Liquid‐Crystalline Hybrid Materials Based on [60]Fullerene and Bent‐Core Structures

Vergara, Jorge; Barberá, Joaquín; Serrano, José Luís; Ros, M. Blanca; Sebastián, Nerea; Fuente, M. R. de la; López, David; Fernández, Gustavo; Sánchez, Luis; Martı́n, Nazario

doi:10.1002/ange.201104866

Cited by 12 publications

(5 citation statements)

References 69 publications

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“…Although the central angle for the tetrahydropyrane BU is 109.5 • according to its molecular conformation, the calculated bend angle based on AM1 molecular modeling is 147 • , presumably due to its less rigid ester linkage [45]. It should be noted that the Ros and Kaszynski group reported two novel achiral bent-core compounds with fullerene [47] and m-carborane [48] BUs, respectively. There are many examples of bent-core molecules with five-membered aromatic central BUs (Fig.…”

Section: General Molecular Structure Of Bent-core Lcsmentioning

confidence: 99%

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

Zhang¹

2013

Intelligent Stimuli‐Responsive Materials

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The three classic states of matter are well known and ubiquitous in everyday life: solid, liquid, and gas. Liquid crystals (LCs), an intermediate state between solid crystal and isotropic liquid, constitute a new fascinating class of condensed soft matter uniquely combining both fluidity and long-range order. The fluid-like mobility enables LCs to be switchable under external stimuli, and crystal-like long-range order bestows anisotropic physical properties on LCs. LCs can be divided into two main classes: thermotropic and lyotropic. Thermotropic LCs consist of individual molecules (or ion pairs) and exhibit phase transitions with the change of temperature. In this case, temperature is the fundamental thermodynamic factor determining mesophase formation. Lyotropic LCs are a special type of solution system that can form mesophases as a function of both temperature and concentration of LC molecules. The building block of a lyotropic phase is an aggregate (called a micelle) formed via self-assembly of many molecules (typically on the order of 100). Examples of LCs can be found both in the natural world and in technological applications. Thermotropic LCs find 189 190 ELECTRIC-AND LIGHT-RESPONSIVE BENT-CORE LIQUID CRYSTALS a wide variety of uses in displays, and an important example of lyotropic LCs is cell membranes formed by amphiphilic lipids. Surfactants in water (i.e., soap water) constitute another useful example of lyotropic LCs. Although the majority of LCs are organic molecules, there exist many LC materials incorporating metals into organic anisotropic molecules [1-3]. These organic-inorganic hybrid LC materials are described as metallomesogens and are recently called metallotropic LCs [4] as distinguished from two main LC classes. In fact, metallomesogens can be classified as either thermotropic or lyotropic LCs depending on their composition and conditions. However, it should be noted that metallomesogens offer a material platform to incorporate magnetic, electronic, optical, redox, and catalytic properties common to inorganic materials into LCs.Although thermotropic LCs have been known to scientists for over 100 years since a discovery by the Austrian botanical physiologist Friedrich Reintizer in 1888, it was only in the late 1960s that they began to be used in display applications. Today, they are best known for their exceptionally successful commercial applications in flat panel display products such as TVs, smart phones, computer displays, and digital projectors. Although today's LC display technology is becoming very advanced, LC materials used in display devices possess the simplest nematic (N) phase and their molecules have been variants on simple rod shapes (Fig. 6.1a). Besides nematic phases, LCs can exhibit other phases: smectic (Sm), columnar (Col), and cubic phases, depending on the orientational or positional orders of their molecules. Nematic phases have only long-range orientational order, smectic mesophases exhibit one-dimensional (1D) positional order and form two-dimensional (2D) layered ...

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Section: General Molecular Structure Of Bent-core Lcsmentioning

confidence: 99%

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

Zhang¹

2013

Intelligent Stimuli‐Responsive Materials

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“…In non-symmetric dimers, bent-core mesogens were interconnected with discotic units like triphenylene [28], with adamantan [29], with fullerene [30], and with cholesterol [31,32].…”

Section: Introductionmentioning

confidence: 99%

Banana-calamitic Dimers: Further Variations of the Bent-core Mesogenic Unit

et al. 2014

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Banana-calamitic dimers are a topic in the field of bent-core mesogens. New materials were prepared by chemical variations at the bent-core fragment that is by a cyano group terminally attached to the bent-core fragment, by lateral substitution with a chlorine atom and methyl group, respectively, and by increasing the number of phenyl rings from five to six. The bent-core and the calamitic mesogenic moieties are connected by aliphatic spacers of different length. The materials were investigated by optical microscopy, DSC, X-ray diffraction studies and electro-optical measurements. This way nematic, smectic and various types of polar columnar phases have been characterized. The low temperature phase in a sequence of two nematic phases exhibiting different properties can be classified as a nematic twist-bend phase. Such NTB phases are only formed if a bend exists along the molecular long axes. This prerequisite can be doubly achieved in banana-calamitic dimers: by the intrinsic bend of one of the mesogenic fragments and by an odd-numbered spacer.

