Duncan Bruce
University of York, Chemistry, Faculty Member
A series of five crystal structures of 1 : 1 halogen-bonded complexes were obtained from 4-[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]pyridine and 1,3,5-trifluorotriiodobenzene. Electronic structure calculations show that the N... more
A series of five crystal structures of 1 : 1 halogen-bonded complexes were obtained from 4-[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]pyridine and 1,3,5-trifluorotriiodobenzene. Electronic structure calculations show that the N (oxadiazole) ⋯I interaction in the new synthon is as strong as the classic N (pyridine) ⋯I interaction. Oxygen to sulfur atom subsitution on the oxadiazole ring results in a different supramolecular packing where the N (pyridine) ⋯I interaction is favored, which could be rationalized by the changes in the molecular electrostatic potential predicted from the theoretical calculations.
Research Interests:
Rare-earth-containing metallomesogens with 4-alkoxy-N-alkyl-2-hydroxybenzaldimine ligands are reported. The stoichiometry of the complexes is (Ln(LH)3(NO3)3), where Ln is the trivalent rare-earth ion (Y, La, and Pr to Lu, except Pm) and... more
Rare-earth-containing metallomesogens with 4-alkoxy-N-alkyl-2-hydroxybenzaldimine ligands are reported. The stoichiometry of the complexes is (Ln(LH)3(NO3)3), where Ln is the trivalent rare-earth ion (Y, La, and Pr to Lu, except Pm) and LH is the Schiff base. The Schiff base ligands are in the zwitterionic form and coordinate through the phenolic oxygen only. The three nitrate groups coordinate in a bidentate fashion.
Research Interests:
Surfactant Ru(II) complexes have been used to template mesoporous silicates using the true liquid crystal templating method, giving evenly dispersed, nanometer-sized ruthenium particles which show very high catalytic activity and... more
Surfactant Ru(II) complexes have been used to template mesoporous silicates using the true liquid crystal templating method, giving evenly dispersed, nanometer-sized ruthenium particles which show very high catalytic activity and selectivity in the hydrogenation of 1-hexene.
Research Interests:
This chapter discusses the relatively new discovery of liquid crystallinity induced by halogen bonding. Liquid crystals are first introduced and then, to give the work some context, background information is given concerning liquid... more
This chapter discusses the relatively new discovery of liquid crystallinity induced by halogen bonding. Liquid crystals are first introduced and then, to give the work some context, background information is given concerning liquid crystal phases induced by other, non-covalent interactions. In particular, hydrogen bonding is examined, as the two interactions are rather similar as are the molecular components that might
Research Interests:
A low temperature sample orientation device providing three axes of rotation has been successfully built and is in testing for use on several spectrometers at the spallation neutron source (SNS). Sample rotation about the vertical (omega)... more
A low temperature sample orientation device providing three axes of rotation has been successfully built and is in testing for use on several spectrometers at the spallation neutron source (SNS). Sample rotation about the vertical (omega) axis of nearly 360° and out of plane tilts (phi and v) of from -3.4° to 4.4° and from -2.8° to 3.5°, respectively, are
Research Interests:
Two columnar phases of bent-core molecules have been observed, with a two-dimensional (2D) structure modulated in the plane perpendicular to the direction of the spontaneous polarization vector. The phases are switchable under an applied... more
Two columnar phases of bent-core molecules have been observed, with a two-dimensional (2D) structure modulated in the plane perpendicular to the direction of the spontaneous polarization vector. The phases are switchable under an applied electric field, contrary to the commonly observed 2D modulated B1 phase. These new phases are built from broken smectic layers with orthogonal or tilted molecules. The
Research Interests:
Metal-containing liquid crystals have been intensively studied in recent years [l]. The inclusion of a metal atom in a mesogenic molecule provides one way of changing the properties of liquid crystals for particular require-ments. For... more
Metal-containing liquid crystals have been intensively studied in recent years [l]. The inclusion of a metal atom in a mesogenic molecule provides one way of changing the properties of liquid crystals for particular require-ments. For example, the creation of liquid crystals with a ...
Research Interests:
Mixtures of rodlike and disklike liquid crystals suffer from phase separation. However, such mixtures can be homogenized if a molecule is added which comprises a rod- and a disklike fragment linked together covalently. We have termed such... more
Mixtures of rodlike and disklike liquid crystals suffer from phase separation. However, such mixtures can be homogenized if a molecule is added which comprises a rod- and a disklike fragment linked together covalently. We have termed such a molecule a shape amphiphile and believe that this represents a new class of amphiphilicity.
Research Interests:
Richard Date was born in 1963 and studied Chemistry with Physics at the University of Southampton. After completing an M.Sc. in spectroscopy from the University of East Anglia he then studied for a Ph.D. in the synthesis of thermotropic... more
Richard Date was born in 1963 and studied Chemistry with Physics at the University of Southampton. After completing an M.Sc. in spectroscopy from the University of East Anglia he then studied for a Ph.D. in the synthesis of thermotropic liquid crystals in the research ...
