Dynamic and Reversible Polymorphism of Self-Assembled Lyotropic Liquid Crystalline Systems Derived from Cyclic Bis(ethynylhelicene) Oligomers

Saito, Nozomi; Kanie, Kiyoshi; Matsubara, Masaki; Muramatsu, Atsushi; Yamaguchi, Masahiko

doi:10.1021/jacs.5b02003

Cited by 48 publications

(33 citation statements)

References 89 publications

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“…Most hydrogen‐bonding systems forming columnar mesophases assemble hydrogen‐bond acceptors and donors about a centre, which can be regarded as an exo ‐receptor . In the last years an increasing number of reports on large macrocyclic mesogens were published, in which a cavity can uptake guests or which possessed a quasi empty centre of a column . These molecules are defined as endo ‐receptors and are interesting for sensing applications or ion conduction.…”

Section: Introductionmentioning

confidence: 99%

Crowded Star Mesogens: Guest‐Controlled Stability of Mesophases from Unconventional Liquid‐Crystal Molecules

Lehmann

Maier

Grüne

et al. 2016

Chemistry A European J

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The molecular design of crowded hexasubstituted star mesogens based on a benzene core and alternating substitution with oligo(phenylenevinylene) arms and aryl units generates free space between the conjugated arm scaffolds. Various arylcarboxy building blocks, decorated with alkoxy chains, have been incorporated in the void by mixing, hydrogen bonding or covalent bonds to the aryl groups. The mesogens assemble in columnar stacks ranging from soft crystals to rectangular and hexagonal columnar liquid crystals, revealed by polarized optical microscopy, differential scanning calorimetry, X-ray scattering and modelling. The stability of the mesophases is crucially influenced by the binding mode of the arylcarboxy guest building blocks. The origin of the variation in clearing temperature is unravelled by modelling, cohesive energy density considerations and solid-state NMR spectroscopy. The control over the transition temperature is important for the formation of aligned thin films and thus for potential applications.

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Section: Introductionmentioning

confidence: 99%

Crowded Star Mesogens: Guest‐Controlled Stability of Mesophases from Unconventional Liquid‐Crystal Molecules

Lehmann

Maier

Grüne

et al. 2016

Chemistry A European J

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“…This natural organisation of life is driven by noncovalent forces and it is known that polymer fibers and liquid crystals (LLC) all self-assemble in solution based on the same principles that drive natural molecular assembly [8]. Recently, Saito et al [9] have developed a stimuliresponsive self-assembled system from lyotropic LLCs composed of cyclic ethynylhelicene oligomers. Through the careful control of temperature, the LLCs were able to be dynamically changed from anisotropically aligned fibers to turbid gels.…”

Section: Self-assemblymentioning

confidence: 99%

“…Through the careful control of temperature, the LLCs were able to be dynamically changed from anisotropically aligned fibers to turbid gels. It is thought that these systems have potential biological applications in mimicking actin [9]. Stupp et al [10] have used peptide amphiphiles (PAs) in combination with hyaluronic acid in the dynamic selfassembly of hierarchical nanofibers that are under electrostatic control.…”

Section: Self-assemblymentioning

confidence: 99%

Synthetic stimuli-responsive ‘smart’ fibers

Bou

Ellis

Ebara

2016

Current Opinion in Biotechnology

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“…Molecular thermal hysteresis is discussed in section 10. A cyclic design connecting identical ethynylhelicene oligomers produced anisotropic self-assembled lyotropic liquid crystals (LLCs) (71). Cyclic oligomers (M,M)-18 (n = 4, 6) were synthesized, in which two ethynylhelicene (M)-tetramers (M)-10 (n = 4) or (M)-hexamers (M)-10 (n = 6) were connected by two flexible oligomethylene linkers (Fig.…”

Section: Homo-bidomain Oligomers Connecting Two Ethynylhelicene Oligomentioning

confidence: 99%

Structure and Property Diversity of Chiral Helicene Oligomers

Saito

Shigeno

Yamaguchi

2015

Encyclopedia of Polymer Science and Technology

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alkylthio, and perfluoroalkyl groups. In addition, cyclization of helicene oligomers provides another method of obtaining diversity.A notable aspect in the diversity of helicene oligomers is that they can be connected to provide multidomain oligomers (Fig. 4). When two helicene oligomers are connected, they are referred to herein as homo-bidomain oligomers. Cyclic homo-bidomain oligomers are also conceivable. Hetero-multidomain oligomers can be obtained by connecting different structures of oligomers. Such manipulations provide a large diversity of structures.Because helicene can generate characteristic π−π interactions, helicene oligomers often form bimolecular, trimolecular, tetramolecular, and polymolecular aggregates in which homoaggregation and heteroaggregation can also occur. Such aggregates self-assemble to form fibrils, vesicles, liquid crystals, and surface monolayers. These noncovalent bonding interactions provide diversity of the structure of helicene oligmers. Diverse Properties of Helicene OligomersStructural diversity is directly related to diversity of properties, and the properties of a helicene oligomer can be varied by structural modifications. In addition, multidomain oligomers can be designed, in which properties A and B of each domain can be combined. Such compounds exhibit property A + B or even another property C, a result regarded as the "synthesis of a property or function." Aggregation and self-assembly of helicene oligomers further increase property diversity, which covers materials with a broad range of sizes from subnanometersized molecules through nano-and micrometer-sized molecular aggregates and molecular self-assemblies to macroscopic bulk materials. Helicene oligomers are sensitive to changes in the environment such as temperature, solvent, and concentration. Different properties appear in dilute solution, in concentrated Amidohelicene oligomers: (a) acylcic oligomers (P)-1 (n = 1−9) with dianiline spacer, cyclic oligomers (P)-2 (n = 1−10) with dianiline spacer, (b) acyclic oligomers (P)-3 (n = 1−9) with m-phenylene spacer, and acyclic reverse oligomers (P)-4 (n = 1−4). (c) Schematic representation of reversible change between helix dimer and random coils of (P)-3 and (P)-4. solution, in the crystalline state, in the amorphous state, on the solid surface, at the solid-liquid interface, in fiber assemblies, in liquid crystals, and in gels. Dynamic properties of helicene oligomers are also interesting, and structural changes are largely affected by the environment, providing a stimulus response or possible molecular switching materials. It is also noteworthy that the process of a structure change can produce unusual transient phenomena. Amidohelicene OligomersStudies on helicene oligomers were initiated with amide derivatives (Fig. 5a, top), in which the spacer has a bent shape and includes both hydrogen bonding donor and acceptor moieties (24). (P)-5,8-Helicenedicarboxylate was reacted with bis(2,6-dimethylanilino)cyclohexane to give a series of acyclic helicene oligomers 1 up t...

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Dynamic and Reversible Polymorphism of Self-Assembled Lyotropic Liquid Crystalline Systems Derived from Cyclic Bis(ethynylhelicene) Oligomers

Cited by 48 publications

References 89 publications

Crowded Star Mesogens: Guest‐Controlled Stability of Mesophases from Unconventional Liquid‐Crystal Molecules

Crowded Star Mesogens: Guest‐Controlled Stability of Mesophases from Unconventional Liquid‐Crystal Molecules

Synthetic stimuli-responsive ‘smart’ fibers

Structure and Property Diversity of Chiral Helicene Oligomers

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