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840 results on '"Bruce, Duncan W."'

54. Synthesis and liquid-crystalline properties of diazabutadiene complexes of rhenium(I)

Author

Morrone, Stefania, Guillon, Daniel, and Bruce, Duncan W.

Subjects
Liquid crystals -- Research, Rhenium -- Research, Chemistry
Abstract

New N,N'-bis(4-((4-alkoxybenzoyl)oxy)phenyl)-1,4-diaza-1,3-butadiene (L) ligands, derived by condensation of 4-((alkoxybenzoyl)oxy)anilines and glyoxal, were complexed to various (ReX(CO)3) fragments to produce the complexes (ReX(L)(CO)3) (X=Cl,Br,I) and (Re(CF3SO3)(L)(CO)3)*THF. The chloro and bromo complexes were obtained by direct reaction of the ligands with (ReX(CO)5) (X=Cl,Br), while the iodo and triflato derivatives were obtained by metathesis of the chloro or bromo precursors with potassium iodide or silver triflate, respectively.

Published
1996

55. Towards magnetic liquid crystals

Author

Day, P., primary, Underhill, A. E., additional, Binnemans, Koen, additional, Bruce, Duncan W., additional, Collinson, Simon R., additional, Deun, Rik Van, additional, Galyametdinov, Yury G., additional, and Martin, Françoise, additional

Published
1999
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60. Spatially resolved mapping of phase transitions in liquid-crystalline materials by X-ray birefringence imaging

Author

Zhou, Yating, primary, Patterson, Rhian, additional, Palmer, Benjamin A., additional, Edwards-Gau, Gregory R., additional, Kariuki, Benson M., additional, Kumar, N. S. Saleesh, additional, Bruce, Duncan W., additional, Dolbnya, Igor P., additional, Collins, Stephen P., additional, Malandain, Andrew, additional, and Harris, Kenneth D. M., additional

Published
2019
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73. Oxidation of organoplatinum(II) by coordinated dimethylsulfoxide: metal-metal bonded, dinuclear, liquid-crystalline complexes of platinum(III)

Author

Santoro, Amedeo, Wegrzyn, Marcin, Whitwood, Adrian C., Donnio, Bertrand, and Bruce, Duncan W.

Subjects
Dimethyl sulfoxide -- Chemical properties, Organometallic compounds -- Chemical properties, Organometallic compounds -- Structure, Oxidation-reduction reaction -- Analysis, Platinum -- Chemical properties, Pyridine -- Chemical properties, Pyridine -- Structure, Chemistry
Abstract

The reaction of [Pt[Cl.sub.2][(dmso).sub.2]] with 2,5-(dialkoxyphenyl)pyridine in HOAc has led to a dinuclear, acetate-bridged, metal-metal bonded complex of platinum(III), where dmso in the presence of acid is responsible for the oxidation. Platinum dimers with longer alkoxy chains are unique examples of liquid crystals of platinum(III).

Published
2010

74. Reactive-Atom Scattering from Liquid Crystals at the Liquid-Vacuum Interface : [C12mim][BF4] and 4-Cyano-4′-Octylbiphenyl (8CB)

Author

Purcell, Simon M., Tesa-Serrate, Maria A., Marshall, Brooks C., Bruce, Duncan W., D'Andrea, Lucía, Costen, Matthew L., Slattery, John M., Smoll, Eric J., Minton, Timothy K., and McKendrick, Kenneth G.

Abstract

Two complementary approaches were used to study the liquid-vacuum interface of the liquid-crystalline ionic liquid 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C12mim][BF4]) in the smectic A (SmA) and isotropic phases. O atoms with two distinct incident translational energies were scattered from the surface of [C12mim][BF4]. Angle-dependent time-of-flight distributions and OH yields, respectively, were recorded from high- and low-energy O atoms. There were no significant changes in the measurements using either approach, nor the properties derived from them, accompanying the transition from the SmA to the isotropic phase. This indicates that the surface structure of [C12mim][BF4] remains essentially unchanged across the phase boundary, implying that the bulk order and surface structure are not strongly correlated for this material. This effect is ascribed to the strong propensity for the outer surfaces of ionic liquids to be dominated by alkyl chains, over an underlying layer rich in anions and cation head groups, whether or not the bulk material is a liquid crystal. In a comparative study, the OH yield from the surface of the liquid crystal, 8CB, was found to be affected by the bulk order, showing a surprising step increase at the SmA-nematic transition temperature, whose origin is the subject of speculation.

Published
2016

75. Mesomorphism and Photophysics of Some Metallomesogens Based on Hexasubstituted 2,2':6', 2'-Terpyridines : 6', 2'-Terpyridines

Author

Kumar, N. S Saleesh, Shafikov, Marsel Z., Whitwood, Adrian C., Donnio, Bertrand, Karadakov, Peter B., Kozhevnikov, Valery N., and Bruce, Duncan W.

