11 mm. Input power was 9 W at 1480 nm. (<b>a</b>) After 1.5 hours’ exposure and (<b>b</b>) almost simultaneous with (a).</p> Full article ">Figure 6
<p>R2 failure in SMF at a bend diameter of 17 mm. Input power was 9 W at 1480 nm.</p> Full article ">
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 6461
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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<p>Asymmetric unit of <b>1</b> and the prolongation of the ethanesulfonate ligands, which are drawn in transparency mode (hydrogen atoms are omitted for clarity).</p> Full article ">Figure 2
<p>The Bi–SO<sub>3</sub> framework of <b>1</b>. The carbon and hydrogen atoms are omitted for clarity.</p> Full article ">Figure 3
<p>View of the Bi layers in the <span class="html-italic">y</span>- direction (the hydrogen atoms are omitted for clarity).</p> Full article ">Figure 4
<p>Experimental powder pattern of the sample in comparison to the theoretical powder pattern of <b>1</b> as based on the single-crystal structure determination.</p> Full article ">
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 5272
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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<p>Chemical scheme for sparfloxacin (C<sub>19</sub>H<sub>22</sub>N<sub>4</sub>O<sub>3</sub>F<sub>2</sub>).</p> Full article ">Figure 2
<p>The asymmetric unit of <b>1</b> (50% displacement ellipsoids), expanded to show the complete Cd<sup>2+</sup> coordination sphere. Hydrogen bonds are shown as double-dashed lines and the minor disorder components of the piperazine rings of the ligands and the disordered, uncoordinated water molecule are omitted for clarity. See <a href="#crystals-02-01366-t001" class="html-table">Table 1</a> for symmetry codes.</p> Full article ">Figure 3
<p>Detail of <b>1</b> showing the coordination geometry of the Cd<sup>2+</sup> ion (50% displacement ellipsoids for Cd and O). The octahedral edges are shown as open lines and the C atoms of the chelate rings are shown as spheres. See <a href="#crystals-02-01366-t001" class="html-table">Table 1</a> for symmetry codes.</p> Full article ">Figure 4
<p>Fragment of a [100] polymeric chain in <b>1</b> showing only the O atoms and linking C atoms of the ligands (50% displacement ellipsoids; symmetry codes as in <a href="#crystals-02-01366-t001" class="html-table">Table 1</a>). The bonds of the C1 and C20 spar<sup>−</sup> anions are colored mint and plum, respectively.</p> Full article ">
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