Crystal and molecular structure of dihydro-8b,8c-diphenyl-1H,3H,4H,5H,7H,8H,-2,6-dioxa-3a,4a,7a,8a-tetraazacyclopenta[def]fluorene-4,8-dithione

The title compound C₂₀H₁₈N₄O₂S₂ crystallizes in the monoclinic space group P2₁/n witha=8.4930(1) Å,b=11.4880(1) Å,c=20.0709(2) Å, =94.933(1)°,V=1951.01(3) ų,Z=4. The crystal structure has been solved by vector search methods and refined by fullmatrix least-squares toR=0.04 for 2888 reflections and 116 restraints. The title compound has a suitable geometry for synthesizing receptor molecules with a cleft for selective complexation.     

Photochemical reaction products. CI:8b-methoxy-1,3-diphenyl-2a,8b-dihydrocyclobuta[a]naphthalene. CII:8b-methoxy-2,3-diphenyl-2a,8b-dihydrocyclobuta[a]naphthalene

The title compound CI, C₂₅H₂₀O₁, crystallizes in the monoclinic space groupCc with cell parametersa = 1.0186(2),b = 1.6327(6),c = 1.1000(4) nm, = 99.43(2) °,Z = 4, andV = 1.8047 nm³; title compound CII, C₂₅H₂₀O₁, crystallizes in the tetragonal space groupP4₂/n with cell parametersa =b = 2.4218(7),c = 0.6352(2) nm,Z = 8, and V = 3.7255 nm³. Both structures were refined by full-matrix least squares using diffractometer data to reliability indices (R) of 0.048 and 0.053, respectively. In each structure one single carbon-carbon bond, C2a-C8b, was significantly elongated (4.5 pm), otherwise the geometry observed was not unusual.     

Synthesis, crystal structure, and magnetic properties of a Li8FeSm22O38 single crystal

Li₈FeSm₂₂O₃₈ single crystals have been grown by spontaneous flux crystallization, and their structure has been identified by X-ray diffraction analysis as follows: cubic crystals, a = 11.9078(5) Å, sp.gr. $Im\bar 3m$ , Z = 2. Fe atoms occupy two mixed positions. Magnetic ions have different ligand environments: a regular octahedron (Sm/Fe)O₆, a three-cap trigonal prism SmO₉, and a square antiprism SmO₈. The rather low Neel temperature (～3 K) can be explained by the considerable variation in the angles and lengths of exchange couplings between magnetic ions.     

Crystal structure of a cyclobutane derivative: 4,8-dibromo-3,7-diketo-3, 4,4a,4b,7,8,8a,8b-octahydrodibenzo- [a,g] -biphenylene

The crystal structure of a cyclobutane derivative, 4,8-dibromo-3,7-diketo-3,4,4a,4b,7,8,8a,8b-octahydrodibenzo-[a,g]-biphenylene (C₂₀H₁₄O₂Br₂), has been determined from 1614 intensities collected with a four-circle diffractometer and refined by three-dimensional least-squares techniques. The crystals are monoclinic, space groupP2₁/c, with four molecules in a unit cell of dimensionsa = 10·863 ± 0·006,b = 21·060 ± 0·011,c = 7·772 ± 0·005 Å and β = 105·33 ± 0·04 °. The cyclobutane ring was found to have a bent configuration with a dihedral angle of 157 °.     

Synthesis and base promoted intramolecular nucleophilic reaction of 8-hydroxy-1,2,3,4-tetrachloro-9,9-dimethoxy-1α,4α,4aα,6,7,8β,8aα-hexahydro-1,4-methanonaphthalene-5(1H)-one

Catalytic hydrogenation of two substituted hexahydro-1,4-dimethanonaphthalene-5,8-diones results in reduction of the enedione carbon-carbon double bond with concomitant reduction of only one of the two chemically equivalent C=O groups. Reaction of one partially reduced product with base results in intramolecular addition to the carbon-carbon double bond.     

8-氨基喹啉席夫碱锌配合物的合成,晶体结构及发光性质

合成了一个新的锌配合物[Zn(8-ahsb)(N3)](1)(8-ahsb=8-氨基喹啉水杨醛席夫碱阴离子),并对其进行了元素分析、红外光谱和X-射线单晶衍射表征.配合物1属于单斜晶系,空间群为C2/c,a=0.6762(3)nm,b=2. 2842(9)nm,c=1.8162(8)nm,β=91.309(7)°,V=2.805(2)nm3,Z=8.中心离子Zn(II)为三角双锥配位构型,分别与四个N原子、一个氧原子配位,其中1个8-氨基喹啉席夫碱配体提供了2个N原子、一个氧原子,剩余两个N原子分别来自于两个N3-阴离子,且每个N-3桥联邻近的两个Zn2+形成一维无限链状结构.荧光光谱的分析表明该化合物具有强的绿色发光性能,且可作为荧光探针检测低浓度的铜离子.     

