Chiroptical Switching between Liquid Crystalline Phases

Mecca

Rosini

et al. 2003

Chemistry A European J

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137

Section: A Chiroptical Molecular Switch With Distinct Chiral and Photmentioning

confidence: 99%

A Chiroptical Molecular Switch with Distinct Chiral and Photochromic Entities and Its Application in Optical Switching of a Cholesteric Liquid Crystal

Mecca

Rosini

et al. 2003

Chemistry A European J

Self Cite

137

“…It is well known that the organization in the LC matrix is usually sensitive to the nature of (chiral) dopants present (27). Based on this property, a variety of photochromic compounds have been used to alter the alignment of LC phases upon irradiation (22,23,28,29). It has been demonstrated that switching between positive and negative cholesteric phases could be accomplished by using chiroptical molecular switches (28)(29)(30).…”

mentioning

confidence: 99%

“…Based on this property, a variety of photochromic compounds have been used to alter the alignment of LC phases upon irradiation (22,23,28,29). It has been demonstrated that switching between positive and negative cholesteric phases could be accomplished by using chiroptical molecular switches (28)(29)(30). Cholesteric LC films show reflection at a specific wavelength () dependent on the pitch (p), the angle of the incident light (␣), and the average refractive index (n):…”

mentioning

confidence: 99%

Unidirectional rotary motion in a liquid crystalline environment: Color tuning by a molecular motor

Proc. Natl. Acad. Sci. U.S.A.

Koumura

Harada³

et al. 2002

Self Cite

189

105

Life could not exist without motion induced by a variety of molecular motors. The construction of artificial motors by chemical synthesis, which can power motions that lead to macroscopic detectable effects in a system, is a major endeavor in contemporary science. To move toward this goal, a host-guest system, composed of a nematic liquid crystal film doped with a chiral light-driven molecular motor, is assembled. Irradiation of the film results in unidirectional rotary motion of the molecular motor, which induces a motion of the mesogenic molecules leading to a molecular reorganization and, as a consequence, a change in the color of the film. In this way, by control of the rotary motion at the molecular level, color tuning over the entire visible spectrum is achieved. These findings demonstrate that a molecular motor can exert a visually observable macroscopic change in a material.

“…In addition, these systems have proven to be excellent trigger elements to control, via the light-induced motion and change in helicity, the mesoscopic organization and properties of liquid crystalline materials. Photochemical switching of LC phases using chiral photochromic guest molecules offers an alternative to current methods of addressing display materials [22]. Using a related helical-shaped photobistable alkene 2, switching between enantiomers at a single wavelength of light could also be accomplished, and the slight stereochemical bias that was found can be amplified in a liquid crystal film [23].…”

Section: Methodsmentioning

confidence: 99%

In control of switching, motion, and organization

Feringa

Pure and Applied Chemistry

Wiel

2003

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Nature’s solutions to control organization, switching, and linear and rotary motion are not only extremely elegant, but fascinating if one considers the design and synthesis of artificial molecular systems with such functions in order to add components to the nanotoolbox. The synthesis of chiroptical molecular switches and their application in the control of the organization of liquid crystalline materials is outlined. The first light-driven unidirectional molecular motor is described, and the second-generation motor as well as approaches to control the speed of the rotary motion are discussed.