Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes

References

• Panov VP, Nagaraj M, Vij JK, et al. Spontaneous periodic deformations in nonchiral planar-aligned bimesogens with a nematic-nematic transition and a negative elastic constant. Phys Rev Lett. 2010;105:167801.
   PubMed Web of Science ®Google Scholar
• Beguin L, Emsley JW, Lelli M, et al. The chirality of a twist–bend nematic phase identified by NMR spectroscopy. J Phys Chem B. 2012;116:7940–7951.
   PubMed Web of Science ®Google Scholar
• Borshch V, Kim Y-K, Xiang J, et al. Nematic twist-bend phase with nanoscale modulation of molecular orientation. Nat Commun. 2013;4:2635.
   PubMed Web of Science ®Google Scholar
• Hoffmann A, Vanakaras AG, Kohlmeier A, et al. On the structure of the Nx phase of symmetric dimers: inferences from NMR. Soft Matter. 2015;11:850–855.
   PubMed Web of Science ®Google Scholar
• Cestari M, Diez-Berart S, Dunmur DA, et al. Phase behavior and properties of the liquid-crystal dimer 1′′,7′′-bis(4-cyanobiphenyl-4′-yl) heptane: A twist-bend nematic liquid crystal. Phys Rev E. 2011;84:031704.
   PubMed Web of Science ®Google Scholar
• Shamid SM, Dhakal S, Selinger JV. Statistical mechanics of bend flexoelectricity and the twist-bend phase in bent-core liquid crystals. Phys Rev E. 2013;87:052503.
   PubMed Web of Science ®Google Scholar
• Zhang Z, Panov VP, Nagaraj M, et al. Raman scattering studies of order parameters in liquid crystalline dimers exhibiting the nematic and twist-bend nematic phases. J Mater Chem C. 2015;3:10007–10016.
   Web of Science ®Google Scholar
• Carvalho J, Cruz C, Figueirinhas JL, et al. Proton and Deuterium NMR study of the CBC9CB dimer system. J Phys Chem B. 2019;123:1442–1451.
   PubMed Web of Science ®Google Scholar
• Sebastián N, Tamba MG, Stannarius R, et al. Mesophase structure and behaviour in bulk and restricted geometry of a dimeric compound exhibiting a nematic–nematic transition. Phys Chem Chem Phys. 2016;18:19299–19308.
   PubMed Web of Science ®Google Scholar
• Sebastián N, Robles-Hernández B, Diez-Berart S, et al. Distinctive dielectric properties of nematic liquid crystal dimers. Liq Cryst. 2017;44:177–190.
   Web of Science ®Google Scholar
• Stevenson WD, Ahmed Z, Zeng XB, et al. Molecular organization in the twist–bend nematic phase by resonant X-ray scattering at the Se K-edge and by SAXS, WAXS and GIXRD. Phys Chem Chem Phys. 2017;19:13449–13454.
   PubMed Web of Science ®Google Scholar
• Stevenson WD, Zou H, Zeng X, et al. Dynamic calorimetry and XRD studies of the nematic and twist-bend nematic phase transitions in a series of dimers with increasing spacer length. Phys Chem Chem Phys. 2018;20:25268–25274.
   PubMed Web of Science ®Google Scholar
• Zhu C, Tuchband MR, Young A, et al. Resonant Carbon K-edge soft X-ray scattering from lattice-free heliconical molecular ordering: soft dilative elasticity of the twist-bend liquid crystal phase. Phys Rev Lett. 2016;116:147803.
   PubMed Web of Science ®Google Scholar
• Imrie CT, Paterson DA, Gao M, et al. Understanding the twist-bend nematic phase: the characterisation of 1-(4-cyanobiphenyl-4ʹ-yloxy)-6-(4-cyanobiphenyl-4ʹ-yl) hexane (CB6OCB) and comparison with CB7CB. Soft Matter. 2016;12:6827–6840.
   PubMed Web of Science ®Google Scholar
• Pająk G, Longa L, Chrzanowska A. Nematic twist–bend phase in an external field. Proc Natl Acad Sci. 2018;115:E10303–E10312.
   PubMed Web of Science ®Google Scholar
• Barbero G, Evangelista LR, Rosseto MP, et al. Elastic continuum theory: towards understanding of the twist-bend nematic phases. Phys Rev E. 2015;92:030501.
   Web of Science ®Google Scholar
• Ramou E, Welch C, Hussey J, et al. The induction of the Ntb phase in mixtures. Liq Cryst. 2018;45:1929–1935.
   Web of Science ®Google Scholar
• Aluculesei A, Cachitas H, Carvalho J, et al. 1H NMR study of molecular order and dynamics in the liquid crystal CB-C9-CB. Phys Chem Chem Phys. 2019; 21:4523–4537.
   PubMed Web of Science ®Google Scholar
• Merkel K, Welch C, Ahmed Z, et al. Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers. J Chem Phys. 2019;151:114908.
