Videos de Conceptos Relacionados
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
01:26Protein Modifications in the RER
Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
01:14Drug Metabolism: Phase II Reactions
Phase II reactions are essential for the detoxification and elimination of drugs from the body. These reactions involve the conjugation of parent drugs or their phase I metabolites with endogenous molecules, resulting in more hydrophilic drug conjugates. The primary conjugation reactions in this phase are sulfation and glucuronidation. Both sulfation and glucuronidation typically produce biologically inactive metabolites. However, in some cases involving prodrugs, active metabolites may be...
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
01:19Phase II Reactions: Miscellaneous Conjugation Reactions
Phase II biotransformations are detoxification mechanisms that conjugate xenobiotics with endogenous substances, neutralizing their toxicity.
A key example involves the conjugation of cyanide ions, which impair cellular respiration and alter hemoglobin into non-oxygen-carrying cyanmethemoglobin. To neutralize this threat, a sulfur atom from thiosulphate is transferred to the cyanide ion, catalyzed by the enzyme rhodanese, resulting in an inactive compound called thiocyanate. The production of...
A key example involves the conjugation of cyanide ions, which impair cellular respiration and alter hemoglobin into non-oxygen-carrying cyanmethemoglobin. To neutralize this threat, a sulfur atom from thiosulphate is transferred to the cyanide ion, catalyzed by the enzyme rhodanese, resulting in an inactive compound called thiocyanate. The production of...
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Video Experimental Relacionado
Updated: Jul 1, 2026
10:51
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Interacciones donante / receptor en los oligonucleótidos Ru (II) -Os (II) modificados sistemáticamente.
1Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358, USA.
Journal of the American Chemical Society
|October 31, 2002
Resumen
Las interacciones de donante/aceptor en duplexos de ADN se estudiaron utilizando nucleósidos de rutenio (II) y osmio (II). Se analizaron los mecanismos de transferencia de energía, revelando la transferencia dipolo-dipolo de Förster como dominante, con posibles contribuciones del mecanismo Dexter a distancias cortas.
Área de la Ciencia:
- La fotoquímica y la fotofísica.
- Química supramolecular de las moléculas.
- Química biofísica y bioquímica.
Sus antecedentes:
- Las interacciones donante/aceptante (D/A) son cruciales en los procesos de transferencia de energía.
- Los dúplex de ADN ofrecen un andamio versátil para el estudio de las interacciones moleculares debido a su estructura definida.
- La comprensión de los mecanismos de transferencia de energía en el ADN es vital para el desarrollo de nuevos dispositivos moleculares y sondas.
Objetivo del estudio:
- Para investigar las interacciones donante/aceptor (D/A) en duplexos de ADN modificados.
- Para dilucidar el mecanismo dominante de transferencia de energía (Förster vs. Dexter) en los sistemas puentes de ADN.
- Para analizar la influencia de la rigidez del enlace en la dinámica de transferencia de energía.
Principales métodos:
- Síntesis de duplexos de ADN de 19 mer con nucleósidos donantes Ru(II) y aceptores Os(II) enlazados con etinil a distancias variables.
- Espectroscopia de luminiscencia en estado estacionario y con resolución de tiempo para medir la vida útil del apagado y el estado excitado.
- Análisis de la transferencia de energía utilizando los mecanismos de Förster y Dexter, incluyendo consideraciones sobre el factor de orientación.
Principales resultados:
- El apagado de la luminiscencia de Ru(II) disminuyó con el aumento de la separación entre el donante y el aceptador (16 Å a 61 Å).
- Las vidas en estado excitado mostraron una correlación lineal con la eficiencia de apagado.
- El análisis indicó la transferencia de energía dipolo-dipolo de Förster como el mecanismo principal, con desviaciones posiblemente debidas a factores de orientación.
- La sustitución de un enlace rígido por uno flexible mejoró la correlación del mecanismo de Förster.
- Sorprendentemente, el análisis del mecanismo de Dexter también mostró una buena correlación, destacando la complejidad de interpretar las interacciones D/A.
Conclusiones:
- La transferencia de energía dipolo-dipolo de Förster es la vía dominante para las interacciones D/A en estos dúplex de ADN.
- Una contribución menor del mecanismo de intercambio de electrones Dexter puede ocurrir a distancias cortas.
- El estudio hace hincapié en el potencial de los sistemas Förster para exhibir un comportamiento similar a Dexter, advirtiendo contra los modelos simplificados para las díadas con puentes de ADN.