Intercambio de helicidad complementaria de helicenos supramoleculares-enantioméricos con capacidad de conmutación
Chien-Tien Chen1, Chien-Hsiang Chen, Tiow-Gan Ong
1Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan. ctchen@mx.nthu.edu.tw
Journal of the American Chemical Society
|March 26, 2013
Resumen
Los helicenos pseudoenantioméricos se autoensamblan en fibras helicoidales. Estas fibras exhiben un comportamiento de fotointercambio complementario, lo que permite operaciones de lógica ternaria a través de transiciones gel-sol-gel desencadenadas por longitudes de onda específicas.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Materiales orgánicos Ciencia de la materia orgánica.
- La fotoquímica es la fotoquímica.
Sus antecedentes:
- Los helicenos son hidrocarburos aromáticos quirales con estructuras helicoidales únicas.
- El autoensamblaje es un proceso clave para crear complejas arquitecturas supramoleculares.
- Los materiales fotointercambiables ofrecen un control dinámico sobre las propiedades del material.
Objetivo del estudio:
- Para sintetizar y caracterizar una pareja de heliceno pseudoenantiomérico que contiene gallamida.
- Para investigar el comportamiento de autoensamblaje de estos helicenos en solución.
- Para explorar las capacidades de fotoswitching y el potencial para las operaciones de lógica ternaria.
Principales métodos:
- Síntesis de helicenos pseudoenantioméricos que contienen gallamida con un núcleo de dibenzosuberano.
- Caracterización mediante el uso de técnicas espectroscópicas (NMR, UV-Vis, etc.) En el caso de las personas que se encuentran en situación de exclusión social.
- Análisis del autoensamblaje mediante microscopía y métodos de dispersión.
- Investigación del comportamiento de conmutación de fotos mediante irradiación UV y monitoreo de la transición gel-sol.
Principales resultados:
- Síntesis exitosa del par de helicenos objetivo.
- Formación de fibras helicoidales empaquetadas a través de la unión H de amida intermolecular y el apilamiento π-π.
- Observación del fotoswitching complementario de la lógica ternaria en longitudes de onda específicas (280, 318, 343 nm).
- Demostración de la interconversión reversible entre (-) -gel-sol-(+) -gel.
Conclusiones:
- Los helicenos pseudoenantioméricos que contienen gallamida pueden autoensamblarse en estructuras helicoidales ordenadas.
- Estos conjuntos exhiben propiedades sintonizables de conmutación fotográfica.
- El sistema demuestra potencial para el desarrollo de dispositivos avanzados de lógica molecular.
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...
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg&w=3840&q=75)
01:21[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
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,...
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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