Fotoswitching dinámico de inversión helicoidal en cristales líquidos que contienen dopantes axialmente quirales fotorresponsivos
Video Experimental Relacionado
Updated: May 25, 2026
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Hiroyuki Hayasaka1, Tatsuaki Miyashita, Masaru Nakayama
1Department of Polymer Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan.
Journal of the American Chemical Society
|February 3, 2012
Resumen
Los investigadores desarrollaron nuevos dopantes quirales para cristales líquidos (LC). Estos dopantes permiten el control dinámico de las propiedades ópticas mediante la quiralidad de conmutación fotográfica, lo que lleva a la inversión helicoidal en las LCs quirales nemáticas.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química orgánica es la química orgánica.
- Química Física es la química física.
Sus antecedentes:
- La conmutación de quiralidad en materiales a nanoescala ofrece un control dinámico de las propiedades electrónicas y ópticas.
- Los cristales líquidos quirales fotoswitchables (LC) son prometedores para aplicaciones en pantallas, almacenamiento de datos y síntesis asimétrica.
- El control de la quiralidad en los cristales líquidos quirales nemáticos (N*-LC) es clave para las funcionalidades avanzadas de los materiales.
Objetivo del estudio:
- Desarrollar nuevos dopantes quirales fotorresponsivos para el control dinámico de las propiedades N*-LC.
- Para investigar la conmutación fotoquímica de la inversión helicoidal en N*-LCs utilizando dopantes sintetizados.
- Para demostrar el fotoswitching reversible y las transiciones de fase en N*-LCs.
Principales métodos:
- Síntesis de nuevos derivados fotorresponsivos de dietienilethene quiral con fracciones de binaftil quiral axialmente.
- Incorporación de estos derivados como dopantes en N*-LCs.
- Investigación de los cambios inducidos por la fotoisomerización en los ángulos diédricos y su efecto en la estructura helicoidal de LC.
Principales resultados:
- Los derivados sintetizados del dietienileteno exhibieron fotoisomerización entre formas abiertas y cerradas, alterando los ángulos diédricos del binaftil.
- Los N*-LCs dopados con estos compuestos mostraron fotoscambio reversible de la inversión helicoidal.
- Se observó una transición de fase reversible entre las fases N*-LC y LC nemática tras la fotoirradicación.
Conclusiones:
- Los dopantes quirales desarrollados son los primeros en inducir la inversión helicoidal en N*-LCs a través de la fotoisomerización del dietienileteno.
- Este trabajo proporciona una nueva estrategia para el control óptico dinámico en materiales de cristal líquido.
- Los hallazgos abren vías para dispositivos electroópticos avanzados y aplicaciones de materiales quirales.
Videos de Conceptos Relacionados
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
02:52Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
02:05Prochirality
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
02:24Properties of Enantiomers and Optical Activity
It is essential to understand the difference between chiral and achiral interactions and the implications thereof in optical activity and their applications. Just as our feet, which are chiral, interact uniquely with chiral objects, such as a pair of shoes, but identically with achiral socks, enantiomers of a molecule exhibit different properties only when they interact with other chiral media. An example of a significant implication from this facet is the phenomenon known as optical activity,...
02:33Stereoisomerism of Cyclic Compounds
In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...
00:58¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
Replacing each alpha-hydrogen in chloroethane by bromine (or a different functional group) yields a pair of enantiomers. Such protons are called prochiral or enantiotopic and are related by a mirror plane. Enantiotopic protons are chemically equivalent in an achiral environment. Because most proton NMR spectra are recorded using achiral solvents, enantiotopic hydrogens yield a single signal.
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...