All Outputs (13)

Dipole-dipole correlations in the nematic phases of symmetric cyanobiphenyl dimers and their binary mixtures with 5CB (2023)
Journal Article
Zavvou, E. E., Ramou, E., Ahmed, Z., Welch, C., Mehl, G. H., Vanakaras, A. G., & Karahaliou, P. K. (2023). Dipole-dipole correlations in the nematic phases of symmetric cyanobiphenyl dimers and their binary mixtures with 5CB. Soft matter, 19(47), 9224-9238. https://doi.org/10.1039/d3sm01017a

We report on the temperature dependence of birefringence and of the static dielectric permittivity tensor in a series of binary mixtures between the symmetric, bent-shaped, 1′′,9′′-bis(4-cyanobiphenyl-4′-yl)nonane (CB9CB) dimer and the monomeric nema... Read More about Dipole-dipole correlations in the nematic phases of symmetric cyanobiphenyl dimers and their binary mixtures with 5CB.

Electrochemically Induced Mesomorphism Switching in a Chlorpromazine Hydrochloride Lyotropic Liquid Crystal (2021)
Journal Article
Crapnell, R. D., Alhasan, H. S., Partington, L. I., Zhou, Y., Ahmed, Z., Altalhi, A. A., Varley, T. S., Alahmadi, N., Mehl, G. H., Kelly, S. M., Lawrence, N. S., Marken, F., & Wadhawan, J. D. (2021). Electrochemically Induced Mesomorphism Switching in a Chlorpromazine Hydrochloride Lyotropic Liquid Crystal. ACS Omega, 6(7), 4630-4640. https://doi.org/10.1021/acsomega.0c05284

The discovery of electrochemical switching of the Lα phase of chlorpromazine hydrochloride in water is reported. The phase is characterized using polarizing microscopy, X-ray scattering, rheological measurements, and microelectrode voltammetry. Fast,... Read More about Electrochemically Induced Mesomorphism Switching in a Chlorpromazine Hydrochloride Lyotropic Liquid Crystal.

Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes (2020)
Journal Article
Heist, L. M., Samulski, E. T., Welch, C., Ahmed, Z., Mehl, G. H., Vanakaras, A. G., & Photinos, D. J. (2020). Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes. Liquid crystals, 1-16. https://doi.org/10.1080/02678292.2019.1711214

The quadrupolar splittings of perdeuteriated n-decane dissolved in nematic phases formed by mesogenic dimers of the CBnCB series, for n = 7,9,10,11, are measured throughout the entire temperature range of these phases. These results are reported toge... Read More about Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes.

Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers (2019)
Journal Article
Merkel, K., Welch, C., Ahmed, Z., Piecek, W., & Mehl, G. H. (2019). Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers. The Journal of chemical physics, 151(11), 114908. https://doi.org/10.1063/1.5114824

Wide band dielectric spectroscopy of bent-shaped achiral liquid-crystal dimers 1′′-n′′-bis(4-cyanobiphenyl-4′-yl) n-alkanes (CBnCB n = 7, 9, 11) has been investigated in a frequency range 0.1 Hz–100 MHz using planar-aligned cells of sample thicknesse... Read More about Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers.

The induction of the Ntb phase in mixtures (2018)
Journal Article
Ramou, E., Welch, C., Hussey, J., Ahmed, Z., Karahaliou, P. K., & Mehl, G. H. (2018). The induction of the Ntb phase in mixtures. Liquid crystals, 45(13-15), 1929-1935. https://doi.org/10.1080/02678292.2018.1524523

We report the induction of the Ntb phase over a wide temperature and concentration range in a binary system. This was achieved by addition of a flexible dopant without LC properties to a flexible dimer exhibiting only a nematic LC phase. The Ntb phas... Read More about The induction of the Ntb phase in mixtures.

Supramolecular organization of liquid-crystal dimers-bis-cyanobiphenyl alkanes on HOPG by scanning tunneling microscopy (2018)
Journal Article
Krzyzewska, K., Jaroch, T., Maranda-Niedbała, A., Pociecha, D., Górecka, E., Ahmed, Z., Welch, C., Mehl, G. H., Proń, A., & Nowakowski, R. (2018). Supramolecular organization of liquid-crystal dimers-bis-cyanobiphenyl alkanes on HOPG by scanning tunneling microscopy. Nanoscale, 10(34), 16201-16210. https://doi.org/10.1039/c8nr02069h

2D supramolecular organization of a series of six cyanobiphenyl bimesogens deposited on highly oriented pyrolytic graphite (HOPG) is studied by scanning tunneling microscopy (STM). The adsorbates
are 1,ω-bis(4-cyanobiphenyl-4’-yl)alkanes (CBnCB) with... Read More about Supramolecular organization of liquid-crystal dimers-bis-cyanobiphenyl alkanes on HOPG by scanning tunneling microscopy.

Molecular organization in the twist–bend nematic phase by resonant X-ray scattering at the Se K-edge and by SAXS, WAXS and GIXRD (2017)
Journal Article
Stevenson, W. D., Ahmed, Z., Zeng, X. B., Welch, C., Ungar, G., & Mehl, G. H. (2017). Molecular organization in the twist–bend nematic phase by resonant X-ray scattering at the Se K-edge and by SAXS, WAXS and GIXRD. Physical chemistry chemical physics : PCCP, 19(21), 13449-13454. https://doi.org/10.1039/c7cp01404j

© the Owner Societies 2017. Using a magnetically aligned liquid crystal mixture containing a novel Se-labelled dimer and the difluoroterphenyl dimer DTC5C7, the twist-bend nematic phase (N tb ) was studied by the resonant scattering of hard X-rays an... Read More about Molecular organization in the twist–bend nematic phase by resonant X-ray scattering at the Se K-edge and by SAXS, WAXS and GIXRD.

