Prerequisite for virtually all nematic field-effects on which liquid crystal displays (LCDs) are based is stable, uniaxial surface alignment with defined bias tilt angle between the long liquid crystal (LC) axes and their display boundaries. Since the invention of the TN-LCD [1Schadt, M., & Helfrich, W. (1972). Mol. Cryst. Liq. Cryst., 17, 355.[Taylor & Francis Online], [Web of Science ®], [Google Scholar]] in 1970 until recently this was achieved by confining liquid crystals between mechanically brushed surfaces [2Cognard, J. (1982). J. Mol. Cryst. Liq. Cryst. Suppl. Ser., 1, 1–74.[Google Scholar]–4Aoyama, H., Yamazaki, Y., Matsuura, N., Mada, H., & Kobayashi, S. (1981). Mol. Cryst. Liq. Cryst. Lett., 72, 127.[Taylor & Francis Online], [Web of Science ®], [Google Scholar]]. We have first shown in the 1990s that, non-mechanical, uniaxial, tilted and patterned LC-alignment is possible by anisotropic Van der Waals surface interactions [5Schadt, M., Seiberle, H., & Schuster, A. (1996). Nature, 381, 212. US Patent (1995) US-6, 215, 539.[Crossref], [Web of Science ®], [Google Scholar]], namely by directional polymerization of photo-sensitive side-chain polymers films [5Schadt, M., Seiberle, H., & Schuster, A. (1996). Nature, 381, 212. US Patent (1995) US-6, 215, 539.[Crossref], [Web of Science ®], [Google Scholar], 6Schadt, M., Schmitt, K., Kozinkov, V. & Chigrinov, V.G. (1992). Jpn. J. Appl. Phys., 31, 2155. US patent (1991) US 5,389,698.[Crossref], [Web of Science ®], [Google Scholar]] by linear polarized UV light. The LPP model is reviewed and its applications enabling high resolution multi-domain liquid crystal displays operated in transmission and reflection are discussed. Examples are given for optical retarders integrated into LCDs, anisotropic liquid crystal polymer (LCP)-films for 3D imaging, interference color filters, wide-view films and anisotropic polymer surface topologies. 相似文献
A new class of supramolecular calix[4 (a) Kuang, G.C., Jia, X.R., Teng, M.J., Chen, E.Q., Li, W.S., Ji, Y., Chem Mater. 2012, 24,71–80; (b) Macros, M., Omenat, A., Serrano, J.L., and Ezcurra, A., Adv. Mater. 1992, 4, 285–287.[Crossref], [Web of Science ®], [Google Scholar], [Google Scholar]]resorcinarene substituted alkoxy side chain (-OC5H11, -OC8H17, -OC10H21) has been synthesized and well characterized. These supramolecular compounds were investigated by polarizing optical microscope (POM), differential scanning calorimetry (DSC), thermogravimmetric analysis (TGA) and high-temperature X-ray diffraction studies (XRD). The present synthesized supramolecular derivatives are promising to stabilize the hexagonal columnar phase over a broad thermal range. All the synthesized derivatives showed hexagonal columnar phase at lower temperature and showed enantiotropical nature. Compound 2a with small alkyl spacer on eight side showed higher thermal stability as compare to higher alkyl spacer substituted compounds 2b and compound 2c. These research results suggest that calix[4 (a) Kuang, G.C., Jia, X.R., Teng, M.J., Chen, E.Q., Li, W.S., Ji, Y., Chem Mater. 2012, 24,71–80; (b) Macros, M., Omenat, A., Serrano, J.L., and Ezcurra, A., Adv. Mater. 1992, 4, 285–287.[Crossref], [Web of Science ®], [Google Scholar], [Google Scholar]]resorcinarene was a good platform to construct bowl-shaped derivatives to exhibits the columnar liquid crystal phase and the observed liquid crystalline properties were greatly effected by the substituted alkoxy side chain on eight side of calix[4 (a) Kuang, G.C., Jia, X.R., Teng, M.J., Chen, E.Q., Li, W.S., Ji, Y., Chem Mater. 2012, 24,71–80; (b) Macros, M., Omenat, A., Serrano, J.L., and Ezcurra, A., Adv. Mater. 1992, 4, 285–287.[Crossref], [Web of Science ®], [Google Scholar], [Google Scholar]]resorcinarene skeletone. All the synthesized compounds were characterized by FT-IR, 1H NMR and 13C NMR spectroscopy. 相似文献
Tourmaline is a kind of borosilicatemineral and has spontaneous polarization property. Due to this property, it can generate a feeble current around 0.06 mA[1O'Regan, B., &; Grätzel, M. (1991). Nature353, 737.[Crossref], [Web of Science ®], [Google Scholar]]. We fabricated the TiO2 photoanode with different wt.% ratio of tourmaline and investigated the effect of tourmaline additive on dye sensitized solar cells (DSSCs). We carried out electrochemical impedance spectroscopy (EIS) and current density-voltage (J-V) measurement. The results showed that the electron lifetime and the power conversion efficiency of the DSSCs with TiO2 photoanode containing 3wt% tourmaline were enhanced by about 42% and 20%, respectively, as compared to the DSSCs using pristine TiO2 photoanode. 相似文献
A series of bipolar host materials containing dibenzo[b,d]thiophene (DBT) or dibenzo[b,d]thiophene 5,5-dioxide core were successfully synthesized, and their physical, photophysical, and electrochemical properties were investigated. The three host materials showed well-localized electron distribution at the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states, as evidenced by theoretical calculations. Triplet energies of the new host materials are higher than 2.6 eV, and the blend film with bis[2-(4,6-difluorophenyl)pyridinato-C2Misra, A. et al. (2006). Semicond. Sci. Technol., 21, R35.[Crossref], [Web of Science ®], [Google Scholar],N](picolinato)iridium(III) (FIrpic) as a blue phosphorescent dopant showed highly efficient energy transfer between the host material and dopant. 相似文献
The solid state structure of an N-heterocyclic borane 1,1,3,3-tetramethyl-1,3λ4,2-diazaborolidin-1-ium chloride is reported. This molecule features numerous Cl?H hydrogen bonds.
