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
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.
01:11Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
01:32UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this process,...
01:24Characteristics and Nomenclature of Copolymers
Copolymers are the products obtained from the polymerization of multiple monomer species. So, in a polymer chain itself, there can be multiple repeating units that come from different monomers. The process of synthesizing a polymer from different monomer species is called copolymerization. When two monomers are involved, the polymer is known as a bipolymer. Polymers with three and four monomers are termed terpolymers and quaterpolymers, respectively. Figure 1 depicts the copolymerization of...
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Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds
Published on: October 15, 2019
Almacenamiento de datos ópticos de dos fotones reversibles en copolímeros basados en cumarina.
Konstantinos Iliopoulos1, Oksana Krupka, Denis Gindre
1Laboratoire MOLTECH-Anjou, CNRS UMR 6200, Université d'Angers, 2 Bd Lavoisier, 49045 Angers cedex, France.
Journal of the American Chemical Society
|October 1, 2010
Resumen
Una nueva película de polímero permite el almacenamiento de datos ópticos reescribibles mediante dimerización fotoinducida reversible. Este método permite escribir, leer y borrar datos de alto contraste, detectables exclusivamente a través de imágenes de generación de segunda armonía (SHG).
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La óptica es la óptica.
- Química de Polímeros La química de los polímeros es la química de los polímeros.
Sus antecedentes:
- El almacenamiento óptico de datos es crucial para la tecnología de la información.
- El desarrollo de medios de almacenamiento reescribibles y de alto contraste sigue siendo un desafío.
- La generación de segunda armonía (SHG) ofrece capacidades únicas de detección.
Objetivo del estudio:
- Proponer una película de polímero funcionalizada para el almacenamiento eficiente de datos ópticos.
- Para demostrar una secuencia completa de escritura-lectura-borrado-escritura usando SHG.
- Para aprovechar la dimerización fotoinducida reversible para la manipulación de datos.
Principales métodos:
- Fabricación de una película de polímero funcionalizado que incorpora un cromóforo de cumarina.
- Utilizando la dimerización fotoinducida reversible para escribir y borrar datos.
- Empleando imágenes SHG para la detección y lectura de datos de alto contraste.
Principales resultados:
- Logró un ciclo sencillo y completo de escritura-lectura-borrado-escritura.
- Capacidades demostradas de almacenamiento de datos de alto contraste.
- Confirmado que los datos son exclusivamente detectables a través de imágenes SHG.
Conclusiones:
- La película de polímero propuesta ofrece una plataforma prometedora para el almacenamiento de datos ópticos reescribibles.
- El proceso asistido por SHG permite una manipulación de datos eficiente y selectiva.
- Esta tecnología tiene aplicaciones potenciales en sistemas avanzados de memoria óptica.