Video Experimental Relacionado
Updated: Jul 7, 2026
09:26
Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
Cambios estructurales reversibles impulsados por la luz entre las alineaciones de apilamiento mono- y bicapa en
Osamu Ohtani1, Hiroki Kato, Tatsuto Yui
1Department of Crystalline Materials Science, School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
Journal of the American Chemical Society
|November 20, 2003
Resumen
La exposición a la luz desencadena cambios estructurales reversibles en las películas de N-metil-4-octadecylloxystilbazolium arylcarboxylate. Estas películas delgadas se expanden y encogen, demostrando transformaciones morfológicas controlables para aplicaciones potenciales.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La fotoquímica es la fotoquímica.
- Química supramolecular de las moléculas.
Sus antecedentes:
- Las películas multilamelares compuestas de N-metil-4-octadeciloxistilbazolio arilcarboxilatos (C18OStz+X-) exhiben propiedades únicas.
- Comprender los cambios morfológicos inducidos por la luz es crucial para el desarrollo de materiales avanzados.
Objetivo del estudio:
- Para investigar las transformaciones morfológicas impulsadas por la luz en películas multilamellares de C18OStz+X-.
- Para aclarar el mecanismo detrás de los cambios estructurales observados y su reversibilidad.
Principales métodos:
- Análisis de difracción de rayos X (XRD) para estudiar los cambios estructurales a lo largo del eje c.
- Iluminación UV alternativa (>350 nm y 254 nm) para inducir y revertir cambios estructurales.
- Microscopía electrónica de barrido (SEM) y microscopía de fluorescencia para analizar el patrón de la superficie.
Principales resultados:
- Se observó la expansión y contracción fotostimulada de películas delgadas apiladas a lo largo del eje c bajo diferentes longitudes de onda UV.
- La transformación reversible entre las unidades mono- y bicapa dentro de las películas impulsa los cambios lamelares.
- Los ajustes estructurales, incluida la transformación de monocapa a bilaer, se iniciaron mediante la fotociclodimerización de las fracciones de stilbazolio, incluso con una baja formación de ciclodímero (10%).
Conclusiones:
- La irradiación de luz puede alterar de forma controlable la morfología de las películas multilamellares C18OStz+X-.
- La naturaleza reversible de los cambios estructurales, impulsados por la fotociclodimerización, ofrece potencial para materiales fotorresponsivos.
- Se demostró con éxito el patrón fotoinducido en superficies de película, destacando aplicaciones potenciales en ingeniería de superficies.
Videos de Conceptos Relacionados
02:42Ionic Crystal Structures
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
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...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
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,...
01:26Photochemical 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
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...