Graphical Abstract
The crystal structure of 1,1,3,3-tetramethyl-1,3λ4,2-diazaborolidin-1-ium chloride shows multiple C–H?Cl interactions in the solid state.
Molecular clips hold the potential of self-association and the ability to form host–guest complexes. Here we describe the synthesis of a 1,2-dimethoxyphenyl terminated glycoluril molecular clip (2) that binds with smaller solvent molecules by π?H–C and C=O?H–O non-covalent interactions. We obtained single crystals of 2 and 2 + CH2Cl2, CH3OH, CH3CN, and DMF solvents complexed within the clip. These solvents always form two π?H–C interactions between the aromatic rings in the clip, and CH3OH formed an additional C=O?H–O hydrogen bond with the glycoluril carbonyl group. Based on single crystal data we found that π?H–C interactions of 2 + CH2Cl2 are stronger than 2 + CH3CN and 2?+?DMF, due to the presence of stronger electron withdrawing groups in CH2Cl2, which lead to a decrease in dihedral angle of two glycoluril aromatic planes. We also investigated the non-covalent interaction energies of these solvent molecules with 2 using computational methods.
Graphical Abstract
Several solvent adducts of a glycoluril derivative have been isolated and characterized by single crystal X-ray diffraction, revealing two common pi?H–C non-covalent bonds within the molecular clip.
The title chalcone, of formula C15H11F1O2, crystallized in the orthorhombic space group P212121 (# 19) with crystal parameters a?=?6.9998(8) Å, b?=?12.6740(15) Å, c?=?12.8997(15) Å, V?=?1144.4(2) Å3, Z?=?4, determined at 100 K with MoKα radiation. The solid-state structure displays an intramolecular S(6) hydrogen bond and the crystal architecture is maintained by intermolecular F?H, O?H, and C?C short contacts. A DFT geometry optimization is compared with the experimental structure. As 19F NMR spectroscopy can be used for metabolic tagging of biologically active compounds (including chalcones), the solution-state 19F chemical shift and 13C19F coupling constants (nJ) are also reported.
Novel tetraiminodiphenolate (tidf2?) supramolecular assemblies containing palladium, cobalt, copper and iron(II) have been prepared and characterized by X-ray crystallography, and FTIR and UV–Vis spectroscopies. Complex 1 crystallizes as [PdCo(tidf)(H2O)2]2([Fe(CN)5NO])2·7H2O, and contains a planar macrocycle, while complex 2, [PdCu(tidf)(H2O)(ClO4)]2([Fe(CN)4(CNH)2])·2H2O, shows a slightly bent heterocyclic unit. Both structures exhibited supramolecular architectures maintained through extensive hydrogen bonding networks.
Graphical Abstract
Two unique polynuclear complexes 2[PdCo(tidf)(H2O)2]([Fe(CN)5)NO])2·7H2O and 2[PdCu(tidf)(H2O)(ClO4)]([Fe(CN)4(CNH)2])·2H2O (tidf is a symmetrical tetraiminodiphenolate Robson type macrocyclic ligand) were prepared and their molecular structures and spectroscopic properties are discussed.
The title compound, ethyl 2-(4-methoxyphenyl)-1H-benzo[d]imidazole-5-carboxylate dihydrate (5), was synthesized and its crystal structure was studied by single-crystal X-ray diffraction technique. Compound 5 is crystallized in the centrosymmetric triclinic space group \(P\bar {1}\) with Z?=?4 and Z′?=?2, and unit-cell parameters of a?=?8.9190 (3) Å, b?=?12.6888 (4) Å, c?=?14.7111 (5) Å, α?=?98.4855 (10)°, β?=?101.6379 (9)°, γ?=?95.4346 (10)° and V?=?1599.43 (9) Å3. Its starting material, 4-fluoro-3-nitrobenzoic acid (1), is crystallized in the non-centrosymmetric monoclinic space group P21 and Z?=?4 with unit-cell parameters of a?=?3.7170 (4) Å, b?=?12.6475 (13) Å, c?=?15.5237 (15) Å, α?=?90°, β?=?91.9786 (16)°, γ?=?90° and V?=?729.35 (13) Å3. It was noted that strong hydrogen bonds play important roles in the crystal packing of both compounds, especially in 5, in which the co-crystallized water molecules act as both strong hydrogen bond donor and strong hydrogen bond acceptor.
Graphical Abstract
Two molecule of compound 5 crystallized in a non symmetrical manner with four co-crystallized water molecules which play an important role in the crystal packing as strong hydrogen-bond donors.
