Video Experimental Relacionado
Updated: Jun 21, 2026
09:22
Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Actividad óptica mejorada por moléculas similares a varillas de achiral nanosegregadas en la estructura B4 de
Taketo Otani1, Fumito Araoka, Ken Ishikawa
1Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S8-42, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
Journal of the American Chemical Society
|August 1, 2009
Resumen
La quiralidad surge de moléculas de núcleo doblado en mezclas con cristales líquidos 5CB parecidos a varillas. Las señales de dicroísmo circular mejoradas aparecen cuando las moléculas 5CB forman superestructuras helicoidales dentro de nanofilamentos de núcleo doblado.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física de los cristales líquidos Física de los cristales líquidos
- Química supramolecular de las moléculas.
Sus antecedentes:
- La quiralidad es una propiedad fundamental en los sistemas moleculares.
- Los cristales líquidos de núcleo doblado exhiben comportamientos de fase únicos.
- Las mezclas de diferentes tipos de cristales líquidos pueden dar lugar a nuevas estructuras supramoleculares.
Objetivo del estudio:
- Investigar el origen y las características de la quiralidad en una mezcla de cristales líquidos de núcleo flexionado (P8-O-PIMB) y de tipo varilla (5CB).
- Comprender la relación entre la disposición molecular y las señales de dicroísmo circular (CD) observadas.
- Para explorar la formación de superestructuras helicoidales en mezclas de cristales líquidos.
Principales métodos:
- Espectroscopia de dicroísmo circular (CD) precisa utilizando células de muestra delgadas.
- Análisis del comportamiento de fase de la mezcla P8-O-PIMB y 5CB.
- Observación microscópica de la organización molecular (implicado).
Principales resultados:
- Las señales de CD se originan en moléculas de núcleo doblado segregadas quiralmente en la fase B ((4) (5CB isotrópico).
- Se observa una señal de CD mejorada en la fase B (X) (5CB nemática).
- Las moléculas 5CB están incrustadas dentro de nanofilamentos helicoidales formados por P8-O-PIMB, creando superestructuras helicoidales.
Conclusiones:
- La quiralidad observada está directamente relacionada con el autoensamblaje de las moléculas de núcleo doblado.
- La fase nemática de 5CB juega un papel crucial en la amplificación de las señales de CD mediante la formación de superestructuras helicoidales.
- Este estudio revela un mecanismo para generar señales gigantes de CD a través de la incorporación molecular y la formación de superestructuras helicoidales en mezclas de cristales líquidos.
Más Videos Relacionados
Videos de Conceptos Relacionados
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,...
02:30Chirality in Nature
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid. The...
02:25Molecules with Multiple Chiral Centers
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
02:25Chirality
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
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...
01:19Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...