Research Interests:
Research Interests:
Aryl-and alkyl-substituted tertiary phosphines are among the most common ligands used in homogeneous catalysts, but they are hydrophobic, as in general are the products of the catalysis. Therefore, there are two basic problems in... more
Aryl-and alkyl-substituted tertiary phosphines are among the most common ligands used in homogeneous catalysts, but they are hydrophobic, as in general are the products of the catalysis. Therefore, there are two basic problems in homogeneous catalysis, namely the ...
Research Interests:
The study of metallomesogens has added several new dimensions to the wider field of liquid crystals. In this Account, just one family of complexes is considered, namely alkoxystilbazole complexes of various silver(I) salts. These... more
The study of metallomesogens has added several new dimensions to the wider field of liquid crystals. In this Account, just one family of complexes is considered, namely alkoxystilbazole complexes of various silver(I) salts. These complexes show an incredibly rich and diverse mesomorphism ranging from nematic and smectic to columnar phases; in particular, many complexes show the still rare thermotropic cubic phase. Through systematic structural variations, it has been possible to gain a good understanding of the factors influencing the behavior of these fascinating systems.
Research Interests:
The rst mesogens showing a cubic phase were the nitrobiphenyl carboxylic acids synthesized by Gray in the 1950s [1], and for many years after this the cubic phase remained a rare curiosity, at least in the eld of thermotropic mesogens.... more
The rst mesogens showing a cubic phase were the nitrobiphenyl carboxylic acids synthesized by Gray in the 1950s [1], and for many years after this the cubic phase remained a rare curiosity, at least in the eld of thermotropic mesogens. More recently, the phase has ...
Research Interests:
Research Interests:
... Duncan W. Bruce,* David A. Dunmur, Lourdes S. Santa and Michael A. Wali Department of Chemistry, The University, Sheffield S3 7HF, UK 363 ... Gaspard et aL4 then reported some mono-meso-substituted porphyrins and some 5,15 -... more
... Duncan W. Bruce,* David A. Dunmur, Lourdes S. Santa and Michael A. Wali Department of Chemistry, The University, Sheffield S3 7HF, UK 363 ... Gaspard et aL4 then reported some mono-meso-substituted porphyrins and some 5,15 - bis(4-alkoxyphenyl)-2,3,7,8,12,13,17,18 ...
Research Interests:
Abstract The synthesis of a new series of heterocyclic mesogens, the trans-4-alkyloxy-4'-stilbazoles (CnH2n+ 1OC6H4CH= CHC5H4N), is described and the phase behaviour is reported for all homologues between methyloxy (C1) and... more
Abstract The synthesis of a new series of heterocyclic mesogens, the trans-4-alkyloxy-4'-stilbazoles (CnH2n+ 1OC6H4CH= CHC5H4N), is described and the phase behaviour is reported for all homologues between methyloxy (C1) and dodecyloxy (C12). For n< 3, the ...
Research Interests:
... DANIEL GUILLON*, BENOfT HEINRICH IPCMS, Groupe des Materiaux Organiques, 23 rue du Loess, BP 20 (CR), 67037 Strasbourg ... chemical composition was determined by ele-mental analysis (table 2), vapour pressure osmometry measurements... more
... DANIEL GUILLON*, BENOfT HEINRICH IPCMS, Groupe des Materiaux Organiques, 23 rue du Loess, BP 20 (CR), 67037 Strasbourg ... chemical composition was determined by ele-mental analysis (table 2), vapour pressure osmometry measurements (Eu complex), magnetic ...
Research Interests:
Research Interests:
Research Interests:
... A. Esteruelas,b Susan E. Hunt," Ronan Le Lagadec," Peter M. Maitlis," Julian R. Marsden/ Eduardo Solab and John M.... more
... A. Esteruelas,b Susan E. Hunt," Ronan Le Lagadec," Peter M. Maitlis," Julian R. Marsden/ Eduardo Solab and John M. Stacey" a Department of ... We thank Professors Jose-Luis Serrano and Luis Oro (Insti-tuto de Ciencias de Materiales de Aragon) for useful dis-cussions and Dr ...
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Page 1. JOURNAL OF CHEMISTRY Materials Reduction of the transition temperatures in mesomorphic lanthanide complexes by the exchange of counter-ions Koen Binnemans,a Yury G. Galyametdinov,b Simon R. Collinsonc ...
Research Interests:
Research Interests:
Metallomesogens are metal complexes which exhibit liquid-crystalline properties, forming the same type of mesophases as found in purely organic materials. Indeed, nematic, smectic and columnar mesophases have all been observed, as well... more
Metallomesogens are metal complexes which exhibit liquid-crystalline properties, forming the same type of mesophases as found in purely organic materials. Indeed, nematic, smectic and columnar mesophases have all been observed, as well as, in a few cases, the more elusive cubic mesophases. The complexes may have a covalent (neutral) or an ionic character, and a large number of low molar
Research Interests:
The mesomorphism of various series of polycatenar metallomesogens is described and, by considering various structure/mesomorphism arguments, a model is proposed to rationalise cubic phase formation in calamitic and polycatenar mesogens.