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“…As an analogy can be point out the increasing external pressure, which induced more efficient dimerization of C 60 to produce C 120 in a co-crystallite than in the amorphous bulk [ 45 ]. Co-crystallizations and supramolecular assemblies are giving rise to an explosion of new fullerene-containing liquid crystals (LC), functionalized often by different mesogenic units: hexaalkyloxytriphenylene [ 46 , 47 ], pyrrolidine [ 48 , 49 , 50 ], triethyleneglycol chains [ 51 ], cyanobiphenyl [ 52 ], alkoxy chains [ 53 ], and others [ 54 ]. Liquid crystalline fullerenes can be used in optical and electronic applications; recently, the interest has turned to formation strategies, where they are assembled spontaneously into macroscopic rods [ 55 , 56 ], vesicles [ 57 ], bent-cores [ 49 ], and discs [ 58 ].…”

Section: Introductionmentioning

confidence: 99%

“…Co-crystallizations and supramolecular assemblies are giving rise to an explosion of new fullerene-containing liquid crystals (LC), functionalized often by different mesogenic units: hexaalkyloxytriphenylene [ 46 , 47 ], pyrrolidine [ 48 , 49 , 50 ], triethyleneglycol chains [ 51 ], cyanobiphenyl [ 52 ], alkoxy chains [ 53 ], and others [ 54 ]. Liquid crystalline fullerenes can be used in optical and electronic applications; recently, the interest has turned to formation strategies, where they are assembled spontaneously into macroscopic rods [ 55 , 56 ], vesicles [ 57 ], bent-cores [ 49 ], and discs [ 58 ]. Self-assembling of fullerenopyrrolidine with long alkyl substituents occurrs in solvents of different polarities to form ordered supramolecular ensembles with the 1D, 2D, or 3D architecture such as vesicles, disks and cones, containing bilayers as the fundamental structural unit.…”

Section: Introductionmentioning

confidence: 99%

Exohedral Functionalization of Fullerene by Substituents Controlling of Molecular Organization for Spontaneous C60 Dimerization in Liquid Crystal Solutions and in a Bulk Controlled by a Potential

et al. 2021

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A study was carried out on the possibility of orderly and spontaneous dimerization at room temperature of C60 cages in fullerene liquid crystal fullerene dyads (R-C60). For this purpose, dyads with a structural elements feature supporting π-stacking and Van der Waals interactions were tested, due to the presence of terthiophene donors linked through an α-position or dodecyloxy chains. In addition, this possibility was also tested and compared to dyads with shorter substituents and the pristine C60. Research has shown that only in dyads with the features of liquid crystals, π-dimerization of C60 units occurs, which was verified by electrochemical and spectroelectrochemical (ESR) measurements. Cyclic voltammetry and differential voltammetry studies reveal π-dimerization in liquid crystal dyad solution even without the possibility of previous polymerization (cathodic or anodic) under conditions in the absence of irradiation and without the availability of reaction initiators, and even with the use of preliminary homogenization. These dyads undergo six sequential, one-electron reductions of π-dimer (R-C60···C60-R), where two electrons are added successively to each of the two fullerene cages and first form two radical anion system (R-C60)•−(R-C60)•− without pairing with the characteristics of two doublets. Similarly, the second reductions of π-dimer occur at potentials that are close to the reduction potential for the conversion to a system of two triplet dianions (R-C60)2−(R-C60)2−. Electron paramagnetic resonance spectra indicate a significant interaction between C60 cages. Interestingly, the strength of intermolecular bonds is so significant that it can overcome Coulombic repulsion, even with such highly charged particles as dianions and trianions. Such behavior has been revealed and studied so far only in covalently bonded C60 dimers.

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Liquid‐Crystalline Hybrid Materials Based on [60]Fullerene and Bent‐Core Structures

Cited by 12 publications

References 69 publications

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

Banana-calamitic Dimers: Further Variations of the Bent-core Mesogenic Unit

Exohedral Functionalization of Fullerene by Substituents Controlling of Molecular Organization for Spontaneous C60 Dimerization in Liquid Crystal Solutions and in a Bulk Controlled by a Potential

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