Video Experimental Relacionado
Updated: Jul 12, 2026
11:33
All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
El mapeo del efecto isotópico de la ionización de la glucosa demuestra un compartimiento de carga inusual
Brett E Lewis1, Vern L Schramm
1The Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Journal of the American Chemical Society
|June 26, 2003
Resumen
La sustitución de tritio reveló diferencias sutiles en la acidez de la glucosa (pK ((a)) a un pH alto. Se observaron efectos isotópicos, particularmente en H1 y H4, lo que sugiere un compartimiento único de carga en los aniones acuosos de glucosa.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Química Física es la química física.
- Química de los Isótopos Química de los Isótopos
Sus antecedentes:
- La sustitución isotópica influye en las velocidades y los equilibrios de las reacciones químicas.
- Comprender la ionización de la glucosa es crucial para los procesos bioquímicos.
Objetivo del estudio:
- Para investigar el equilibrio de glucosa (glucosa (((-) + H (((+)) utilizando la sustitución de tritio.
- Para detectar diferencias sutiles en la pK (a) de la glucosa bajo condiciones de alto pH.
Principales métodos:
- Utilizado tritio ((3) H) y carbono-14 ((14) C) etiquetado con glucosa.
- Se empleó cromatografía de intercambio aniónico a pH alto (11.7).
- Se analizó la titulación de la base y los cambios en el desplazamiento químico (13) C.
- Se realizaron cálculos de efecto isotópico ab initio en aniones de glucosa en fase gaseosa.
Principales resultados:
- Se observó que la (3) H-glucosa se eluye antes que la (14) C-glucosa a un pH de 11.7.
- Se han reportado efectos isotópicos significativos para la sustitución de tritio en varias posiciones de glucosa (H1, H2, H3, H4, H5, H6,6).
- Se encontraron efectos de isótopos elevados en H1 y H4, lo que indica una distribución inusual de la carga en la glucosa acuosa aniónica.
Conclusiones:
- El pH alto favorece las formas piranosas de glucosa en solución acuosa.
- Los efectos isotópicos proporcionan información sobre la estructura electrónica y la distribución de la carga de los aniones de glucosa.
Videos de Conceptos Relacionados
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as annulenes. In...
01:13¹H NMR Signal Multiplicity: Splitting Patterns
When protons A and X are coupled, their nuclear spin energy levels are slightly modified. This is because the energy required to excite proton A to a spin state parallel to proton X is slightly different from the energy required for it to become anti-parallel to spin X. Consequently, there are two possible excitation frequencies for A (A1 and A2), depending on the spin state of X, and vice versa. The mutual nature of coupling implies that the difference between frequencies A1 and A2, indicated...
01:19Thomson's e/m Experiment
In a beam of charged particles created by a heated cathode, the particles move at different speeds. However, many applications need a beam with uniform particle speeds. An arrangement known as a velocity selector uses electric and magnetic fields to pick particles with a particular speed from the beam.
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
01:24Electrochemical Systems
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution, the Zn metal, composed...
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...