Research Interests:
ABSTRACT
Research Interests:
The optimized geometries and corresponding binding energies of complexes between fluorohalides, FX (X = Cl, Br, and I), and isocyanides, CNY (Y = CN, NC, NO(2), F, CF(3), Cl, Br, H, CCF, CCH, CH(3), SiH(3), Li, and Na), were calculated at... more
The optimized geometries and corresponding binding energies of complexes between fluorohalides, FX (X = Cl, Br, and I), and isocyanides, CNY (Y = CN, NC, NO(2), F, CF(3), Cl, Br, H, CCF, CCH, CH(3), SiH(3), Li, and Na), were calculated at the MP2(Full)/aug-cc-pVTZ (aug-cc-pVTZ-PP on I) level of theory, without and with basis set superposition error (BSSE) corrections through the counterpoise (CP) method. The optimized complex geometries were analyzed through the Steiner-Limbach relationship, which can be used to establish correlations between the F-X and X-C bond lengths. For all complexes, the correlations were shown to improve considerably when using optimized geometries including BSSE corrections. It was shown that further improvements can be achieved through the introduction of an extended four-parameter form of the Steiner-Limbach relationship which accounts for all differences between the valences associated with the two bonds involving the halogen in an A-X···B complex. The results indicate that chlorine as a halogen bond donor is affected by the basicity of the isocyanides and forms different types of halogen bonds as the F-Cl bond lengthens in parallel with the shortening of the distance between Cl and the isocyanide carbon. This is not observed for iodine and bromine as halogen-bond donors, which is illustrated by the low levels of correlation obtained when applying the standard and extended Steiner-Limbach relationships to the corresponding complexes.
Research Interests:
ABSTRACT A series of 16 symmetric, dimeric, dicationic liquid-crystalline ionic liquids with mesogenic 3,4,5-tris(alkyloxy)benzyl moieties tethered to two bridged imidazolium cations were designed and synthesised. As a comparison, 12... more
ABSTRACT A series of 16 symmetric, dimeric, dicationic liquid-crystalline ionic liquids with mesogenic 3,4,5-tris(alkyloxy)benzyl moieties tethered to two bridged imidazolium cations were designed and synthesised. As a comparison, 12 monocationic imidazolium liquid crystals with the same mesogens were also prepared. The mesomorphic properties of these ionic liquids were characterised in terms of polarised optical microscopy (POM) and differential scanning calorimetry (DSC), while thermal stabilities were obtained by thermogravimetric analysis (TGA). All compounds having chloride (Cl−) and tetrafluoroborate (BF4−) anions exhibit hexagonal columnar (Colh) liquid crystal mesophases, with the dimeric materials showing mesophases over an extended temperature range. The effect of the linking chain, alkyl substituents, and anion type on the thermal properties of these dimers was examined and showed a significant influence. For example, Colh mesophases were only observed for ionic liquids having Cl− and BF4− anions, whereas systems with the bis(trifluoromethylsulfonyl)imide (Tf2N−) anion melted directly to an isotropic liquid. A shorter spacer paired with longer alkoxy chains tends to give rise to broad-temperature-range Colh ionic liquid crystal phases.
Research Interests:
The interaction between rare gas atoms and trifluoromethylhalides and iodomethane is investigated using ab initio and density functional theory (DFT) methods: MP2, CCSD, B3LYP, M06, M06-L, M06-2X, M06-HF, X3LYP, PBE, B97-D, B3LYP-D3, and... more
The interaction between rare gas atoms and trifluoromethylhalides and iodomethane is investigated using ab initio and density functional theory (DFT) methods: MP2, CCSD, B3LYP, M06, M06-L, M06-2X, M06-HF, X3LYP, PBE, B97-D, B3LYP-D3, and M06-L-D3, in combination with the aug-cc-pVTZ and aug-cc-pVTZ-PP basis sets. A weakly attractive interaction is observed for all complexes, whose strength increases as the rare gas and halogen bond donor become more polarizable, and as the group bound to the halogen bond donor becomes more electron-withdrawing. The separation between iodine and krypton in the complex CF(3)I···Kr, calculated at the MP2 and B3LYP-D3 levels of theory, agrees very well with recent experimental results (Stephens, S. L.; Walker, N. R.; Legon, A. C. J. Chem. Phys. 2011, 135, 224309). Analysis of the ability of theoretical methods to account for the dispersion interaction present in these complexes leads to the conclusion that MP2 and B3LYP-D3, which produce very similar results, are the better performing methods, followed by B97-D and the M06 suite of functionals; the popular B3LYP as well as X3LYP perform poorly and significantly underestimate the interaction strength. The orbitals responsible for the interaction are identified through Edmiston-Ruedenberg localization; it is shown that, by combining the key orbitals, it is possible to observe a molecular orbital picture of a σ-hole interaction.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT A graphical abstract is available for this content