Abstract

The luminescent and mesomorphic properties of a series of metal complexes based on hexacatenar 2,2':6',2''-terpyridines are investigated using experimental methods and density functional theory (DFT). Two types of ligand are examined, namely 5,5''-di(3,4,5-trialkoxyphenyl)terpyridine with or without a fused cyclopentene ring on each pyridine and their complexes were prepared with the following transition metals: ZnII, CoIII, RhIII, IrIII, EuIII and DyIII. The exact geometry of some of these complexes was determined by single X-ray diffraction. All complexes with long alkyl chains were found to be liquid crystalline, which property was induced on complexation. The liquid-crystalline behaviour of the complexes was studied by polarising optical microscopy and small-angle X-ray diffraction. Some of the transition metal complexes (for example, those with ZnII and IrIII) are luminescent in solution, the solid state and the mesophase; their photophysical properties were studied both experimentally and using DFT methods (M06-2X and B3LYP).

Published
2016

76. Blue and Green Phosphorescent Liquid-Crystalline Iridium Complexes with High Hole Mobility

Author

Wang, Yafei, Cabry, Christopher P., Xiao, ManJun, Male, Louise, Cowling, Stephen J., Bruce, Duncan W., Shi, Junwei, Zhu, Weiguo, and Baranoff, Etienne

Abstract

Blue- and green-emitting cyclometalated liquid-crystalline iridium complexes are realized by using a modular strategy based on strongly mesogenic groups attached to an acetylacetonate ancillary ligand. The cyclometalated ligand dictates the photophysical properties of the materials, which are identical to those of the parent complexes. High hole mobilities, up to 0.004 cm2 V-1 s-1, were achieved after thermal annealing, while amorphous materials show hole mobilities of only approximately 10-7-10-6 cm2 V-1 s-1, similar to simple iridium complexes. The design strategy allows the facile preparation of phosphorescent liquid-crystalline complexes with fine-tuned photophysical properties.

Published
2016

78. Nanosegregation and Structuring in the Bulk and at the Surface of Ionic-Liquid Mixtures

Author

Bruce, Duncan W., primary, Cabry, Christopher P., additional, Canongia Lopes, José N., additional, Costen, Matthew L., additional, D’Andrea, Lucía, additional, Grillo, Isabelle, additional, Marshall, Brooks C., additional, McKendrick, Kenneth G., additional, Minton, Timothy K., additional, Purcell, Simon M., additional, Rogers, Sarah, additional, Slattery, John M., additional, Shimizu, Karina, additional, Smoll, Eric, additional, and Tesa-Serrate, María A., additional

Published
2017
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81. A generalized model for the molecular arrangement in the columnar mesophases of polycatenar mesogens. Crystal and molecular structure of two hexacatenar mesogens

Author

Donnio, Bertrand, Heinrich, Benoit, Allouchi, Hassan, Kain, Jens, Diele, Siegmar, Bruce, Duncan W., and Guillon, Daniel

Subjects
Palladium -- Chemical properties, Palladium -- Electric properties, X-rays -- Diffraction, X-rays -- Research, Chemistry
Abstract

The columnar mesophases of two series of hexacatenar palladium(II) mesogens are studied in detail by a combination of X-ray diffraction on aligned and unaligned samples and dilatometry. A model is proposed that differs from that generally accepted for the arrangement of polycatenar mesogens in columnar phases.

Published
2004

82. Halogen bonding: a new interaction for liquid crystal formation

Author

Nguyen, H. Loc, Horter, Peter N., Hursthouse, Michael B., Legon, Anthony C., and Bruce, Duncan W.

Subjects
Chemical reactions -- Research, Liquid crystals -- Research, Chemistry
Abstract

The hydrogen bond is referred to as a property attributed to the absence of an inner electron core in the H atom and the consequent ability of this atom to approach closely the neucleophilic center of B. The use of halogen bonding as a directing force in the realization of three dimensional, solid state structures is demonstrated with the interactions between the chemicals.

Published
2004

84. Shape amphiphiles: mixing rods and disks in liquid crystals

Author

Date, Richard W. and Bruce, Duncan W.

Subjects
Surface active agents -- Research, Liquid crystals -- Research, Chemistry
Abstract

A study is conducted to show that rods and disks can be mixed using a shape amphiphile. The amphiphile can either act as a surfactant leading to the formation of a dispersion or act as a cosolvent leading to statistical mixing of the components.

Published
2003

86. Unexpected, photochemically induced activation of the tetrabutylammonium cation by hexachloroplatinate(iv).

Author

Sethi, Navpreet K., Chechik, Victor, Whitwood, Adrian C., Bruce, Duncan W., Silalahi, Imelda H., and Shafikov, Marsel Z.

