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Compound Shows (compound + shows)
Selected AbstractsAir-Stable n-Type Organic Field-Effect Transistors Based on Carbonyl-Bridged Bithiazole DerivativesADVANCED FUNCTIONAL MATERIALS, Issue 6 2010Yutaka Ie Abstract An electronegative conjugated compound composed of a newly designed carbonyl-bridged bithiazole unit and trifluoroacetyl terminal groups is synthesized as a candidate for air-stable n-type organic field-effect transistor (OFET) materials. Cyclic voltammetry measurements reveal that carbonyl-bridging contributes both to lowering the lowest unoccupied molecular orbital energy level and to stabilizing the anionic species. X-ray crystallographic analysis of the compound shows a planar molecular geometry and a dense molecular packing, which is advantageous to electron transport. Through these appropriate electrochemical properties and structures for n-type semiconductor materials, OFET devices based on this compound show electron mobilities as high as 0.06,cm2 V,1 s,1 with on/off ratios of 106 and threshold voltages of 20,V under vacuum conditions. Furthermore, these devices show the same order of electron mobility under ambient conditions. [source] Synthesis, structure and electrochemical properties of two new unsymmetrical tetrathiafulvalene derivativesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2005Ming Xu Two new unsymmetrical tetrathiafulvalene (TTF) derivatives, 2,3-bis(cyanoethylthio)-6,7-(methyl-ethylenedithio)tetrathiafulvalene (6a) and 2,3-bis(cyanoethylthio)-6,7-(cyclopentodithio)tetrathiafulvalene (6b), have been prepared and characterized by NMR, MS, IR and Elemental analyses. The molecular structures have been determined by X-ray crystallography. Their redox properties have been investigated by cyclic voltammetry in dichloromethane solution and each compound shows two reversible single-electron redox couples. [source] Modulated structure and phase transitions of Sr10Ga6O19ACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2009Hannes Krüger The crystal structure of Sr10Ga6O19 was investigated by in situ single-crystal X-ray diffraction in the temperature range 298,673,K. At ambient conditions the compound shows a (3,+,1)-dimensional modulated structure in the superspace group C2/c(0,0)s0 [a = 34.9145,(13), b = 7.9369,(2), c = 15.9150,(7),Å and , = 103.551,(3)°] with a modulation wavevector of q = 0.4288,(2)b*. Whereas the presented structural model uses first-order harmonic modulation functions only, some features of the modulations are discussed utilizing an electron density derived by the maximum entropy method. Furthermore, two phase transitions were identified: between 453 and 503,K the incommensurate superstructure is replaced by a doubling of the a and b lattice constants, and between 503 and 673,K a phase with the basic cell is formed, identical to ,-Sr10Ga6O19. Under some cooling conditions crystals showing a combined diffraction pattern of both superstructures can be obtained. The relation of these results to ,-Sr10Ga6O19 [Kahlenberg (2001). J. Solid State Chem.160, 421,429] is discussed. [source] Metal,Organic Perovskites: Synthesis, Structures, and Magnetic Properties of [C(NH2)3][MII(HCOO)3] (M=Mn, Fe, Co, Ni, Cu, and Zn; C(NH2)3= Guanidinium)CHEMISTRY - A EUROPEAN JOURNAL, Issue 44 2009Ke-Li Hu Abstract We report the synthesis, crystal structures, and spectral, thermal, and magnetic properties of a family of metal,organic perovskite ABX3, [C(NH2)3][MII(HCOO)3], in which A=C(NH2)3 is guanidinium, B=M is a divalent metal ion (Mn, Fe, Co, Ni, Cu, or Zn), and X is the formate HCOO,. The compounds could be synthesized by either diffusion or hydrothermal methods from water or water-rich solutions depending on the metal. The five members (Mn, Fe, Co, Ni, and Zn) are isostructural and crystallize in the orthorhombic space group Pnna, while the Cu member in Pna21. In the perovskite structures, the octahedrally coordinated metal ions are connected by the anti,anti formate bridges, thus forming the anionic NaCl-type [M(HCOO)3], frameworks, with the guanidinium in the nearly cubic cavities of the frameworks. The Jahn,Teller effect of Cu2+ results in a distorted anionic Cu,formate framework that can be regarded as Cu,formate chains through short basal CuO bonds linked by the long axial CuO bonds. These materials show higher thermal stability than other metal,organic perovskite series of [AmineH][M(HCOO)3] templated by the organic monoammonium cations (AmineH+) as