Polymer-stabilized blue phase liquid crystal with a negative Kerr constant

A polymer-stabilized blue-phase liquid crystal (BPLC) with a negative Kerr constant is reported. In a voltage-on state, the double-twist BPLC molecules within the lattice cylinders are reoriented perpendicular to the applied electric field because of their negative dielectric anisotropy. As a result, the induced birefringence has a negative value, which leads to a negative Kerr constant. The negative sign of Kerr constant is experimentally validated by using a quarter-wave plate and a vertical field switching cell. Such a BPLC shows a negligible (similar to 1%) hysteresis and fast response time (similar to 1ms) at the room temperature, although its Kerr constant is relatively small because the employed host has a small Delta epsilon

Lanthanide complexes with a chelating methylenediphosphonate

7 pagesThe complexation behaviour of the bidentate ligand tetrakis(O-isopropyl)methylenediphosphonate (L = (iPrO)(2)P(O)CH2-P(O)(OiPr)(2)) with lanthanide ions has been studied by using triflates Ln(OTf)(3) (Ln = La, Pr, Nd) as sources of the Ln(3+) cations. At the 2:1 L:Ln stoichiometric ratio, adducts of composition [Ln(OTf)(3)(L)(2)(OH2)(2)] were isolated (Ln = La, Pr, Nd). In the X-ray structure of the cationic [Nd(OTf)(2)(L)(2)(OH2)(2)](OTf), the two coordinated triflates are monodentate. Finally, at higher L/Ln ratios, complexes were difficult to isolate because of a high degree of solvation, but, in one instance, with Ln = La, by using inert atmosphere techniques, the tripositive complex. [La(L)(4)](OTf)(3)(CH3CN)(3) has been obtained and characterised by X-ray. By contrast, in the crystal structures of [Ln(NO3)(3)(L)(2)](CH3CN)(2), (Ln = Ce, Pr, Nd), all three nitrates are bidentate. (c) 2005 Elsevier Ltd. All rights reserved

synthesischaracterizationandluminescentpropertiesoftwocoppericomplexesbasedon22biquinolineandphosphorousligand

Three new copper(I) complexes, namely Cu(DPEphos)(Biq)CF3SO3 (1) and Cu(PPh3)(2)(Biq)CF3SO3 (2) and Cu(PPh3)(2)(Biq)ClO4(3) (DPEphos = bis 2-(diphenylphosp hino)phenylether, PPh3 = triphenylphosphine and Biq = 2,2'-biquinoline), are synthesized and characterized by IR, H-1 NMR, P-31 NMR, fluorescence spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 1 crystallizes in triclinic, space group P (1) over bar with a = 12.6997(5), b = 13.2813(5), c = 15.3593(6) angstrom, alpha = 80.211(3)degrees, beta= 88.752(3)degrees, gamma = 70.113(3)degrees, V = 2398.85(15) angstrom(3), C55H41.2CUF3N2O2,M-r = 1018.27, Z = 2, D-c = 1.410 g/cm(3), F(000) = 1048, mu = 0.628 mm(-1), the final R = 0.0450 and wR = 0.1105 for 9419 observed reflections (I > 2 sigma(I)). Complex 2 crystallizes in monoclinic, space group C2/c with a = 19.9961(7), b = 15.9774(5), c = 17.7908(6) angstrom, beta = 119.758(4)degrees, V = 4982.8(3) angstrom(3), C56.47H47.88CuF3N2O4.47P2S, Mr = 1040.54, Z = 4, D-c = 1.387 g/cm(3), F(000) = 2154, mu = 0.606 mm(-1), the final R = 0.0430 and wR = 0.1218 for 4897 observed reflections (I > 2 sigma(I)). Complex 3 crystallizes in monoclinic, space group C2/c with a = 19.7534(8), b = 15.0797(5), c = 17.8097(7) angstrom, beta = 116.400(5)degrees, V = 4751.8(3) angstrom(3), C-56 H(45)C1CuN(3)O(4)P(2), M-r= 984.88, Z = 4, D-c= 1.377 g/cm(3), F(000) = 2040, mu = 0.635 mm(-1), the final R = 0.0731 and wR = 0.2180 for 4670 observed reflections (I > 2 sigma(I)). In the emission spectra, shifts of emission peak are derived from ligand-centered (pi-pi*) transition

synthesischaracterizationandluminescentpropertiesoftwocoppericomplexesbasedon22biquinolineandphosphorousligand