Subjects
BUTADIENE, PHOTOLYSIS (Chemistry), CATIONS
Abstract

A dinuclear, butadiene-bridged complex, trans-μ2:η2,η2-1,3-butadiene-bis(trichloroplatinate(ii)) (1) was unexpectedly obtained on photolysis of acetone solutions of (NBu4)2[PtCl6]. [ABSTRACT FROM AUTHOR]

Published
2018
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87. Oxidation of Organoplatinum(II) by Coordinated Dimethylsulfoxide: Metal−Metal Bonded, Dinuclear, Liquid-Crystalline Complexes of Platinum(III)

Author

Santoro, Amedeo, Wegrzyn, Marcin, Whitwood, Adrian C., Donnio, Bertrand, and Bruce, Duncan W.

Abstract

Reaction of [PtCl2(dmso)2] with 2,5-(dialkoxyphenyl)pyridine in HOAc leads to a dinuclear, acetate-bridged, metal−metal bonded complex of platinum(III); dmso in the presence of acid is found to be responsible for the oxidation. The dimer is analogous structurally to PdIIIdimers implicated in catalytic acetoxylation. Platinum dimers with longer alkoxy chains are shown to be unique examples of liquid crystals of platinum(III).

Published
2024
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88. Experimental and Theoretical Study of Halogen-Bonded Complexes of DMAP with Di- and Triiodofluorobenzenes. A Complex with a Very Short N···I Halogen Bond

Author

Roper, Laila C., Präsang, Carsten, Kozhevnikov, Valery N., Whitwood, Adrian C., Karadakov, Peter B., and Bruce, Duncan W.

Abstract

X-ray single crystal structures are reported for 2:1 halogen-bonded complexes of 4-(N,N-dimethylamino)pyridine (DMAP) with 1,4- and 1,3-diiodotetrafluorobenzene and 1,3-diiodo-4,5,6-trifluorobenzene and for a 3:1 complex of DMAP with 1,3,5-triiodotrifluorobenzene. The complex between DMAP and 1,4-diiodotetrafluorobenzene shows the shortest halogen bond recorded for fluorinated iodoarenes. Model systems based on complexes between the same iodofluorobenzenes and ammonia are investigated by Hartree−Fock and DFT calculations to gain insights into the features of halogen bonding in di- and triiodo systems. The calculations reveal a weak charge-transfer component to the halogen bond and account for the lengthening of the C−I bond on complexation in terms of the C−I antibonding character observed within the localized molecular orbital describing the N···I bond.

Published
2024
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91. Reactive-Atom Scattering from Liquid Crystals at the Liquid–Vacuum Interface: [C12mim][BF4] and 4-Cyano-4′-Octylbiphenyl (8CB)

Author

Purcell, Simon M., primary, Tesa-Serrate, Maria A., additional, Marshall, Brooks C., additional, Bruce, Duncan W., additional, D’Andrea, Lucía, additional, Costen, Matthew L., additional, Slattery, John M., additional, Smoll, Eric J., additional, Minton, Timothy K., additional, and McKendrick, Kenneth G., additional

Published
2016
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98. Platinum-based metallomesogens bearing a Pt(4,6-dfppy)(acac) skeleton: synthesis, photophysical properties and polarised phosphorescence application.

Author

Xuefeng Yang, Xiugang Wu, Di Zhou, Junting Yu, Guohua Xie, Bruce, Duncan W., and Yafei Wang

Subjects
METALLOMESOGENS, PLATINUM compounds, PHOSPHORESCENCE, POLARIZATION (Electricity), LIQUID crystal displays, BIPHENYL compounds
Abstract

Polarised phosphorescence has a bright future in backlighting for conventional liquid crystal displays due to its theoretical 100% internal quantum efficiency and low cost. However, there are scarce reports on polarised phosphorescence from metallomesogens. In this contribution, a platinum-based metallomesogen containing a mesogenic biphenyl (Pt1) was prepared and characterised. To further explore the effect of the substituent on mesophase and emission properties, a related complex Pt2 containing a tetraphenylethene (TPE) moiety was also synthesised. Both complexes melt at elevated temperatures but thereafter do not appear to crystallise on cooling. Complex Pt1 shows an enantiotropic nematic phase from which a broad emission can be seen when spread as a film; in solution, an intense, sky-blue emission is observed. For Pt2, which shows a monotropic SmA phase, the emission in the condensed phase is suppressed and there is only weak emission in solution. Polarisation-dependent photoluminescence with a polarised ratio of 5.4 was obtained for the aligned film of a Pt1:polyimide mixture. Using Pt1 as an emissive layer, nondoped, polarised organic light-emitting diodes presented a broad emission spectrum in the range of 450-900 nm with a polarised ratio of 1.33 and the highest external quantum efficiency of 1.1%. This research has an important significance for achieving broad-based polarised phosphorescence from platinum complex-based metallomesogens. [ABSTRACT FROM AUTHOR]

Published
2018
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