Self-organisation through size-exclusion in soft materials

Mandle, Richard J.; Davis, Edward J.; Voll, Constantin-Christian A.; Lewis, Daniel; Cowling, Stephen J.; Goodby, John W.

doi:10.1039/c4tc02991g

Cited by 57 publications

(88 citation statements)

References 38 publications

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“…Qutemol was used to visualise output files of selected conformers [38]. The small-angle X-ray scattering (SAXS) setup used is described elsewhere [39]. Compound 7 (CBO5OCB) was prepared as described by Emsley et al [40].…”

Section: Methodsmentioning

confidence: 99%

Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases

et al. 2017

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The twist-bend phase (N TB ) is most commonly observed in materials with a gross-bent shape: dimers; bent-cores; bent-oligomers. We had suggested previously that the bend-angle of such systems effectively dictates the relative thermal stability of the N TB phase. However, our earlier paper relied on the use of a single energy-minimum conformer and so failed to capture any information about flexibility and conformational distribution. In the present work, we revisit our hypothesis and examine a second set of dimers with varying linking groups and spacer composition. We have improved on our earlier work by studying the conformational landscape of each material, allowing average bend-angles to be determined as well as the conformer distribution. We observe that the stability of the N TB phase exhibits a strong dependence not only on the Boltzmann-weighted average bend-angle (rather than just a static conformer), but also on the distribution of conformers. To a lesser extent, the flexibility of the spacer appears important. Ultimately, this work satisfies both theoretical treatments and our initial experimental study and demonstrates the importance of molecular bend to the N TB phase. ARTICLE HISTORY

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Section: Methodsmentioning

confidence: 99%

Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases

et al. 2017

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“…In 31 this phase, formed by achiral molecules, the director exhibits 32 periodic twist and bend deformations forming a conical helix 33 having doubly degenerate domains of opposite handedness. 34 Although initially described for dimers of the CBnCB family, 35 the discovery of a low temperature nematic phase boosted 36 research in the area, and a number of materials combining 37 different mesogenic units linked by chains have been identified 38 which exhibit the N TB phase [16][17][18] and its chiral counterpart 39 [19,20]. It is now recognized that molecular curvature plays 40 a crucial role in stabilizing the twist-bend nematic phase.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics of a binary mixture of twist-bend nematic liquid crystal dimers studied by dielectric spectroscopy

et al. 2016

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“…We next turned our attention to incorporating ether linkages, as well as either alkyne or methylene linkers, into tetramesogenic materials with a view to obtaining further examples of oligomeric twist-bend materials. The two hydroxyl-terminated alkoxycyanobiphenyls (i1 and i2) used in Scheme 2 were prepared as described previously [58], and the preparation of 1,9-bis(4-bromophenyl)nona-1,8-diyne (i6) was reported in a previous publication [40]. Palladium on carbon (5%) poisoned with diaminoethane (denoted as Pd/C{En} in the text) was prepared by us previously [40,66].…”

Section: Resultsmentioning

confidence: 99%

“…The experimental set-up used for X-ray scattering experiments has been described previously [58,59]. Details of chemical synthesis and characterisation are given in the supplementary information to this article.…”

Section: Methodsmentioning

confidence: 99%

Developments in liquid-crystalline dimers and oligomers

2017

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Liquid-crystalline dimers and bimesogens have attracted much attention due to their propensity to exhibit the spontaneously chiral twist-bend mesophase (N TB ), most often by dimers with methylene spacers. Despite their relative ease of synthesis, the number of ether-linked twistbend materials significantly lags behind those of methylene-linked compounds. In this work, we have prepared and studied a range of ether-linked bimesogens homologous in structure to the FFO9OCB; as with methylene-linked systems, it appears that it is molecular topology and the gross molecular shape that are the primary drivers for the formation of this phase of matter. Dimers and bimesogens are well studied within the context of the twist-bend phase; however, present understanding of this mesophase in oligomeric systems lags far behind. We report our recent efforts to prepare further examples of oligomeric twist-bend nematogens, including further examples of our 'n+1' methodology, which may allow the synthesis of high-purity, monodisperse materials of any given length to be prepared. We have observed that there is a tendency for these materials to exhibit highly ordered soft-crystalline mesophases as opposed to the twist-bend phase.ARTICLE HISTORY

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Self-organisation through size-exclusion in soft materials

Abstract: Can the interplay between steric and electronic properties induced by end-groups be used to dictate self-organisation in soft materials?

Cited by 57 publications

References 38 publications

Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases

Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases

Molecular dynamics of a binary mixture of twist-bend nematic liquid crystal dimers studied by dielectric spectroscopy

Developments in liquid-crystalline dimers and oligomers

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