Video Experimental Relacionado
Updated: May 27, 2026
06:31
Preparation of SNS Cobalt(II) Pincer Model Complexes of Liver Alcohol Dehydrogenase
Published on: March 19, 2020
Paso a paso las molaridades efectivas en los complejos oligoméricos de porfirina: la preorganización da como
Hannah J Hogben1, Johannes K Sprafke, Markus Hoffmann
1Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, United Kingdom.
Journal of the American Chemical Society
|November 19, 2011
Resumen
Los complejos oligoméricos de porfirina de zinc exhiben una alta estabilidad debido a la coordinación intramolecular. Los hexámeres cíclicos muestran molaridades efectivas significativamente más altas que los oligómeros lineales, lo que indica una mayor fuerza de unión.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Coordinación Química de la Coordinación
- La Química Física es la química física.
Sus antecedentes:
- Los oligómeros de porfirina de zinc forman complejos con ligandos multivalentes.
- Estos complejos pueden ser desestabilizados (denaturados) mediante la adición de un exceso de ligandos monodentados.
- Comprender la estabilidad compleja es crucial para el diseño de materiales moleculares avanzados.
Objetivo del estudio:
- Para determinar la estabilidad de los complejos hexámero de zinc-porfirina con ligandos multidentados variables.
- Para comparar la estabilidad de los complejos oligoméricos de porfirina cíclicos frente a los lineales.
- Investigar los mecanismos de unión cooperativa en estos sistemas supramoleculares.
Principales métodos:
- Las titulaciones de desnaturalización utilizando un ligando monodentado (quinuclidina).
- Análisis de perfiles complejos de especiación durante la desnaturalización.
- Cálculo de las molaridades efectivas por etapas (EM) para eventos de coordinación intramolecular.
Principales resultados:
- Los hexámeres cíclicos de zinc-porfirina muestran molaridades efectivas escalonadas excepcionalmente altas (EM = 10^210^3 M) para la coordinación intramolecular.
- Los oligómeros lineales de porfirina exhiben modestas molaridades efectivas (EM ≈ 0,05 M).
- Los equilibrios de desnaturalización siguen un modelo cooperativo de dos estados con un mínimo de especies intermedias.
Conclusiones:
- Las arquitecturas cíclicas de porfirina mejoran dramáticamente la estabilidad de la coordinación intramolecular en comparación con las lineales.
- Los altos EM en los sistemas cíclicos se atribuyen a la preorganización y a factores entrópicos favorables.
- Estos hallazgos proporcionan información sobre los principios de diseño para ensamblajes supramoleculares estables.
Más Videos Relacionados
08:25Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)
Published on: January 17, 2020
10:27Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides
Published on: July 14, 2015
Videos de Conceptos Relacionados
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...
01:23Complexation Equilibria: Overview
Complexation reactions take place when dative or coordinate covalent bonds form between metal ions and ligands. The compounds formed in these reactions are called coordination compounds. The number of bonds formed between the metal ion and the ligands is called its coordination number. Generally, most metal ions in an aqueous solution are solvated by water molecules and thus exist as aqua complexes.
The equilibrium constant of the complexation reaction is represented as the formation constant...
The equilibrium constant of the complexation reaction is represented as the formation constant...
00:56Extraction: Advanced Methods
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is formed in...
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
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...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...