Video Experimental Relacionado
Updated: Jul 13, 2026
11:34
Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels
Published on: September 8, 2016
Inducción de la quiralidad macromolecular en el poli- isocyanuro de 4-carboxifenoil ópticamente inactivo con aminas
Masayoshi Ishikawa1, Katsuhiro Maeda, Eiji Yashima
1Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
Journal of the American Chemical Society
|June 20, 2002
Resumen
Los derivados ópticamente inactivos del poli (fenilisocianuro) obtienen actividad óptica a través de estímulos quirales. Este cambio conformacional dinámico, observado a través del dicroísmo circular inducido, sugiere el potencial de nuevos materiales funcionales.
Área de la Ciencia:
- Química de Polímeros La Química de Polímeros es la química de los polímeros.
- Ciencia de los materiales Ciencia de los materiales.
- Química supramolecular de las moléculas.
Sus antecedentes:
- Los poliisocianuros ópticamente activos se exploran para materiales funcionales.
- Los poliisocianuros con grupos laterales voluminosos suelen adoptar una conformación helicoidal estable.
- Las características conformamentales de los derivados del polifenilo isocyanuro (PPI) siguen siendo objeto de debate.
Objetivo del estudio:
- Investigará el comportamiento conformacional del poli- ((4-carboxifenilisocianuro) (poli-1), un derivado de PPI ópticamente inactivo.
- Determinar si los estímulos quirales externos pueden inducir la actividad óptica en la columna vertebral del polímero.
- Explorar el mecanismo de inducción de helicidad en los derivados de PPI.
Principales métodos:
- Síntesis del isocyanuro de poli ((4-carboxifenoil) (poli-1). también conocido como poli-1).
- Análisis espectroscópico que incluye espectroscopia UV-visible y dicroísmo circular inducido (ICD).
- (1) Espectroscopia de RMN H y simulaciones dinámicas moleculares para analizar cambios conformacionales.
Principales resultados:
- El poli-1 ópticamente inactivo exhibe dicroísmo circular inducido (DCI) al interactuar con aminas quirales en DMSO.
- Las intensidades de ICD aumentaron con el tiempo, alcanzando hasta tres veces el valor inicial.
- Se observaron cambios conformacionales lentos en el poli-1 y sus derivados, lo que sugiere una conformación proquiral dinámica.
Conclusiones:
- Los IPP con sustitutos menos voluminosos pueden poseer una conformación proquiral s-trans (zigzag), no una hélice 4 ().
- Los grupos funcionales capaces de interactuar con los compuestos quirales pueden inducir una conformación dinámica helicoidal de una sola mano.
- Este estudio revela un mecanismo para la inducción de la helicidad en los poliisocianuros a través de transiciones conformacionales dinámicas.
Videos de Conceptos Relacionados
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...
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
00:54Radical Formation: Homolysis
A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.
01:26Polymer Classification: Stereospecificity
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
![[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F13097.jpg&w=3840&q=75)
01:24[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
The Claisen rearrangement is a [3,3] sigmatropic rearrangement of allyl vinyl ethers to unsaturated carbonyl compounds. The rearrangement is a concerted pericyclic reaction proceeding via a chair-like transition state.