Three new copper(I) complexes, namely Cu(DPEphos)(Biq)CF3SO3 (1) and Cu(PPh3)(2)(Biq)CF3SO3 (2) and Cu(PPh3)(2)(Biq)ClO4(3) (DPEphos = bis 2-(diphenylphosp hino)phenylether, PPh3 = triphenylphosphine and Biq = 2,2'-biquinoline), are synthesized and characterized by IR, H-1 NMR, P-31 NMR, fluorescence spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 1 crystallizes in triclinic, space group P (1) over bar with a = 12.6997(5), b = 13.2813(5), c = 15.3593(6) angstrom, alpha = 80.211(3)degrees, beta= 88.752(3)degrees, gamma = 70.113(3)degrees, V = 2398.85(15) angstrom(3), C55H41.2CUF3N2O2,M-r = 1018.27, Z = 2, D-c = 1.410 g/cm(3), F(000) = 1048, mu = 0.628 mm(-1), the final R = 0.0450 and wR = 0.1105 for 9419 observed reflections (I > 2 sigma(I)). Complex 2 crystallizes in monoclinic, space group C2/c with a = 19.9961(7), b = 15.9774(5), c = 17.7908(6) angstrom, beta = 119.758(4)degrees, V = 4982.8(3) angstrom(3), C56.47H47.88CuF3N2O4.47P2S, Mr = 1040.54, Z = 4, D-c = 1.387 g/cm(3), F(000) = 2154, mu = 0.606 mm(-1), the final R = 0.0430 and wR = 0.1218 for 4897 observed reflections (I > 2 sigma(I)). Complex 3 crystallizes in monoclinic, space group C2/c with a = 19.7534(8), b = 15.0797(5), c = 17.8097(7) angstrom, beta = 116.400(5)degrees, V = 4751.8(3) angstrom(3), C-56 H(45)C1CuN(3)O(4)P(2), M-r= 984.88, Z = 4, D-c= 1.377 g/cm(3), F(000) = 2040, mu = 0.635 mm(-1), the final R = 0.0731 and wR = 0.2180 for 4670 observed reflections (I > 2 sigma(I)). In the emission spectra, shifts of emission peak are derived from ligand-centered (pi-pi*) transition

synthesesstructuralcharacterizationsandspectroscopicpropertiesoftwocoppericomplexesbasedondiphosphineligandsand23fpyrazino110phenanthroline

Two novel copper(I) complexes Cu(dppBz)(dpq)ClO4 (1) and Cu(dppe)(dpq)ClO4 (2) (dppBz=1,2-bis (diphenylphosphino)benzene, dppe=1,2-bis(diphenylphosphino)ethene, dpq=2,3-fpyrazino1,10phenanthroline) have been synthesized and characterized by X-ray diffraction, elemental analysis, infrared spectroscopy, absorption spectra, luminescent spectra, 11-1 NMR, 31P NMR spectroscopy and terahertz (THz) time-domain absorption spectroscopy. The central Cu(I) ion is chelated by a diimine ligand and a diphosphine ligand forming a distorted tetrahedron configuration for 1, and the configuration of 2 is similar to 1. The luminescent spectra of 2 indicated that the emission has metal-to-ligand charge transfer (MLCT) characteristics. The terahertz time-domain absorption spectroscopy analysis in a range of 0.2-2.8 THz showed that the absorption peaks at 0.40-0.90 THz are related to the coordination of the central Cu(I). CCDC: 1874580, 1; 1874581, 2

Influence of aromatic heterocycle of conjugated side chains on photovoltaic performance of benzodithiophene-based wide-bandgap polymers

Extensive efforts have been focused on the study of wide-band gap (WBG) polymers due to their important applications in multiple junction and ternary blend organic solar cells. Herein, three WBG copolymers named PBDT(X)-T1 (X = O, S, Se) were synthesized based on the benzodithiophene (BDT) donor unit and 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c???]dithiophene-4,8-dione (T1) acceptor unit. Different aromatic heterocycle groups (furan, thiophene and selenophene) were introduced to modify the BDT unit to investigate the influence of conjugated side chains on the photovoltaic properties of conjugated polymers. Photophysical properties, electrochemistry, charge transport and crystalline properties of the polymers were studied to discuss the role of chalcogen atoms on the performance of conjugated polymers. Solar cells based on these three WBG copolymers were fabricated. Among them, the PBDT(Se)-T1-based solar cell shows the best photovoltaic performance with the highest power conversion efficiency (PCE) of 8.52%, an open-circuit voltage (Voc) of 0.91 V, and a high fill factor (FF) of 72%. The high crystallinity and preferential face-on orientation in the blend film partially explain the superior photovoltaic performance achieved in PBDT(Se)-T1-based solar cells. The results indicate the important role of chalcogen atoms in conjugated side chains and that high photovoltaic performance can be realized through side chain engineering of BDT-based WBG conjugated polymers.clos