Preparation,structure and thermal properties of CuGa5Se8

The structural parameters, the axial thermal expansion coefficients and the characteristic Debye temperatures for the order vacancy compound CuGa₅Se₈ with the chalcopyrite‐related structure, prepared by the Bridgman technique, were determined at different temperatures between 90 and 650 K by the X‐ray diffraction method. The melting point of this compound was defined from the differential thermal analysis data. The anisotropy of thermal expansion in CuGa₅Se₈ is shown to exist with the coefficients along a ‐axis being larger than those along the c ‐axis throughout the temperature range studied.     

Dielectric Studies of Three Liquid Crystals HBT,E8 and PCH-1132

The dielectric behavior of a Schiff base N-(P-Hexyloxybenzylidene)-P-toluidine (HBT) and two technologically important mixtures, E₈ and PCH-1132, are reported in the radio frequency region. The value of the mean dielectric constant increases by ～5% on going from the nematic to the isotropic phase in the case of E₈ and PCH-1132. This may perhaps be due to antiferroelectric arrangement of the molecules in the nematic phase. These mesogens show unusual dielectric behavior and exhibit positive anisotropy at lower frequencies and negative dielectric anisotropy above a critical frequency termed as isotropic frequency. The isotropic frequency is found to be temperature dependent. All these nematogens exhibit single relaxation in the radio frequency region which is due to hindered rotation of the molecules under nematic potential. The relaxation frequencies are 3.98 MHz (at 61.4°C), 2.27 MHz (at 34.3°C), 1.87 MHz (at 33°C) in case of HBT, E₈ and PCH-1132 respectively. The activation energy is found to be 16.7 KCal/mole, 14.6 KCal/mole and 16.1 KCal/mole for HBT, Ea and PCH-1132 respectively. In smectic B phase of HBT, the dipolar orientations are found to be somewhat “locked” similar to that in solids. The inversion of the sign of dielectric anisotropy in S_B phase of HBT is also discussed.     

Crystal and molecular structure of 2-bromo-5,6-dihydro-6-methyl-4H,8H-pyrido [3,2,1-de]phenanthridin-8-one

Crystals of the title compound, C₁₇H₁₄BrNO, are monoclinic, with space groupP2₁/a,a = 14.314(5),b = 15.009(11),c = 6.596(3) Å, and = 102.39(3) °. Diffraction data were collected with CuK radiation to a Bragg angle of 77 °. The structure was solved by the heavy-atom method and refined to anR index of 0.059 for 2129 reflections. In agreement with NMR results, the C=O group is orientedanti to the benzene ring, and the methyl group at C(6) is axial. Unlike 1-(p-bromobenzoyl)-2-methyl-1,2,3,4-tetrahydroquinoline, the heterocyclic ring assumes a well defined half-chair conformation. Except for C(5) and the methyl group at C(6), the whole molecule is very nearly planar.     

Crystal and molecular structure of p-Toluquinone-monoguanylhydrazone,C8H10N4O

The crystal structure of p-toluquinone-monoguanylhydrazone is orthorhombic, space group Pna2₁ with 4 formula units C₈H₁₀N₄O in the unit cell. The lattice constants are a = 7.589, b = 20.117, and c = 5.699 Å. The structure was refined to the conventional R = 0.05. The configuration and conformation of the molecule as well as the unusual hydrogen bridge system are discussed.     

Crystal structure and spectroscopic study of 6a,7a,13b,13c-tetrahydro-6a-hydroxy-2,3,11,12-tetramethoxy-6,6,8,8-tetramethyl-6H,8H-bischromeno-[3,4-b:4′,3′-d]furan,a dimer of precocene II 3,4-epoxide

The X-ray crystal structure of the title compound has been determined. The crystals are orthorhombic:Pcab, a=9.857(5),b=15.274(5),c=32.601(14) Å,V _c =4908.4 ų;Z=8;D _x =1.279 Mg m^–3; (MoK)=0.71069 Å;=0.88 cm^–1,F(000)=2016, temperature of measurement 294 K. The structure was solved by direct methods, and refined with 932 reflections to a finalR value of 0.071. The two six-membered rings show distorted boat conformations and the tetrahydrofuran ring exhibits a half-chair conformation. Mass spectra, IR spectrum, and¹H and¹³C NMR spectra are also reported.     

Influence of temperature variation on field effect transistor properties using a solution-processed liquid crystalline semiconductor,C8BTBT

In this study, we used a LC semiconductor, C₈BTBT, solution (e.g. 0.1 wt % in heptane) for forming an organic semiconductor layer by casting method, and fabricated bottom-gate/bottom-contact type FETs. The FETs mobility was determined 0.17 cm² V^?1 s^?1 which was comparable to that determined by time-of-flight technique in a sandwich type cell at room temperature. We have investigated the surface morphology and the influence of temperature variation on FET properties. The LC FET mobility was kept below 60°C and drastically decreased after heat stress above 100°C irreversibly.     

Editorial board page for “Molecular Crystals and Liquid Crystals”, Volume 41, Number 8

This is a scanned image of the original Editorial Board page(s) for this issue.     

Crystal Growth and Properties of the CuIn5S8 and AgIn5S8 Compounds

The optical and electrophysical properties as well as the structural characteristics and thermal expansion coefficients at different temperatures for the CuIn₅S₈ compound, grown by the vertical Bridgman-Stockbarger technique, and for the AgIn₅S₈ compound, prepared by the directed crystallization of the melt, were investigated.