Light scattering study of the “pseudo-layer” compression elastic constant in a twist-bend nematic liquid crystal (2016)
Journal Article
Parsouzi, Z., Pardaev, S. A., Welch, C., Ahmed, Z., Mehl, G. H., Baldwin, A. R., Gleeson, J. T., Lavrentovich, O. D., Allender, D. W., Selinger, J. V., Jákli, A., & Sprunt, S. (2016). Light scattering study of the “pseudo-layer” compression elastic constant in a twist-bend nematic liquid crystal. Physical chemistry chemical physics : PCCP, 18(46), 31645-31652. https://doi.org/10.1039/C6CP06292J

The nematic twist-bend (TB) phase, exhibited by certain achiral thermotropic liquid crystalline (LC) dimers, features a nanometer-scale, heliconical rotation of the average molecular long axis (director) with equally probable left- and right-handed d... Read More about Light scattering study of the “pseudo-layer” compression elastic constant in a twist-bend nematic liquid crystal.

Comparative analysis of anisotropic material properties of uniaxial nematics formed by flexible dimers and rod-like monomers (2016)
Journal Article
Cukrov, G., Mosaddeghian Golestani, Y., Xiang, J., Nastishin, Y. A., Ahmed, Z., Welch, C., Mehl, G. H., & Lavrentovich, O. D. (2017). Comparative analysis of anisotropic material properties of uniaxial nematics formed by flexible dimers and rod-like monomers. Liquid crystals, 44(1), 219-231. https://doi.org/10.1080/02678292.2016.1240248

We report temperature dependencies of material properties such as dielectric anisotropy, birefringence, splay (K₁₁), twist (K₂₂), and bend (K₃₃) elastic constants of the uniaxial nematic (N) phase formed by flexible dimers of DTC5C9 and compare their... Read More about Comparative analysis of anisotropic material properties of uniaxial nematics formed by flexible dimers and rod-like monomers.

Deuteron and proton NMR study of D₂, p-dichlorobenzene and 1,3,5-trichlorobenzene in bimesogenic liquid crystals with two nematic phases (2016)
Journal Article
Burnell, E. E., Ahmed, Z., Welch, C., Mehl, G. H., & Dong, R. Y. (2016). Deuteron and proton NMR study of D₂, p-dichlorobenzene and 1,3,5-trichlorobenzene in bimesogenic liquid crystals with two nematic phases. Chemical Physics Letters, 659, 48-54. https://doi.org/10.1016/j.cplett.2016.07.005

The solutes dideuterium, 1,3,5-trichlorobenzene and p-dichlorobenzene (pdcb) are co-dissolved in a 61/39 wt% mixture of CBC9CB/5CB, a bimesogenic liquid crystal with two nematic phases. NMR spectra are collected for each solute. The local electric fi... Read More about Deuteron and proton NMR study of D₂, p-dichlorobenzene and 1,3,5-trichlorobenzene in bimesogenic liquid crystals with two nematic phases.

Mesophase structure and behaviour in bulk and restricted geometry of a dimeric compound exhibiting a nematic-nematic transition (2016)
Journal Article
Sebastián, N., Tamba, M. G., Stannarius, R., de la Fuente, M. R., Salamonczyk, M., Cukrov, G., Gleeson, J., Sprunt, S., Jákli, A., Welch, C., Ahmed, Z., Mehl, G. H., & Eremin, A. (2016). Mesophase structure and behaviour in bulk and restricted geometry of a dimeric compound exhibiting a nematic-nematic transition. Physical chemistry chemical physics : PCCP, 18(28), 19299-19308. https://doi.org/10.1039/c6cp03899a

We present structural studies of a dimeric compound composed of a central heptyl spacer linking two mesogens consisiting of terphenyl units at which two adjacent fluoro groups are attached to each central ring. The terminal rings are linked to pentyl... Read More about Mesophase structure and behaviour in bulk and restricted geometry of a dimeric compound exhibiting a nematic-nematic transition.

The stabilisation of the Nx phase in mixtures (2016)
Journal Article
Ramou, E., Ahmed, Z., Welch, C., Karahaliou, P. K., & Mehl, G. H. (2016). The stabilisation of the Nx phase in mixtures. Soft matter, 12(3), 888-899. https://doi.org/10.1039/c5sm01961c

The phase behaviour of mixtures between two symmetric dimers, CBC9CB and the ether-linked analogue CBOC9OCB was investigated by Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) studies. The dime... Read More about The stabilisation of the Nx phase in mixtures.

The design and investigation of the self-assembly of dimers with two nematic phases (2015)
Journal Article
Ahmed, Z., Welch, C., & Mehl, G. H. (2015). The design and investigation of the self-assembly of dimers with two nematic phases. RSC advances, 5(113), 93513-93521. https://doi.org/10.1039/c5ra18118f

A series of non-symmetric dimers were synthesised containing either cyanobiphenyl or difluoroterphenyl moieties on one side and a range of long, short, bent, polar or apolar mesogens on the other side of the molecules. The dielectric anisotropy of th... Read More about The design and investigation of the self-assembly of dimers with two nematic phases.