   PubMed Web of Science ®Google Scholar
• Mandle RJ, Goodby JW. A novel nematic-like mesophase induced in dimers, trimers and tetramers doped with a high helical twisting power additive. Soft Matter. 2018;14:8846–8852.
   PubMed Web of Science ®Google Scholar
• Mandle RJ, Goodby JW. Does topology dictate the incidence of the twist-bend phase? Insights gained from novel unsymmetrical bimesogens. Chem – Eur J. 2016;22:18456–18464.
   PubMed Web of Science ®Google Scholar
• Jákli A, Lavrentovich OD, Selinger JV. Physics of liquid crystals of bent-shaped molecules. Rev Mod Phys. 2018;90:045004.
   Web of Science ®Google Scholar
• Tschierske C. Mirror symmetry breaking in liquids and liquid crystals. Liq Cryst. 2018;45:2221–2252.
   Web of Science ®Google Scholar
• You R, Park W, Carlson E, et al. Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase. Liq Cryst. 2019;46:316–325.
   Web of Science ®Google Scholar
• Samulski ET, Vanakaras AG, Photinos DJ. The twist bend nematic: a case of mistaken identity. 47;13:2092–2097
   Google Scholar
• Vanakaras AG, Photinos DJ. A molecular theory of nematic–nematic phase transitions in mesogenic dimers. Soft Matter. 2016;12:2208–2220.
   PubMed Web of Science ®Google Scholar
• Vanakaras AG, Photinos DJ. Molecular dynamics simulations of nematic phases formed by cyano-biphenyl dimers. Liq Cryst. 2018;45:2184–2196.
   Web of Science ®Google Scholar
• Kumar A, Vanakaras AG, Photinos DJ. Polar molecular ordering in the NX phase of bimesogens and enantiotopic discrimination in the NMR spectra of rigid prochiral solutes. J Phys Chem B. 2017;121:10689–10703.
   PubMed Web of Science ®Google Scholar
• Luz Z, Poupko R, Samulski ET, et al. and molecular ordering in the cholesteryl alkanoates mesophases. J Chem Phys. 1981;74:5825–5837.
   Web of Science ®Google Scholar
• Czarniecka K, Samulski ET. Polypeptide liquid crystals: a deuterium NMR study. Mol Cryst Liq Cryst. 1981;63:205–214.
   Web of Science ®Google Scholar
• Lesot P, Aroulanda C, Zimmermann H, et al. Enantiotopic discrimination in the NMR spectrum of prochiral solutes in chiral liquid crystals. Chem Soc Rev. 2015;44:2330–2375.
   PubMed Web of Science ®Google Scholar
• Kumar A, Vanakaras AG, Photinos DJ. Molecular interactions in chiral nematic liquid crystals and enantiotopic discrimination through the NMR spectra of prochiral molecules I: rigid solutes. J Phys Chem B. 2016;120:10844–10853.
   PubMed Web of Science ®Google Scholar
• Burnell EE, Ahmed Z, Welch C, et al. Deuteron and proton NMR study of D2, p-dichlorobenzene and 1,3,5-trichlorobenzene in bimesogenic liquid crystals with two nematic phases. Chem Phys Lett. 2016;659:48–54.
   Web of Science ®Google Scholar
• Photinos DJ, Samulski ET, Toriumi H. Alkyl chains in a nematic field. 2. Temperature and chain length dependence of orientational ordering. J Phys Chem. 1990;94:4694–4700.
   Web of Science ®Google Scholar
• Photinos DJ, Poliks BJ, Samulski ET, et al. n-Hexane proton dipolar couplings and the rotational isomeric state approximation. Mol Phys. 1991;72:333–344.
   Web of Science ®Google Scholar
• Photinos DJ, Samulski ET, Toriumi H. Molecular flexibility in nematics: from alkanes to dimer mesogens. J Chem Soc Faraday Trans. 1992;88:1875–1883.
   Google Scholar
• Emsley JW, Lelli M, Lesage A, et al. A comparison of the conformational distributions of the achiral symmetric liquid crystal dimer CB7CB in the achiral nematic and chiral twist-bend nematic phases. J Phys Chem B. 2013;117:6547–6557.
   PubMed Web of Science ®Google Scholar
• Krzyżewska K, Jaroch T, Maranda-Niedbała A, et al. Supramolecular organization of liquid-crystal dimers – bis-cyanobiphenyl alkanes on HOPG by scanning tunneling microscopy. Nanoscale. 2018;10:16201–16210.
   PubMed Web of Science ®Google Scholar
• Archbold CT, Andrews JL, Mandle RJ, et al. Effect of the linking unit on the twist-bend nematic phase in liquid crystal dimers: a comparative study of two homologous series of methylene-and ether-linked dimers. Liq Cryst. 2017;44:84–92.
