Liquid crystalline and nonlinear optical properties of bent-shaped compounds derived from 3,4′-biphenylene

Pintre, Inmaculada C.; Gimeno, Nélida; Serrano, José Luís; Ros, M. Blanca; Alonso, Ibón; Folcia, C. L.; Ortega, J.; Etxebarría, J.

doi:10.1039/b700636e

Cited by 55 publications

(31 citation statements)

References 46 publications

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“…For a value of (D -d) ∼1 pm/V (typical in banana compounds [13]), the measured SHG efficiency can be accounted for by a distortion angle ϕ ∼ 1 • . It is impossible to perceive this small perturbation perceived by direct texture observation, but it is detectable by SHG measurements due to the high sensitivity of this technique to small perturbations in the structure of bent-core mesophases.…”

Section: Resultsmentioning

confidence: 99%

The SmA phase of a bent-core V-shaped compound: structure and electric-field response

et al. 2010

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2010) The SmA phase of a bent-core V-shaped compound: structure and electric-field response,The smectic A (SmA) phase of a V-shaped mesogen with a molecular bending angle of 60 • was studied. According to X-ray measurements, the molecules are arranged with the 'bow-string' direction parallel to the smectic layer. This point was confirmed by birefringence analysis and the result is compatible with a non-polar structure. A detailed study of the (001) smectic layer reflection versus temperature was also carried out to determine the smectic translational order parameter. The results indicate that the material presents a high degree of translational order. In addition, the electric field response of the material was studied by means of second harmonic generation. This technique turned out to be highly sensitive to small structural distortions due to the V-shape of the constituent molecules.

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Section: Resultsmentioning

confidence: 99%

The SmA phase of a bent-core V-shaped compound: structure and electric-field response

et al. 2010

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“…In contrast, only a few percent of chromophores are aligned in poled polymers, or ∼20% in conventional FLCs. However, since the early bent-core molecules incorporated chromophores with small molecular hyperpolarizabilities, the measured NLO coefficients (1.9 ≤ D (pm/V) ≤ 8; 1 ≤ d (pm/V) ≤4, = 1.064 m) via SHG for bent-core compounds is insufficient for NLO applications [182][183][184][185].…”

Section: Nonlinear Opticsmentioning

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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“…A characterization of these materials is reported in Refs. [17,18] and in Refs. [5,6,19], respectively.…”

Section: Methodsmentioning

confidence: 99%

Electric-field-induced phase transitions in bent-core mesogens determined by x-ray diffraction

et al. 2011

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The changes in the x-ray diffraction diagram induced by an electric field have been studied in four bent-core liquid crystals. Two of the compounds present columnar B 1 phases and the other two show dark conglomerate (DC) structures. In the B 1 materials the electric field gives rise to switchable phases whose diffraction pattern is that of the smectic C polar (SmCP) phase. In the DC structures the positions of the Bragg reflections remain essentially unaltered, but in one of the compounds the peaks become narrower under field, indicating that the correlation length of the smectic order increases. A slight enhancement of the smectic spacing is found in the DC phases upon field application.

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Liquid crystalline and nonlinear optical properties of bent-shaped compounds derived from 3,4′-biphenylene

Cited by 55 publications

References 46 publications

The SmA phase of a bent-core V-shaped compound: structure and electric-field response

The SmA phase of a bent-core V-shaped compound: structure and electric-field response

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

Electric-field-induced phase transitions in bent-core mesogens determined by x-ray diffraction

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