a result of the stronger hydrogen bonding between guanidinium and the formate of the framework. A magnetic study revealed that the five magnetic members (except Zn) display spin-canted antiferromagnetism, with a Néel temperature of 8.8 (Mn), 10.0 (Fe), 14.2 (Co), 34.2 (Ni), and 4.6,K (Cu). In addition to the general spin-canted antiferromagnetism, the Fe compound shows two isothermal transformations (a spin-flop and a spin-flip to the paramagnetic phase) within 50,kOe. The Co member possesses quite a large canting angle. The Cu member is a magnetic system with low dimensional character and shows slow magnetic relaxation that probably results from the domain dynamics. [source] The Molecular Basis of Self-Assembly of Dendron,Rod,Coils into One-Dimensional NanostructuresCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2006Eugene R. Zubarev Prof. Abstract We describe here a comprehensive study of solution and solid-state properties of self-assembling triblock molecules composed of a hydrophilic dendron covalently linked to an aromatic rigid rod segment, which is in turn connected to a hydrophobic flexible coil. These dendron,rod,coil (DRC) molecules form well-defined supramolecular structures that possess a ribbonlike morphology as revealed by transmission-electron and atomic-force microscopy. In a large variety of aprotic solvents, the DRC ribbons create stable networks that form gels at concentrations as low as 0.2,% by weight DRC. The gels are thermally irreversible and do not melt at elevated temperatures, indicating high stability as a result of strong noncovalent interactions among DRC molecules. NMR experiments show that the strong interactions leading to aggregation involve mainly the dendron and rodlike blocks, whereas oligoisoprene coil segments remain solvated after gelation. Small-angle X-ray scattering (SAXS) profiles of different DRC molecules demonstrate an excellent correlation between the degree-of-order in the solid-state and the stability of gels. Studies on two series of analogous molecules suggest that self-assembly is very sensitive to subtle structural changes and requires the presence of at least four hydroxyl groups in the dendron, two biphenyl units in the rod, and a coil segment with a size comparable to that of the rodlike block. A detailed analysis of crystal structures of model compounds revealed the formation of stable one-dimensional structures that involve two types of noncovalent interactions, aromatic ,,, stacking and hydrogen bonding. Most importantly, the crystal structure of the rod,dendron compound shows that hydrogen bonding not only drives the formation of head-to-head cyclic structures, but also generates multiple linkages between them along the stacking direction. The cyclic structures are tetrameric in nature and stack into ribbonlike objects. We believe that DRC molecules utilize the same arrangement of hydrogen bonds and stacking of aromatic blocks observed in the crystals, explaining the exceptional stability of the nanostructures in extremely dilute solutions as well the thermal stability of the gels they form. This study provides mechanistic insights on self-assembly of triblock molecules, and unveils general strategies to create well-defined one-dimensional supramolecular objects. [source] Dichloro[1,1,-(5,9-dithia-2,12-diazoniatrideca-1,12-diene-1,13-diyl)dinaphthalen-2-olato-,2O,O,]dimethyltin(IV) acetonitrile solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2003Stanley A. Bajue Reaction of the potentially hexadentate ligand 1,9-bis(2-hydroxy-1-naphthalenemethylimino)-3,7-dithianonane with dimethyltin chloride gave the title 1:1 adduct, in which the long ligand wraps around the SnCl2Me2 unit and in which the stereochemistry is fully trans. This compound crystallizes from acetonitrile as the 1:1 solvate [Sn(CH3)2(C29H30N2O2S2)Cl2]·C2H3N. During the reaction, the hydroxyl protons move to the N atoms. Most of the chemically equivalent bond lengths agree to within experimental uncertainty, but the Sn,Cl bond that is inside the ligand pocket is substantially longer than the Sn,Cl bond that points away from the long ligand [2.668,(1) versus 2.528,(1),Å]. The O,Sn,O angle is 166.0,(1)°. Comparison of the Sn,O, C,O and aryl C,C bond lengths with those of related compounds shows that the most important resonance forms for the Schiff base aryloxide ligand are double zwitterions, but that the uncharged resonance forms having carbonyl groups also contribute significantly. [source] | ||||||||||