   Web of Science ®Google Scholar
• Mandle RJ, Davis EJ, Lobato SA, et al. Synthesis and characterisation of an unsymmetrical, ether-linked, fluorinated bimesogen exhibiting a new polymorphism containing the NTB or ‘twist-bend’ phase. Phys Chem Chem Phys. 2014;16:6907–6915.
   PubMed Web of Science ®Google Scholar
• Ramou E, Ahmed Z, Welch C, et al. The stabilisation of the Nx phase in mixtures. Soft Matter. 2016;12:888–899.
   PubMed Web of Science ®Google Scholar
• Photinos DJ, Samulski ET, Toriumi H. Alkyl chains in a nematic field. 1. A treatment of conformer shape. J Phys Chem. 1990;94:4688–4694.
   Web of Science ®Google Scholar
• Greco C, Ferrarini A. Entropy-driven chiral order in a system of achiral bent particles. Phys Rev Lett. 2015;115:147801.
   PubMed Web of Science ®Google Scholar
• Greco C, Ferrarini A, Luckhurst GR, et al. Structural insights into the twist-bend nematic phase from the integration of 2H-NMR data and modelling: CB7CB and CB6OCB as case studies. Liq Cryst. 2018;45:2361–2375
   Web of Science ®Google Scholar
• Salamończyk M, Vaupotič N, Pociecha D, et al. Structure of nanoscale-pitch helical phases: blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering. Soft Matter. 2017;13:6694–6699.
   PubMed Web of Science ®Google Scholar
• Luckhurst GR, Timimi BA, Wells NJ, et al. On orientational order in nematic and twist-bend nematic phases: a 2H-NMR study of binary mixtures of the odd dimer,1″,9″-bis(4-cyanobiphenyl-4′-yl) nonane, (CB9CB), and the monomer, 4-pentyl-4′-cyanobiphenyl, (5CB-d2). Liq Cryst. 2018;45:1913–1928.
   Web of Science ®Google Scholar
• Emsley JW, Lelli M, Luckhurst GR, et al. 13C NMR study of the director distribution adopted by the modulated nematic phases formed by liquid-crystal dimers with odd numbers of atoms in their spacers. Phys Rev E. 2017;96:062702.
   PubMed Web of Science ®Google Scholar
• Emsley JW, Lelli M, Joy H, et al. Similarities and differences between molecular order in the nematic and twist-bend nematic phases of a symmetric liquid crystal dimer. Phys Chem Chem Phys. 2016;18:9419–9430.
   PubMed Web of Science ®Google Scholar
• Challa PK, Borshch V, Parri O, et al. Twist-bend nematic liquid crystals in high magnetic fields. Phys Rev E. 2014;89:060501.
   PubMed Web of Science ®Google Scholar
• Vanakaras AG, Photinos DJ. Thermotropic biaxial nematic liquid crystals: spontaneous or field stabilized? J Chem Phys. 2008;128:154512.
   PubMed Web of Science ®Google Scholar
• Droulias S, Vanakaras AG, Photinos DJ. Extending the Maier–saupe theory to cybotactic nematics. Liq Cryst. 2010;37:969–976.
   Web of Science ®Google Scholar
• Francescangeli O, Vita F, Fauth F, et al. Extraordinary magnetic field effect in bent-core liquid crystals. Phys Rev Lett. 2011;107:207801.
   PubMed Web of Science ®Google Scholar
• Francescangeli O, Vita F, Ferrero C, et al. Cybotaxis dominates the nematic phase of bent-core mesogens: A small-angle diffuse X-ray diffraction study. Soft Matter. 2011;7:895–901.
   Web of Science ®Google Scholar
• Salili SM, Tamba MG, Sprunt SN, et al. Anomalous increase in nematic-isotropic transition temperature in dimer molecules induced by a magnetic field. Phys Rev Lett. 2016;116:217801.
   PubMed Web of Science ®Google Scholar
• Toriumi H, Furuya H, Abe A. Deuterium NMR studies on the orientational order in dimeric thermotropic liquid crystals. Polym J. 1985;17:895–898.
   Web of Science ®Google Scholar
• Imrie CT, Henderson PA. Liquid crystal dimers and higher oligomers: between monomers and polymers. Chem Soc Rev. 2007;36:2096–2124.
   PubMed Web of Science ®Google Scholar
• Samulski E. The mesomorphic state. In: Mark J, editor. Phys. Prop. Polym. 3rd ed. Cambridge: Cambridge University Press; 2004; p. 316–380. doi:10.1017/CBO9781139165167.006.
   Google Scholar
• Tripathi CSP, Losada-Pérez P, Glorieux C, et al. Nematic-nematic phase transition in the liquid crystal dimer CBC9CB and its mi xtures with 5CB: A high-resolution adiabatic scanning calorimetric study. Phys Rev E. 2011;84:041707.
   PubMed Web of Science ®Google Scholar