Video Experimental Relacionado
Updated: Jul 18, 2026
09:32
Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
Published on: June 15, 2017
Mecanismo y dinámica de la fotoisomerización del azobenzeno
Thomas Schultz1, Jason Quenneville, Benjamin Levine
1Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1N 0R6.
Journal of the American Chemical Society
|July 3, 2003
Resumen
Los investigadores estudiaron la dinámica del estado excitado del trans-azobenzeno utilizando espectroscopia avanzada y simulaciones. Descubrieron dos estados excitados clave, explicando las inconsistencias anteriores en la investigación de la fotoisomerización y proponiendo un nuevo mecanismo.
Área de la Ciencia:
- La fotoquímica es la fotoquímica.
- La dinámica molecular es la dinámica molecular.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- El trans-azobenzeno exhibe una fotoisomerización compleja.
- Estudios previos informaron mecanismos contradictorios y rendimientos cuánticos.
- El paisaje de estado excitado del trans-azobenzeno no se entiende completamente.
Objetivo del estudio:
- Para dilucidar la dinámica del estado excitado del trans-azobenzeno.
- Para resolver las discrepancias en el mecanismo de fotoisomerización.
- Para investigar la dependencia de la longitud de onda del rendimiento cuántico.
Principales métodos:
- Espectroscopia de fotoelectrones con resolución de tiempo de cinco segundos.
- Simulaciones de dinámica molecular desde el principio.
Principales resultados:
- Identificación de dos estados excitados pi pi* casi degenerados (S2 y S3,4).
- Estos estados existen en una región espectral que anteriormente se pensaba que contenía un solo estado.
- Los hallazgos proporcionan una base para la comprensión de informes experimentales contradictorios.
Conclusiones:
- Se propone un modelo revisado para el mecanismo de fotoisomerización del trans-azobenzeno.
- Los estados excitados recién identificados son cruciales para explicar los fenómenos observados.
- Este trabajo avanza en la comprensión de la fotoquímica del azobenzeno.
Videos de Conceptos Relacionados
02:20Dynamic Equilibrium
A reversible chemical reaction represents a chemical process that proceeds in both forward (left to right) and reverse (right to left) directions. When the rates of the forward and reverse reactions are equal, the concentrations of the reactant and product species remain constant over time and the system is at equilibrium. A special double arrow is used to emphasize the reversible nature of the reaction. The relative concentrations of reactants and products in equilibrium systems vary greatly;...
01:57Protein Complexes with Interchangeable Parts
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...
01:28Forced Transdifferentiation
Transdifferentiation, also known as lineage reprogramming, was first discovered by Selman and Kafatos in 1974 in silkmoths. They observed that the moths’ cuticle-producing cells transformed into salt-producing cells. Many such cases of natural transdifferentiation occur in organisms. In humans, pancreatic alpha cells can become beta cells. In newts, the loss of the eye’s lens causes the pigmented epithelial cells to transdifferentiate into the lens cells.
Artificial transdifferentiation occurs...
Artificial transdifferentiation occurs...
01:22Carrier Generation and Recombination
Carrier generation is the process by which electron-hole pairs (EHPs) are created within the semiconductor. In direct-bandgap semiconductors, such as gallium arsenide (GaAs), this occurs efficiently when energy absorption prompts valence electrons to leap into the conduction band, leaving behind holes.
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...